Alimentary System Flashcards
What is digestion for
Function of digestion is to break down food into small enough pieces that it can be absorbed
Absorption is
Transfer of nutrients to circulation
2 groups of organs in the alimentary system
Digestive tract organs like stomach intestines oral cavity
Accessory organs like salivary glands gallbladder liver pancreas
What organs are part of the digestive tract
Oral cavity
Pharynx
oesophagus
Stomach
Small intestine
Large intestine
What are the accessory digestive organs
Pancreas
Liver
Salivary glands
Teeth tongue
Gallbladder
What is the histological components of the GI system
Mucosa (epithelium, lamina propria, muscularis mucosae)
Submucosa
Muscularis externa
Adventitia/serosa
Describe Barrett’s oesophagus
Acid reflux leading to Metaplasia or even worse dysplasia
Where is fundic glands found
In the upper stomach, in the lamina propria
Describe coeliac disease
What is the function of mucous cells in the large intestine
Protect the lining from the undigested food moving along it
Describe ulcerative colitis and Crohn’s disease. What’s the difference
Crohn’s disease is the inflammation of the digestive system, and can occur anywhere along the GIT.
Ulcerative colitis is a long term condition where the colon and rectum become inflamed.
What is the difference between muscularis mucosae and muscularis externa
Muscularis mucosae is smooth muscle in the mucosa. Muscularis externa is a layer on it own and is a thicker layer of smooth muscle. Had inner circular muscle and outer longitudinal muscle for peristalsis
Difference between adventitia and serosa
Adventitia is fibrous connective tissue that surround organs. Serosa is serous membranes that secrets fluid to reduce friction at the other organs
In summary, adventitia and serosa are both connective tissue layers that surround organs in the body, but adventitia covers organs not involved in the digestive system and is composed mainly of collagen fibers, while serosa covers organs involved in the digestive system and is composed of a layer of mesothelium and a layer of connective tissue.
Where does the most absorption take place
Small intestine
Secretions in the GITrack
Saliva
Liquids
Bile
Gastric juice
Pancreatic juice
Intestinal juice
Faeces
Digestion: mechanical and chemical
Mechanical is motility and chemical is mainly the enzymes Secreted at different points ie saliva or pancreas enzymes
Motility
Chewing, swallowing, churning, peristalsis at the intestine, defaecation
Functions of the mouth
- Sensory (pain, temp,movement,taste)
- Motor (speech, swallowing, chewing)
- Salivation
- Lymphoid tissue (tonsils are first line of defence)
- Reflexes (gagging)
Nociception
Pain receptors
What is sialoadenitis
Inflammation of the salivary glands
What is sialolithiasis
Salivary gland stones
Lingual frenulum
Lingual vein
Jaw muscles
Masseter
Temporalis
Medial and lateral pterygoids
Facial muscles
Orbicularis oris
Buccinator
Buccinator
Puffing jaw, pushes food to the middle of mouth
Gustation
Taste
What is cervical viscera
Viscera means neck
Viscera means organs in the main cavities in the body especially those in the abdomen
Where is the pharynx located
From the base of the skull to oesophagus (C6)
What is the function of the pharynx
Conducts air
Muscular tube that directs food from out to oesophagus
What constitutes the pharynx
Nasopharynx (upper) ( nose)
Oropharynx (middle) (Oro for oral cavity)
Laryngopharynx (lower) (voice box)
What is the function of nose hair
Filter dust and dirt, first line of defence
Where is the nasopharynx located and what is it’s function
Nasopharynx is located from below the skull to the uvula. It has a respiratory function
Name the duct that is located in the Nasopharynx. (Very important)
Nasolacrimal duct
What does the nasolacrimal duct do?
It’s also known as the tear duct. Lacrimal glands produce tears. Connection of the eyed to nasal cavity and pharynx
4 types of tonsils and location
Tubal tonsils (x2 lymphoid, inflammatory tissues) (in nasopharynx)
Pharyngeal tonsils (In Nasopharynx)
Palatine tonsil (x 2at the back of the mouth, oropharynx)
Lingual tonsils (surface of the base of the tongue,Oropharynx)
Location and function of Oropharynx
Digestive function and respiratory function
Located in between the soft palate and epiglottis
Structure and function of epiglottis
Closes trachea when swallowing so as to cover the opening of the larynx so that food doesn’t go down trachea.
