GI system Flashcards
what are the functions of the digestive system?
digestion - process food
absorption - transfer of nutrients to circulation
what are the 2 groups of organs in the digestive system?
digestive tract
accessory organs eg salivary glands, gallbladder, liver, pancreas
what do the salivary glands do?
secrete a watery solution (serous) or a thicker solution (mucous) or a mix of these 2. it helps to buffer pH, protects surface id mouth and gut, has antimicrobial action and maintains tooth structure.
what does the gall bladder do?
helps store and concentrate bile which is produced in the liver and helps with fat digestion
what is the order of the GI tract
-oral cavity
-pharynx
-oesophagus
-stomach
-small intestine
-large intestine
what is the pharynx
muscular tube responsible for food and air to pass through. extends from base of the skill to oesophagus. conducts air, muscle directs food to oesophagus.
nasopharynx- base of skull to soft palate
oropharynx- soft palate to epiglottis
laryngopharynx- epiglottis to splitting into the trachea and oesophagus
what is the oesophagus?
muscular tube (20-25cm). extends from pharynx and reaches stomach. passes behind the heart and trachea. stratified squamous non keratinising.
changes from skeletal muscle at the top to smooth muscle at the bottom
what is the stomach?
muscular organ located in the upper right of the abdomen. secretes acid and enzymes that start digestion.
what are the small intestine?
3 parts, duosenum, jejunum, ileum.
duodenum - secretions from pancreas and bile enter at this point. bile helps with fat digestion and protein and other carbs.
what does the pancreas do?
its secretions help with the digestion of fat, protein digestion and starch and other carbs. it also secretes bicarbonate rich fluids to maintain an alkaline pH.
what happens to material not absorbed or digested by ilium?
moves to large intestine
how is GI tract seen histologically?
haematoxylin and eosin.
what is lamina propria?
thin layer of loose connective tissue which lies beneath the epithelium. contains inflammatory cells and provides support and nutrients to the overlying epithelium,
what is the mucularis mucosae?
composed of smooth muscle and is continuous all the way through the GI tract
what is the submucosa?
deep to the muscular mucosae. composed of dense irregular connective tissue and contains many blood vessels which collects additional fluid around the body outside the vasculature
what is the muscularis propria?
comprised of inner circular layer and outer longitudinal layer. smooth muscle and is responsible for peristalsis the movement of food.
what is the adventitia?
outer layer of fibrous connective tissue surrounding an organ. in the gut it would be at the oral cavity. it is the part of the tissue that is fixed. the serous membrane allows for reduction of friction.
what is meissners and auberbachs plexus?
nerve plexuses
what are brunners glands?
secrete biocarbonate ions to neutralise acid from the stomach
what are Peyers patches?
lymphoid follicles and form part of the immune function preventing the growth of dangerous bacteria.
what is the epithelium in colon?
simple columnar
how is the abdomen divided?
into 9 or sometime into 4 quadrants.
what are the 9 segments of stomach?
right hypercondrium- liver
epigastric - duodenum, liver, gall bladder, pancreas, stomach
left hypercondrium - spleen and stomach
right lumbar - ascending colon, kidney
umbilical n- stomach, head of pancreas, small intestine, transverse colon, lower aspects of right and left kidneys.
left lumbar - descending colon, left kidney
right iliac fossa - caecum, appendix, part of ascending colon
suprapubic - bladder, uterus, parts of small intestine
lest iliac fossa - sigmoid colon, descending colon,
where is the stomach located?
left hypercondrium and epigastric region
where does the greater momentum attach?
to the greater curvature
what does the pyloric sphincter do?
controls secretions from the stomach
what are rugae?
folds of the stomach which can be seen by naked eye and to increase surface area.
what do endocrine cells do?
produce hormone gastrin
what is found in the uppermost layer - mucosa?
endocrine cells
parietal cells (secretions of HCL)
chief cells (create pepsinogen)
mucous neck cell
what is the epithelium of the stomach onwards?
simple columnar
what is the small intestine?
primary site for digestion absorption
what do villi do?
increase surface area by 30 times. finger like projections increase SA and aid digestion and absorption. dimininsh in number towards the end of the tract.
how many layers of muscle does the small intestine have?
2
what is the function of the gall bladder (to aid digestion)?
helps store and concentrate bile which is produced by the liver and helps with fat digestion.
what does haematoxylin do?
stains the nucleus blue
what are sphincters?
circular muscles that open and close passages in the body to regulate the flow of substances such as bile, urine and faeces
what does eosin do?
stains the cytoplasm and ECM pink.
what is the epithelium like in the oesophagus?
stratified squamous and is non keratinised
where does the pharynx go to?
C6
what is the nasopharynx?
base of skull to the soft palate (top part of the pharynx)
what is the oropharynx?
soft palate to epiglottis
what is the epiglottis?
a flap of tissue that sits beneath the tongue at the back of the throat. main function is to close over the trachea while your eating to prevent food from entering airway.
where is the pylorus?
the very end of the stomach, just before it reaches the duodenum.
how many layers of muscle does the stomach have in the stomach wall?
3 which make up the muscularis propria