GI Flashcards

Question

What is acute blockage of the small intestine?

Answer 1

Present with Pain (in their back), vomiting and bloating

Answer 2

Vascular structures in the anal canal that aid with stool control. When they become swollen and inflamed they are painful, itchy and blood may be present in stool.

Answer 3

Literally means ‘to fall out of place’. Prolapse is a condition where organs fall down or slip out of place. E.g. the rectum can prolapse.

Answer 4

Pressure is too high in the colon, producing an abnormal ‘outpouching’ to form a hollow. The sigmoid colon is the area most prone as the blood supply causes an area of weakness (?)

Answer 5

A pouch in the lower part of the small intestine, a vestigial remnant of the yolk sac. It can produce ectopic gastric mucosa that may then produce gastric acid, causing irritation.

Answer 6

The large intestine is a common site of malignancies, and colo-rectal cancer is a major cause of mortality.

Answer 7

The mouth is the entrance to the GI tract. It serves to disrupt foodstuffs and mix them with saliva to form boluses to be swallowed.

Answer 8

The teeth cut (incisors), crush (molars) and mix food with saliva.

Answer 9

The powerful muscles of mastication, the Masseter, generate the force behind teeth. A branch of the trigeminal nerve innervates the Masseter. .

Answer 10

The tongue is a collection of 8 muscles that work to manipulate food for mastication and form it into a bolus. It also aids in swallowing by pushing the bolus to the back of the mouth

Answer 11

The oropharynx lies behind the oral cavity, and forms the portion of the pharynx below the nasopharynx but above the laryngopharynx. It extends from the uvula, which is the end of the palate, to the level of the hyoid bone/ epiglottis Because both food and air pass through the oropharynx, a flap of tissue called the epiglottis closes over the glottis to prevent aspiration.

Answer 12

The oesophagus is a muscular tube that passes food from the pharynx to the stomach. It is continuous with the lower part of the laryngopharynx.

Answer 13

The oesophagus has several layers, from inside to out: o Mucosa composed of non-keratinized stratified squamous epithelium, lamina propria and a layer of smooth muscle (Muscularis Mucosa) o Submucosa containing the mucous secreting glands o Mucularis externa. Upper third of oesophagus is striated, skeletal muscle under conscious control for swallowing. The lower two thirds are smooth muscle under autonomic control (peristalsis).

Answer 14

1.5 litres of saliva is produced each day.

Answer 15

``` It has several functions: 1. Lubricates and wets food 2. Starts the digestion of carbohydrates (Amylase) 3. Protects oral environment o Keeps mucosa moist o Washes teeth o Maintains alkaline environment • Neutralises acid produced by bacteria o High Ca2+ concentration ```

Answer 16

Insufficient Saliva production. You are still able to eat provided food is moist, but teeth and mucosa degrade very quickly.

Answer 17

o Water • Hypotonic solution o Electrolytes • Na+, Cl-, usually at a lower concentration than plasma • Ca2+, K+, I- (iodide) usually at a higher concentration than plasma o Alkali • HCO3- at a higher concentration than plasma o Bacteriostats o Mucus - (Mixture of mucopolysaccharides) o Enzymes - Salivary amylase (can live without it, relatively minor)

Answer 18

There are three paired salivary glands. They are all ducted, exocrine glands, but do not all excrete the same thing. Exocrine glands are made up of blind-ended tubes (Acini), lined with acinar cells. The acini are connected via a system of ducts to a single outlet, lined by duct cells. Acinar cells and duct cells have different functions. o Parotid Glands • Watery secretion, rich in enzymes but little mucus • Serous saliva • 25% of volume secreted o Sub-lingual glands • Viscous secretion, no enzymes but lots of mucus • Mucus saliva • 5% of volume secreted o Sub-maxillary glands • All components of saliva (mixed serous and mucus) • Mixture of serous and mucus acini leading to a common duct • 70% of volume secreted

Answer 19

Saliva is a hypotonic solution, but there is no cellular mechanism to secrete water. Therefore more concentrated solution is secreted, and solute is then reabsorbed from it to leave the final hypotonic solution. Acinar Cells secrete an isotonic fluid containing enzymes. Duct Cells then remove Na+ and Cl- and add HCO3-. The gaps between duct cells are tight, so water does not follow the resulting osmotic gradient and so saliva remains hypotonic.

Answer 20

At a low flow rate, the duct cells have the opportunity to remove most Na+, so saliva is very hypotonic.

Answer 21

The rate at which duct cells can modify saliva is limited, so at a high flow rate a smaller fraction is removed and the saliva becomes less hypotonic. However, the stimulus for secretion promotes HCO3- secretion, so saliva becomes more alkaline. (At a high flow rate)

Answer 22

Cl- ions are actively secreted from Acinar cells into the lumen of the duct. Water and other ions (Na+) will then follow passively.

Answer 23

The action of the Na/K-ATPase Antiporter in the Basolateral membrane of duct cells lowers the [Na+] inside the cell. This means there is a concentration gradient, where [Na+] is high in the duct lumen and low in the duct cells. Na+ diffuses passively back into the Duct cells. The action of the Na/K-ATPase Antiporter also increases the [K+] concentration in side the cell. The resulting concentration gradient drives the expulsion of Cl- from the duct cells into the ECF. Again, a concentration gradient is set up between the duct lumen and cells, with [Cl-] low inside and [Cl-] high outside. This gradient drives the expulsion of HCO3- into the duct lumen.

Answer 24

Salivary secretion is mostly controlled by the autonomic nervous system. Parasympathetic Parasympathetic stimulation increases the production of primary secretion (Acinar cells) and increases the addition of HCO3- (Duct cells) o Parotid Gland • Glossopharyngeal Nerve (9th cranial nerve) • Otic ganglion o Submandibular and Sublingual Glands • Facial Nerve (7th cranial nerve) • Submandibular ganglion o Muscarinic receptors • Blocked by atropine like drugs o Co-transmitters stimulate extra blood flow ``` Outflow is mediated by: o From centres in the medulla o Afferent information from: • Mouth and tongue o Taste receptors, especially acid • Nose • Conditioned reflexes o Pavlov’s dogs ``` Sympathetic Sympathetic stimulation reduces the blood flow to the salivary glands, limiting salivary flow and producing the typical dry mouth of anxiety. o Superior cervical ganglion The rate of ductal recovery of Na+ is also increased by the release of aldosterone from the adrenal cortex. ( high ENaC, high Na/K/ATPase), making saliva even more hypotonic.

Answer 25

Once food has been masticated and mixed with saliva to form a bolus, it must be swallowed. Swallowing is in three phases: 1. Voluntary Phase 2. Pharyngeal Phase 3. Oesophageal Phase

Answer 26

o Tongue moves the bolus back onto the pharynx

Answer 27

o Afferent information from pressure receptors in the palate and anterior pharynx reaches the swallowing centre in the brain stem. o A set of movements is triggered • Inhibition of breathing • Raising of the larynx • Closure of the glottis • Opening of the upper oesophageal ‘sphincter’

Answer 28

o The muscle in the upper third of the oesophagus is voluntary striated muscle under somatic control o The muscle of the lower two thirds is smooth muscle under control of the parasympathetic nervous system. o A wave of peristalsis sweeps down the oesophagus, propelling the bolus to the stomach in ~9 seconds. o Coordinated by extrinsic nerves from the swallowing centre of the brain o Lower oesophageal ‘sphincter’ opens

Answer 29

Dysphagia – The symptom of difficulty in swallowing

Answer 30

Dysphagia may result as a consequence of a primary oesophageal disorder, for example motility problems of the smooth muscle preventing peristalsis. The name for this condition is achalasia. Dysphagia may also result as a secondary consequence of another issue, E.g. obstruction or compression of the oesophagus due to a tumour.

Answer 31

Odynophagia – The symptom of pain whilst swallowing

Answer 32

o Dysphagia for Solids | • Investigate with a barium swallow/endoscopy

Answer 33

o Dysphagia for liquids • Investigate with a flexible endoscopy evaluation of swallowing. This will allow you to view the entire trachea/oesophagus. • Most commonly due to a stroke

Answer 34

The stomach produces strong acids (HCl) and enzymes (pepsin) to aid in the digestion of food. The mucosa of the stomach provides protection from it’s harmful content, but the mucosa of the oesophagus does not have this protection. The oesophagus is protected from these acids by a one way valve mechanism at it’s junction with the stomach. This one way valve is called the lower oesophageal sphincter. This coupled with the angle of His that is formed at this point prevents the contents of the stomach refluxing back into the oesophagus. The crus of the diaphragm helps with the sphincteric action.

Answer 35

Barrett's oesophagus | Gastro-oesophageal Reflux Disease (GORD)

Answer 36

An abnormal change of the epithelial cells of the oesophagus. This is a metaplasia from non-keratinised stratified squamous epithelia to columnar epithelium and goblet cells. This is in an attempt to better resist the harmful contents of the stomach. Barrett’s oesophagus is strongly associated with adenocarcinoma, a particularly lethal cancer.

Answer 37

The reflux of the stomach’s contents into the oesophagus and pharynx causes several symptoms, including a cough, hoarseness and asthma. All of the symptoms result from the acidic contents of the stomach refluxing back out.

Answer 38

Although it is continuous, the abdominal wall is subdivided into the anterior wall, right and left lateral walls and the posterior wall. The boundary between the anterior and the lateral walls is indefinite; therefore the term anterolateral abdominal wall is used. The anterolateral abdominal wall is bounded superiorly by the cartilages of the 7th-10th ribs, and the xiphoid process of the sternum, and inferiorly by the inguinal ligament and the superior margins of the anterolateral aspects of the pelvic girdle (iliac crests, pubic crests and pubic symphysis).

Answer 39

The anterolateral abdominal wall consists of skin, subcutaneous tissue (superficial fascia/fat), muscles and their aponeuroses, deep fascia, extraperitoneal fat and parietal peritoneum.

Answer 40

``` Umbilicus Epigastric Fossa (Pit of the stomach) Linea Alba Pubic Crest and Symphysis Inguinal Groove Semilunar lines Tendinous Intersections of Rectus Abdominis Arcuate Line (aka Douglas’ line) ```

Answer 41

Obvious feature of the anterolateral abdominal wall at Spinal Level L3

Answer 42

Slight depression in the epigastric region, just inferior to the xiphoid process. Particularly noticeable when a person is in the supine position because the abdominal organs spread out. Heartburn is commonly felt at this site.

Answer 43

Aponeuroses of abdominal muscles, separating the left and right rectus abdominis. Visible in lean individuals because of the vertical skin groove superficial to it. If the linea alba is lax, when the rectus abdominis contract the muscles spread apart. This is called divarication of recti.

Answer 44

The upper margins of the pubic bones and the cartilaginous joint that unite them. Can be felt at the inferior end of the linea alba.

Answer 45

A skin crease that is parallel and just inferior to the inguinal ligament (runs between ASIS and pubic tubercle). Marks the division between the abdominal wall and the thigh.

Answer 46

Slightly curved, Tendinous line on either side of the rectus abdominis.

Answer 47

Clearly visible in persons with well-developed rectus muscles. The interdigitating bellies of the serratus anterior and external oblique muscles are also visible.

Answer 48

Where the fibrous sheath stops (inferior limit of the posterior layer of the rectus sheath). 1/3 of the way from the umbilicus to the pubic crest.

Answer 49

There are five (bilaterally paired) muscles in the anterolateral abdominal wall, three flat muscles and two vertical muscles. Flat Muscles – External Oblique, Internal Oblique and Transversus Abdominis Vertical Muscles – Rectus Abdominis and Pyramidalis The three flat muscles’ fibres have varying orientations, with the fibres of the Obliques running diagonally and perpendicular to each other, and the fibres of the Transversus running transversely. All three flat muscles are continued anteriorly and medially as strong, sheet-like aponeuroses. Between the mid-clavicular line and the midline, the aponeuroses form the tough, aponeurotic, tendinous rectus sheath that encloses the Rectus Abdominis. The aponeuroses then interweave with their fellows of the opposite side, forming the linea alba, which extends from the xiphoid process to the pubic symphysis. The interweaving is not only between right and left sides, but also between intermediate and deep layers. The two vertical muscles of the anterolateral abdominal wall are contained within the rectus sheath, the large Rectus Abdominis and small Pyramidalis.

Answer 50

When designing an incision, we want one that we can close and provide long-lasting strength, thus minimising the incidence of incisional herniae. If we try to sew muscle together, the sutures will ‘cut out’.

Answer 51

Surgeons suture the linea alba together to provide a strong closure.

Answer 52

Surgeons suture the external oblique aponeuroses together to provide a strong closure

Answer 53

o Incision at McBurney’s point o 2/3rds of the distance between the umbilicus and ASIS o Through a ‘gridiron’ muscle-splitting incision

Answer 54

Put scissors in and open and close them to separate out the muscle fibres, followed by the next two layers. Have to separate out the fibres of the external and internal oblique’s and the transversalis.

Answer 55

Can present at birth or in later life in men when they develop bladder outflow obstruction due to benign prostatic hypertrophy.

