digestive and excretory systems Flashcards
digestion
break down of food into smaller organic molecules for absorption
absorption
how nutrients really enter the body
bolus
broken down food with saliva
salivary amylase
begin breaking up sugars
esophagus
takes food from mouth to stomach where it enters a spincter
GERD
issue with the gastroesophageal sphincter where acid moves back up
pepsin
stomach protease
cleaved form of pepsinogen
- cleaves proteins at aromatic residue
parietal cells
cells of stomach that secrete stomach acid (acidic)
chief cells
secrete zymogen of pepsin known as pepsinogen, so no self destruction in stomach occurs
Foveolar cells
secrete bicarbonate to protect stoamch from acidiity
intrinsic factor
secreted by stomach to help absorb vitamin b12
pyloric sphincter
connects stomach and small intestine
portions of small intestine
dueodenum, jejunum, ileum
chyme after stomach
highly acidic and must be neutralized by small intestine
what structures contain brush border enzymes
microvilli in small intestine
types of brush border enzymes
disaccharidases, peptidases
pancreas
secretes digestive fluiid with enzymes for breakdown
liver
secretes bile , which breaks down all major macromolecules
bile
emulsify fats and help convert them into micelles
- produced in liver
gallbladder
where bile is stored and released from
how is the duedoenum alkaline when the stomach is acidic
pancreatic juices are alkaline, duedenum secretes bicarbonate , bile is alkaline
villi
fingerlike projections of small intestine that extend into lumen of the intestine and increase surface area
- lined with enterocytes
enterocytes
cells of intestinal lining with microvilli (increase surface area for cell funciton)
large intestine
ascending colon, transverse colon, descending colon, sigmoid coloon, rectum
cecum
part of small intestine that is attached to ileus of small intestine
appendix
attached to cecum
- vestigal organ
function of the large intestine
absorbs water from food undergoing digestion
- contains microbiota
microbiota
symbiotic bacteria living in the large colon that produce vitamin K and B7
does chemical digestion occur in the large intenstine
no
peristalsis
wave like contraction of smooth muscle that pushes bolus down the digestive tract
- involuntary
sphincters
canals in various parts of digestive tract
hunger hormones
grhelin and leptin
grehlin
grr makes you hungry
- secreted from stomach when it is empty
- increase appetitie
leptin
hormone secreted when food is in stomach and we are satiated
- secreted by adipocytes
G cells
cells of stomach that secrete gastrin
gastrin
promotes digestion by stimulating parietal cells to release HCL
parietal cells
cells of stomach that secrete gastric acid (w HCl)
secretin
s cells of small intestine
- triggers secretion of pancreatic bicarbonate to neutralize acidic chyme for optimal function in digestion of SI
CKK
secreted by cells of small intestine , stimulate secretion of pancreatic juices and digestive enzymes, release of bile
what does ckk inhibit
inhibits appetite
somatostatin
slows digestion down
- inhibits release of digestive enzymes
- gastin, ckk
- inhibits growth hormone release
treatment for gigantisism
somatostatin because it inhibits GH
enteric nervous system
nervous system connected to digestion
sns effect on digestion
inhibits digestion
function of villi
dramatically increase surface area for abosrption
function of microvilli
similar to villi projections but from inidividual cells located on villi to increase SA
what must happen to carbohydrates in order to be absorbed
broken down into monosaccharides
how is glucose transferred into the cell
secondary transort coupled with in take of NA
how are lipids aborbed via microvilli
formed into micelles and inidivudal lipids break off for absorption
- diffuse through membrane
chylomocrons
TAGs, proteins, vitamins are packaged and released into lymphatic system
hepatic portal vein
runs from small intestine to liver and the heptaic portal system
hepatic portal system
system of veins that transports blood from the digestive tract to the liver
important metabolic tasks of the liver
- detoxification
- metabolizing medications and drugs
- store excess carbs as glycogen and excess fat as TAG
- mobilize lipids via lipoproteins and glycogenolysis
where are chylomircons and other lipids returned for degredation
liver
digestive path for proteins
broken down by pepsin , then peptidases in SI ,
pepsidases in SI
trypsin and aminopeptidase
where does typsin cleave proteins
carboxyl end of lysine or argenine
where does aminopeptidase cleave
at amine end of any protein
