3 Flashcards
Which arteries innervate the foregut, midgut and hindgut?
Foregut – celiac artery
Midgut – superior mesenteric artery
Hindgut – inferior mesenteric artery
What is the mesogastrium?
The middle region of the abdomen between the epigastrium + the hypogastrium
There is a ventral + dorsal mesogastrium
How is the lesser sac (a.k.a. omental bursa) formed?
It’s a hollow space formed by the greater & lesser omentum and its adjacent organs
Which direction does the line of attachment of the ventral and dorsal mesogastrium swing to as the foregut develops
The line of attached of the ventral mesogastrium swings the R and forms the lesser curve and top of proximal duodenum.
The line of attachment of the dorsal mesogastrium swings to the L and forms the greater curve of the stomach and underside of the proximal duodenum.
Where does the ventral mesogastrium line of attachment run along?
Lesser curve of the stomach
Where does the dorsal mesogastrium line of attachment run along?
Greater curve of the stomach
Which section is the distal duodenum a part of?
Dorsal mesogastrium.
Which section is the ascending and descending colon a part of?
Ascending colon – midgut
Descending colon – hindgut
What is the distal 1/3 of the transverse colon a part of?
Hindgut
What is the digestive tract composed of?
The GIT and accessory digestive organs
List the accessory digestive organs
Teeth, tongue, salivary glands, liver, gallbladder and pancreas
Why is rugae needed in the stomach?
Rugae – series of ridges produced by folding of the wall of an organ.
The function of the gastric rugae is to allow the stomach and other tissue to expand as needed to assist in the digestion of food.
Which plane does the pyloric sphincter lie on?
Transpyloric plane
Which order do the following go in from stomach to anus: caecum, transverse colon, left colic flexure jejunum, ilium, duodenum, descending colon, ascending colon, sigmoidal colon, right colic flexure.
Stomach, duodenum, jejunum, ilium, caecum, ascending colon, , transverse colon, , descending colon, sigmoid colon, rectum, anus
What is the duodenum involved in breaking down mainly?
Proteins
What are Brunner’s glands and where are they located?
Produce mucus-rich alkaline secretion containing bicarbonate.
What are micelles?
Lipid molecules that arrange themselves in a spherical form in aqueous solutions.
What is the epithelial layer of the GIT?
It’s part of the mucosa layer directly in contact w/ contents of the GIT lumen
What does the submucosa consist of?
Areolar connective tissue; has many blood and lymph vessels, submucosa plexus, glands
What are the 2 main types of nerves that are innervating the GIT?
Intrinsic (ENS) and extrinsic (ANS)
What does stimulating the parasympathetic system do in the GIT?
Increases GI secretions and motility by increasing enteric nervous system activity.
What do the plexuses of ENS in GIT contain?
Motor neurons interneurons, sensory neurons
What kind of emotions may slow down digestion?
Anger, fear, anxiety
What lies between the layers of muscularis?
Myenteric plexus
What is ascites?
When peritoneal cavity becomes distended by fluid accumulation in certain diseases
What does that peritoneum consist of?
Simple squamous epithelium layer (mesothelium) w/ underlying supporting layer of areolar tissue.
What makes peritoneum different to pericardium and pleura?
Peritoneum is the largest serous membrane of the body.
It has folds that binds organs to each other and to walls of abdominal cavity.
What is the purpose of the folds of the peritoneum?
Mesentery and mesocolon – hold intestines loosely allowing muscular movements w/ contractions.
Protection from damage
Attaches organs to abdominal cavity.
What is the largest peritoneal fold called?
Greater omentum
What attaches the liver to the anterior abdominal wall and diaphragm?
Falciform ligament
What does the mesentery fold do?
Binds jejunum and ileum to posterior abdominal wall
List the 5 peritoneal folds.
Greater omentum, faliciform ligament, lesser omentum, mesentery, mesocolon
Which peritoneal fold binds the transverse colon and sigmoid colon to the posterior abdominal wall?
Mesocolon
Which peritoneal fold attaches the stomach, duodenum and transverse colon?
Greater omentum
How many layers does the greater omentum have?
4 layers because it doubles back onto itself
Where does the lesser omentum attach?
Stomach and duodenum to the liver.
What do the 3 muscles of the tongue with the prefix ‘–glossus’ do?
They are the extrinsic muscles that manoeuvre food for chewing, shaping into rounded mass and force food to back of mouth for swallowing.
Which tongue muscles are used for speaking and swallowing?
Intrinsic
What type of epithelium does the oral mucosa have?
Thick stratified squamous
Why is the epithelium thick?
Because oral; cavity lining is subject to lots of tear and tear
Which areas of the oral cavity has keratinised epithelium and why?
Keratinised – gums, hard palate, upper surfaces e.g. tongue
Unkeratinised – mobile areas (soft palate, cover surface of tongue, floor of mouth, cheeks lips)
What would happen is a salivary gland is occluded?
Painful, cause enlargement of gland, infection can contract into the gland from oral cavity
What are the vestibule and oral cavity?
Vestibule – space between lips and teeth
Oral cavity proper – behind teeth and gums to fauces (opening between oral cavity and throat)
Name the 3 types of salivary glands and say where they are found
Parotid– inferior and anterior to ears.
Submandibular – medial and inferior to body of mandible
Sublingual – under tongue and mylohyoid muscle
Which salivary gland consists of only serous acini?
Parotid
Which of the salivary glands are the largest? Where does its duct open into the mouth?
Parotid, parotid duct pierces buccinator muscle to open into vestibule (opposite upper 2nd maxillary molar)
Which salivary glands lie between (under) the tongue and mylohyoid muscle?
Sublingual
Are the submandibular or sublingual glands most superior and lateral?