Answer 56

Vitelline Duct – omphalomesenteric duct- attaches the yolk sac (via the umbilicus) to the midgut lumen of the developing foetus Can persist resulting in a number of different abnormalities- Meckel's diverticulum in particular

Answer 57

``` Also known as Ilieal Diverticulum, and is the most common GI abnormality. It is a ‘cul-de-sac’ in the ileum. Meckel’s Diverticulum follows a Rule of 2’s: o 2% of the population affected o 2 feet from the ileocecal valve o 2 inches long o Usually detected in under 2’s • Can be asymptomatic o 2:1 Male:Female The diverticulum can contain ectopic gastric or pancreatic tissue. The ectopic tissue will secrete enzymes and acids into tissue not protected from them, causing ulceration. The reason for this is not clear. ```

Answer 58

The vitelline duct forms fibrous strands at either end.

Answer 59

There is direct communication between the umbilicus and the intestinal tract. This results in faecal matter coming out of the umbilicus

Answer 60

Omphalocoele is the persistence of physiological herniation. A part of the gut tube fails to return to the abdominal cavity following its normal herniation into the umbilical cord. Since the umbilical cord is covered by a reflection of the amnion, this epithelial layer covers the defect. Compare but DO NOT CONFUSE WITH umbilical hernia.

Answer 61

Gastroschisis is the failure of closure of the abdominal wall during folding of the embryo, leaving the gut tube and its derivatives outside the body cavity. There is no covering over the gut tube/derivatives as they herniate through the abdominal wall directly into the amniotic cavity.

Answer 62

Pain caused by a noxious stimulus to the proximal part of a somatic nerve that is perceived in the distal dermatome of the nerve. E.g. Shingles affects nerves; pain is felt distally along the nerves from the problem. Source - tissues such as skin, muscle, joints, bones, and ligaments - often known as musculo-skeletal pain. Receptors activated - specific receptors (nociceptors) for heat, cold, vibration, stretch (muscles), inflammation (e.g. cuts and sprains which cause tissue disruption), and oxygen starvation (ischaemic muscle cramps). Characteristics - often sharp and well localised, and can often be reproduced by touching or moving the area or tissue involved.

Answer 63

In the thorax and abdomen, visceral afferent pain fibres follow sympathetic fibres back to the same spinal cord segments that gave rise to the preganglionic sympathetic fibres. The CNS perceives visceral pain as coming from the somatic portion of the body supplied by the relevant spinal cord segments. Visceral pain is caused by ischaemia, abnormally strong muscle contraction, inflammation and stretch. Touch, burning, cutting and crushing does not cause visceral pain. Source - internal organs of the main body cavities. There are three main cavities - thorax (heart and lungs), abdomen (liver, kidneys, spleen and bowels), pelvis (bladder, womb, and ovaries). Receptors activated - specific receptors (nociceptors) for stretch, inflammation, and oxygen starvation (ischaemia). Characteristics - often poorly localised, and may feel like a vague deep ache, sometimes being cramping or colicky in nature. It frequently produces referred pain to the back, with pelvic pain referring pain to the lower back, abdominal pain referring pain to the mid-back, and thoracic pain referring pain to the upper back.

Answer 64

Foregut Pain – Epigastric region Midgut pain – Periumbilical region Hindgut Pain – Suprapubic region

Answer 65

Retroperitoneal structures can cause central back pain, e.g. pancreas and abdominal aorta.

Answer 66

In early appendicitis the pain begins at the umbilicus, since the innervation of the appendix enters the spine at that Level (T10). Later, as the appendix becomes more inflamed it irritates the surrounding bowel wall, localising the pain to the right lower quadrant (irritation to somatic nerve).

Answer 67

Doubled over in pain. Small bowel colic Periumbilical (midgut) Large bowel colic Suprapubic (hindgut)

Answer 68

Patient rolls around on the floor. Pain is “worse than child birth”.

Answer 69

o Ruptured spleen o Ectopic Pregnancy o Perforated ulcer Blood pools in pelvis, giving pain. The patient feels faint due to the loss of blood, so lies down causing the blood to rush up to the diaphragm (C3/4/5). The presence of blood here results in referred pain to the left shoulder (Liver is in the way of the blood at the right diaphragm).

Answer 70

The peritoneal cavity is a potential space of capillary thinness between the parietal and visceral layers of peritoneum. It contains no organs, but contains a thin film of peritoneal fluid. Lymphatic vessels, particularly on the interior surface of the diaphragm absorb the peritoneal fluid.

Answer 71

In males the peritoneal cavity is completely closed, but in females there is a communication pathway to the exterior of the body through the uterine tubes, cavity and vagina. The communication constitutes a potential pathway of infection from the exterior.

Answer 72

The peritoneum is a continuous, two layered membrane - the parietal peritoneum, which lines the internal surface of the abdominal wall and the visceral peritoneum, which invests viscera such as the stomach and intestines. Both layers of the peritoneum consist of mesothelium, a layer of simple squamous epithelial cells.

Answer 73

The parietal peritoneum is served by the same blood, lymphatic and somatic nerve supply as the region of the wall it lines. Therefore, like the overlying skin, the interior of the body wall is sensitive to pressure, pain, heat and cold and laceration. Pain is generally well localised, apart from on the inferior surface of the central part of the diaphragm, which is innervated by the phrenic nerve (C3/4/5, referred pain to shoulder). This explains why the pain from appendicitis shifts to over the appendix, as the parietal peritoneum becomes inflamed, localising the pain.

Answer 74

The visceral peritoneum shares the same blood, lymphatic and visceral nerve supply as the organs it covers. Also, like the organs it covers the visceral peritoneum is insensitive to touch, heat and cold and laceration; it is stimulated primarily by stretching and chemical irritation. The pain produced is poorly localised, being referred to the dermatomes of the spinal ganglia providing the sensory fibres.

Answer 75

A mesentery is a double layer of peritoneum that occurs as a result of the invagination of the peritoneum by an organ and constitutes a continuity of the visceral and parietal peritoneum. A mesentery connects an intraperitoneal organ to the body wall (usually the posterior abdominal wall)

Answer 76

An omentum is a double-layered extension or fold of peritoneum that passes from the stomach and proximal part of the duodenum to adjacent organs in the abdominal cavity

Answer 77

A prominent, four-layered peritoneal fold that hands down like an apron from the greater curve of the stomach. After descending it folds back and attaches to the anterior surface of the transverse colon and its mesentery.

Answer 78

A much smaller, double-layered peritoneal fold that connects the lesser curvature of the stomach and the proximal part of the duodenum to the liver. It also connects the stomach to the portal triad.

Answer 79

A double layer of peritoneum that connects an organ with another organ or to the abdominal wall

Answer 80

Peritoneal Ligaments Connect the Liver to: o Anterior abdominal wall – Falciform Ligament o Stomach – Hepatogastric Ligament (membranous portion of lesser omentum) o Duodenum – Hepatoduodenal Ligament (the thickened free edge of the lesser omentum, which conducts the portal triad – portal vein, hepatic artery, bile duct)

Answer 81

Peritoneal Ligaments Connect the Stomach to: o Inferior surface of the diaphragm – Gastrophrenic Ligament o Spleen – Gastrosplenic ligament o Transverse colon – Gastrocolic ligament (greater omentum)

Answer 82

o Intraperitoneal are completely covered by peritoneum, however not completely enclosed due to the mesentery (think of the concept of a fist in the balloon). o Retroperitoneal / extraperitoneal are outside the peritoneal cavity and thus are only partially covered by the parietal peritoneum, for example the kidneys lie between parietal peritoneum (only found on the anterior surface) and the posterior abdominal wall. • Kidneys, ureters, and the bladder • The aorta and the IVC, • The oesophagus • The duodenum (except for the proximal part) • Most of the pancreas, • The ascending and descending colon, and the rectum.

Answer 83

The abdomen is divided by the midclavicular lines vertically and the subcoastal and transtubercular lines horizontally. Right hypochondriac, epigastric, left hypochondriac Right lumbar, umbilical, left lumbar Right iliac, suprapubic, left iliac

Answer 84

The Transverse Mesocolon (mesentery of the transverse colon) divides the abdominal cavity into a Supracolic Compartment, containing the stomach, liver, and spleen, and an Infracolic Compartment, containing the small intestine and ascending and descending colon. The Infracolic Compartment lies posterior to the greater omentum and is divided into the right and left Infracolic spaces by the mesentery of the small intestine.

Answer 85

Free communication occurs between the Supracolic and the Infracolic compartments through the Paracolic Gutters, the groves between the lateral aspect of the ascending or descending colon and the posterolateral abdominal wall.

Answer 86

The Greater Sac is made up of the Supracolic and Infracolic compartments

Answer 87

The Lesser Sac, or Omental bursa, is an extensive sac-like cavity that lies posterior to the stomach, lesser omentum, and adjacent structures. It has a superior recess, limited superiorly by the diaphragm and the posterior layers of the coronary ligament of the liver, and an inferior recess between the superior parts of the layers of the greater omentum. Most of the inferior recess becomes sealed off from the main part (posterior to the stomach) after adhesion of the anterior and posterior layers of the greater omentum. The Lesser Sac/Omental bursa permits free movement of the stomach on the structures posterior and inferior to it because it’s anterior and posterior walls slide smoothly over one another.

Answer 88

The Greater and Lesser (omental bursa) Sacs communicate through the omental foramen (epiploic foramen), an opening situated posterior to the free edge of the less omentum (hepatoduodenal ligament – see above). The omental foramen can located by running a finger along the gall bladder to free the edge of the lesser omentum, and usually admits two fingers.

Answer 89

The Right Subphrenic Space lies between the diaphragm and the anterior, superior and right lateral surfaces of the right lobe of the liver. It is bounded on the left side by the falciform ligament and behind by the upper layer of the coronary ligament. It is a relatively common site for collections of fluid after right-sided abdominal inflammation.

Answer 90

The Left Subphrenic Space lies between the diaphragm, the anterior and superior surfaces of the left lobe of the liver, the anterosuperior surface of the stomach and the diaphragmatic surface of the spleen. It is bounded to the right by the falciform ligament and behind by the anterior layer of the left triangular ligament. It is much enlarged in the absence of the spleen and is a common site for fluid collection, particularly after a splenectomy.

Answer 91

The left Subphrenic space is substantially larger than the right (liver is on the right).

Answer 92

In females the peritoneum passes from the rectum to the posterior vaginal fornix and then back to the uterine cervix and body as the recto-uterine fold, which descends to form the recto-uterine pouch (of Douglas). The peritoneum spreads over the uterine fundus to its anterior surface as far as the junction of the body and cervix, from which it is reflected forwards to the upper surface of the bladder, forming a shallow Vesico-uterine pouch.

Answer 93

In males the peritoneum leaves the junction of the middle and lower thirds of the rectum, passing forwards to the upper poles of the seminal vesicles and superior aspect of the bladder. Between the rectum and bladder it forms the rectovesical pouch.

Answer 94

A broad, fan shaped fold, connecting the coils of the jejunum and ileum to the posterior abdominal wall. Between the two sheets of peritoneum are blood vessels, lymph vessels are nerves. This allows these part of the intestine to move relatively freely within the abdominal cavity. The attached, parietal border is the root of the mesentery about 15 cm from the duodenojejunal flexture at the level of left side L2, obliquely (towards inferior right) to the ileocaecal junction. The root of the mesentery crosses the second and third parts of the duodenum, abdominal aorta, inferior vena cava, right ureter, right psoas major muscle and right gonadal artery.

Answer 95

This is a peritoneal fold attaching the sigmoid colon to the pelvic wall, the attachment being an inverted V with an apex near the division of the left common iliac artery. The left limb descends medial to the left psoas major and the right passes into the pelvis to end in the midline at the level of the third sacral vertebra. Sigmoid and superior rectal vessels run between its layers and the left ureter descends into the pelvis behind its apex.

Answer 96

Inguinal Femoral Umbilical Epigastric

Answer 97

The inguinal canal is an oblique passage that extends in a downward and medial direction. It begins at the deep (internal) inguinal ring and continues for approximately 4cm, ending at the superficial (external) inguinal ring. The canal lies in between the muscles of the anterior abdominal wall and runs parallel and superior to the medial half of the inguinal ligament (the inguinal ligament is the inferior border of the aponeurosis of the external oblique muscle, attached between the ASIS and the pubic tubercle). The spermatic cord in men and the round ligament of the uterus in women passes through the canal. Additionally, in both sexes the ilioinguinal nerve passes through part of the canal.

Answer 98

An inguinal hernia is a protrusion of the abdominal cavity contents through the inguinal canal. They are very common (Lifetime risk 27% for men, 3% for women).

Answer 99

Protrudes into the inguinal canal through a weakened area in the transversalis fascia near the medial inguinal fossa within an anatomical region known as the Inguinal / Hesselbach’s triangle.

Answer 100

Protrudes through the deep inguinal ring, within the diverging arms of the transversalis fascial sling. Most indirect inguinal hernias are the result of the failure of embryonic closure of the deep inguinal ring after the testicle has passed through it.

Answer 101

Epigastric Hernias occur in the epigastric region, in the midline between the xiphoid process and the umbilicus, through the linea alba. The primary risk factors are obesity and pregnancy.

Answer 102

Umbilical Hernias occur through the umbilical ring. They are usually small and result from increased intra-abdominal pressure in the presence of weakness and incomplete closure of the anterior abdominal wall after ligation of the umbilical cord at birth. Acquired umbilical hernias occur in adults, most commonly in women and obese people.

Answer 103

Femoral Hernias are a protrusion of abdominal viscera into the femoral canal, occurring through the femoral ring.

Answer 104

A protrusion of the abdominal cavity contents through the umbilical ring

Answer 105

A protrusion of the abdominal cavity contents in the midline between the xiphoid process and the umbilicus- through the linea alba

Answer 106

Femoral Hernias are a protrusion of abdominal viscera into the femoral canal, occurring through the femoral ring. A femoral hernia appears as a mass, often tender, in the femoral triangle. Femoral Hernias are bounded by the femoral vein laterally and the lacunar ligament medially. The hernia compresses the contents of the femoral canal (loose connective tissue, fat and lymphatics) and distends the wall of the canal. Initially femoral hernias are small, as they are contained within the canal, but they can enlarge by passing inferiorly through the saphenous opening into the subcutaneous tissue of the thigh. Femoral Hernias are more common in females as they have wider pelves. Strangulation of femoral hernias may occur because of the sharp, rigid boundaries of the femoral ring.

Answer 107

The constriction of blood vessels, preventing the flow of blood to tissue

Answer 108

Hernia cannot be reduced, or pushed back into place, at least not without very much external effort.

Answer 109