carbohydrate digestive path
broken down by salivary amylase in mouth, then sent to stomach , pancreatic amylase, dissachraridases in SI
disaccharidases of Small intestine
sucrase, maltase, lactase
lipid digestion path
first broken down by lingual lipase , majoirty broken down by pancreatic lipase , bile packages free FA into micelles for chylomicrons and released into lacteals
vitamins
non-macronutrient compounds necessary for funcitoning
- not synthesized naturally
lipid soluble vitamins
A, D, E, K
- accumulate in adipose tissue
water soluble vitamins
B and C
- circulate blood and easily excreted
vitamin A
retinol
function - vision
vitamin D
help absorb calcium and phosphate in gut
vitmain E function
antioxidant
vitamin k function
coagulation
vitamin c
absorbic acid
function: required for collagen synthesis and antioxidant
vitamin b1 function
thiamine
cofactor for PDC complex
vitamin b2
riboflavin
precursor for FAD
vitamin B3
niacin
precursor for NAD and NADP
vitamin b5
required for syntehsis of coA
vitamin b6
coenzyme in metabolism
vitamin b7
biotin
cofactor for carboxylases
vitamin B9
folic acid
- neuro development and healthy pregnancy
vitamin b12
coenzyme for dna synthesis
scurvy
vitmain C synthesis
- improper formation of collagen
rhodopsin
protein formed from binding of vitamin A and opsin in the rods of the retina for low light vision
retinol
form of vitamin A we absorb in the small intestine
- unstable so it is converted into a retiol ester for long term storage
vitamin D
multiple forms and acts as a hormone to act oh phopshphate and calcium levels
- converted into calcitrol
calcitrol
increases calcium levels , acts on intestine to absorb more calcium
microbiota produce what vitamin
K
excretory function of the kidneys
formation of urine
divided into renal cortex and renal medulla
nephrons
structural unit of the kidneys that produce urine
- renal corpuscle and renal tubule
renal corpuscle
carries out initial filtration
- in adrenal cortex
renal tubule
projects down into the medulla
- urine drains into the collecting duct
urinary bladder
muscular and flexible
urinary sphincter
controls release of urine from the urethra
- divided into internal and external
external urinary sphincter
skeletal muscle, voluntary control
internal urinary sphincter
smooth muscle, involuntary control
structures of the renal corpuscle
glomerulus and bowmans capsule
function of glomerulus
filters blood
function of bowmans capsule
also filters blood
main parts of renal tubule
proximal convoluted tubule
loop of henle
disal convoluted tubule
function of renal tubule
absorb water, salt, glucose back into blood
PCT
two way exchange
- absorbtion dominates
- na absorption
- excretion of waste inito urine also happens here
loop of henle
ushaped
goal: reduce volume of water
- deeper into medulla = more concentrated with solute
descending loop of henle
permiable to water, NOT ions
ascending loop of henle
impermiable to water, allows ions to leave
end product of loop of henle filtration
less blood volume, more concetrated
DCT
can increase calcium absorption in response to PTH
what structures does aldosterone act on to increase sodium absorption
DCT and collecting duct
- promotes na reabosrption and water reabosrption to increase blood volume and pressure
what hormone targets the collecting duct directly
ADH/ vasopressin
- increases water absorption directly
ANP effect
opposite of aldosterone, prevents sodium reabsorption
- decreases water absorbed
-lowers bp and bv
major parameters that effect bp
bp, osmoregulation, acid bace balencning, size of vessel, flow of blood
main hormones that effect fluid balence
aldosterone, anp, adh
how does aldosterone affect fluid retnetion
- acts on DCT and CD to increase sodium absorption which causes water retention
- increase in BV and BP
how does ADH/vasopressin affect fluid retention
acts on the CD to increase water retention directly
- increase in BP
how does ANP affect fluid retention
acts against aldosterone and prevents na absorption in DCT
what organ and release system regulates aldosterone
kidneys via the renin-angiotensin release system
what kind of receptors release renin from the kidneys when BP is low
baroreceptors
renin function
cleaves angiotensinogen into angiotensin 1
ACE function
cleaves angiotensin 1 into angiotensin 2
function of angiotensin 2
increases bp via vasoconstriction and triggers release of aldosterone
how does the excretory system regulate blood pH
can increase blood pH by excreting h+ ions
urea
nitrogen waste excreted via excretory system
- carbonyl )c=0) with 2 amine groups on both side
- excrete unnecessary nitrogen