Sublingual glands are superior and lateral to submandibular glands
What are the boundaries of the mouth? – roof, floor, lateral walls, anterior, posterior
Roof – hard and soft palate Floor – mylohyoid muscle Lateral walls – cheeks (buccinator muscles, connective tissue, mucous membrane, skin) Anterior – labia Posterior – palatoglossal folds
List the 4 muscles of mastication and their functions.
Temporalis – elevation and retraction of mandible
Masseter – elevation of mandible
Lateral pterygoid – protrusion and side-to-side movements of mandible
Medial pterygoid – elevation and side-to-side movements of mandible
What is the 5th muscle that is an accessory muscle of mastication?
Buccinator – accessory mastication muscle
What is the function of the motor neurons of the myenteric plexus?
Control gut motility
What is the function of the motor neurons of the submucosal plexus?
Control secretion
What are the 2 types of sensory neurons of the ENS of the GIT?
Chemoreceptors – responds to chemical changes in food within the lumen
Mechanoreceptors – activated when food distends the walls of GI organs
What is the function of the sensory neurons in the GIT?
Detect stimuli in the lumen
Where is the submucosal plexus found?
Within the submucosa
Where is the myenteric plexus found?
Between the longitudinal and circular smooth muscles of the muscularis layers.
What are retroperitoneal organs?
Give examples.
Organs that lie on posterior abdominal wall and are covered by peritoneum only
What does parietal peritoneum line?
Walls of abdominal cavity
What does visceral peritoneum line?
Some of the organs in the cavity
Where does the peritoneal cavity lie relative to the parietal and visceral peritoneum?
Between them, Contains lubricating serous fluid.
What is the tongue composed of?
Skeletal muscle
What is the tongue covered with?
Mucous membranes
What are the 2 types of muscles of the tongue?
What is their function?
Extrinsic – move tongue side-to-side, in and out (manoeuvre food)
Intrinsic – alter shape and size (for speaking and swallowing)
Which nerve innervates the teeth and gums?
Maxillary nerve
Where does the oropharynx lie relative to the oral cavity?
Behind the oral cavity
What are the folds running off from either side of the uvula?
Anterior fold – palatoglossal fold
Posterior fold – palatopharyngeal fold
What is located between anterior (palatoglossal) and posterior (palatopharyngeal) folds?
Tonsillar fossa
What are fauces?
Arched opening at back of the mouth leading to the oropharynx
What is the function of the uvula?
Prevents swallowed food from entering nasal cavity
What are the functions of the incisors, canines, premolars and molars?
Incisors – cut food
Canines – tear food
Premolars – crush and grind food
Molars – grind food
At which vertebral level does the pharynx end?
C6
Where does the oesophagus start and end relative to the vertebral levels?
C6 – start
T10 – end
Where does the oesophagus pierce the diaphragm?
T10
What is the narrowing where the pharynx and oesophagus meet called?
Pharyngo-oesophageal narrowing
What type of muscle is the upper and lower oesophageal sphincters made from?
Upper – skeletal
Lower – smooth
Which sphincter prevents gastro-oesophageal reflux?
Lower oesophageal sphincter
List the 3 anatomic constrictions of the oesophagus.
Pharyngo-oesophageal narrowing
Upper oesophageal sphincter
Lower oesophageal sphincter
What is the histological change that occurs at the gastro-oesophageal junction?
Pink stratified squamous epithelium to red simple columnar epithelium
What is Barrett’s oesophagus and what causes it?
When there is too much acid reflux in the stomach and it enters the oesophagus.
The oesophagus protects itself by changes its epithelium into gastric epithelium.
What is the histological colour change at the gastro-oesophageal junction. And what causes it?
Pink to red
The blood vessels are closer to surface with a simple columnar layer and more further away with the pink stratified squamous epithelium.
Name the vertical lines that make up the 9 divisions of the abdominal regions
L and R midclavicular lines
Name the horizontal lines that make up the 9 divisions of the abdominal regions
Transpyloric plane
Transtubercular plane
The stomach is fixed proximally at the what?
Diaphragm
What is the distance from incisors to gastro-oesophagus junction?
40cm
What nerve supplies the stomach?§
- Sympathetic fibres via splanchnic nerves and celiac ganglion supply blood vessels and musculature
- Parasympathetic fibres from the medulla travel in the gastric branches of the vagi
- Sensory vagal fibres – gastric secretion.
What nerve supplies the stomach?
- Sympathetic fibres via splanchnic nerves and celiac ganglion supply blood vessels and musculature
- Parasympathetic fibres from the medulla travel in the gastric branches of the vagi
- Sensory vagal fibres – gastric secretion.
What nerve supplies the jejunum and ileum?
Lesser splanchnic nerves
What nerve supplies the gallbladder?
Celiac plexus supplies sympathetic innervation, the vagus nerve supplies parasympathetic innervation, and the right phrenic nerve conveys sensory information.
List the 4 functions of the stomach
Mixes saliva, food, gastric juice to form chyme
Secretes gastrin into blood
Secretes gastric juice which contains HCl, pepsin, intrinsic factor
What is a peritoneal organ? Give an example.
Organ wrapped in peritoneal lining. E.g. stomach
What is gastrin?
What function does it have?
A peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility.
What is gastrin secreted by?
Secreted by: G cells in the pyloric antrum (stomach), duodenum, pancreas
What is the function of the ligament of Treitz?
Attaches the duodenojejunal flexure to the anterior wall
Where does the pancreatic duct and common bile duct meet?
Hepatopancreatic ampulla
What does secretions from the pancreas and bile duct enter through into the duodenum?
Major duodenal papilla
What is the hepatopancreatic ampulla (of Vater)?
It’s a duct that joins the common bile cut and pancreatic duct
What is the uncinated process?