``` Glossopharangeal nerve (CN9) Otic ganglion ```

Answer 110

``` Facial nerve (CN7) Submandibular ganglion (submaxillary) ```

Answer 111

Superior cervical ganglion

Answer 112

Aldosterone Increases activity of ENaC and Na/K ATPase Makes saliva very very hypotonic

Answer 113

Muscular tube connecting pharynx to the stomach About 8 inches long Lined by mucosa- non keratinised stratified squamous Runs posteriorly to trachea and heart Runs anteriorly to spine Just before entering the stomach it passes through the diaphragm Upper 1/3 - voluntary striated muscle Lower 2/3 - smooth muscle under control of PSNS

Answer 114

Carries food, liquids, and saliva (bolus) from mouth to stomach

Answer 115

The borders of Hesselbach’s triangle are: o Inferiorly – Medial half of the inguinal ligament o Medially – Lower lateral border of rectus abdominis o Laterally – Inferior epigastric artery

Answer 116

Normally has 3 constrictions where adjacent structures produce impressions - cervical constriction (upper oesophageal spinchter) - at its beginning at the pharyngo-oesophageal junction; approx. 15cm from incisor teeth; caused by cricopharyngeus muscle - thoracic (broncho-aortic) constriction- compound constriction where it is first crossed by the arch of the aorta 22.5cm from incisor teeth, and then where it is crossed by the left main bronchus 27.5cm from the incisor teeth - diaphragmatic constriction- where it passes through oesophageal hiatus of diaphragm, approx. 40cm from incisor teeth

Answer 117

Has internal circular and external longitudinal layers of muscle Superior 1/3 - voluntary striated muscle Middle 1/3 - both Inferior 1/3 - smooth muscle

Answer 118

Passes through elliptical oesophageal hiatus in the muscular right crus of the diaphragm, just to the left of the median plane at level of T10 vertebra

Answer 119

Terminates by entering the stomach at the cardial orifice of the stomach to the left of the midline at the level of the 7th left costal cartilage and T11 vertebra

Answer 120

Oesophageal (nerve) plexus

Answer 121

Food passes through rapidly because of the peristaltic action if it's musculature aided but not dependent on gravity

Answer 122

Oesophagus attached to margins of oesophageal hiatus in the diaphragm by the phrenico- oesophageal ligament - extension of inferior diaphragmatic fascia Permits independent movement of the diaphragm and oesophagus during respiration and swallowing

Answer 123

Abdominal part of the oesophagus only 1.25cm long passes from oesophageal hiatus pin the right crus of the diaphragm to the cardial orifice of the stomach, widening as it approaches, passing anteriorly and to the left as it descends inferiorly

Answer 124

Anterior surface covered with peritoneum of the greater sac, continuous with that covering the anterior surface of the stomach Posterior part of abdominal part of oesophagus is covered with peritoneum of the omental bursa, continuous with that covering the posterior surface of the stomach

Answer 125

Right border- Continuous with the lesser curvature of the stomach Left border- separated from fundus of stomach by cardiac notch between oesophagus and fundus

Answer 126

Fits into a groove on the posterior surface of the liver

Answer 127

Abdominal oesophagus- left gastric artery, (branch of coeliac trunk) and left phrenic artery

Answer 128

Submucosal veins - portal venous sytem via left gastric veins Submucosa veins - systemic venous system via the oesophageal veins entering the azygous system

Answer 129

Of abdominal part is to left gastric lymph nodes - efferent lymphatic vessels from these nodes drain mainly to celiac lymph nodes

Answer 130

Stores food Disinfects food Breaks food down into chyme- chemical disruption (acid and enzymes) and physical disruption (motility)

Answer 131

From gastric pits (contain neck cells) -indentations in stomach mucosa that are openings to gastric glands (contain parietal, chief and G cells (& smooth muscle cells))

Answer 132

Parietal cells | Acid keeps the pH<2

Answer 133

Chief cells | Non specifically breaks down proteins - > peptides

Answer 134

Neck cells | Sticky so that it's not easily removed from the stomach lining and basic, due to amine group on the proteins

Answer 135

Neck cells | Secreted by neck cells into the mucus and provide a buffer for H+ ions

Answer 136

Binds to surface receptor on the parietal cell stimulating acid and intrinsic factor (B12- anaemia)

Answer 137

In mitochondria of parietal cells, water is split into H+ and OH- ions- generating lots of H+ ions Generated OH- ions combine with CO2 fro metabolism to form HCO3- which is exported to the blood (for every mole of H+ secreted into the stomach, 1 mole of HCO3- enters the blood) H+ produced at a fast rate as parietal cells have lots of mitochondria - but can't be allowed to accumulate in the cells Parietal cells have canaliculi (invaginations of the cell wall) which have proton pumps - expel H+ against a high concentration gradient As concentration gradient is very high, it's a very energy intensive process

Answer 138

Gastrin Histamine Acetyl chlorine

Answer 139

Peptides | Acetyl choline from intrinsic neurones - after they have detected distension (ACh also acts directly in parietal cells)

Answer 140

Hormone is secreted by G cells in stomach Polypeptide, main form is 17AAs long Binds to surface receptor on parietal cell Stimulates acid and intrinsic factor secretion via second messenger pathway

Answer 141

Low pH in stomach - negative feedback

Answer 142

Gastrin and ACh stimulate mast cells to secrete histamine

Answer 143

Released from mast cells Binds to H2 surface receptors on parietal cells, locally Acid secretion stimulated via c-amp Works as an amplifier

Answer 144

Released from postganglionic parasympathetic neurones Acts on muscarinic receptor in the parietal cell Stimulates acid secretion by second messenger pathway

Answer 145

Distension

Answer 146

Cephalic phase Gastric phase Intestinal phase

Answer 147

The ‘brain led’ phase. The sight and smell of food, and the act of swallowing, activates the parasympathetic nervous system, which stimulates the release of Ach. This stimulates parietal cells directly and via histamine (increases Acid).

Answer 148

Once food reaches the stomach, it causes distension, further stimulating Ach release, and subsequently parietal cells (increases Acid). The arrival of food will also buffer the small amount of stomach acid in the stomach in between meals, causing luminal pH to rise. This disinhibits Gastrin (increases Acid). Acid and enzymes will then act on proteins to produce peptides, further stimulating Gastrin release as the pH falls and the initial disinhibition is removed (increases Acid).

Answer 149

Once chyme leaves the stomach in significant quantities, it stimulates the release of the hormones Cholecystokinin and Gastric Inhibitory Polypeptide from the intestines that antagonise Gastrin (decreases Acid). Coupled with this, the small amount of acid left in the stomach is no longer being buffered by food, and the low pH inhibits Gastrin (decreases Acid).

Answer 150

Acid secretion may be reduced by inhibition of: o Histamine at H2 Receptors E.g. Cimetidine Removes the amplification of Gastrin/Ach signal o Proton Pump Inhibitors (PPIs) E.g. Omeprazole Prevents H+ ions being pumped into parietal cell canaliculi o also treat ulcers by eliminTing H pylori with antibiotics

Answer 151

The luminal pH of the stomach is usually below 2. Without any protection, this would dissolve mucosa. Neck cells secrete mucus to protect the mucosa. Mucus is Sticky, so is not easily removed from the stomach lining. It is also Basic, due to Amine groups on the proteins. The mucus forms a ‘unstirred layer’ that ions cannot move through easily. H+ ions slowly diffuse in and react with the basic groups on mucus and with HCO3- that is secreted by surface epithelial cells. Because of the unstirred layer, HCO3- stays close to the surface cells. This means the pH at the surface cells is well above 6. Mucus and HCO3- secretion from neck cells and surface cells respectively is stimulated by prostaglandins, which are promoted by most factors that stimulate acid secretion.

Answer 152

o Alcohol • Dissolves the mucus, allowing the acid to attack the stomach o H. Pylori • Surface cells become infected, inhibiting mucus/HCO3- production o NSAIDS • Inhibit prostaglandins, therefore reducing defences • Some, like aspirin are converted to a non-ionised form by stomach acid, allowing them to pass through the mucus layer into cells before they re-ionise.

Answer 153

Receptive relaxation | Rhythmic contractions

Answer 154

As food travels down the oesophagus, a neural reflex carried out by the vagus nerve triggers the relaxation of the muscle in the stomach’s wall, so pressure does not increase. This means that pressure in the stomach does not increase as it fills limiting reflux and allowing us to consume large meals (but not if there is damage to the vagus nerve).

Answer 155

The stomach has longitudinal and circular muscle that is driven by a pacemaker in the cardiac region. The pacemaker fires ~3 times a minute, causing regular, accelerating peristaltic contractions from the Cardia to Pylorus. This, combined with the stomach’s funnel shape both mixes the contents of the stomach and moves liquid chyme into the pyloric region. This occurs as the accelerating peristaltic wave overtakes larger lumps, driving them back into the fundus. Chyme however is decanted into the pyloric region.

Answer 156

Accelerating, rhythmic, peristaltic contraction moving solid lumps backwards into the fundus of the stomach whilst letting liquid chyme moving forwards As chyme enter pyloric region, a small squirt is ejected before the peristaltic wave reaches the Pylorus and shits it - so rest of chyme returns to stomach

Answer 157

3 peristaltic waves - 3 ejected squirts of chyme a minute Squirt volume affected by rate of acceleration of peristaltic wave and hormones from the intestine Gastric emptying slowed by fat, low pH and hypertonicity in the duodenum

Answer 158

Expanded part of the GI tract between the oesophagus and duodenum

Answer 159

Specialised for accumulation of ingested food

Answer 160

``` Cardia Fundus Body Antrum Pylorus ```

Answer 161

Greater and lesser

Answer 162

Inferior oesophageal spinchter | Pyloric spinchter

Answer 163

Lies to left of T11 vertebral on horizontal plane through tip of xiphoid process Immediately superior to Z line diaphragmatic musculature forming the oesophageal hiatus functions as a physiological spinchter that contracts and relaxes This coupled with the cardiac notch prevents reflux

Answer 164

Line where the mucosa abruptly changes from oesophageal to gastric is the Z line

Answer 165

At pyloric end of stomach, circular muscle coat is thickened to produce the pyloric spinchter This controls the discharge of stomach contents through the pyloric orifice into the duodenum

Answer 166

When empty the gastric mucosa is thrown into longitudinal folds called RUGAE Gastric canal forms temporarily between gastric folds along lesser curvature of stomach to allow saliva and other fluids (and small amounts of chewed food) to pass along to the pylorus

Answer 167

Columnar type epithelia Cardia- neck cells--> mucus Fundus and body- neck cells --> mucus ; parietal cells --> acid ; chief cells --> pepsinogen Pylorus - neck cells--> mucus ; G cells --> gastrin

Answer 168

Greater omentum Lesser omentum Epiploic foramen Coeliac trunk

Answer 169

A prominent, four-layered peritoneal fold that hands down like an apron from the Greater Curve of the Stomach. After descending it folds back and attaches to the anterior surface of the Transverse Colon and its mesentery

Answer 170

A much smaller, double-layered peritoneal fold that connects the Lesser Curvature of the Stomach and the Proximal part of the Duodenum to the Liver. It also connects the stomach to the portal triad.

Answer 171

The Greater and Lesser (omental bursa) Sacs communicate through the omental foramen (epiploic foramen), an opening situated posterior to the free edge of the less omentum (hepatoduodenal ligament – see above). The omental foramen can located by running a finger along the gall bladder to free the edge of the lesser omentum, and usually admits two fingers.

Answer 172

Originates from the abdominal aorta, giving rise to left gastric, splenic and common hepatic arteries

Answer 173

Lesser curvature - supplied by left gastric artery and common hepatic artery leading to the right gastric artery // drained by left and right gastric veins that drain to the hepatic portal vein Greater curvature - supplied by splenic artery leading to the left epiploic artery and the common hepatic artery leading to the gastroduodenal artery and the right epiploic artery // drained by left epiploic vein that drains to the splenic vein and the right epiploic vein that drains to the SMV- splenic vein and SMV drain into hepatic portal vein Fundus and body- supplied by splenic artery leading to the posterior gastric/ small gastric artery // drained by small gastric vein that drains into the splenic vein which drains into the hepatic portal vein

Answer 174

o Lower oesophageal sphincter – which is usually closed and transiently relaxes as part of physiology of swallowing to allow bolus to move into stomach o Oesophagus enters stomach in abdominal cavity o Pressure in abdominal cavity is higher than that of thoracic o Right crus of diaphragm acts as sling around the lower oesophagus

Answer 175

Some acid reflux is normal and this is normally dealt with by secondary peristaltic waves, gravity and salivary bicarbonate.

Answer 176

Clinical features of GORD occur when antireflux mechanisms fail and there is prolonged contact of gastric juices with lower oesophageal mucosa. Gastro-oesophageal reflux disease (GORD)

