Exam 4: Digestive System Part 2 Flashcards
where does the duodenum receive secretions from
liver and pancreas
main function of duodenum
carries out majority of chemical digestion
duodenal secretions (4)
secretin
CCK
GIP
Maltase, sucrase, lactase
secretin
triggered by acid from stomach
stimulates pancreas and gallbladder to release water and bicarb
water to dilute the acid and bicarb to neutralize
CCK
gives contractions in gallbladder and secretions from pancreas to have enzymes coming in
GIP
released if eat heavy meal and ned to slow the release of nutrients coming through from stomach
maltase, sucrase, lactase
enzymes released from wall of duodenum
take disaccharides and break into simple sugars - rest of digestion
maltase and sucrase produce for rest of life
lactase: some people can only make when young and become lactose intolerant
duodenum secretions received from gallbladder (liver)
- bile salts: emulsify fats, lipid and cholesterol with charged ends, embed in larger complexes of fats to repel and break down
- bicarbonate: neutralizes
- wastes: billirubin, cholesterol
duodenum secretions received from pancreas
amylases - break carbohydrates
proteases and peptidases-activated by enterokinases, into AA
lipase: fats
nuclease: nucleic acids
portal system of liver
- to absorb from intestines and stomach and salvage operations in spleen
-many portal veins
-superior mesenteric vein: SI and beginning of LI
-inferior mesenteric vein: lower part of LI, colon
-gastrosplenic vein: combo of gastro and spleen
fuse to get hepatic portal vein
functions of the liver (7)
- carbohydrate metabolism: regulating blood glucose levels
- lipid metabolism: breaks down fats, processes cholesterol and triglycerides, produes bile salts
- protein metabolism: proteins for clotting, transport, plasma proteins, proteins for gluconeogenesis
- detoxification of drugs and hazardous materials
vitamin D activation
storage
excretion
where are secretions of the liver stored
gallbladder
nutrients absorbed from the lower GI tract and spleen are directed to the liver through the
hepatic portal system
exocrine secretions from pancreas (5)
pancreatic amylase: carbohydrates into disaccharides
proteases: trypsin and chymotrypsin
carboxypeptidase
pancreatic lipase
nucleases: ribonuclease and deoxyribonuclease
if gallstone blocks common bile duct
no waste products coming in, no bicarb or bile salts coming through
issue with jaundice bc billirubin build up - problem digesting and breaking down nutrients
-painful but not life-threatening
if gallstone down in ampulla
blocks secretions from the pancreas itself
pancreas stimulated anytime food passes into SI - keeps sending CCK signals
if blocked, activated enzymes attack pancreas, pancreatitis
liver and pancreas damaged
CAN kill you
jejunum
primary site of nutrient absorption
plica circulares
jejunum permanent transverse folds tha are covered in villi that have microvilli (high SA)
Plica, villi, microvill - all inc absorbitive SA
absorption in villi of jejunum - 2 ways
capillary bed
lacteal
capillary bed absorption in villi (5)
glucose and galactose - cotransport with Na+
fructose: facilitated diffusion
AA: active transport
Small lipids: simple diffusion
water soluble vitamins (C and most B) - active transport - NO B12 until ileum
lacteal absorption - villi (2)
lacteal: lipid capillary
cholesterol and fatty acids - absorbed in complexes (chylomicrons)- brings into blood supply to be processed
fat soluble vitamins (ADEK)
how do chylomicrons transport lipids from the diet
through the lymph and into the circulatory syste
Apoproteins
form the transport unit and regulate interaction with tissues
ApoC
transport and interaction with adipose to put triglycerides into storage
ApoE
interaction with hepatic and nerve cells
helps give cholesterol or fat to nerve cells
remnants of chylomicrons are taken up by the liver and used to produce
VLDLs
VLDLs
distribute lipids to the tissues
HDLs
used as scavenging system to return cholesterol to the liver
ApoA
HDLs help bind and transport cholesterol
dietary fat processing once in bloodstream (endogenous pathway)
-some fatty acids may get taken out by adipose tissue and skeletal muscle
-IDL: chylomicron dropped off some triglycerides
can give off all triglycerides and just have cholesterol - LDL taken into liver
if excess cholesterol and fats than you need
need to scavenge, receptor dependent pathway - their tissues need for hormones or membranes can get from LDL supply
can get plaques
macrophages help clean up
while liver making and putting out LDLs it also makes
HDLs that have no cholesterol , they are the scavengers and go into the blood nd pick up cholesterol to clean it out
then return to liver and throw it out with bile
should you be concerned if lowHDLs but normal LDLS
yes bc HDLs help clean up the excess cholesterol
ileum
absorbitive but less SA than jejunum
primarily absorbs water and electrolytes lost in secretions
receptors to transport/absorb complex of intrinsic factor and V B12
Peyer’s patches aid in immunological defense
ileum
absorbitive but less SA than jejunum
primarily absorbs water and electrolytes lost in secretions
receptors to transport/absorb complex of intrinsic factor and V B12
Peyer’s patches aid in immunological defense
3 types of enterogastric reflexes
enterogastric reflex
gastrocolic reflex
colonileal reflex
enterogastric reflex
high acid levels inhibit gastrin and slow stomach emptying
gastrocolic reflex
distension of stomach inc motility in intestines
why when osmeone eats they have to use restroom 25-40 min later - moves through intestines to make more room for new food coming in
coloineal reflex
regulates movement from SI to colon (ileocecal valve)
large intestine (colon) structure
thinner walls than SI
several ribbons of smooth muscle (tenia coli) run the length of colon
Haustrations or pouches of the wall are connected to the tenia coli
appendix at end of colon
appendix composition
lmphatic tissue - role in maintaining normal flora - defensive mechanism
what does the normal flora produce
several vitamines (K, biotin, B5) that are absorbed in colon
- normal bacteria produces here like E.coli
also takes up space to outcrowd the bacteria
when people take large doses of antibiotics like erythromycin they can kill off and dirupt normal flora - GIupset
what does the colon absorb
electrolytes and water
where is the rectum in women vs men
women: behind uterus - uterus between bladder and rectum
men: behind bladder
diverticulosis
when weak area of colon (diverticula) from out-pockets in the wall
not a lot of fiber in diet , suffering from constipation - get openings - not smooth walls
divertiulitis
if divertiulosa become infected this painful and dangerous condition develops
when you get something stuck in here
- if ruptures: can get peritonitis which is life threatening
if swelling but no rupture - get blockage and causes necrosis of tissue
if another intestine closer can get fistula
genetic predisposition for some
defecation
peristaltic activity moves fecal mater from colon into rectum
distension of rectal wall initiates defecation reflex
contraction of rectal wall puts P on internl sphincter
opening internal sphincter puts P on external (voluntary) anal sphincter which can be opened to expel feces
if no defecation: feces return to sigmoidal colon until peristaltic waves inc P
how can gas pass without opening the external sphincter
channels/grooves in anal canal