Hook-shaped projection/protuberance from a bone/organ.
What is pancreatic juice composed of?
Sodium bicarbonate, water, some salts, several enzymes
What chemical gives pancreatic juice a slightly alkaline pH?
Sodium bicarbonate
How is white adipose tissue used for energy?
It’s moved to the liver, muscle and kidney.
The fat is turned into a ketone body which can be used by body cells and brain (only in starvation state).
Name the enzymes in pancreatic juice.
Pancreatic amylase, trypsin, chymotrypsin, caryboxypeptidase, andelastase, pancreatic lipase, ribonuclease, deoxyribonuclease
What does the Ventral Mesogastrium run along?
The lesser curve of the stomach
What does the Dorsal Mesogastrium run along?
The greater curve of the stomach
What does the Dorsal Mesogastrium grow to become?
The greater omentum
What does collateral circulation mean?
Alternate circulation around a blocked artery/vein via another path.
What is the purpose of collateral circulation?
To maintain blood circulation around a blocked artery or vein via another path
E.g. circle of Willis
What are some of the pathological conditions which may be provoked by the formational of anastomoses?
High vascular resistance or ischaemia
What is neovascularisation?
Formation of new blood vessels between adjacent blood vessels
What type of an ulcer causes pain to start about 2-3 hours after eating?
Duodenal ulcer
List the 4 muscles making up the abdominal wall.
Rectus abdominus, transverse abdominus, internal oblique, external oblique
What is the aponeurosis?
Layers of flat broad tendons w/ wide attachment area
What forms the inguinal ligament?
Inferior border of the external oblique aponeurosis
Which 2 muscles that make up the abdominal wall are at right angles to one another?
Internal and external oblique.
External (hands in pocket direction).
Internal (hips to medial linea alba)
Which abdominal muscle has 3 tendinous intersections that interrupt its anterior surface?
Abdominus rectus
Which 4 abdominal muscles form the anterolateral abdominal wall?
External oblique, internal oblique, transverse abdominus, rectus abdominis, pyramidalis
What does ‘rectus’ mean?
Straight
Which is more superficial: external oblique or internal oblique?
External oblique
Which abdominal muscle originates from the crest of pubis and pubic symphysis?
Transverse abdominus
Which abdominal muscle inserts are the costal cartilages 5-9 and xiphisternum?
Rectus abdominus
Is the rectus abdominus or the transverse abdominus most deep?
Transverse abdominus
Which abdominal muscle originates from the lumbar fascia, iliac crest, costal cartilages 7-12?
Transverse abdominus
What is the linea alba?
A fibrous structure that runs down the midline of the abdomen
At the level of the umbilicus how does the aponeurosis cover the rectus abdominus?
External oblique and ½ internal oblique pass anteriorly to the rectus abdominus and the other ½ f internal oblique and transverse abdominus passes posteriorly.
At the level of arcuate line and below why do all the aponeuroses go in front of the rectus abdominus?
To allow blood to reach the muscle from the inferior epigastric arteries.
Which arteries supply the rectus abdominus and what is their function?
Inferior and superior epigastric arteries; to increase the intra-abdominal pressure –> .allows defecation, depress ribs, supports intestines.
What double fold of the peritoneum attaches transverse and sigmoid colon to the posterior abdominal wall?
Mesocolon
What is the purpose of the hole in the anterolateral abdominal wall?
Allows the spermatic cords in men and round ligament in women to reach the testes/uterus by passing through the inguinal canal.
What passes through the deep inguinal ring, through the canal, out the superficial inguinal ring?
Spermatic cords – men
Round ligament of uterus- women
Why is the inguinal canal a point of weakness?
Pressure on this area of weakness can lead to a direct or indirect hernia. Indirect more common
What is fascia?
A band or sheet of connective tissue, beneath the skin that attaches, stabilises, encloses, and separates muscles and other internal organs.
What forms the deep inguinal ring?
Transverse abdominal muscle and fascia
What forms the superficial inguinal ring?
External oblique muscle
What forms the spermatic cord?
Ductus deferens, nerves, lymph and blood vessels
What double fold of the peritoneum attaches jejunum and ileum to the posterior abdominal wall?
Mesentery
Through which inguinal ring does the ductus deferens enter the inguinal canal?
Deep inguinal ring
What does the duodenum receive and where from?
Gastric chyme (stomach), pancreatic juice (pancreas), bile (liver)
Where does bile emulsify fats into micelles?
Duodenum
Where is iron absorbed?
Duodenum
Where are most nutrient absorbed?
Jejunum
How long is the large intestine?
5ft
Name the parts that makeup the LI in order.
Duodenum, jejunum, ileum, caecum
Name the muscles that form the posterior abdominal wall.
Quadratus lumborum, psoas major, psoas minor, iliacus, diaphragm
What is the ileocecal junction?
Where the ileum (SI) meets the caecum (LI).
What causes ulcer formation? – tongue, peptic, duodenal
Tongue – biting the tongue disrupts the lining which allows bacteria to get in and cause disruption of the underlying tissue.
Peptic – disruption of stomach lining allows bacteria to enter and disrupt underlying tissues
Duodenal – digestive tract
What is the vagus nerve?
It’s the 10th cranial nerve.
It interfaces w/ parasympathetic control of the heart, lungs and digestive tract.
It’s the longest nerve of the ANS.
Has sympathetic function via the peripheral chemoreceptors
List the main regions of the stomach.
Cardia, fundus, body, antrum, pylorus
Which type of cells can be found in the cardia, pylorus and fundus?
Neck cells – mucus secretion
Which type of cells can be found in the fundus?