Answer 177

``` o Dyspepsia (heartburn) • Worse on lying down, bending over and drinking hot drinks. ```

Answer 178

Usually clinical diagnosis made without investigation on symptoms alone, no need to investigate unless alarming symptoms (such as dysphagia) or hiatus hernia is suspected (which would be investigated by endoscopy.

Answer 179

o Lifestyle • Lose weight, stop smoking, reduce alcohol consumption, reduce consumption of food groups known to aggravate (e.g. chocolate, fatty foods) o Medication • Simple antacids – e.g. calcium carbonate (neutralisies acid) • Raft antacids (alginates) – e.g. Gaviscon liquid, taken after eating which creates protective raft that sits on top of stomach contents to prevent reflux • PPIs – e.g. omeprazole – reduction in acid secretion by parietal cells • H2 antagonists – e.g. ranitidine – blocks H2 receptors which reduced acid secretion

Answer 180

Continual contact of gastric juices with oesophageal mucosa can lead to metaplastic change to Barrett’s oesophagus

Answer 181

Peptic ulcer is break in superficial epithelial cells penetrating down into Muscularis mucosa of either stomach (GU) or duodenum (DU). Most DUs are found in duodenal cap and GUs are most commonly seen in lesser curvature of stomach

Answer 182

Leading cause in developed world is use of NSAIDs, which inhibit production of prostaglandins, prevents production of protective unstirred layer (innate protection against gastric acid). 50% of patients taking long term NSAIDs have mucosal damage and 30% when endoscoped have peptic ulceration but only 5% will be symptomatic and only 1-2% will have complication such as GI bleed. Also caused most commonly in developing countries by Helicobacter Pylori

Answer 183

o Recurrent, burning epigastric pain (pain is often worse at night and when hungry with Duodenal Ulcers and relieved when eating). Pain may subside with antacids • Persistent, severe pain suggest penetration of ulcer into other organs • Back pain suggest penetrating posterior ulcer o Can also get nausea, vomiting (though less common) o With GUs can get weight loss and anorexia o May be asymptomatic and present for first time with hematemesis when ulcer has perforated blood vessel(s)

Answer 184

o Investigate H pylori infection | o In older patients (over 55y/o) or with other alarming symptoms à endoscopy to exclude cancer

Answer 185

o If due to H pylori infection à Triple Therapy • Proton Pump Inhibitor – Omeprazole • Antibiotics – Clarithromycin / Amoxicillin • H2 Antagonist – Cimetidine o If taking NSAIDs – stop or review – use alternatives (NSAIDs with lower risk of causing PUD), or use prophylactic PPI as well as NSAID • PPI – e.g. omeprazole

Answer 186

o Haemorrhage of blood vessel which ulcer has eroded à presents with hematemesis and melena o Perforation of the ulcer – more common in DUs than GUs – usually perforate into peritoneal cavity o Gastric outlet obstruction à can be pre-pyloric, pyloric or duodenal. Occurs either because of active ulcer with oedema or due to healing of an ulcer with associated fibrosis (scarring). Gastric outlet obstruction normally presents as vomiting without pain.

Answer 187

o H pylori is a gram negative, aerobic, helical, urease producing bacterium that resides in the stomach of infected individuals. o Production of urease produces ammonia, which neutralises acidic environment, which allows bacterium to survive. o It colonises gastric epithelium – in mucous layer or just beneath. Damage to epithelia occurs through enzymes released and through induction of apoptosis. Damage also occurs due to the inflammatory response to the infection (inflammatory cells and mediators)

Answer 188

o IgG detected in serum (relatively good sensitivity and specificity) o 13C-urea breath test (13C-urea ingested – if H pylori present the urease produced will break down 13C-urea to NH3 and CO2 – CO2 (where the carbon is 13C) will be exhaled on breath and detected). o Can also take gastric sample by endoscopy and detect by histology and culture

Answer 189

o Triple therapy. • Proton Pump Inhibitor – Omeprazole • Two Antibiotics – Clarithromycin / Amoxicillin • H2 Antagonist (if severe) o This standard eradication therapy, depending on local resistance, is successful at eradicating infection in 90% of patients. • 7-14 day treatment – 14 days more effective but side-effects of treatment may put patients off finishing two week course

Answer 190

o Gastritis • Usual effect of infection, which is usually asymptomatic. • Chronic gastritis causes hypergastrinaemia due to gastrin release from astral G cells à this increased acid production is usually asymptomatic but can lead to duodenal ulceration (which will eventually produce symptoms) o Peptic ulcer disease • Duodenal ulcers (DUs) à prevalence of DU due to H pylori is falling due to decreased prevalence of H pylori infection. If ulcers due to H pylori infection, eradication of infection relieves symptoms and decreases chances of recurrence. The precise mechanism of ulceration is unclear (only occurs in 15% of infected people) à factors implicated though are genetic predispositions, bacterial virulence, increased gastrin secretion and smoking • Gastric ulcers (GUs) à associated with gastritis affecting the body as well as antrum, which can cause parietal cell loss à reduction in acid production. Ulceration thought to occur due to reduction in gastric mucosal resistance due to cytokine production as a result of infection o Gastric cancer

Answer 191

Acid secretion may be reduced by inhibition of: o Histamine at H2 Receptors E.g. Cimetidine Removes the amplification of Gastrin/Ach signal o Proton Pump Inhibitors (PPIs) E.g. Omeprazole Prevents H+ ions being pumped into parietal cell canaliculi

Answer 192

Acidic- corrected by HCO3- secreted from the pancreas, liver and duodenal mucosa Hypertonic- corrected by osmotic movement of water across the duodenal wall Partly digested- completed by enzymes from pancreas and small intestinal mucosa and bile acids from liver

Answer 193

Exocrine and endocrine gland

Answer 194

Alkaline juice | Enzymes

Answer 195

Proteases- trypsin(ogen), chymotrypsin(ogen), (pro)elastase, (pro)carboxypeptidase Amylases Lipases

Answer 196

Enzymes are synthesised on ribosomes- mostly as inactive precursors They are packaged into condensing vacuoles the Golgi complex to form zymogen granules Zymogen granules are secreted by exocytosis (incorporated into a sac in the membrane that everts) Activated in intestine by enzymatic cleavage

Answer 197

Acinar secretion is stimulated by: CCK- released from duodenal APUD cells in response to hypertonicity and fats in the chyme being detected (often called the intestinal phase) Gastrin- G cells in stomach ACh- stimulated release by vagus nerve (cephalic phase- pancreas begins to make enzymes when food is first smelt etc.)

Answer 198

Acinar cells of pancreas- stimulates enzyme secretion Stomach- inhibits acid secretion Gall bladder- stimulates contraction

Answer 199

Cholecystokinin (CCK)

Answer 200

Largest single organ with many functions

Answer 201

Blood- energy metabolism, detoxification, plasma proteins | Gut- bile secretion 0.25-1l /day (bile acid and alkaline juice for digestion// excretion of bile pigment- bilirubin)

Answer 202

The microscopic structure of the liver supports its function. The basic functional unit is a lobule surrounding a central vein, which drains blood from the liver to the systemic veins. Blood from the hepatic portal vein and hepatic arteries enters vessels at the periphery of the lobule, and flows through sinusoids lined by hepatocytes to the central vein. Hepatocytes are very complex cells that support most of liver functions. Bile is formed in canaliculi, and flows towards the periphery into bile ducts.

Answer 203

Bile acid dependent component | Bile acid independent component

Answer 204

Secreted into canaliculi by hepatocytes | Consists of bile acid and pigment (bilirubin)

Answer 205

Secreted from the hepatic duct cells | Consists of alkaline juice which is practically identical to that from pancreas (HCO3-, ions and water)

Answer 206

Fats are relatively insoluble in water, making them tend to aggregate into large globules, preventing the effective action of digestive enzymes. Acid in the stomach exacerbates this. In the duodenum, bile acids enable fats to be incorporated into small (4-6nm) micelles, with fats in the middle and the polar components of bile acids on the outside. These micelles generate a high surface area for the action of lipases, which cleave the fatty acids from glycerol. The micelles also carry these products into the ‘unstirred layer’ immediately next to the mucosa, where fatty acids can be released to slowly diffuse into the epithelial cells. Once inside the epithelial cells they are reconstituted into triacylglycerols and re-expelled as chylomicrons, structured small particles made up of lipids covered in phospholipids, which facilitate the transport of fat in the lymphatic system from the gut to systemic veins.

Answer 207

Bile acids return to the liver in between meals and are secreted by canaliculi cell walls a long time before they are next needed. Until they are needed, they are stored in the gall bladder. To reduce the volume that needs to be stored, bile acids are concentrated by the transport of salt and water across the gall bladder epithelium. However, the concentration process increases the risks of precipitation, leading to Gall Stones. Gallstones are often asymptomatic, but they can move into the neck of the gall bladder or biliary tree, causing very painful biliary colic or even obstruction. This is often followed by inflammation (Cholecystitis) and infection of the Gall Bladder.

Answer 208

Pain from Gallstones can be worse after eating, as the secretion of Cholecystokinin (CCK) will cause the gall bladder to contract

Answer 209

Cholecystitis

Answer 210

Ascending cholangitis

Answer 211

Pancreatitis

Answer 212

Chronic alcohol abuse | Gall stone in ampulla of varta/ terminal duct

Answer 213

If bile acids or pancreatic enzymes (Lipases) are not secreted in adequate amounts, fat appears in faeces. This makes them pale, float and smell foul. This is relatively common, and is called Steatorrhoea, or ‘Fatty Faeces’.

Answer 214

Bile pigments are excretory products. The most common bile pigment is Bilirubin, produced as a product of haemoglobin breakdown. Bilirubin is conjugated in the liver and secreted in the bile to be excreted in faces. If it cannot be excreted it accumulates in the blood, giving the condition known as Jaundice.

Answer 215

Elongated accessory digestive exocrine and endocrine gland

Answer 216

Lies retroperitoneally Overlies and transversely crosses bodies of L1 and L2 vertebra along the transpyloric plane pm the posterior abdominal wall Lies posterior to stomach, between duodenum on right and spleen on left Transverse mesocolon attaches to its anterior margin

Answer 217

Pancreatic juice from Acinar cells (enzymes) and duct cells (alkaline juice) - enters the duodenum through the main and accessory pancreatic ducts

Answer 218

Glucagon and insulin from pancreatic islets of langerhans | - enter the blood

Answer 219

Head Neck Body Tail

Answer 220

The expanded part of the gland, embraced by the C-shaped curve of the duodenum, to the right of the superior mesenteric vessels and just inferior to the transpyloric plane. Firmly attaches to medial aspect of descending and horizontal part of duodenum. Ulcinate process- projection from inferior part of head, extends medially to left, posterior to SMA. Rests posteriorly on IVC, tight renal artery and vein and left renal vein. Bile duct en route to opening in descending part of duodenum - lies in groove on posterio-superior surface of the head (or is embedded in it)

Answer 221

Short (1.5-2cm), and overlies the superior mesenteric vessels, which form a groove in it’s posterior surface. The anterior surface of the neck is covered with peritoneum and adjacent to the pylorus of the stomach. The SMV joins the splenic vein posterior to the neck to form the hepatic portal vein.

Answer 222

Continues from the neck and lies to the left of the superior mesenteric vessels, passing over the aorta and L2 vertebra, continuing just above the transpyloric plane posterior to the omental bursa. The anterior surface is covered with peritoneum and forms part of the stomach bed. The posterior surface is devoid of peritoneum and is in contact with the aorta, SMA, left suprarenal gland, left kidney and renal vessels.

Answer 223

Lies anterior to the left kidney, where it is closely related to the splenic hilum and the left colic flexure. The tail is relatively mobile and passes between the layers of the splenorenal ligament with the splenic vessels.

Answer 224

The main pancreatic duct begins at the tail of the pancreas and runs through the gland to the head. It then turns inferiorly, and is closely related to the bile duct. The two usually unite to form to short, dilated hepatopancreatic Ampulla of Vater, which opens into the descending part of the duodenum at summit of major duodenal papilla. 3 spinchters- spinchter of pancreatic duct, spinchter of bile duct, hepatopancreatic spinchter

Answer 225

Opens into duodenum at summit of minor duodenal papilla. Usually communicates with main pancreatic duct. Sometime main pancreatic duct is smaller than the accessory duct and so two are not connected and the accessory duct will carry more pancreatic juice.

Answer 226

The arterial supply of the pancreas is derived mainly from the branches of the Splenic Artery. Multiple Pancreatic arteries that form arches with pancreatic branches of the Gastroduodenal and Superior Mesenteric arteries. The Anterior and Posterior Superior Pancreaticoduodenal Arteries (branches of the Gastroduodenal Artery) and the Anterior and Posterior Inferior Pancreaticoduodenal Arteries (branches of the SMA) form anteriorly and posteriorly placed arches that supply the head.

Answer 227

Venous drainage from the pancreas occurs via a corresponding Pancreatic Veins. The head of the pancreas has corresponding Superior and Inferior Pancreaticoduodenal Veins. Most pancreatic veins empty into the splenic vein, but some empty into the SMV.

Answer 228

Derived from vagus and abdominal splanchnic nerves- passing through the diaphragm PSNS and SNS fibres also distributed to acinar cells and islets PSNS fibres are secretomotor but pancreatic secretions are primarily mediated by CCK and secretin (hormones formed by epithelia cells of duodenum and proximal intestinal mucosa under stimulus of acid contents from stomach)

Answer 229

The liver is the largest gland in the body, and after the skin, the largest single organ. Except for fat, all nutrients absorbed from the digestive tract are initially conveyed to the liver by the portal venous system.

Answer 230

The liver lies mainly in the right upper quadrant of the abdomen where it is protected by the rib cage and diaphragm. The normal liver lies deep to ribs 7-11 on the right side and cross the midline towards the left nipple. Consequently, the liver occupies most of the right hypochondrium and upper epigastrium and extends into the left hypochondrium.

Answer 231

The liver moves with the excursions of the diaphragm and is located more inferiorly when standing due to gravity.

Answer 232

The liver has a convex Diaphragmatic surface (anterior, superior and some posterior) and a relatively flat or even concave Visceral surface (posteroinferior), where are separated anteriorly by its sharp Inferior border that follows the right costal margin inferior to the diaphragm.

Answer 233

``` Subphrenic recesses (superior extensions of the peritoneal cavity (great sac) exist between the diaphragm and the anterior and superior aspects of the diaphragmatic surface of the liver. The Subphrenic recesses are separated into right and left recesses by the Falciform ligament, which extends between the liver and the anterior abdominal wall. The attachment of the Falciform ligament divides the Right Lobe from the much smaller Left Lobe. The portion of the Supracolic compartment of the peritoneal cavity immediately inferior to the liver is called the subhepatic space. ```

Answer 234

The round ligament, or ligamentum teres is contained within the Falciform ligament. (Liver) It is the embryonic remnant of the umbilical vein.

Answer 235

The Diaphragmatic surface of the liver is covered with visceral peritoneum, except posteriorly in the Bare Area of the liver, where it lies in direct contact with the diaphragm. There is a deep groove in the bare area, where the inferior vena cava travels.

Answer 236

The bare are is marked out by the reflection of the peritoneum from the diaphragm to it as the anterior (upper) and poster (lower) layers of the Coronary Ligament. These layers met on the right to form the Right Triangular Ligament and diverge towards the left to enclose the triangular bare area. Near the apex of the wedge-shaped liver, the layers meet on the left to form the Left Triangular Ligament.

Answer 237

The visceral surface of the liver is covered with peritoneum, except at the fossa for the gallbladder and the porta hepatis (like a hilum) a transverse fissure where vessels (hepatic portal vein, hepatic artery and lymphatics) that supply and drain the liver enter and leave it. In contrast to the smooth diaphragmatic surface, the visceral surface bears multiples fissures and impressions from contact with other organs.

Answer 238

The liver is split into two anatomical and two accessory lobes by the reflections of peritoneum from its surface, the fissures formed in relation to those reflections and the vessels serving the liver and the gallbladder. Left lobe Right lobe- contains within it the caudate and quadrate lobes Liver has 8 functional lobes but 4 anatomical lobes

Answer 239

On the visceral surface, the right and left sagittal fissures split the right lobe with the porta hepatis into the Quadrate Lobe (gallbladder) anteriorly and inferiorly and the Caudate Lobe (IVC) posteriorly and superiorly.

Answer 240

The Gallbladder is 7-10cm long and lies in the fossa for the gallbladder on the visceral surface of the liver. This fossa lies at the junction of the right and left lobes of the liver. The Gallbladder is pear-shaped and can hold up to 50ml of bile. Peritoneum completely surrounds it’s fundus and binds it’s body and neck to the liver. The hepatic surface of the gallbladder is attached to the liver by connective tissue of the fibrous capsule of the liver. The gallbladder has three parts: o Fundus o Body o Neck The neck of the gallbladder joins the cystic duct

Answer 241

The Biliary Ducts convey bile from the liver to the duodenum. Hepatocytes produce bile continuously, secreting it into canaliculi. The canaliculi drain into the small interlobular biliary ducts and then into the large collecting bile ducts, which in turn merge to form the right and left hepatic ducts. Shortly after leaving the porta hepatis, these hepatic ducts unite to form the common hepatic duct, which is joined on the right side by the cystic duct to form the common bile duct, which conveys the bile to the duodenum, through the Ampulla of Vater (spinchter of Oddi). Shortly before this, the Pancreatic Duct joins the common bile duct.

