digestive system Flashcards
draw a diagram showing 9 abdominal regions
from top left to right: right hypocondruim, epigastrium, left hypocondrium
middle: right lumbar, umbilical, left lumbar
bottom: right iliac, hypogastrium (suprapubic), left iliac
what is the function of the digestive system
to prepare food for cellular consumption
which 2 abdomen landmarks are in the rib area
xiphisternum and costal margin
which abdomen landmark is in the hip area
iliac crest
which abdomen landmark is in the pubic region
inguinal ligament
what are the abdominal quadrants called and what is the name of the area which goes across the abdomen across the centre of the four quadrants
right upper quadrant, left upper quadrant, right lower quadrant and left lower quadrant. The trans-umbilical plane
what is the peritoneum
double layered serous layer which covers the abdominal and pelvic cavity
what are the 2 layers of the peritoneum called and what do they cover
parietal peritoneum - lines body wall
visceral peritoneum - covers organs
what is the name of the disease which is caused by fluid filling the peritoneal cavity
peritonitis
which organs are fully covered by peritoneum
stomach, part of small intestines
which organs are partly covered by peritoneum
pancreas, part of duodenum
what are the names of the 2 specialised parts of the peritoneum and what do they do
mesentery - attaches an organ to the body wall
omentum - attaches one organ to another
what are the 4 layers of the gastrointestinal tract
mucosa (inner most)
submucosa
muscularis externa
serosa/adventia (outer most)
what is the structure/role of the mucosa layer
smooth muscle. protective, secretive/absorbative. contains vessles, glands and lymphoid tissue
what is the structure/role of the submucosa layer
dense connective tissue that supports the mocosa. contains part of enteric plexus (nervous system of GI tract)
what is the structure/role of the muscularis externa/propria
smooth muscle (inner circular, outer longitudinal. responsible for peristalsis
what is the structure/role of the serosa/adventia?
serous membrane that covers those structures within the peritoneal cavity
what are the names of the 3 branches of the abdominal aorta which supply blood to the GI tract
celiac trunk, superior mesenteric artery, inferior mescenteric artery (from top to bottom)
blood from which digestive system organs drains to the liver via the hepatic portal system
stomach, pancreas, small and large intestines
the autonomic nervous system is responsible for long or short reflexes
long - eg large scale peristalsis
what controls the short reflexes e.g local peristalsis and glandular secretion
the enteric nervous system
what which part of the layers of gastrointestinal tract is the enteric nervous system located
submucosal and myenteric
the enterendocrine glands secrete which 3 hormones
gastrin, secretin, cholecystokinin
what parts of the body are used for chewing (mastication)
teeth, tongue, salivary glands, temporomandibular joint and muscles
where does churning occur
stomach and large intestine
what does mechanical digestion do
breaks down the food into a bolus with a greater surface area to facilitate digestion
what does segmentation do and where does it occur?
mixes bolus with enzymes and flattens it out. occurs in small intestine
what is propulsion
the movement of digestive materials along the tract
what are the 3 stages of swallowing
oral, pharyngeal, oesophageal
what is peristalsis
waves of muscular contractions that move the bolus
what are mass movements and where do they occur
powerful peristaltic contractions that push bolus into rectum stimulated by distension (enlargement) of stomach and duodenum. can produce urge to defecate. occurs in the large intestine
what stimulates the defication reflex
faeces in the rectum
what happens to the internal and external sphincters upon defecation
the internal sphincter relaxes and external sphincter contracted - requires conscious effort to relax external sphincter
during chemical digestion what are carbohydrates, proteins and lipids broken down into
carbohydrates - simple sugars
proteins - amino acids
lipids - fatty acids and monoglycerides
where are carbohydrates broken down
mouth (initiated by salivary amylase) and small intestine
where are proteins broken down
stomach and small intestine
where are lipids broken down
mouth (lingual lipase) and small intestine
what do exocrine glands (salivary glands) release
enzymes (salivary amylase), water, salts mucus and buffers
what do cells of the stomach, small intestine and liver release
enzymes, water, salts mucus, buffers plus bile
what do endocrine glands such as the pancreas and neuroendocrine cells of the stomach produce
hormones
what is absorption and where does it occur
passage of substances across the digestive epithelium into the blood or lymph. occurs in the stomach, small and large intestine (mostly small)
what 3 things does the GI tract have to protect itself against
acids, mechanical trauma and bacteria
what are the 3 glands of the mouth called and what do they produce
parotid, sublingual, submandibular. they produce salivary amylase, serous fluid, mucin (lubrication), lysosome (antibacterial) immunoglobulin (bicarb)
what are the 3 parts of the oesophagus and what type of muscle are each part made up of