Parietal/oxyntic – produces HCL (activating pepsinogen) and IF
Chief cells – secretes proteolytic enzymes e.g. pepsinogen (precursor of pepsin)
Neck cells – mucus
Chief cells of the stomach produce pepsinogen and chymosin. What is chymosin also known as?
What is its role?
Chymosin, known also as rennin, is a proteolytic (protease) enzyme related to pepsin.
Its role in digestion is to curdle or coagulate milk in the stomach, a process of considerable importance in the very young animal.
Which type of cells in the stomach produces HCl?
Parietal cells
What do chief cells secrete?
Proteolytic enzymes
Pepsinogen + Chymosin
Pepsinogen is activated into pepsin when it comes in contact with HCl produced by gastric parietal cells.
What activates pepsinogen in the stomach?
HCl
What causes bleeding around a stomach ulcer?
Blood vessels around the ulcer base if degraded
What is immediately inferior to the fundus?
Body of the stomach
Makes up the bulk of stomach
What is the pyloric part of the stomach made up of?
Pyloric atrium – wider, more lateral part
Pyloric canal – narrow part
Pylorus and sphincter – distal sphincteric region, has thicker circular layer of smooth muscle that controls the discharge of contents through the pyloric orifice.
Which type of histamine receptors increases acid secretion and cardiac stimulation?
H2
Where can H3 receptors be found?
Myenteric plexus, presynaptic sites in the brain
What do H2 receptor antagonists do?
Block histamine receptors in the gastric mucosa, cardiac muscle, brain and mast cells.
What class are the following drugs: cimetidine, ranitidine, famotidine?
H2 receptor antagonist
Which type of histamine receptors are found in gastric mucosa, cardiac muscle, brain, smooth muscle, immune cells, myenteric plexus, endothelium of brain, and mast cells?
Gastric mucosa – H2 Cardiac muscle – H2 Brain – H2 Smooth muscle – H1, H2 Immune cells – H4 Myenteric plexus in GIT– H3 Endothelium brain – H1 Mast cells – H2
Which anti-nausea medication has no effect on motion sickness?
5HT3 receptor antagonist
What is the action of PPIs?
Reduce H+ secretion from the parietal cells.
Which class of drug acts on parietal cells to reduce acid secretion?
PPIs
What class are the following drugs?
Omeprazole, esomeprazole, pantoprazole. PPIs
Why can a single dose of a PPI persist up to 3 days?
Because proton pump inhibition via ATPase is irreversible
Is omeprazole reversible or irreversible?
Irreversible
What are canaliculi?
Microscopic canals
What are PPIs used to treat?
Acid reflux, stomach and duodenal ulcers
How can NSAIDs cause ulcer formation?
They inhibit prostaglandins which maintains the stomach lining by reducing gastric acid secretion and increasing mucus and HCO3- secretion
What is given w/ NSAIDs to prevent ulcer formation?
Misoprostol
What is misoprostol?
Synthetic analog of natural prostaglandin E1
What is the function of thromboxanes?
A vasoconstrictor and potent hypertensive agent, and it facilitates platelet aggregation
What is arachidonic acid?
Eicosanoic acid – saturated fatty acid w/ a 20-carbon chain
What happens in the body when the vomiting reflex is activated?
Contraction of diaphragm and abdominal muscles, lower oesophageal sphincter relaxation, stomach squeezed, antiperistalsis, closure of glottis, respiration stop
Electrolyte/fluid imbalance leads to what?
Arrhythmias, renal impairment, tetany
What do muscarinic receptor antagonists do?
Block ACh receptors
What is 5HT3 (hydroxytryptamine) used for?
Prevent chemotherapy and radiotherapy induced NandV by reducing activity of the vagus nerve
On inhalation and exhalation where does the liver move?
Inhalation – down below rib cage
Exhalation – as high as the 4th IC space
List the 6 main functions of the liver.
Nutrient metabolism, protein synthesis, storage, excretion, filters blood and phagocytosis
What are transaminase enzymes?
Enzymes that amino groups are transferred to. They transfer the amino group to a different keto-acid forming the amino acid corresponding to that keto-acid
What are the following: ALT, AST and glutamate aminotransferase?
Transaminases (enzymes)
What is carried from the liver and gallbladder to the duodenum?
Liver – bile salts and bilirubin
Gallbladder – bile (concentrated)
What are the 3 types of amino acids?
Essential – cannot be synthesised by the body
Semi-essential – can be synthesised in body, demand may exceed synthetic capacity under metabolic stress/trauma.
Nonessential – can be synthesised by transamination
What does the cystic duct from gallbladder join to form the common bile duct?
Common hepatic duct
Name some of the proteins synthesised by the liver.
Albumin, coagulation factors, complement factors, transferrin, protease inhibitors
Adipose issues take up glucose and turn it into what?
Glycerol which binds to fatty acids –> triglycerides
What 2 ducts anastomose to form the common hepatic duct from liver?
R and L hepatic ducts.
What does the liver store?
Iron (ferritin), copper, vitamins A, B12, D, E, K, glycogen.
What is the peritoneum divided into?
Greater and lesser peritoneal sacs.
The greater sac comprises most the peritoneal cavity. The lesser sac (also known as the omental bursa) is smaller and lies posterior to the stomach and lesser omentum.
What does the liver excrete?
Bile salts, bilirubin
What is the function of bile?
Helps SI digest fats and absorb fats, cholesterol, fat soluble vitamins.
What does the liver filter the blood for?
Oestrogen, aldosterone, vasopressin, alcohol, amphetamines barbiturates, steroids.
What does aldosterone do?
Hormone that acts mainly in the kidneys to aid in the conservation of sodium, secretion of potassium, water retention and to stabilize blood pressure.
What is copper needed for in the body?
Copper works w/ iron to help the body form RBCs.
What does vitamin K do in the body?