Answer 242

The arterial supply of the gallbladder and cystic duct is from the Cystic Artery, which commonly arises in the triangle between the common hepatic duct, cystic duct and visceral surface of the liver, the cystohepatic triangle (of Calot).

Answer 243

The venous drainage from the neck of the gallbladder and cystic duct flows via the Cystic Veins. These small and usually multiple veins enter the liver directly or drain through the hepatic portal vein. The venous drainage from the fundus and body of the gallbladder pass directly into the visceral surface of the liver and drain into the hepatic sinusoids.

Answer 244

The spleen is an ovoid, usually purplish, pulpy mass about the size and shape of a fist. It is relatively delicate and considered the most vulnerable abdominal organ.

Answer 245

The spleen is located in the Upper Left Quadrant (ULQ) or hypochondrium of the abdomen, resting on the left colic flexure. It is entirely covered by a layer of visceral peritoneum, except at the splenic hilum, where the splenic branches of the splenic artery and vein enter and leave.

Answer 246

``` The relations of the spleen are: o Anteriorly The stomach Attached by the Gastrosplenic Ligament o Posteriorly The left part of the diaphragm, which separates it from the pleura, lung and ribs 9-11 o Inferiorly The left colic flexure o Medially The left kidney Attached by the Splenorenal ligament ```

Answer 247

The arterial supply of the spleen is from the Splenic Artery, the largest branch of the coeliac trunk. It follows a tortuous course posterior to the omental bursa, anterior to the left kidney and along the superior border of the pancreas. Between the layers of the splenorenal ligament, the splenic artery divides into five or more branches that enter the hilum, supplying the different vascular segments of the spleen.

Answer 248

The venous drainage of the spleen flows via the Splenic Vein, formed by several tributaries that emerge from the hilum. It is joined by the Inferior Mesenteric Vein and runs posterior to the body and tail of the pancreas throughout most of its course. The splenic vein unites with the Superior Mesenteric Vein posterior to the neck of the pancreas to form the Hepatic Portal Vein.

Answer 249

``` Inevitably, when we ingest food and water we also risk ingesting toxins. These include: o Chemical o Bacteria o Viruses o Protozoa o Nematodes (Roundworms) o Cestodes (Tapeworms) o Trematodes (Flukes) ```

Answer 250

o Sight / Smell • If food looks or smells bad you don’t eat it o Memory • If food tastes bad, you don’t eat it next time o Saliva • pH 7.0 • Contains lysozyme, lactoperoxidase, complement, IgA and polymorphs • Washes toxins down into the stomach o Stomach Acid • Low pH kills the majority of bacteria and viruses o Small Intestine Secretions • Bile • Proteolytic enzymes • Lack of nutrients • Shedding of epithelial cells o Colonic mucus • Protects the colonic epithelium from it’s contents o Anaerobic environment (Small bowel, colon) o Peristalsis/Segmentation • Normal intestinal transit time is 12 – 18hrs. If peristalsis is slowed, gut infections are prolonged. E.g. shigellosis.

Answer 251

Severe illness and/or dehydration results in a reduced salivary flow (xerostomia) and dry mouth, which then leads to microbial overgrowth in the mouth and dental caries Can lead to parotitis caused by infection by staphylococcus aureus (mortality of 25%)

Answer 252

Condition where patients don't produce enough gastric acid in the stomach Usually have pernicious anaemia, and are on drugs such as H2 antagonists and proton pump inhibitors Usually makes the patient more susceptible to shigellosis, cholera and salmonella infections

Answer 253

C. Difficile

Answer 254

MTB is resistant to gastric acid (acid and alcohol fast bacterium AAFB)- so gastric washings can be used to collect the bacteria for diagnostic purposes H. Pylori produces urease which acts in urea to produce a protective cloud of ammonia Enteroviruses such as HEPATITIS A, POLIO and COXSACKIEVIRUS are resistant to gastric acid

Answer 255

Cellular Innate Defences o Neutrophils- trap and kill bacteria o Macrophages- circulating monocytes --> tissue macrophages ; lungs liver and spleen • Kupffer cells in the Liver o Natural Killer cells (Kill virus infected cells) o Tissue Mast Cells- from basophils in blood; release histamine - vasodilator causing lots of fluid loss o Eosinophils • Parasitic infections

Answer 256

Gut infections which activate complement recruit mast cells which release histamine- causes vasodilation and increased capillary permeability --> massive fluid loss

Answer 257

1l/hour | 50% mortality (untreated)

Answer 258

Sunken eyes Dehydration Washer woman hands (wrinkly) Rice water urine (mucus and enterocytes)

Answer 259

Asthma Hay fever Parasitic infections (worms)

Answer 260

Adaptive Defences (Cellular) o B Lymphocytes o Produce antibodies including IgA and IgE that are particularly effective against extracellular microbes o T Lymphocytes o Directed against intracellular organisms o Lymphatic Tissues o Mucosal Associated Lymphoid Tissue (MALT) in the GI tract is called Gut Associated Lymphoid Tissue (GALT) o GALT is diffusely distributed by also nodular in three locations: • Tonsils (mouth is high risk oxen and so needs a large amount of lymphatic tissue at back of throat- palatine, Ingush and nasopharyngeal tonsil) • Peyer’s patches • Appendix

Answer 261

Inflammation of tonsils

Answer 262

o Ileocaecal lymphatic tissue o Mesenteric adenitis is a common cause of right iliac fossa pain in children, and can easily be mistaken for appendicitis o Caused mostly by adenovirus/coxsackie virus o Typhoid fever causes inflamed Peyer’s patches in terminal ileum, which can perforated and kill patients

Answer 263

Many cases arise from lymphoid hyperplasia at the appendix base leading to an obstructed outflow o Stasis à Infection • Purulent appendicitis is commoner during epidemics of chickenpox in children • Appendix may be obstructed by a faecolith o Calcified faecal matter, visible on an X-ray • Appendix may be obstructed by a worm

Answer 264

Gut Ischaemia The GI tract’s defence mechanisms require the GI tract itself to have an intact blood supply. Intestinal/hepatic ischaemia due to arterial disease, systemic hypotension, or intestinal venous thrombosis can (frequently does) lead to overwhelming sepsis and rapid death (within hours)

Answer 265

Liver Failure Liver failure gives an increased susceptibility to infections, toxins, drugs and hormones. There is also increased blood ammonia due to the failure of the urea cycle. Ammonia is produced by colonic bacteria and the deamination of amino acids, and can cause hepatic encephalopathy. ``` Causes of Liver Failure: o Viral hepatitis • Main cause worldwide o Alcohol • Main cause in the UK o Drugs • Paracetamol, halothane o Industrial solvents o Mushroom poisoning ```

Answer 266

Cirrhosis (Hepatic Fibrosis) Hepatic fibrosis leads to portal venous hypertension, leading to porosytemic shunting and therefore toxin shunting. Portosystemic shunting leads to oesophageal varices, haemorrhoids and caput medusa.

Answer 267

Bile Pigments Bile pigments are excretory products. The most common bile pigment is Bilirubin, produced as a product of haemoglobin breakdown. Bilirubin is conjugated in the liver and secreted in the bile to be excreted in faces. If it cannot be excreted it accumulates in the blood, giving the condition known as Jaundice.

Answer 268

Hormones | The liver breaks down many hormones, notably insulin.

Answer 269

Albumin Albumin is the most abundant plasma protein. Albumin is essential in maintaining the oncotic pressure needed for proper distribution of body fluids.

Answer 270

``` The liver produces several coagulation factors: o I – Fibrinogen o II – Prothrombin o V o VII o IX o X o XI As well as Protein C, Protein S and Antithrombin. ```

Answer 271

Thombopoietin | A glycoprotein hormone that regulates the production of platelets by bone marrow.

Answer 272

Amino Acid Synthesis | o Transamination

Answer 273

Hepatocellular Damage If hepatocytes are damaged, their ruptured membranes will allow Aminotransferases into the blood stream. Their presence there is indicative of liver damage (ALT/AST). Cholestasis (Bile ducts) Bilirubin – Unable to excrete bilirubin, plasma concentration rises Alkaline Phosphatase – Enzyme in cells lining the liver’s biliary ducts. Plasma levels rise with an obstruction. ``` Synthetic function Albumin – Levels reduced in chronic liver disease Prothrombin time (Clotting) – Measures the clotting tendency of blood ```

Answer 274

Damaged hepatocytes have a reduced capacity to excrete bilirubin. This leads to bilirubin accumulating in the blood, giving Jaundice. The increased levels of bilirubin (Hyperbilirubinaemia) results in a yellowish pigmentation of the skin, conjunctival membranes over the scleae and other mucus membranes. Jaundice is clinically detectable at >40mmol/L (Normal range <22mmol/L)

Answer 275

Pre-Hepatic Jaundice Excessive Bilirubin Production, usually due to an increased breakdown of red blood cells (haemolysis) o Liver unable to cope with excess bilirubin

Answer 276

``` Lab Findings: o Unconjugated hyperbilirubinaemia o Reticulocytosis o Anaemia o increase LDH o decrease Haptoglobin ```

Answer 277

``` Causes: o Inherited • Red Cell Membrane defects • Haemoglobin abnormalities • Metabolic defects o Congenital Hyperbilirubinaemias • Gilbert’s syndrome ß 10% of the population • Crigler-Najjar syndrome ß Rare • Dublin-Johnson syndrome ß Rare o Acquired • Immune • Mechanical ß E.g. RBC’s running across metal heart valves • Acquired membrane defects • Infections • Drugs • Burns ```

Answer 278

Hepatic Jaundice | Reduced capacity of liver cells to secrete conjugated bilirubin into the blood

Answer 279

Lab Findings: o Mixed unconjugated and conjugated hyperbilirubinaemia o increased Liver enzymes (ALT/AST) o Abnormal Clotting

Answer 280

``` Causes o Congenital • Gilbert’s Syndrome • Crigler-Najjar syndrome o Hepatic Inflammation • Viral (Hepatitis A, B, C and E, Epstein Barr Virus (EBV)) • Autoimune hepatitis • Alcohol • Haemochromotosis • Wilson’s disease o Drugs • Paracetamol o Cirrhosis • Alocohol • Chronic hepatitis • Metabolic disorders o Hepatic tumours • Hepatocellular carcinoma • Metastases ```

Answer 281

Post-Hepatic Jaundice Obstruction to drainage of bile, causing a back up of bile acids into the liver. Can be intrahepatic or extrahepatic. The passage of conjugated bilirubin is blocked.

Answer 282

``` Lab Findings o Conjugated hyperbilirubinaemia o Bilirubin in urine (dark) o increased Canalicular enzymes (ALP) o -/increased liver enzymes (ALT/AST) ```

Answer 283

``` Causes o Intrahepatic • Hepatitis • Drugs • Cirrhosis • Primary biliary colic o Extrahepatic • Gallstones/Biliary stricture • Carcinoma o Head of pancreas o Ampulla o Bile duct o Porta hepatis lymph nodes o Liver metastases • Pancreatitis • Sclerosing cholangitis ```

Answer 284

Fatty liver o Alcohol metabolism generates NADH from NAD+ • increase NADH induces fatty acid synthesis • decrease NAD+ results in decrease fatty acid oxidation o Accumulation of fatty acids in the liver • Glycerol à TAGs o TAGs accumulate, giving fatty liver Alcoholic Hepatitis o Inflammation of hepatocytes Cirrhosis Liver cell necrosis followed by nodular regeneration and fibrosis, resulting in increased resistance to blood flow and deranged liver function.

Answer 285

``` o Hepatocellular carcinoma o Liver failure o Wernicke-Korsakoff syndrome o Encephalopathy o Dementia o Epilepsy ```

Answer 286

``` Causes o Alcohol o Wilson’s Disease o a1-antitrypsin deficiency o Biliary cirrhosis o Haemochromotosis o Hepatitis B or C o Autoimmune hepatitis ```

Answer 287

``` Clinical Features o Liver dysfunction o Jaundice o Anaemia o Bruising o Palmar erythema o Dupuytren’s contracture ```

Answer 288

``` Investigations o - / increase ALT/AST o increase ALP o increase Bilirubin o decrease Albumin o Deranged clotting ```

Answer 289

The management of Cirrhosis includes stopping drinking, treating complications and transplantation.

Answer 290

Portal hypertension is defined as portal venous pressure > 20mmHg

Answer 291

o Obstruction of the portal vein • Congenital, thrombosis or extrinsic compression o Obstruction of flow within the liver • Cirrhosis, hepatoportal sclerosis, Schistosomiasis, sarcoidosis)

Answer 292

Ascites The high pressure in the portal venous system means blood is backed up into the abdomen. The increase in hydrostatic pressure in the abdomen means less fluid is reabsorbed into blood vessels at the end of capillary beds. If the liver is damaged, reduced oncotic pressure inside the vessels, due to lack of plasma proteins, may also contribute.

Answer 293

Splenomegaly – Due to subsequent increased B.P. in the spleen

Answer 294

There are several anastomoses between the hepatic portal and systemic veins. As such, when the pressure is increased in the portal venous system, blood is backed up through these anastomoses. The increased blood pressure causes the vessels to dilate, protrude into the lumen, rupture/ulcerate and haemorrhage. o Oesophageal varices o Rectal varices o Caput Medusae Portal to Systemic . Left Gastric to Azygous/Oesophageal Oesophageal Varices . Superior rectal to Inferior rectal Rectal Varices . Paraumbilical to Small epigastric of abdominal wall Caput Medusae . Colic/Splenic/Portal to Retroperitoneal veins of posterior abdominal wall or diaphragm Portal veins here are on the posterior aspects (bare areas) of secondarily retroperitoneal viscera or the liver.

Answer 295

Bile acids return to the liver in between meals and are secreted by canaliculi cell walls a long time before they are next needed. Until they are needed, they are stored in the gall bladder. To reduce the volume that needs to be stored, bile acids are concentrated by the transport of salt and water across the gall bladder epithelium. However, the concentration process increases the risks of precipitation, leading to Gall Stones. Gallstones are often asymptomatic, but they can move into the neck of the gall bladder or biliary tree, causing very painful biliary colic or even obstruction. This is often followed by inflammation (Cholecystitis) and infection of the Gall Bladder. Pain from Gallstones can be worse after eating, as the secretion of Cholecystokinin (CCK) will cause the gall bladder to contract.

