Digestion and Excretory
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mouth - esophagus - stomach - small intestine - large intestine - rectum - anus
digestion starts where, and how?
alpha-amykase in saliva
alpha amylase does what?
degrades starch into polysaccharides
increases surface area allowing more enzymes to work on food molecules
How are food molecules pushed to esophagus?
What is primary function of the stomach?
mixes and stores food - reduces it to chyme
exocrine glands in stomach
begins protein digestion with pepsin
What is the pH of the stomach
4 cell types in the stomach
What do mucous cells do?
line stomach wall and exocrine glands
allows food to slide along without damaging the cell
What are mucous cells composed of?
sticky glycoproteins and electrolytes
What do chief cells do?
What is pepsinogen? What is it activated by? What does it do?
pepsinogen = zymogen of pepsin
activated by low pH of the stomach
What do parietal cells do?
lowers pH of stomach and raise blood pH
What are parietal cells stimulated by?
release of gastrin
What do G-cells do?
What is gastrin, and what does it do?
gastrin = peptide hormone
absorbed into the blood - stimulates parietal cells
What are the major hormones that affect secretion of stomach juices?
acetylcholine, gastrin, and histodine
3 parts of the small intestine and their functions
duodenum (most digestion)
wall of small intestine contains what, and why?
increases surface area
(brush border in light microscope)
What does lysozyme do?
regulates bacteria within the intestine
Where does chime move to after the small intestine?
Main function of the pancreas
acts as an exocrine gland
secretes bicarbonate ions
What is the pH in the small intestine and how?
pH = 6
bicarbonate ions released from small intestine
Which enzyme activates all other zymogen forms released from the pancreas
major enzymes released from the pancreas and their function
trypsin and chymotrypsin = degrade proteins
amylase = polysaccharides into di and trisaccharides
lipase = degrades fat (triglycerides)
Trypsin degrades proteins into small polypeptides. How are they reduced to amino acids?
when they reach the brush border
bile - where is it produced, where is it stored, what does it do?
produced in liver
stored in gull bladder
emulsifies fat = increases surface area
What happens to bile after it emulsifies fat molecules?
reabsorbed by small intestine and transported back to liver
Primary function of large intestine
How is glucose absorbed into cells?
secondary active transport
down Na+ gradient
How is fructose absorbed into cells
How are proteins absorbed into cells?
co=transport down Na+ gradient
Do we want a high or low intracellular amino acid concentration?
When fats are absorbed, they are first converted into what, how?
converted to fatty acids to brush border
diffuse through enterocyte membrane
return to triglycerides at smooth ER
delivers lymph to venous circulation
delivers fat to the blood
Where does liver receive blood from?
capillary beds of the intestines, stomach, spleen, pancreas
Why is there a secondary blood supply to the liver?
sent to oxygenate it
Where does all of the blood received by the liver move to?
through flattened spaces
leads to vena cava
liver funcitons (5)
- 1. blood storage and filtration
- 2. carb, fat, and protein metabolism
- 3. detoxification
- 4. erythrocyte destruction
- 5. vitamin storage
When liver mobilizes fat or protein for energy, what happens to blood acidity levels?
afferent/efferent arterioles - glomerulus - Bowman's capsul - proximal convulated tubule - loop of Henle - distal convulated tubule - collecting duct - bladder/urethra
uterer and urethra
uterer = carrries urine to the bladder
urethra = drains the bladder
afferent and efferent arterioles
afferent = carries blood into nephron
efferent = carries filtered blood out of nephron
what is the renal capsule
glomerulus and Bowman's capsule
how does filtrate move from glomerulus to Bowman's capsule?
What goes on in proximal tubule?
secondary active transport
wanted material is reabsorbed into capillary system
glucose reabsorption in proximal tubule
in a healthy adult, glucose is completely reabsorbed
Is insulin absorbed or excreted?
loop of Henle - location
crosses border from renal cortex into renal medulla
only permeable to water
- H2O leaves loop and into medulla
- (because medulla is salty)
filtrate osmolarity in descending loop
only permeable to salts
slats leave filtrate
reabsorbs Na+ and Ca2+
secretes K+ , H+ and HCO3-
collects waster products of multiple nephrons
transports waste to bladder
increases permeability of water - water is absorbed into medulla (since it's salty)
Always Digging Holes
Where is the urine concentrated?
descending loop of Henle
mostly in collecting duct
What does aldosterone do?
increases Na+ and K+ membrane transport proteins
so it increases Na+ absorption and K+ secretion
monitors filtrate pressure in distal tubule
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