Important role in blood clotting
What does vitamin B12 (cobalamin) do in the body?
Production of RNA and DNA. Works w/ B9 to make RBCs.
B9 - folate
Which vessel(s) can be found in the perivenous end of a liver sinusoid?
Central vein
Where is pain from gallstones referred to?
Right hypochondriac region
What is hypercalcitoninemia associated w/?
Low calcium levels
Name the 4 semi-essential amino acids
Glutamine, arginine, glycine, proline
Where does deamination take place?
Primarily in the liver, glutamate also deaminated in kidneys
When does deamination occur?
If there is an excess of protein intake.
Amino acid is converted to ammonia.
What’s the difference between deamination and transamination?
Deamination – removal of an amine group from molecule.
Transamination – release of amino group from amino acid
What is cholelithiasis?
Presence of gallstones (concentrations that form in the biliary tract, usually in gallbladder)
What is left when an amino group is removed from an aa?
Keto-acid
What does the transaminase enzyme accept?
Amino group
What does the transaminase enzyme transfer onto an acceptor?
Amino group
Is biotransformation phase 1 or 2 of drug metabolism?
Phase 1
Is synthesis phase 1 or 2 of drug metabolism?
Phase 2
In immune damage to gastric parietal cells which intestinal secretion is affected?
HCl and intrinsic factor
What is intrinsic factor?
A glycoprotein produced by the parietal cells of stomach. It’s necessary for absorption of vitamin B12 (cobalamin) later in the small intestine.
What is pepsinogen?
A substance secreted by stomach wall and converted into the enzyme pepsin by gastric acid.
What is secretin?
A hormone released into bloodstream by duodenum (especially in response to acidity) to stimulate secretion by the liver and pancreas. Inhibits gastric acid production.
Which muscles retract the mandible?
Temporalis
What is impedance?
Obstruction / opposition to passage or flow, as of an electric current or other form of energy.
The resistance in alternating current circuits.
Which structure is normally bimanually palpable?
Kidneys
Which structures does the transpyloric plane cut?
The pylorus of stomach, tips of 8th costal cartilages, lower border of 1st lumbar vertebra
What does the gallbladder store?
Bile from the liver
What is the function of bile?
Absorption of the fat-soluble substances (e.g. vitamins A, D, E, K).
Besides its digestive function, bile serves also as the route of excretion for bilirubin, a by-product of RBCs recycled by liver.
What do you ballot?
Kidneys
What happens in phase 1 of drug metabolism?
Biotransformation: oxidation, hydrolysis, hydroxylation, deamination. Involves cytochrome P350 enzymes.
What is hypercalcaemia?
High calcium (Ca2+) level in the blood serum.
Major cause = overactive parathyroid glands (hyperparathyroidism).
The parathyroid gland is the major control mechanism for what?
Parathyroid – calcium.
What does the thyroid control?
Thyroid – metabolic rate, heart and digestive functions.
Name a 5-HT receptor antagonist which specifically inhibits interneuron transmission to alleviate nausea associated w/ chemotherapy but not motion sickness.
Metoclopramide
Which muscles move the mandible side-to-side?
Lateral and medial pterygoid
What muscles are found in the lateral walls of the oral cavity?
Buccinator
Failure to re-absorb bile salts is caused by what?
Several gut-related problems, main 1 = chronic diarrhoea.
What substance found in the diet will provide the most calories per gram after ingestion?
Fats
Which nerve(s) innervate the muscles of mastication?
Branches of the mandibular nerve which is a branch of the trigeminal nerve
Where is the apex beat of the heart normally felt?
5th IC, mid-clavicular line
What is the inside of the oral cavity lined by?
Mucous membrane, non-keratinised stratified squamous
What effect will obstruction of the common bile duct have?
Bile builds up in liver and jaundice develops due to the increasing levels of bilirubin in the blood.
What separated the oral cavity from the nasal cavity?
Front – hard palate and back – soft palate
Define hypotonic.
Having reduced pressure or tone.
What are D2 receptor antagonists?
Examples include: chlorpromazine, metoclopramide
They bind to D2 dopamine receptors in the chemoreceptor trigger zone and competitively inhibits dopamine. Controls NandV.
What is perphenazine?
D1 and D2 receptor antagonist.
Controls severe NandV in adults.
What is ondansetron?
5-HT3 receptor antagonist.
Prevents NandV associated w/ chemotherapy and radiation.
What do PPIs inhibit?
H+/K+-ATPase enzyme in gastric parietal cells and blocks final step in gastric acid secretion.
Treatment of peptic ulcers, benign gastric ulcers, heartburn, GERD.
What do histamine receptor antagonists treat?
H1 R An – competitively inhibits H1 receptors in vomiting centre in the CTZ. Treats NandV and dizziness.
H2 R An – competitive H2 inhibitor at parietal cells supresses normal secretion of gastric acid.
Promethazine, cinnarizine and cyclizine are all examples of what?
H1 receptor antagonists. Treatment of N+V.
Which classes of drug treat peptic ulcer diseases?
H2 R An – e.g. ranitidine
(PPIs) H+/K+-ATPase An – e.g. omeprazole, esomeprazole
Antacids – e.g. Mg trisilicate, gaviscon
What is orlistat?
Lipase enzyme inhibitor. Treats hyperlipidaemia.
Where does absorption of most nutrients takes place in the intestines?
Jejunum
Where does the external oblique originate and insert?
Origin – 8 digitations from inferior 8 ribs
Insertion – iliac crest, pubic tubercle, linea alba
Which abdominal muscle originates from the lumbar fascia and iliac crest?
Internal oblique
What is the difference between the duodenum, jejunum and ileum in terms of glands found and secretions.