Answer 296

Pancreatitis is an inflammatory process, caused by the effects of enzymes released from pancreatic Acini

Answer 297

Acute o Oedema, Haemorrhage, Necrosis o Severe pain, vomiting, dehydration, Shock o increased Amylase, Glycaemia, ALP/Bilirubin o decreased Ca2+

Answer 298

Chronic o Fibrosis, Calcification o Pain, Malabsorption (Steatorrhoea, decreased albumin, weight loss)

Answer 299

``` Causes of Pacreatitis – GET SMASHED o Gallstones (Block Pancreatic duct/Amuplla of Vater) o Ethanol (Hyper-stimulation of pancreatic secretions) o Trauma o Steroids o Mumps o Autoimmune o Scorpion bite o Hyperlipidaemia o ERCP/Iatrogenic o Drugs ```

Answer 300

90% of pancreatic carcinomas are Ductal Adenocarcinomas, and they account for ~5% of cancer deaths. Clinical Presentation: Initially symptomless, but then lots of symptoms all at the same time: o Obstructive jaundice, pain, vomiting, Malabsorption, diabetes

Answer 301

In response to Gastric emptying, the duodenum secretes Cholecystokinin (CCK). This stimulates the contraction of the Gall Bladder, ejecting concentrated bile acids together with enzymes from the pancreas. Alkali from the Pancreas and Liver is also released in response to Secretin. Bile acids are released through the Ampulla of Vater, and aid with the digestion and absorption of fats. They continue to the terminal ileum, where they are actively absorbed by the epithelium. The venous return from the gut enters the hepatic portal blood, where hepatocytes actively take up Bile Acids and re-secrete them into Canaliculi. Most bile acids are recovered, but some are unconjugated by the action of gut bacteria and are lost. Hepatocytes subsequently replace it by synthesising more.

Answer 302

Bile acids return to the liver in between meals and are secreted by canaliculi cell walls a long time before they are next needed. Until they are needed, they are stored in the gall bladder.

Answer 303

Related to cholesterol Relatively insoluble in water- amphipathic - travel in bile as micelles (bile acids, cholesterol and phospholipids) Two main bile acids- cholic acid, chenodeoxycholic acid Conjugated to amino acids Needed for digestion and absorption of fats- emulsification of large fat globules into smaller globules, increasing surface area over which enzymes can act on fat and break it down

Answer 304

HCO3- is present in the blood at elevated concentrations due to gastric acid secretion. The pancreatic duct cells secrete the HCO3- using the same cellular mechanism as other HCO3- secreting cells: o Na-K-ATPase sets up a Na+ concentration gradient o Hydrogen ions are exported from the duct cell into ECF using the Na+ concentration gradient via NHE (normally on apical membrane in kidney- but here on by membrane!) o H+ ions combine with HCO3- to form H2O and CO2, which are taken up into the cell o H2O and CO2 reform H+ and HCO3- inside the cell o HCO3- is exported into the duct lumen o H+ ion is recycled, ‘going around in a circle’ to carry more HCO3- from the ECF to the Lumen

Answer 305

Duct secretion is stimulated by Secretin, which is released from Jejunal cells in response to low pH caused by acid from stomach. Cholecystokinin (CCK) facilitates secretin’s action.

Answer 306

Duodenum Jejunum Ileum

Answer 307

``` 25 cm long Breadth of 1w fingers First and shortest segment Widest and most fixed part C shaped around head of pancreas ```

Answer 308

C shaped around the head of pancreas Begins at Pylorus (RHS) and ends at duodenojejunal flexure on LHS Most is fixed to structures on posterior abdominal wall by peritoneum Partly retroperitoneal

Answer 309

The first 2cm of the superior part of the duodenum, immediately distal to the pylorus is known as the ampulla or duodenal cap. It has a mesentery and is mobile. In contrast, the rest of the duodenum is retroperitoneal and immobile.

Answer 310

As the duodenal cap is immediately distal to the pylorus, this is a common site of ulceration. If the ulcer erodes backwards through the Gastroduodenal artery, blood loss can be severe (“Like turning on a tap”).

Answer 311

The superior part of the duodenum ascends from the pylorus and is overlapped by the liver and gallbladder. Peritoneum covers its anterior aspect, but it is bare of peritoneum posteriorly (except for the duodenal cap). The proximal part has the hepatoduodenal ligament (part of the lesser omentum) attached superiorly, and the greater omentum attached inferiorly.

Answer 312

The descending part of the duodenum runs inferiorly, curving around the head of the pancreas. The Bile and Main pancreatic ducts enter its posteromedial wall via the Ampulla of Vater. The descending part of the duodenum is entirely retroperitoneal. The anterior surface of its proximal and distal thirds is covered with peritoneum; however the peritoneum reflects in its middle third to form the double-layered mesentery of the transverse colon, the Transverse Mesocolon.

Answer 313

The inferior (horizontal) part of the duodenum runs transversely right à left, passing over the IBC, aorta and L3 vertebra. The Superior Mesenteric Artery and Vein and the root of the mesentery of the jejunum and ileum cross it. Where these structures cross is the only part of its anterior surface not covered with peritoneum. Posteriorly it is separated from the vertebral column by the right psoas major, IVC, aorta and the right testicular/ovarian vessels.

Answer 314

The ascending part of the duodenum runs superiorly and along the left side of the aorta to reach the inferior border of the body of the pancreas. Here it curves anterior to join the jejunum at the duodenojejunal flexure, supported by the attachment of a suspensory muscle of the duodenum (Ligament of Treitz). Contraction of this muscle widens the flexure, facilitating movement.

Answer 315

The jejunum is the second part of the small intestine, beginning at the duodenojejunal flexure where the digestive tract resumes an intraperitoneal course. Together, the jejunum and ileum are 6-7 metres long, the jejunum constituting approximately two fifths and the ileum three fifths of the intraperitoneal section of the small intestine. Most of the Jejunum lies in the left upper quadrant (LUQ) of the Infracolic compartment.

Answer 316

The third part of the small intestine, the ileum, ends at the ileocaecal junction. Together, the jejunum and ileum are 6-7 metres long, the jejunum constituting approximately two fifths and the ileum three fifths of the intraperitoneal section of the small intestine. Most of the ileum lies in the right lower quadrant (RLQ). The terminal ileum usually lies in the pelvis, from which it ascends, ending in the medial aspect of the cecum.

Answer 317

The mesentery is a fan-shaped fold of peritoneum that attaches the jejunum and ileum to the posterior abdominal wall. Between its two layers are the superior mesenteric vessels, lymph nodes, a variable amount of fat and autonomic nerves. The root of the mesentery crosses the ascending and inferior parts of the duodenum, abdominal aorta, IVC, right ureter, right psoas major, and right testicular/ovarian vessels.

Answer 318

``` Deep red Large diameter 2-4 cm Thick and heavy wall Large vascularity Long vasa recta A few large arcades Little fat in mesentery Large, tall and closely packed plicae circulares Few Peyers patches ```

Answer 319

``` Pale pink Small diameter (2-3cm) Thin and light wall Little vascularity Short vasa recta Many small short arcades Lots of fat in mesentery Low and sparse plicae circulares Many Peyers patches ```

Answer 320

Foregut derivative Coeliac trunk Coeliac Trunk --> Gastroduodenal --> Superior Pancreaticoduodenal

Answer 321

Midgut derivative Superior mesenteric artery Abdominal Aorta --> SMA --> Inferior Pancreaticoduodenal

Answer 322

The Veins of the Duodenum follow the arteries and drain into the Hepatic Portal Vein, some directly, some through the Superior Mesenteric and Splenic Veins.

Answer 323

The Jejunum and Ileum are both derived from the Midgut. Abdominal Aorta --> SMA --> Jejunal Abdominal Aorta --> SMA --> Ileal The SMA usually arises from the abdominal aorta at the level of the L1 vertebra, approximately 1cm inferior to the celiac trunk, and runs between the layers of mesentery, sending 15-18 branches to the jejunum and ileum. These arteries unite to form loops or arches called arterial arcades, which gives rise to straight arteries called vasa recta.

Answer 324

The large intestine consists of the Caecum, Appendix, Ascending, Transverse, Descending and sigmoid colon, Rectum and Anal Canal.

Answer 325

The large intestine can be distinguished from the small intestine by: o Omental Appendices o Teniae Coli o Haustra o Diameter • Much larger than that of the small intestine

Answer 326

Small, fatty, omentum-like projections

Answer 327

* Three distinct longitudinal bands of muscle * Begin at the appendix, where it’s longitudinal muscle splits into 3 bands * Run the length of the large intestine * Merge together again at the rectosigmoid junction into a continuous layer around the rectum

Answer 328

• Sacculations of the wall of the colon between teniae

Answer 329

The Caecum is the first part of the large intestine and is continuous with the ascending colon. It is a blind intestinal pouch, approximately 7.5cm in both length and breadth. It lies in the Iliac Fossa of the Right Lower Quadrant of the abdomen, inferior to the junction of the terminal ileum and caecum (ileocaecal junction). If distended with faeces or gas, the caecum may be palpable through the anterolateral abdominal wall. The caecum usually lies within 2.5cm of the inguinal ligament, is almost entirely enveloped by peritoneum and is mobile. However, the caecum has no mesentery. Because of this relative freedom, it may be displaced from the iliac fossa, but is commonly bound to the lateral abdominal wall by one or more cecal folds of peritoneum.

Answer 330

The appendix is a blind intestinal diverticulum (6-10cm in length) that contains masses of lymphoid tissue. The appendix arises from the posteromedial aspect of the caecum inferior to the ileocaecal junction. It is usually retrocaecal, but its position is variable. The appendix has a short, triangular mesentery, the Mesoappendix, which derived from the posterior side of the mesentery of the terminal ileum. The mesoappendix attaches to the caecum and the proximal part of the appendix.

Answer 331

Midgut derivative | Abdominal Aorta --> SMA --> Ileocolic

Answer 332

Midgut derivative | Abdominal Aorta --> SMA --> Ileocolic --> Appendicular

Answer 333

Venous drainage from the Caecum and Appendix flows through a tributary of the SMV, the Ileocolic vein.

Answer 334

Ascending colon Transverse colon Descending colon Sigmoid colon

Answer 335

o The ascending colon passes superiorly on the right side of the abdominal cavity from the Caecum to the right lobe of the liver, where it turns to the left at the Right Colic Flexure (hepatic flexure). The flexure lies deep to the 9th and 10th ribs and is overlapped by the inferior part of the liver. o The ascending colon is narrower than the caecum and is secondarily retroperitoneal along the right side of the posterior abdominal wall, covered by peritoneum anteriorly and on its sides. It is separated from the anterolateral abdominal wall by the greater omentum. o The ascending colon has a short mesentery in 25% of people. o A deep vertical groove lined with parietal peritoneum, the Right Paracolic Gutter, lies between the lateral aspect of the ascending colon and the adjacent abdominal wall.

Answer 336

o The transverse colon is the third, longest and most mobile part of the large intestine. It crosses the abdomen from the Right to Left colic flexures, where it turns inferior to become the descending colon. o The Left Colic Flexure (splenic flexure) is usually more superior, more acute and less mobile than the right. It lies anterior to the inferior part of the left kidney and attaches to the diaphragm through the Phrenicocolic Ligament. o The transverse colon and its mesentery, the Transverse Mesocolon, loops down often inferior to the level of the iliac crests. The mesentery is adherent to or fused with the posterior wall of the omental bursa. The root of the transverse Mesocolon lies along the inferior border of the pancreas and is continuous with the parietal peritoneum posteriorly. o Being freely movable, the transverse colon is variable in position, usually handing to the level of the umbilicus (L3), but in tall, thin people it may extend down into the pelvis.

Answer 337

o The descending colon occupies a secondarily retroperitoneal position (covered by peritoneum anteriorly and laterally, binding it to the posterior abdominal wall), between the Left Colic Flexure to the Left Iliac Fossa, where it is continuous with the sigmoid colon. o As it descends, the colon passes anterior to the lateral border of the left kidney. o The descending colon has a short mesentery in 33% of people. o As with the ascending colon, a deep vertical groove lined with parietal peritoneum, the Left Paracolic Gutter, lies between the lateral aspect of the ascending colon and the adjacent abdominal wall.

Answer 338

The sigmoid colon, characterised by its S-Shaped loop of variable length, links the Descending Colon and the Rectum, running from the iliac fossa to the S3 vertebra. o The termination of teniae coli, approximately 15cm from the anus, indicates the rectosigmoid junction. o The Sigmoid Colon usually has a long mesentery, the Sigmoid Mesocolon, and therefore has considerable mobility, especially it’s middle part. This can lead to Volvulus of the Sigmoid Colon. o The root of the sigmoid Mesocolon has an inverted V-shaped attachment, extending medially and superiorly along the external iliac vessels to the anterior aspect of the sacrum. o The left ureter and the division of the left common iliac artery lie Retroperitoneally, posterior to the apex of the root of the sigmoid Mesocolon.

Answer 339

Midgut derivative | Abdominal aorta --> SMA --> ileocolic --> right colic

Answer 340

Midgut derivative Abdominal Aorta --> SMA --> Right Colic Abdominal aorta --> SMA --> middle colic --> right middle colic Anastamoses of right colic and right middle colic artery

Answer 341

Midgut and hindgut derivative R + L middle colic artery Abdominal aorta --> middle colic --> L+R middle colic

Answer 342

Hindgut derivative Abdominal aorta --> SMA --> middle colic --> left middle colic Abdominal aorta --> IMA --> left colic Anastamoses of left middle colic and left colic

Answer 343

Hind gut derivative | Abdominal aorta --> IMA --> left colic

Answer 344

Hind gut derivative | Abdominal aorta --> IMA --> sigmoidal branches

Answer 345

Hind gut derivative Abdominal aorta --> IMA --> Rectal branches of IMA Aorta --> IMA --> Superior Rectal --> R+L Branch Aorta --> Common Iliac --> R+L Internal Iliac --> R+L Middle Rectal Aorta --> Common Iliac --> R+L Internal Iliac --> Inferior Pudendal --> R + L Inferior Rectal

Answer 346

Venous drainage of the ascending colon and right colic flexure is through the Ileocolic and Right Colic Veins, which drain into the SMV and subsequently the portal vein.

Answer 347

Venous drainage of the transverse colon is through the Middle Colic Vein, which drains into the SMV and subsequently the portal vein.

Answer 348

Venous drainage of the descending and sigmoid colon is through the Left Colic and Sigmoid Veins, which drain into the IMV and subsequently the Splenic and Portal Veins.

Answer 349

The Rectum is the fixed, primarily retroperitoneal and subperitoneal, terminal part of the large intestine. o First Third • Peritoneum covers the anterior and lateral surfaces o Middle Third • Peritoneum only covers the anterior surface o Final third • No covering, as it is subperitoneal The rectum is continuous with the sigmoid colon at the level of S3 vertebra. At this point, the rectosigmoid junction, the teniae coli of the sigmoid colon spread to form a continuous outer longitudinal layer of smooth muscle.

