Class Nine Flashcards
what substances does the liver deal with
hydrophobic or large waste products that can’t be filtered out by the kidneys
what important substance does the liver synthesize? what does it do?
urea
carrier of excess nitrogen resulting from protein breakdown
role of the large intestine
reabsorption of water + ions
can also excrete excess ions
what controls sweating (2)
temperature and level of sympathetic NS activity
what does the kidney do (3)
excretion of hydrophilic waste
maintenance of solute conc + pH
maintenance of fluid volume
3 main processes of kidney excretion
filtration
selective reabsorption
secretion
what does blood enter the kidneys through
renal artery
how does purified blood enter the circulatory system from the kidneys
via renal veins
sphincters of the bladder
internal - smooth muscle (involuntary)
external - skeletal muscle (voluntary)
outer region of a kidney
cortex
inner region of a kidney
medulla
where are collecting ducts doun
in the medulla
where does the renal pelvis empty into
ureter
2 components of a nephron
capsule (where filtration occurs)
renal tubule (receives filtrate & empties into a collecting duct)
explain the process of filtration - glomerulus
afferent arteriole → glomerulus → efferent arteriole
constriction of efferent = high pressure & leaking into Bowman’s capsule
large substances do not pass in
explain the process of selective reabsorption
good substances are picked up by peritubular capillaries
where does most reabsorption occur
proximal convoluted tubule (PCT)
solute movement in the PCT is accompanied by..
water movement
where does most secretion take place - glomerulus
in the DCT and collecting ducts
this is how drugs & toxins go into the urine
what two hormones affect concentration and dilution
ADH and aldosterone
how does ADH affect urine
ADH is released by posterior pituitary during dehydration
increases water reabsorption in the distal nephron (makes it permeable to water)
what part of the body is impermeable to water
DCT
why do you pee a lot after alcohol consumption
alcohol inhibits ADH secretion by the posterior pituitary
how does aldosterone affect urine
released due to low BP → causes increased sodium reabsorption in the distal nephron
increased water retention → increased BP
triggers for aldosterone release (3)
low blood osmolarity
low blood volume
angiotensin II
countercurrent multiplier - loop of henle
the loop of hence makes the medulla very salty which allows for water reabsorption from the collecting duct
role of juxtaglomerular cells
baroreceptors that monitor BP
decrease in BP → releases renin
what do JG cells release? why is it important?
releases renin in response to low BP
renin converts angiotensinogen → angiotensin I which is then turned into angiotensin II with ACE
angiotensin II is a vasoconstrictor that raises BP + causes aldosterone release
role of macula dense
causes dilation of the afferent arterioles to increase BF to the glomerulus
where does aldosterone come from
adrenal cortex
where does ADH come from
posterior pituitary
where does calcitonin come from
C cells
where does parathyroid hormone come from
parathyroid
where does erythropoietin come from
kidney
main role of aldosterone
causes sodium reabsorption → increased BV → increased BP
main role of ADH
causes water reabsorption → increases BV → increases BP
main role of calcitonin
causes calcium to be removed from the body (released in response to too much calcium)
main role of parathyroid hormone
opposite function of calcitonin
increases calcium in the body
role of EPO
causes increases synthesis of RBCs in bone marrow
what causes EPO to be released
decreased blood oxygen levels
what is digestion
breakdown of polymers into their building blocks
apical surface
faces into the lumen
function of villi & microvilli
increase SA
two layers of SM in the gut
longitudinal layer
circular layer
how does food move through the gut
peristalsis
2 components of the enteric nervous system
myenteric plexus
submucosal plexus
what is the myenteric plexus
found between circular and longitudinal muscles
regulates gut motility
what is the submucosal plexus
found in the submucosa
regulates enzyme secretion
exocrine vs endocrine
exocrine glands secrete their products into ducts
endocrine glands are ductless → picked up by capillaries and enters BS
3 main roles of the mouth - digestion
fragmentation
lubrication
some enzymatic digestion
what does salivary amylase do
hydrolyzes starch
what does lingual lipase do
fat digestion
what does lysozyme do
attaches bacterial cell walls
what is pepsin secreted by? what does it do?
chief cells
catalyzes protein breakdown
how pepsinogen → pepsin
conversion is catalyzed by gastric acidity
food mixed with gastric secretions is..
chyme
when is the opening of the pyloric sphincter inhibited
when the small intestine already has lots of chyme in it
what secretes gastrin? what does it do?
G cells
stimulates acid and pepsin secretion + gastric motility
what stimulates gastrin secretion (2)
food in the stomach and parasympathetic NS
what is released in response to gastrin
histamine
3 segments of the small intestine
duodenum
jejunum
ileum
3 reasons why the small intestine has a large surface area
length
villi
microvilli
purpose of lacteals
absorb dietary fats
transports to the thoracic duct
what do Peyer’s paches do
collection of lymphocytes that monitor GI content for gut pathogens → immunity
what two facts empty into the duodenum
pancreatic duct
common bile duct
where is bile stored
in the gall bladder
2 functions of bile
vehicle for disposal of waste
essential for fat digestion
what is the sphincter of oddi
where common bile duct and hepatic duct meet
what does enterokinase do
activates trypsinogen → trypsin
3 main duodenal hormones
CCK
secretin
enterogastrone
when is CCK secreted
in response to fats in the duodenum
does CCK increase or decrease gastric motility
decrease
what does enterogastrone do
decreases stomach emptying
when is secretin released
in response to acid in the duodenum
where does absorption of vit B12 occur
ileum
where is the appendix attached
to the cecum
2 reasons why colonic bacteria is important
keeps dangerous bacteria from proliferating
supplies us with vit K → needed for blood clotting
how are pancreatic proteases secreted
in their inactive zymogen forms
CCK effect on pancreas
causes pancreas to secrete enzymes
secretin effect on pancreas
causes the pancreas to release water and bicarb
what do alpha cells secrete
glucagon
what does glucagon do
released in response to low blood sugar
stimulates the liver to hydrolyze glycogen + release glucose into the BS
what do beta cells secrete
insulin
what does insulin do
secreted in response to high BS
turns glucose → glycogen
what do s cells secrete
somatostatin
what does somatostatin do
inhibits many digestive processes
ingredients of bile
bile acids
cholesterol
bilirubin
2 places bile from the liver can go
gall bladder
directly secreted into duodenum
what is a gallstone
large crystal formed from bile (too much cholesterol)
what 2 things stimulate contraction of gallbladder
CCK and parasympathetic NS
what does ghrelin do
stimulates appetite
what does peptide YY do
reduce appetite
what does leptin do
appetite suppressant
what happens if the hypothalamus is resistant to leptin
obesity
vitamin A
visual pigment that changes conformation in response to light
fat sob
vitamin D
stimulates calcium absorption from the gut
fat sob
vitamin E
prevents oxidation of unsaturated fats
fat sob
vitamin K
blood coagulation factors
fat sob
vitamin B1
needed for enzymatic decarboxylations
water sob
vitamin B2
made into FAD, electron transporter
water sob
vitamin B3
made into NAD, electron transporter
water sob
vitamin B6
coenzyme involved in protein and AA metabolism
water sob
vitamin B12
coenzyme involved in the reduction of nucleotides to deoxynucleotides
vitamin C
necessary for collagen formation
vitamin biotin
prosthetic group essential for transport of CO2 groups
vitamin folate
enzyme cofactor used in the methylene groups
water sob
what activates vitamin D
kidneys
what does ANP do (3)
vasodilator
inhibit renin
inhibit aldosterone