Duodenum – Brunner’s glands – alkaline secretion to neutralise stomach acid, nutrients are broken down, fats –> micelles,
Jejunum – Lining specialised for absorption for the nutrients which were broken down in duodenum,
Ileum – Peyer’s patches – pathogens, lining secretes proteases carbohydrase enzymes
Where are brunner’s glands found?
Duodenum
What do Brunner’s glands secrete?
Alkaline secretion to neutralise stomach acid, nutrients are broken down, fats –> micelles,
What is the difference between the duodenum, jejunum and ileum in terms of diameter.
Duodenum – Larger than both jejunum and ileum
Jejunum – larger than ileum, plicae circularis and villi increase SA
Ileum – smaller diameter than ileum and duodenum
What is the difference between the duodenum, jejunum and ileum in terms of, things absorbed.
Duodenum – Fe
Jejunum – Mg, most nutrient
Ileum – Vit B12
Where in the intestines is Mg and most nutrients absorbed?
Jejunum
Where in the intestines is vitamin B12 absorbed?
Ileum
Where in the intestines is iron absorbed?
Duodenum
What is the difference between the duodenum, jejunum and ileum in terms of blood supply.
Duodenum – coeliac trunk and superior mesenteric artery
Jejunum – superior mesenteric artery
Ileum – superior mesenteric artery
What forms the rectus sheath?
By the aponeuroses of the 3 flat muscles (external oblique, internal oblique, transverse abdominis) and encloses rectus abdominis, and pyramidalis muscles.
Where are Peyer’s patches found?
Ileum
Function of Peyer’s patches
Fighting pathogens
Secreting proteases and carbohydrases enzymes
What forms the anterior wall of the rectus sheath?
Aponeuroses of external oblique and ½ internal oblique
What forms the posterior wall of the rectus sheath?
Aponeuroses of ½ internal oblique and transverse abdominus
What is the arcuate line?
Area of transition between having a posterior wall and no posterior wall
Where is the rectus abdominus directly in contact w/ the transversalis fascia?
Approx. midway between umbilicus and pubic symphysis; below the arcuate line
Where does the submandibular and lesser sublingual gland ducts open into?
Both open into the floor of the mouth
What are the phases of gastric secretion?
Cephalic – before food enters tract (stimulated by sight or smell of food due to stimulation of vagus nerve)
Gastric – food is in the stomach
Intestinal wave – food enters the intestines
Which salivary glands secrete mostly mucous? What do they have?
Sublingual salivary glands.
They have mostly mucous acini and few serous acini.
Which salivary glands secrete mostly serous but have a mucosa acini also?
Submandibular glands.
Have mostly serous acini and few mucosa acini.
Which muscles elevate the mandible?
Temporalis, medial pterygoid, masseter
What do the enteroendocrine cells of the stomach secrete?
Protein hormones such as VIP and somatostatin.
Gastrin is secreted from a type of these called G cells in the pyloric region of the stomach.
Which muscles depress (protrusion) the mandible?
Lateral pterygoid
How long are submandibular ducts?
5cm
Which cranial nerve innervates the muscles of mastication?
CNV
What is hepatosplenomegaly?
Both liver and spleen are enlarged, usually due to infection.
Which artery supplies the masseter muscle?
Masseteric artery
Which branches of the maxillary artery supplies the lateral pterygoid and medial pterygoid muscles?
Pterygoid branch
Which artery supplies the temporalis muscle?
Deep temporal artery
How long is the duodenum and list the 4 parts?
25cm
Superior, descending, inferior, ascending
Which part of the duodenum has the major duodenal papilla?
Descending
Which part of the duodenum is the ligament of Treitz found at?
Ascending
What does intrinsic factor aid?
Absorption of vitamin B12
How does H2 receptor stimulation lead to cardiac stimulation?
By the activation of adenylyl cyclase –> activates cAMP –> activates a protein kinase signalling cascade –> proton pump comes to surface of cell –> exchange H+ in to lumen for K+ out.
What do H2 receptor antagonists cause?
Less stomach acid.
Name all 4 receptors that can be targeted to reduce nausea and vomiting.
Muscarinic receptors, H1 receptors, 5HT3 receptors, D2 receptors.
What is the bare area of the liver?
Where there is no peritoneum.
Where liver is in direct contact with the diaphragm.
Caused by the folding of the coronary ligament giving an anterior and posterior ligament.
How many surfaces does the liver have?
2, visceral and diaphragmatic
What is the hepatorenal recess?
Deepest (lowest) part of the abdominal cavity where fluid will gather when the patient is in the supine position.
Lies between the R lobe of the liver, R kidney, and R colic flexure.
What is the ligamentum teres?
In an embryo, where the umbilical vein supplying oxygenated blood is
Superiorly what does the faliciform ligament split into?
The coronary ligament
How many hepatic veins drain into inferior vena cava?
3
What are the extra lobes on the R lobe of the liver?
Caudate (superior) and quadrate (inferior)
What separates the caudate and quadrate lobes of the R lobe of the liver?
The porta hepatis which is like a the hilia of the liver.
Anatomically are the caudate and quadrate lobes on the L or R and why?
Left because they are supplied by the L hepatic artery
What is in the porta hepatis?
Ducts, veins and arteries.
In the porta hepatis what is the order of its contents as you move left and superiorly?
Ducts, artery, vein
Does the hepatic artery enter or leave the liver?
Enter
Does the hepatic portal vein enter or leave the liver?
Enter
Does the hepatic vein enter or leave the liver?
Leave
How many sections does the liver have?
8
What is the function of the gallbladder?
Store and concentrate bile
What is the function of the pancreas?
Secrete digestive enzymes into duodenum
How does the superior mesenteric artery reach the liver?
Via the hepatic portal vein
What is the function of the spleen?