Answer 350

Venous drainage of the rectum is through the Superior, Middle and Inferior Rectal Veins. The Superior Rectal Vein drains into the IMV, then the Splenic and Portal vein The Middle and Inferior Rectal veins drain into the systemic system.

Answer 351

The anastomoses between the Portal and Systemic venous systems in the Rectum/Anal Canal are clinically important in Portal Hypertension (varices).

Answer 352

The anal canal is the terminal part of the large intestine and of the entire digestive canal. The canal begins where the Rectal Ampulla narrows at the level of the U-shaped sling formed by the puborectalis muscle, and ends at the Anus. The anal canal, surrounded by internal and external anal sphincters, descends posteroinferiorly between the anococcygeal ligament and the perineal body. The canal is collapsed, except during the passage of faeces. Both sphincters must relax before defecation can occur. Internally, the superior half of the mucous membrane of the anal canal is characterised by a series of longitudinal ridges called anal columns. These columns contain the terminal branches of the superior rectal artery and vein (see above). The anorectal junction, indicated by the superior end of the anal columns is where the rectum joins the anal canal. At this point the rectal ampulla abruptly narrows as it traverses the pelvic diaphragm. The inferior ends of the anal columns are joined by anal valves and superior to the vales are Anal Sinuses. When compressed by faeces, anal sinuses exude mucus, which aids in evacuation of faeces from the anal canal. The inferior comb like shape of the anal valves forms an irregular line, the Pectinate line. The anal canal superior to the Pectinate line differs from the part inferior to the Pectinate line in its arterial supply, innervation and lymphatic drainage. These differences result from their different embryological origins.

Answer 353

Above the Pectinate line, the Anal Canal is derived from the Hindgut, thus its blood supply is from the IMA, via the Superior Rectal artery Below the Pectinate line, the Anal Canal is derived from Endoderm and gains its blood supply from the two Inferior Rectal Arteries. The Middle Rectal Arteries assist with the blood supply to the anal canal by forming anastomoses with the Superior and Inferior Rectal Arteries.

Answer 354

Above the Pectinate line, nerve supply is visceral. Therefore superior to the Pectinate line, the anal canal is sensitive only to stretching. All visceral afferents travel with the parasympathetic fibres to spinal sensory ganglia S2-S4 (referred pain). Below the Pectinate line, nerve supply is somatic, derived from the Inferior Anal Nerves, branches of the Pudendal Nerve. Therefore, below the Pectinate line, the Anal Canal is sensitive to pain, touch and temperature, and pain is well localised.

Answer 355

In males, after the second third of the rectum, the peritoneum reflects onto the posterior wall of the bladder, forming the floor of the rectovesical pouch.

Answer 356

In females, after the second third of the rectum, the peritoneum reflects onto the posterior part of the fornix of the Vagina, forming the floor of the rectouterine pouch.

Answer 357

The peritoneal reflection in females between the Uterus and Urinary Bladder

Answer 358

The stomach empties chyme into the duodenum, where it is conditioned: o Acidic • Corrected by HCO3- secreted from the pancreas, liver and Duodenal mucosa • HCO3- produced during the production of Gastric Acid o Hypertonic • Corrected by the osmotic movement of water into the duodenum across its wall o Partly digested • Digestion completed by enzymes from the pancreas and Duodenal mucosa, with bile acids from the liver.

Answer 359

``` Absorption requires a large surface area, to which the luminal contents of the small intestine need to be exposed to through gentle agitation for hours. The small intestine is very long and the surface area for absorption is increased by millions of villi projecting into the lumen. Epithelial cells (enterocytes) arise by rapid division in the crypts between the villi, and migrate towards the tips, from which they are shed. They mature as they migrate and their luminal surface is covered with millions of micro villi, further increasing the surface area and forming the brush border. The brush border forms an ‘unstirred layer’ where nutrients meet and react with enzymes secreted by the enterocytes, completing digestion prior to absorption. ```

Answer 360

The large intestines absorb water from the indigestible residues of chyme, converting it into semi-solid stool or faeces that is stored temporarily and allowed to accumulate until defecation occurs. The large intestines have teniae coli (thickened bands of smooth muscle, representing most of the longitudinal coat). They run the length of the large intestine, and because their tonic contraction shortens the part of the wall with which they are associated, the colon becomes sacculated or ‘baggy’ between the teniae, forming Haustra.

Answer 361

``` o Secrete protease / carbohydrase enzymes to complete digestion o Secrete Hormones • Secretin • Gastrin • Cholecystokinin ```

Answer 362

``` o Bile and Pancreatic Secretions added • Ampulla of Vater o Secretes HCO3- to neutralise Chyme o Osmotic movement of water into the Duodenum, making Chyme more hypotonic o Absorption • Iron ```

Answer 363

``` o Absorption • Carbohydrates • Amino Acids o Small enough to soak through the villi • Fatty acids • Vitamins • Minerals • Electrolytes • Water ```

Answer 364

o Absorption • Vitamin B12 • Bile • Anything not absorbed by the jejunum

Answer 365

Takes about 16 hours to finish the digestion of food. o Absorption • Water • Any remaining absorbable nutrients • Vitamins created by colonic bacteria o Vitamin K, B12, Thiamine, riboflavin o Sends indigestible matter to the rectum

Answer 366

o Faeces | • Stores and compacts faecal matter

Answer 367

Carbohydrates are ingested in the form of amyloses, amylopectins or disaccharides such as sucrose. o Amylose – Straight chain a-1,4 bonds o Amylopectin – Branched with a-1,6 bonds at branches a-Amylases act on a-1,4 bonds, and are secreted in saliva and by the pancreas. They yield glucose and maltose from amyloses, and a-limit dextrins from amylopectins. Brush Border Enzymes complete breakdown to glucose. o Isomaltase • Breaks down branched molecules at a-1,6 bonds o Maltase- Maltose to Glucose o Sucrase- Sucrose to Glucose/Fructose diamer o Lactase- Lactose to Glucose/Galactose diamer

Answer 368

Glucose is absorbed actively using the energy from a Na+ gradient set up by Na/K/ATPase in the basolateral membrane. Glucose enters the epithelial cell across its apical membrane via a Na+/Glucose Symporter, SGLT1. This transporter also transports Galactose. Glucose then leaves the epithelia cell into the bloodstream across its basolateral membrane via facilitated diffusion through the GLUT2 transporter. Fructose enters the cell from the lumen via facilitated diffusion

Answer 369

Proteins are digested to short peptides, 10-20 AA’s long (oligopeptides) in the stomach by Pepsin secreted from chief cells. In the Duodenum, Peptidases are secreted from the pancreas. Different enzymes ‘prefer’ breaking different bonds: o Pepsin- Bonds near aromatic AA side chains o Trypsin- Bonds near basic AA side chains o Chymotrypsin- Bonds near aromatic AA side chains o Carboxypeptidase- C-terminal AA’s with basic side chains Both amino acids and small peptides (2/3 AA’s) are absorbed. Further to this, in neonates our guts are ‘open’, so they are able to pick up whole proteins. This allows breast milk to confer passive immunity on babies via IgA absorption.

Answer 370

Active Uptake of Amino Acids There are at least five Na+/Amino acid Co-transporters (below), which work in a similar way to the uptake of glucose by using the Na+ gradient set up by Na-K-ATPase. o Small, neutral AA’s o Neutral AA’s, Basic AA’s and Cystine o Acidic AA’s o Imuno-AA’s o B-AA’s (Mainly Taurine) Some AA uptake is by facilitated passive diffusion. Dipeptides and tripeptides are taken up by an active mechanisms associated with pumping H+ into the lumen, which then returns by co-transport with the peptide.

Answer 371

Fats are relatively insoluble in water, making them tend to aggregate into large globules, preventing the effective action of digestive enzymes. Acid in the stomach exacerbates this. In the duodenum, bile acids enable fats to be incorporated into small (4-6nm) micelles, with fats in the middle and the polar components of bile acids on the outside. These micelles generate a high surface area for the action of lipases, which cleave the fatty acids from glycerol. The micelles also carry these products into the ‘unstirred layer’ immediately next to the mucosa, where fatty acids can be released to slowly diffuse into the epithelial cells. Once inside the epithelial cells they are reconstituted into triacylglycerols and re-expelled as chylomicrons, structured small particles made up of lipids covered in phospholipids, which facilitate the transport of fat in the lymphatic system from the gut to systemic veins.

Answer 372

Sodium is taken up via diffusion into the cell, and actively transported across the basolateral membrane by Na-K-ATPase. This provides the driving force for the majority of absorption (see above). Chloride follows the movement of Na+. The movement of the two ions, coupled with all of the absorption, gives an Osmotic Gradient leading to the uptake of water.

Answer 373

o 700mg/day absorbed out of 6g consumed (Just > 10%) o Enters the cell by facilitated diffusion • Low Intracellular concentration o Pumped out of basolateral membrane by Ca2+-ATPase o Both processes require Vitamin D o Stimulated by Parathyroid Hormone (PTH)

Answer 374

o 20mg a day of Iron is consumed • Mostly haem o Iron can only be absorbed in it’s ferrous form (Fe2+) • Gastric acid solubises iron complexes (Makes it ferrous) • Stomach also secretes Gastroferrin (Binds iron and keeps it ferrous) Intestinal mucosal cells secrete transferrin, which finds to ferrous iron (Fe2+) in the lumen. The complex is taken into cells by endocytosis, split and the iron is exported to the blood, where it binds again to transferrin.

Answer 375

Water-soluble vitamins are absorbed via passive diffusion • Vitamin C, B vitamins o Vitamin B12 is absorbed with a co-factor in the terminal ileum only • Intrinsic Factor – Binds to B12 in the stomach to keep it soluble • Secreted by the stomach mucosa Pernicious anaemia occurs with Vitamin B12 deficiency. It occurs when there is damage to the stomach, preventing it from secreting intrinsic factor, or the terminal ileum has been damaged (e.g. Crohn’s) or removed.

Answer 376

o The uptake of Na+ generates an osmotic gradient, which water follows. o Glucose uptake stimulates Na+ uptake, plus generates its own osmotic gradient So a mixture of glucose and NaCl will stimulate maximum water uptake. This is known as Oral Rehydration Fluid.

Answer 377

Intestinal contents must move very slowly (transit time in hours), whilst being gently agitated for effective absorption. This is achieved by a pattern of motility called Segmenting, which is very different to peristalsis. The small intestine is divided into sections, each with a pacemaker. The frequency of the pacemaker gets less from the duodenum to the terminal ileum (12 times a minute à 8), a phenomenon known as the intestinal gradient. Each pacemaker drives a small section of intestine, causing intermitted contraction of smooth muscle along its length. These contractions separate the intestine into segments where the muscle is not contracted, whose contents are effectively mixed by movement from the portions that do contract. After a few seconds he contractions relax, and at the next pacemaker firing different areas contract. Segmenting itself does not propel contents along the intestine, merely mixes the contents. The intestinal gradient however means that there is a net movement, albeit slow, in a caudal direction.

Answer 378

The large intestine is divided naturally into segments known as Haustra, as the circular muscles are more complete than the longitudinal, which have been reduced to taenia coli (thick circular muscle, thin longitudinal – only 3 layers). Contraction of the smooth muscle in the walls of the Haustra shuffles the contents back and forth, as the slow absorption of remaining water and salts forms faeces. The contents slowly progresses towards the sigmoid colon, with control like segmenting.

Answer 379

Mass Movement Infrequently (once or twice a day), there is a Peristaltic, propelling pattern from the transverse through to the descending colon. This forces faeces rapidly into the rectum, which is normally empty, inducing the urge to defecate. Mass movement is often triggered by eating, the Gastro-colic reflex. They often also happen at certain times of the day, as “people like to be regular”.

Answer 380

Once mass movement has filled the rectum, the urge to defecate arises due to pressure receptors. Waves of contraction in the rectal muscle then force faeces towards the anus. ``` Anal Sphincters Internal o Smooth Muscle o Parasympathetic control • Relaxes ``` External o Voluntary Striated Muscle o Voluntary (normally) control • Relaxes Once both sphincters are relaxes, intra-abdominal pressure is increased (forces expiration) and there is an expulsion of faeces. The voluntary control of the external sphincter is overridden if rectal pressure becomes too high.

Answer 381

``` o Ulcerative Colitis o Crohn’s Disease o Diversion Colitis o Diverticular colitis o Radiation, Drug, Infectious, Ischaemic Colitis ```

Answer 382

``` o Synthesise and excrete vitamins • Vitamin K, Vitamin B12, Thiamine o Prevent colonisation by pathogens • Space, Bacteriosides o Kill non-indigenous bacteria • Bacteriosides o Stimulate the development of GALT o Stimulate production of natural antibodies ```

Answer 383

o Parts of the mouth o Tongue, deep in taste buds, biofilm between teeth, gingival crevice areas o Small Bowel o Colon

Answer 384

The mouth has many Anaerobic bacteria, therefore can cause very nasty/fatal infections o Streptococci • Streptococcus mutans cause dental caries/gingivitis (dental plaque) o Staphylococci • Staphylococcus aureus can cause Parotitis o Candida • Oral Thrush, caused by Candida Albicans o Lactobacillus o Enterococcus

Answer 385

In a malnourished, dehydrated, immunocompromised or systemically unwell patient, these bacteria can cause tissue destruction, known as Noma / Cancrum Oris.

Answer 386

The nose has Staphylococcus and Streptococcus amongst many others. The nose is one of three sites for MRSA screening swabs (Nose, Throat, Perineum), as these are the three sites where Staphylococci are normally found.