Epiglottis is made of elastic cartilage
Must know, palatoglossal and palatopharyngeal arches
What’s the other name of pharyngeal tonsils
Adenoids
Where is the laryngopharynx located
In between the epiglottis and the level of cricoid cartilage
Where does food such as fish bones get stuck in the pharynx?
Piriform fossa
Epithelia of the Nasopharynx
Respiratory epithelium so Ciliated pseudostratified columnar epithelium
What is Waldeyer’s ring?
Ring of lymphoid tissue in the Nasopharynx and Oropharynx formed by the paired palatine tonsils, adenoid tonsils and lingual tonsils
Name the circular muscles in the pharynx and location
Superior constrictor (Oropharynx)
Middle constrictor (laryngopharynx)
Inferior constrictor (laryngopharynx)
What’s so special about the hyoid bone
It is the only bone in the body that doesn’t connect to another bone. It’s prone to fractures if strangled. It’s located between middle and inferior constrictor
Motor nerve supply of the pharynx (MV,SG)
Vagus nerve ( CNX )to all muscles except stylopharyngeus muscle which is controlled by CNIX (glossopharyngeal) and one tensor veli palatini which is controlled by CNV
Sensory nerve supply in pharynx (MV,SG)
Primarily Glossopharyngeal nerve CNIX
Pharyngeal plexus
The region that lies over the middle constrictor, CNIX AND CNX)
Motor and sensory innervation of the majority of the pharynx (except nasopharynx) is achieved by the pharyngeal plexus.
Blood drains from the pharynx back to to the internal jugular veins through the plexus
Which three cranial nerves work together
Trochlear 4
Oculomotor 3
Abducens 6
Dangers of tonsillectomy
Damage nerves and blood vessels close by, especially the carotid artery that supplies 80% of the blood in brain
Name the physiological sphincter at the oesophagus
Lower oesophageal sphincter
Histology of oesophagus
OM Stratified squamous epithelium (non keratinized)
OM Lamina propria
OM Muscularis mucosae
Submucosa (mucous glands here)
Muscularis externa
Adventitia
Why are there mucous glands located in the Submucosa? (Underneath the muscularis mucosae)
Lubricate and protect the esopqhgus from abrasive forces
What are the muscle types as we go down the esophagus
Upper portion of the esophagus can be controlled so it’s skeletal
Middle is a mix of skeletal and smooth
Bottom is smooth muscle
What’s G.o.r.d.
Gastro oesophageal reflux disease
What physiology does the lower oesophageal sphincter have so that it can act as a sphincter and what is it’s function.
Almost a 90deg curvature, it’s function is to prevent n protect the esophagus from reflux of gastric contents
Pharyngeal phase of swallowing
Soft palate raises, depression of epiglottis, contraction of vocal folds/constructors, relaxation of upper sphincter)
Oesophageal phase of swallowing
Constrictor and relaxation of skeletal/ smooth muscles in the oesophagus until reach the cardiac orifice
Where is the abdomen
Abdomen is huge, it’s between the diaphragm and the pelvic inlet. It’s separated from the thorax but connected to the pelvis.
What role does the pelvis play at the abdomen
Pelvis supports (in part) the abdomen
What is the abdominal wall made of
Multilayered, musculo-aponeurotic wall
Adipose tissue
Abdomen has 9 quadrants what are they from 1 to 9
- Right hypochondrium
- Epigastric
- Left hypochondrium
- Right lumbar
- Umbilical
- Left lumbar
- Right iliac fossa
- Suprapubic/ hypogastrium
- Left iliac fossa
Where is the stomach found
Left hypochondrium and epigastric region
Greater and lesser curvature of the stomach (very important)
What is attached to the greater curvature of the stomach
Greater omentum which is fatty tissues that encases infections
Parts of the stomach (cat flips body pillow)
Lower oesophageal sphincter
Cardia
Fundus
Body
Pylorus
Pyloric sphincter
What is the function of the pyloric sphincter?