Storage and breakdown of RBCs
What does the breakdown of RBCs produce?
Bilirubin
What makes the origin of the spleen different from other GI structures?
Spleen – mesodermal origin
Other GI structure – endoderm origin
What does the diaphragmatic surface of the spleen contact?
Diaphragm and ribs 9-11 posteriorly.
Where is pain from appendicitis referred to after inflammation has occurred?
Right iliac region
Where is pain from kidney stones felt?
R and L lumbar regions
Where are chylomicrons formed and why what?
In the ER of the absorptive cells (enterocytes) of the SI.
Where are adrenal glands located relative to kidneys?
Supriorly
What forms the common hepatic duct?
The right hepatic duct and left hepatic duct.
Where does the cystic duct come from?
Gallbladder
What do alpha and beta pancreatic cells produce?
A – glucagon (increases blood glucose levels)
B – insulin (decreases blood glucose levels)
What do Kupffer cells of the liver phagocytose?
Aged RBCs, WBCs and some bacteria.
What is the function of lipoproteins?
Transport fatty acids, triglycerides, cholesterol to and from body cells in aqueous blood
What is used to make bile salts?
Cholesterol
Which cells synthesizes most plasma proteins?
Hepatocytes
What is transamination?
Transfer of an amino group to a keto acid. It can convert essential amino acids to non-essential amino acids.
How many essential amino acids are there?
9
Where are bile acids absorbed and what happens once they are absorbed?
Bile salts (acids) are usually absorbed in the terminal ileum, taken up by the liver and re-secreted.
What is the co-factor for transaminase enzymes?
Vitamin B6
What happens in phase 2 of drug metabolism?
Synthesis: conjugation with glycine, sulphate, glucuronic acid.
What is the 1st pass effect?
On each liver pass a fraction of the drug is converted into inactive metabolites.
Where are ammonia concentrations the highest and why?
Liver
Because this is where it’s produced.
From which arteries do kidneys get blood from?
Renal arteries
Sinusoids in liver drain fluid towards which structure?
Hepatic vein
Where do hepatic veins carry blood to?
Inferior vena cava
Where is pain from a stomach ulcer is referred?
Epigastric region
Where is small bowel pain referred?
Umbilical region
Which organ enlarges from the left hypochondrium towards the right iliac fossa?
Spleen
What does aldosterone mediate?
It regulates electrocytes and blood pH
High aldosterone causes what?
High aldosterone = water retention which increases blood vol which increases BP
What is raised concentration of cortisol associated w/?
Cushing’s syndrome
What is Cushing’s syndrome?
Hypercortisolism – hormonal disorder caused by prolonged exposure of the body’s tissues to high levels of cortisol.
What is conjugation?
Conjugation – attachment of an ionised group to the drug
What is detoxification?
Detoxification – addition of another substance to drug/toxic substance to render it less effective (harmful).
What does phase 2 of drug metabolism lead to?
More polar and less reactive metabolites.
What are liver sinusoids lined with?
Primary liver cells (hepatocytes)
From which artery does blood enter the liver lobule?
Hepatic artery – oxygen rich
What is the ‘terminal hepatic venule end’ a.k.a?
Perivenous end
What is blood in the perivenous end oxygen deprived?
Because the blood has travelled along the sinusoids in the liver lobules which use up much of the oxygen.
Is the periportal zone (1) or centrilobaular (perivenous) zone (3) affected greater during a time of ischaemia and why?
Centrilobaular (zone 3) because it has the poorest oxygenation.
Which zone is most susceptible to viral hepatitis and why?
Zone 1 – periportal zone because it is nearest to the entering vascular supply.
What are zone 1 hepatocytes specialised for?
Oxidative liver functions including: gluconeogenesis, beta oxidation of fatty acids and cholesterol synthesis.
Which type of hepatocytes are specialised for glycolysis, ketogenesis, lipogenesis and cytochrome P450 based drug detoxification reactions?
Centrilobaular zone 3 cells
Which plane does the fundus of the gallbladder cross?
Transpyloric
Which vessel(s) can be found in the periportal end of a liver sinusoid?
Portal venule and hepatic arteriole
How is HCl secreted from gastric parietal cells?
As Cl- and H+
Where is peristaltic waves observed in the stomach?
Note where the waves are more frequent.
Antrum (most propulsion occurs) < body < fundus
When does retropulsion occur?
When food is too large to fit through the pyloric sphincter and is forced back to the body of stomach
What is gastric emptying and how does it occur?
When food particles in chyme are small so they pass through the pyloric sphincter.
What is somatostatin?
A hormone released from D-cells in stomach and duodenum in response to acid.
Inhibits gastric secretion.
What is gastrin?
A hormone secreted by the stomach in response to food especially protein.
What are villi in small intestines made from?
Goblet cells (secrete mucus), arteries, veins (go to the hepatic portal vein), lacteals (used in fat absorption).
Why are proteases secreted as inactive precursors?
So, they don’t digest the digestive tract itself.
What is glycaemic index?
Relative ability of carbohydrate food to increase blood glucose levels.
What is resistant starch?
Starch that escape digestion in SI of healthy people.
Where is alcohol absorbed?
20% - stomach
80% - small intestine
Where are acids and bases absorbed?
Large intestine
Name the fat-soluble vitamins.
A, D, E K
What is emulsification and where does it occur?
Lipid is liquefied and emulsified into small droplets which increases the SA. In the mouth and stomach at 37 degrees.
What degrades TAG?
Lipases
Where do micelles uptake into enterocytes occur?
Jejunum
How are micelles formed?
Lipid droplets are mixed with amphipathic bile salts.
What do chylomicrons exocytose into?
Lacteals which are like lymph ducts.
What are chylomicrons?