Answer 387

``` o Strep. Viridans • 100% of people • Non-pathogenic throat commensal • During teeth brushing, dental procedures and general anaesthesia may enter the blood stream (Bacteraemia) o Strep. Pyogenes • Tonsillitis (30%, 70% is viral) o Strep. Pneumoniae • Community acquired pneumonia (30%) o Staphylococci • 100% of people o Neisseria Meningitidis • 100% of people o Haemophilus Influenzea • Community acquired pneumonia (13%) o Lactobacilli • Makes vagina acidic, so Candida Albicans can’t grow (Thrush) o Corynebacterium Diptheriae o Candida Albicans • Oral/vagina thrush ```

Answer 388

o 70% Viral • Adenovirus, Rhinovirus, Epstein-Barr Virus (EBV) o 30% Bacterial • Step. Pyogenes

Answer 389

o Helicobacter Pylori • At least 50% of the worlds population is infected • Only 10-20% infected develop gastric/duodenal ulcers • Associated with 90% of Duodenal and 70% of Gastric ulcers

Answer 390

``` More than 100 species regularly exist in the colon of humans, 95-99% of which are anaerobes, particularly Bacteroides and Clostridial species. o Always present in the colon • Bacteroides fragillis • Bacteroides oralis • Bacteroides melaninogenicus • E. Coli – Most common cause of UTI • Enterococcus faecalis – Second most common cause of UTI o Other Colonic Bacilli (Gram –‘ve Enteric Bacilli) • Pseudomonas • Proteus • Klebsiella • Salmonella • Shigella • Vibrio cholera • Campylobacter ```

Answer 391

Although it is only the colon that normally contains large numbers of bacteria, if we are operating on the small bowel it will be abnormal. This all gut surgery is viewed as ‘dirty surgery’ with a high risk of wound infection. To reduce surgical wound infection, antibiotics are given prophylactically. They need to be able to cover Anaerobes, Gram –‘ve Bacilli and Gram +’ve Bacilli. Metronidazole kills anaerobes, so it is given with a broad-spectrum antibiotic such as Gentamicin or Cephalosporin.

Answer 392

When faeces containing huge amounts of bacteria gains entry to the otherwise sterile peritoneum. Has a high mortality rate, even in young fit people, due to the huge numbers of bacteria floating free in the peritoneum.

Answer 393

Glands in the anal canal produce mucus for lubrication to aid with passing faeces. Infection of them leads to abscess around the anus – perianal abscess.

Answer 394

Lactobacillus (Gram +’ve Bacilli) is a normal vaginal flora organism. It converts glycogen into lactic acid, providing an acidic environment to prevent other bacteria and candida albicans from growing (Thrush).

Answer 395

o Bacteroides --> Cannot survive O2 --> Not present o E. Coli --> Can survive O2 --> Present o Enterococcus faecalis --> Can survive O2 --> Present o Lactobacillus --> Can survive O2 --> Present

Answer 396

90% of UTIs occur in women, as there is a much shorter distance from the anus to the urethra. The commonest causative organism is E. coli, followed by Enterococcus faecalis and thereafter various Gram –‘ve enteric bacilli (Klebsiella, Proteus, Pseudomonas).

Answer 397

Tetani – Tetanus o Neonatal tetanus kills 60,000 a year Difficile – Pseuomembranous colitis o Severe inflammation of the colon o Often arises after antibiotic treatment o Produces spores, which are present in hospitals Perfringens – Gas/wet gangrene o Anaerobic digestion of glucose leads to ethanol + CO2 (Fluid plus gas), thus wet or gas gangrene

Answer 398

Every year there are epidemics of viral infections, often noro-viruses that produce a short period of vomiting and diarrhoea.

Answer 399

Gastroenteritis (Food Poisoning) may follow consumption of food or drink contaminated with organisms or toxins, often of bacterial origin but already present in food. In both cases there is vomiting and diarrhoea. Onset is very rapid if toxins are ingested, within a very small number of hours, but may take up to 48 hours if caused by organisms. The most common organisms are strains of Salmonella, Campylobacter and Listeria. Toxins may come from Staphylococcus and Clostridium.

Answer 400

Cholera is a severe acute infection, which is endemic in many parts of the world and periodically occurs in epidemics that are a real risk after natural disasters. The organism responsible, Vibrio Cholerae survives in water supplies and has a very specific effect on the ileum, leading to massive movement of water and salt into the lumen by active secretion. This leads to very serious diarrhoea, which after initial evacuation has a characteristic ‘rice-water’ appearance made up of intestinal secretions plus mucus. Rapid, severe dehydration follows, which is severely life threatening. Management must replace lost water and electrolytes with appropriate replacement fluids.

Answer 401

Intestinal parasites are common around the world and can cause a variety of effects. Some protozoans such as Giardia and Cryptosporidium cause Gastroenteritis. Other Helminth infestations may lead to Malabsorption amongst other effects.

Answer 402

In Bacteraemia, the bacteria are rapidly cleared from the bloodstream (by liver/spleen macrophages). No symptoms are produced.

Answer 403

In Septicaemia, bacteria are not cleared and multiply in the blood stream. Sepsis symptoms develop.

Answer 404

Enterotoxinogenic E. Coli (ETEC) is a major cause of Travellers’ diarrhoea in developing countries, caused by heat stable or labile toxins produced from this serotype, which results in severe, cholera-like watery diarrhoea. There is no inflammation and the condition is usually self-limiting.

Answer 405

Amphotericin lozenges

Answer 406

Extremely enlarged tonsil on one side due to an abscess - deviates uvula - struggle to inhale - pop quinsy with scalpel - patients swallow pus - -> but internal carotid artery lies just behind

Answer 407

o Wide Geographical variation • Incidence low in USA, and high around Caspian sea and parts of China o 2% of malignancies in the UK • Males > Females

Answer 408

o Dysphagia • Progressively worsening as tumour grows and occludes lumen o Weight loss

Answer 409

Endoscopy Biopsy Barium swallow

Answer 410

``` o Squamous cell carcinoma • Commonest type • May occur at any level o Adenocarcinoma • Uncommon • Lower third • Association with Barrett’s oesophagus ```

Answer 411

Advanced disease at presentation in most cases o Direct spread through the oesophageal wall o Only 40% resectable o 5% five year survival

Answer 412

``` Gastric cancer is the second most common GI malignancy, with approximately 11,000 new cases in England and Wales each year. o Common • 15% of Cancer deaths worldwide o Men > Women o Geographical variation • Common in Japan, Columbia, Finland o Associated with Gastritis o Commoner in Blood Group A ```

Answer 413

o Symptoms often vague | • Epigastric pain, vomiting, weight loss

Answer 414

Endoscopy Biopsy Barium swallow

Answer 415

o Fungating o Ulcerating o Infiltrative • Linitis plastica

Answer 416

o Intestinal • Variable degree of gland formation o Diffuse • Single cells and small groups, signet ring cells

Answer 417

``` Early Gastric Cancer o Confined to mucosa/sub-mucosa o Good Prognosis Advanced Gastric Cancer o Further spread o Common in the UK o ~10% 5 year survival ```

Answer 418

``` Spread o Direct • Through gastric wall into duodenum, transverse colon, pancreas o Lymph nodes o Liver o Trans-Coelomic • Peritoneum • Ovaries ```

Answer 419

There is a general association of chronic inflammation with cancer. Gastric cancer is common in countries with high H. Pylori prevalence, e.g. Columbia. The association is supported by serological and epidemiological evidence.

Answer 420

o The commonest GI Lymphoma o Starts as a low-grade lesion o Strong association with H. Pylori o Eradication of H. Pylori may lead to regression of tumour o Prognosis much better than gastric cancer

Answer 421

o Uncommon o Derived from interstitial cells of Cajal o The causative mutation, C-kit (CD117) makes it vulnerable to targeted treatment o Unpredictable behaviour • Pleomorphism • Mitoses • Necrosis

Answer 422

``` o Adenomas • Benign, neoplastic lesions in the large bowel (Dysplasia) • Familial Adenomatous Polyposis (FAP) • Gardner’s Syndrome o Adenocarcinomas o Polyps o Anal Carcinoma ```

Answer 423

FAP An autosomal dominant condition on Chromosome 5. By the time the patient is 20 there are thousands of adenomas in the large intestine, giving a high risk of cancer.

Answer 424

Gardner’s is similar to FAP, with bone and soft tissue tumours.

Answer 425

Benign, neoplastic lesions in the large bowel (Dysplasia) o Macroscopic • Sessile or pedunculated o Microscopic • Variable degree of dysplasia o Malignant Potential o Incidence increases with age in western population o Genetic Syndromes- Familial Adenomatous Polyposis (FAP), Gardner’s Syndrome

Answer 426

Rare and unpredictable neuro-endocrine tumour

Answer 427

Rare, may be primary or spread from elsewhere

Answer 428

Rare and unpredictable

Answer 429

``` Morphology o 2/3 in the head o Firm pale mass with a necrotic centre o May infiltrate adjacent structures, e.g. the spleen Histology o 80% are ductal adenocarcinomas o Well formed glands o Some acinar tumours contain zymogen granules o All types have poor prognosis ```

Answer 430

The bile duct is blocked with only a small tumour, leading to jaundice and early presentation when the tumour is still treatable.

Answer 431

``` o Rare o Insulinoma -Hypoglycaemia o Glycagonoma -Characteristic skin rash o Vasoactive Intestinal Peptideoma (VIPoma) -Werner Morrison syndrome o Gastrinoma -Zollinger-Ellison syndrome ```

Answer 432

``` Benign tumours are fairly rare o Hepatic adenoma o Bile duct adenoma/hamartoma o Haemangioma Malignant o Hepatocellular carcinoma o Cholangiocarcinoma o Hepatoblastoma ```

Answer 433

``` Contrast is used to define hollow viscera. Examples of contrast that is used include Barium and water soluble contrast (typically using iodine). • Barium swallow • Barium enema • Barium meal/follow through • Water soluble contrast studies ``` A Barium Enema is a Barium study where the contrast medium is inserted rectally. This study enables the colon to be visualized.

Answer 434

o Use of sound waves to generate image • Frequency above audible range of human hearing (20 KHz) • Usually 2-18 MHz o Cheap compared to CT and MRI o Portable o Highly user dependent Can be used to determine if a patient has Gallstones, or to see if the common bile duct is dilated (an indicator that there is an impacted gallstone in the duct). Abdominal ultrasound scan can also view the Liver and portal vein, even the Appendix. These scans are often difficult to interpret and the usefulness of a scan is often down to who is doing and interpreting the scan.

Answer 435

For both bleeding and ischaemia, being able to visualise the Blood supply to the GI tract is very useful. This is done by injecting a radio-opaque contrast agent intravenously and then using various modalities to capture the images.

Answer 436

Features of an AXR o Stomach o Small and Large Bowel o Soft Tissues o Liver, spleen, kidneys, psoas muscles, bladder, lung bases o Bones Any part of a hollow tube is visible on an X-ray if it is filled with gas (Low density gas acts as a contrast). Fully fluid filled lumens are not visible. You can visualise the stomach (if gas filled) but more commonly we use this to visualise the small bowel.

Answer 437

o Acute abdominal pain o Small or large bowel obstruction o Acute exacerbation of IBD o Renal colic

Answer 438

The small bowel Usually occupies a central position on the Abdominal X-ray and can display its ‘circular folds’ or Valvulae conniventes, which appear as lines that appear to cross the whole of the bowel lumen Large bowel In contrast to the small bowel, this usually occupies a more peripheral position on the abdominal X-ray. It is often possible to see the Haustra on the X-ray, which appear as incomplete lines going across the lumen. Faeces can also appear on the X-ray and this can look like clouds in the lumen.

Answer 439

Small and large bowel obstruction can be noted and follow the rule of 3/6/9. o The small bowel is said to be dilated when it is greater than 3cm diameter. o The large bowel when it is greater than 6cm o The Caecum (when the ileocaecal valve is working) is said to be dilated when it is greater than 9cm o This only applies when the X-ray shown is to scale. You can’t tell on these pictures!

Answer 440

Small bowel usually presents with vomiting (early) and mild distension. Absolute constipation (not passing anything per rectum, even flatus) is a late feature. You vomit early simply because the obstruction is nearer the mouth than a large bowel obstruction. For the same reason constipation is a late feature in small bowel obstruction. There will be colicky pain that presents every 2-3 minutes.

Answer 441

``` o Adhesions o Hernias • Inguinal, Femoral, Incisional o Tumours o Inflammation ```

Answer 442

This presents with abdominal pain and distension with constipation as an early feature (nothing can pass into the rectum and out). The pain is also colicky but not as frequent as small bowel obstruction (every 10-15 minutes). Vomiting is a late feature of large bowel obstruction (it has further to travel to the mouth) and can be faeculant.

Answer 443

``` o Colorectal carcinoma o Diverticular stricture o Hernia o Volvulus o Pseudo-obstruction ```

Answer 444

This is when a viscera twists around itself or more commonly when it twists around its mesentery. Most common is a Sigmoid volvulus or more rarely Caecal volvulus. When this twisting occurs the enclosed loop of bowel dilates and is at risk of perforating or cutting of its blood supply (which runs in the mesentery). At this stage we would not expect you to be comfortable interpreting a volvulus on an abdominal X-ray. I would like you to be aware that it can happen though and what it means

Answer 445

``` o Pancreatitis (chronic) o Aneurysms with calcification o Nodes o Bones o Artifact o Foreign body o Kidney Stones ```

Answer 446

An Erect Chest X-ray can be useful in diagnosing perforated bowel.

Answer 447

``` o Peptic ulcer o Diverticular disease o Tumor o Obstruction o Trauma o Iatrogenic ```

Answer 448

The CXR needs to be erect because you are looking for the diaphragm to be elevated away from any other viscera (the Liver on the right) by the presence of air/gas in the peritoneal cavity. The air/gas will rise to the top of the cavity and so the patient needs to be sat up for 10 minutes prior to the X-ray to ensure this happens. The peritoneal cavity only normally contains a small amount of fluid, so the presence of air/gas is abnormal and could be the result of perforated bowel.

Answer 449

Abdominal CT o High dose radiation o Good spatial resolution (poor contrast resolution vs MRI) o Use of IV or oral/rectal contrast Can be done in a variety of anatomical planes

Answer 450

``` Magnetic resonance imaging (MRI) o Magnetic resonance imaging o First human MRI scan 1977 (in the US) • However developed by Sir Peter Mansfield (University of Nottingham) o No radiation o Good spatial and contrast resolution o Time consuming ```

Answer 451

Magnetic resonance cholangio-pancreatogram (MRCP) is an MRI scan that can visualize the Gallbladder and biliary tree.

Answer 452

UDP- Glucuronyl transferase

Answer 453

Congenital disease Deficiency in UDP- glucuronyl transferase deficiency Bilirubin can't be conjugated (made soluble) in liver High concentration of unconjugated bilirubin in blood

Answer 454

Private study session 8

Answer 455

Increased mean cell volume (MCV) hypersegmented neutrophils hemolysis with reticulocytosis leukopenia and thrombocytopenia.

Answer 456

Werner Morrisons syndrome Vasoactive intestinal polypeptide Stimulates bowel muscle Diarrhoea

Answer 457

Zollinger-Ellison syndrome Produce acid in excess Prolonged gastric irritation