upper 3rd (skeletal) middle third (mixed) lower (smooth)
where is the stomach located
in the epigastrum
what are the functions of the stomach
storage, mech and chem digestion (pepsinogen), protection, absorbtion, production of intrinsic factor
what are the special features of the stomach
it has rugae (folds that flatten when stomach is full)
extra layer of muscle to help churning
stomach has gastric pits and gastric glands which produce enzymes
what are the four secretary cells of the stomach and what do they produce
mucous cells and mucous neck cells (mucous) parietal cells (hydrochloric acid and intrinsic factor) Chief cells (pepsinogen) Enteroendocrine (gastrin)
what activates the secretion of gastric juices
high PH, gastrin, histamine, and ACh
what does Hydrochloric acid do
kills microbes, breaks down connective tissue, activates pepsinogen by converting to pepsin which starts protein digestion
what does gastrin stimulate
secretion of pepsinogen and HCL and contractions of gastric wall
what does intrinsic factor aid
absorbtion of vit B 12
what are the 3 phases that regulate gastric activity
cephalic phase (sight smell taste of food) gastric phase (food in stomach - gastric secretion stimulates gastric juice production) intestinal phase (partially digested food arriving in duodenum slows down production of gastric juices)
how many litres of fluid does the pancreas secrete each day
1.5
where is the pancreas located
retroperitoneal (cavity behind the peritoneum), posterior to stomach
where does the pancreatic duct open into the duodenum
at the sphincter of oddi
which cells in the pancreas secrete exocrine enzymes and what enzymes do they secrete
the Acini cells. Exocrine: propeptidases (trypsinogen, chymotrysinogen, procarboxpepsidase) amylase (carbs) lipase (fats) ribonuclease, dioxyribonuclease (DNA) Endocrine: Islets of langerhan alpha: glucagon beta: insulin
what are the 4 lobes of the liver called
right, left, caudate, and quadrant
what is the only digestion related function of the liver
bile production
where is the liver located
right hypochondruim (upper part of the abdomen) and epigastrium (upper central part of abdomen)
what is the livers main function
metabolism
what does the gall bladder do
stores and concentrates bile
what is the bilary tree made up of
liver, gb, duodenum (first section of duodenum) and various ducts (passage or channel)
what are the 3 parts of the small intestine
duodenum, jejunum (most absorbtion), lleum (vit B12 absorbtion)
what is the duodenal ampulla
Various smooth muscle sphincters regulate the flow of bile and pancreatic juice through the ampulla
what are the 3 special features which increase surface area of the small intestine
plicae circulares (circular folds) villi, microvilli
what are the 3 functions of the small intestine
mechanical digestion (segmentation), chemical digestion and absorbtion
what hormone is secreted in the presence of fats and proteins
Cholecystokinin (CCK)
what does CKK act on
pancreatic acini (enzymes)
gall bladder (bile)
sphincter of Oddi (relax)
stomach (decrease gastric motility and secretion)
when PH levels decrease what is secreted
secretin
what does secretin act on
pancreatic duct cells (water and sodium bicarbonate)
liver (bile)
stomach (decrease gastric motility and secretion)
in protein digestion and absorbtion, what is the pro enzyme which converts trypsinogen to active trypsin at the brush border of the duodenum
enterokinase
what does trypsin do
activates other propepsidases e.g chymotrypsinogen to cyrotripsin
procarboxypeptidase to carboxpeptidase
what do activates papsidases do
break down proteins into amino acids which are then absorbed by facilitated diffusion and cotransport
in carbohydrate digestion and absorption, what does pancreatic amylase do
breaks down carbohydrates into disaccharides and trisaccharides
what converts disaccharides and trisaccarides into monosaccarides
brush border enzymes. For example…
maltase converts maltose into glucose and glucose
lactase converts lactose into glucose and galactose
sucrase converts sucrose into glucose and fructose
which can then be absorbed by facilitated transport by facilitated diffusion and cotransport
in fat digestion and absorption, what emulsifies large lipid droplets into small droplets
bile
what does pancreatic lipase do
breaks down triglycerides into free fatty acids and glycerol which then interact with bile salts to form micelles (coating)
how can miccels enter intestinal cells
by diffusion
what happens to glycerol and free fatty acids if not used at that time
they are resynthesized into triglycerides and coated with protein to form chylomicrons
what happens to chylomicrons once formed
once secreted into interstitial fluid (solution that bathes and surrounds the cell) they diffuse into lacteals (A lacteal is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine)
what are the 5 special features of the large intestine
taenia coli (3 bands of longitudinal muscle) Haustra (pouches) Epiploic appendages (fat globules) crypts (instead of villi) goblet cells (mucus)
what are the 2 functions of the large intestine
absorption (water, electrolytes)
storage of undigested material (faeces: undigested fibre, bacteria, mucus)
what vitamins do the GI tract synthesise
B & K