To prevent chyme from entering the duodenum too fast since there stomach is v acidic
Histology of the stomach
Simple columnar epithelium lines the stomach
What protects the stomach from the very acidic juices
Alkaline mucous layer , mucous glands at the pyloric part secrete more mucous since it’s nearer to the duodenum
Name the third kind of muscle that is only present in the stomach
Oblique muscle at the muscularis externa layer
What is rugae
Rugae in the stomach are folds that allow the stomach to distend
Pyloric stenosis
Abnormal thickening of the the muscles of the pylorus, food cannot move into the duodenum easily
4 types of gastric gland cells and what they secrete
Mucous neck cells
Chief cells (pepsinogen)
Parietal cells (HCL)
Endocrine cells (Gastrin)
What is the significance of HCL for pepsinogen
For pepsinogen to be converted to pepsin, HCL is needed
What is the significance of Gastrin
Gastrin promotes HCL and pepsinogen secretion
What is the function of the palatoglossus
Palatoglossal arch lowers the soft palate and elevates/ arch the tongue
Which nerve innervates the constrictor muscles of the pharynx
Vagus nerve because motor
Main secretion of parietal cells
HCL and intrinsic factor
Main secretion of chief cells
Pepsinogen
What stimulates the parietal cells
Gastrin, ach, histamine
What cells produce gastrin
G cells which are endocrine cells
Function of the piriform fossa
Located on either side of the laryngeal inlet and allow the passage of food into oesophagus
Carbonic anhydrase locations
Lungs
Liver
Pancreas
Kidney
Rbc
Parietal cells
Secretions at the different parts of the stomach
Cardia - mucous
Fundus and body - acid, pepsin gastric juices
Pylorus - mucous and gastrin
Parietal cells and chief cells stain
Parietal cells stain red
Chief cells stain blue
Arteries on the lesser curvature
Left gastric and common hepatic
Arteries on the greater curvature
Biggest splenic artery
Where do the veins of the stomach drain into?
Portal venous system
Left and right Gastric vein -> portal vein
Short gastric vein and left gastroepiploic coercive -> splenic -> superior mesenteric
Right gastroepiploic -> superior mesentric
What does intrinsic factor do
Intrinsic factor produced at the parietal cells, it helps absorption of vitamin b12
Where is oesophagus located respective to the traches
Esophagus located at posterior to the trachea and heart
Otitis media
Middle ear infection
Are parietal cells acidophillic or basophillic
Acidophillic
What artery supplies the pyloric part and the duodenum
Right Gastroepiploic artery that branches off from the gastroduodenal artery (which branches off the common hepatic)
What veins drain into the portal vein
Right and left gastric veins
What veins drain into the splenic vein
Short gastric and left gastroepiploic
What drains into the superior mesenteric
Right gastroepiploic vein
Oesophageal varices
Abnormal, enlarged veins in the tubes that connect oesophagus to the stomach. When portal pressure is larger than inferior venacava pressure, there is portal hypertension.
Retroperitoneal meaning
Organs that are covered on the anterior surface by PARIETAL peritoneum
What are the retroperitoneal organs (sad pucker)
Suprarenal glands
Aorta
Duodenum
Pancreas
Urethra
Colon
Kidneys
Esophagus
Rectum
Intraperitoneal organs
Eg Liver and spleen
Enveloped by visceral organs
Another name for the serous membrane that lines the abdomen
Mesothelium
Histology of mesothelium
Simple squamous
Areolar connective tissue
What is mesentery
Double fold around the small intestine that holds everything together
Structure of the greater omentum
Apron-like fold of the peritoneum with a free lower border
Name the glands of the duodenum and state it’s function and where it’s found
Bruner glands found at the Submucosa of the duodenum. It’s role is to secrete alkaline substance to neutralise the acidic contents entering from the stomach
Location of the duodenum
L1-l4
Cholecystokinin (CCK)
Duodenum hormone
Causes bile to be released from gall bladder into the duodenum CCK is a peptide hormone and helps digest fat and protein. Secreted by cells of the duodenum and highest secretion when there is fatty acids in the chyme entering the duodenum
CCK inhibits gastric emptying but increases the release of pancreatic enzymes, as well as increases the production of bile, contraction of the gall bladder and relaxes the Sphincter of Oddi resulting in better fat digestion.