Re-esterified lipids + apoproteins.
What is steatorrhea and what causes it?
Presence of excess fat in faeces
Pancreatic insufficiency causes it (or not enough bile)
How are bile salts absorbed?
They must be broken down in the ileum then 95% of the breakdown products are reabsorbed into lymphatics and transported back to liver to be remade and reused.
What does omega 3 do?
Anti-inflammatory
Controls blood clotting
Build cell membranes in the brain
Normal growth and development
What is a hepatic lobule?
A small division of the liver defined at the histological scale.
Anatomical liver lobes are not the same thing.
What does omega 6 do?
Pro-inflammatory; brain functions, normal growth and dev
What enzyme does pancreatic juice stop the action of?
Stomach acid
Absorption of what substance may be most affected by disease of the terminal ileum?
Vitamin B12, bile salts
What is ranitidine and how does it differ from omeprazole?
Randitdine – H2 receptor antagonist
Omeprazole – PPI
Where are most lipids absorbed in the GIT?
Small intestines
What is the taenia coli?
3 separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons.
What is the vermiform appendix?
A blind-ended tube connected to the cecum, from which it develops in the embryo.
What is trypsinogen?
Precursor to trypsin (which is formed in the duodenum).
What are Paneth cells?
In the SI, Paneth cells residing at bottom of intestinal crypts are the key effectors of innate mucosal defence.
What are enterocytes?
Simple columnar epithelial cells found in the small intestine which are involved in digestion of molecules.
The pancreas is the source of what?
Insulin, glucagon, proteases, pancreatic lipase, amylase, bicarbonate
What would cause reduced formation of micelles?
Low bile salts
What is the exogenous lipid transport pathway?
Dietary lipids are transported from the intestines to the liver through the blood and there their path ends.
What is the endogenous lipid transport pathway?
Triglycerides and cholesterol produced in liver are transported to tissues where they are metabolised.
What do apoproteins regulate?
Which lipoprotein is made
How does the size of chylomicrons compare to that of other lipoproteins?
They are larger
What are chylomicrons synthesised from?
Triglycerides, lipoproteins and apoproteins
In the blood, what digests chylomicrons?
Lipoprotein lipase
What can fatty acids be taken up by?
Adipose tissue, muscle cells.
What are chylomicron remnants and what happens to them?
They are what’s left to chylomicrons after they’ve been metabolised. They bind to specific receptor (apoE) on liver cells and are endocytosed.
Major reduction in lipase production is caused by what?
Pancreatitis
Reduced formation of chylomicrons is caused by what?
Poor gut absorbance
Where does protein digestion begin?
Stomach – HCl and pepsin
Which are the main absorptive cells in the small intestines?
Enterocytes – simple columnar epithelial cells
How is LPL (lipoprotein lipase) expression linked to insulin?
When there’s a spike of insulin (after eating) LPL is activated. Insulin upregulates LPL.
List the stages in the endogenous pathway.
Triglycerides from liver to peripheral tissues.
VLDL IDL LDL forward cholesterol transport.
When cholesterol high LDL HDL (reverse cholesterol transport).
What are VLDL produced from?
From chylomicron remnants in the liver.
What is the function of HDLs?
Transport cholesterol from tissues back to liver (turns into bile) when cholesterol is excess.
What is forward cholesterol transport?
When cholesterol transported from liver to tissues
What can be used to control hypercholesterolemia?
Statins, bile acid sequestrant, fibrates
How do statins work?
Targets HMG CoA reductase enzymes and elevates HDL levels.
How do bile acid sequestrant work?
Alters the amount of bile acid is secreted.
How do fibrates work?
Alters lipoprotein catabolism to alter the levels of HDL and LDL in the body.
Free fatty acids are produced and transported to the liver in which 2 stages?
Ketogenesis and beta-oxidation
Describe the structure of white adipose tissue.
White – one big droplet.
Describe the structure of brown adipose tissue.
Brown – multiple smaller lipid droplets (contain mitochondria)
In chronic pancreatitis which intestinal secretion is affected?
Lipase production
A raised concentration of what is associated w/ colicky abdominal pain?
Calcium
Why is bile acid needed for action by lipases to occur on dietary fats?
Bile salts must emulsify the fats –> increase SA –> enhance lipase action.
Lipases degrade triacylglycerol –> monoacyglycerols, free fatty acids and glycerol –> taken up by intestinal epithelial cells.
What responds to low calcium concentration?
Parathyroid hormone
Removal of the gall bladder causes what?
Poor storage and concentration of bile salts.
What is the peritoneum made up of?
A layer of mesothelium supported by a thin layer of connective tissue. It’s conduit for blood and lymphatic vessels, nerves of abdo organs.
What happens to chylomicrons once they are absorbed by enterocytes?
Secreted through the basolateral membrane into the lacteals where the join lymph.
What is a consequence of obstruction to the common bile duct?
Reduced formation of micelles.
Where does the foregut run from?
Mid-oesophagus –> 2nd part of duodenum (ampulla of Vater)
Where does the midgut from?
Ampulla of Vater –> 2/3rd transverse colon.
What is the dentate line?
Embryology changes from endodermal –> ectodermal; it’s in rectum.
Which arteries supply the foregut, midgut and hindgut?
Foregut – coeliac trunk, midgut – superior mesenteric A., hindgut – inferior mesenteric A.
Name all the intraperitoneal organs
Stomach, ileum, jejunum, transverse colon, appendix, sigmoid colon, 1st 5cm of duodenum, upper 3rd of rectum, liver
Where does the hindgut end?
Point of the rectum known as the dentate line.
Which nerves supply the foregut, midgut and hindgut?
Foregut – superior splanchnic,
Midgut – lesser splanchnic,
Hindgut – least splanchnic.