Sphincter of oddi
Opening of the pancreas into the duodenum. Major and minor duodenal papilla
4 parts of the ddn
Superior
Descending
Inferior
Ascending
Must know!! Where is the location of the inferior duodenum respective to veins and arteries
The inferior duodenum is located in between the inferior vena cava and superior mesenteric artery + vein
What supplies the superior pancreaticduodenal artery
Coeliac trunk -> gastroduodenal artery -> superior pancreaticduodenka artery
What supplies the inferior pancreaticduodenal artery
Superior mesenteric artery
Infracolic region
Below the colon
Which plexus is located in the Submucosa
Messiner plexus (submucous plexus) - located in Submucosa
Where is the auerbach/myenteric plexus located
Between circular and longitudinal muscle
What 3 special characteristics increases intestinal surface area?
Transverse folds x3
Villi x30
Microvilli X600
What is another name for transverse folds
Plicae circulares
What is the function of a lacteal
Lacteal is located between the veins and arteries, function is fat absorption
Peyer’s patch
Found only in the ileum
Lymphoid tissue
Differences between jejunum and ileum arteries
Jejunum - smaller number of arterial arcades, but longer vasa recta.
Ileum - more arterial arcades with shorter vasa recta.
Mode of transport of hydrogen ions from parietal cells into stomach
Active transport, using potassium ions
Give details of the endocrine portions of the pancreas. What does it secrete and the function
Endocrine - islets of Langerhans
Secretes hormones
Alpha - glucagon
Beta - insulin
Delta - somatostatin
Control of blood sugar levels
Give details of the exocrine portion of the pancreas
99% exocrine
Digestive enzymes
Bicarbonate ions
Insulin function
Promotes glucose absorption
Somatostatin function
Reduce acid secretion, slows down digestive process
Reduces both glucagon and insulin secretion
Inhibits growth hormone
Inactive form of chymotrypsin
Chymotrypsinogen
5 parts of the pancreas
Head uncinate process neck body tail
Where is the uncinate process located
Posterior to superior mesenteric vessels
What is the difference between the tail of the pancreas compared to the head neck body
Tail is intraperitoneal
Exocrine glands in pancreas are what type of glands , serous or mucous
Serous acinar - a lot of digestive enzymes
Ducts secrete bicarbonate
How are the acinar glands connected
Intercalated ducts -> intralobular ducts -> pancreatic ducts
How does cystic fibrosis affect pancreas
Destruction of primary exocrine pancreas
- reduced digestive function
-malabsorption
- steatorrhoea
What is steatorrhoea
Blocked bile ducts, Lack of bile to emulsify fats, fatty stools
Liver function
Important functions
-bile
-proteins for blood clotting
-stores glycogen and releases glucose
-Inactivation of hormones/drugs
Liver location in the gut
Right, left hypochondrium and epigastric
Largest gland
Spleen function
Controls levels of wbc,rbc and blood clots
4 lobes of the liver
Left
Right
Qudrate (inferior)
Caudate (superior)
Histology of parietal and visceral peritoneum
Simple squamous called mesothelium
Along with the external urethral and anal sphincters, this is one of the only three sphincters in the body comprised of skeletal muscle tissue.
What is bile
Bile is made of water cholesterol bicarbonate phospholipids bile pigments and is responsible for fat digestion.
What is a gallstone
A gall stone is a buildup of cholesterol of bilirubin and calcium salts
Porta hepatis
The region where the arteries veins and bile ducts enter the liver
Appendices epiploicae
Out pouches of fat
Haustra
Circular muscle
Taenia coli
3 longitudinal bands of muscle
What is the name of the collection of veins that communicate directly with the systemic venous system in the anus
Internal hemorrhoidal plexus
Internal and external sphincter in the anus nervous control type - involuntary or voluntary
Internal - involuntary
External - voluntary
What action occurs in the small intestine
Segmentation
What action occurs in the large intestine
Squeezing action mainly in caecum and ascending colon due to contraction of circular muscles
Peristalsis in the transverse anddescending colon
Mass movements unique to the large intestine
Segmentation vs peristalsis
Segmentation - circular muscle in small intestine
Peristalsis - longitudinal muscle
Achalasia
The lower oesophageal sphincter doesn’t relax so the food cannot enter the stomach, bird beak appearance on a barium swallowing test
Anastomoses occur where in the git
Oesophagus and stomach
