kidney, excretory system Flashcards
functions of liver
stores glucose as glycogen
makes urea and releases into blood
breaks old heme into bilirubin which is excreted with bile, alongisde hydrophobic or large wastes that the kidney can’t handle
large intestine
reabsorbs water and ions, stores feces. IT can also, interestingly, actively transport excess ions into feces. But no digestion here
what ends up in urine?
water, urea, sodium, bicarbonate. But there shouldn’t be amino acids nor glucose. Furthermore, large proteins such as albumin should never enter filtrate in the first place
for both urine and feces
there is internal sphincter of smooth muscle; external one of skeletal muscle
order for kidneys
glomerular basement membrane > Bowman’s capsule > PCT > loop of Henle > DCT > collecting duct > papilla > calyx > renal pelvis > ureter
efferent arteriole
it is this vessel that constricts to generate the high pressure in the glomerulus to force out filtrate
in the PCT
most of reabsorption occurs here.
Glucose, amino acids - active transport
descending limb
thin walled. It is permeable to water, which exits, but not to ions.
ascending limb
the bottom half is THICK walled.
Here there is active transport of ions OUT of filtrate alongside passive return of K.
Thus, as filtrate moves up it grows more dilute
DCT
reabsorption of water and urea into filtrate. Here, aldosterone acts to promote Na reabsorption.
collecting duct
secretion of K and H+ ions
ADH
released by posterior pituitary. It puts aquaporins the the collecting duct, thus encouraging water retention
What triggers? Low blood volume or high blood osmolarity
aldosterone
secreted by adrenal cortex. It increases Na reabsorption in the distal nephron. (Meanwhile it makes K+ LEAVE the filtrate) Same result as ADH: increases bp.
What triggers Aldosterone release? Angiotensin II, low blood osmolarity, low bp
vasa recta
venous blood here flows in opposite direction of filtrate. It is a countercurrent exchanger
Principally, it pulls water out of filtrate to make it more concentrated
RAA
low bp > juxtaglomerular baroceptorssenses bp in aff arteriole > renin > cleaves angiotensinogen (of liver) into angio I > ACE in lungs cleaves into angio II > stimulates aldosterone release and causes vasoconstriction
carbonic anhydrase
converts CO2 into H2CO3 and is found all throughout nephron. To control blood pH, nephron may increase secretion of HCO3- and H+ alternately
calcitonin
increases Ca excretion in urine. PTH does the oppsoite
erythropoietin
released by kidney, increases RBC synthesis in marrow
brush border enzymes
both proteases and disaccharidases. Whereas pepsin and amylase break the polymers majorly; brush border enzymes break them into monomers (AAs and monosaccharides)
GI epithelium
have microvilli to increase SA. The cells are connected by tight junctions
GI smooth muscle
contracts spontaneously due to enteric pacemaker cells. The smooth muscle also has a functional syncytium like cardiac muscle
ENS
myenteric plexus - primarily does gut motility, which is contraction. Found btw 2 muscle layers
submucosal - found in submucosa - regulates enzyme secretion, blood flow, and osmolarity
goblet cells
make mucus. Line the GI tract
teeth types
incisors - cut
cuspids - tear
molars - grind
components of saliva
amylase, lipase, lysozyme
chief cells
these make pepsinogen
G cells
make gastrin, which acts locally. G cells themselves stimulated by histamine
parietal cells
make acid and intrinsic factor
which 2 ducts empty into duodenum?
pancreatic - digestive enzymes and bicarb
common bile duct - bile made in liver stored in gallbladder.
They both empty through the sphincter of Oddi
secretions of duodenum
enterokinase which cleaves trypsinogen into trypsin
CCK - secreted in response to fats. It stimulates bile release and decreases gastric motility
secretin - in response to acidity It stimulates pancreatic bicarb release
enterogastrone - decrease stomach emptying
intrinsic factor
made by stomach cells but promotes B12 absorption only in ileum
components of pancreas
EXOCRINE - amylase, lipase, nuclease, protease
ENDOCRINE -
alpha secretes glucagon
beta secretes insulin
celsl secrete somatostatin (inhibitory effect)
glucose must be in what form to travel thru blood?
pure glucose. If it is glucose-6-P it cannot cross membrane due to charge
peptide YY
secreted by jejunum to reduce appetite. Due to filling of colon
vitamins
fat soluble A - vision D - increases Ca absorption E - protects against ROS K - blood clotting water soluble B1 - needed for decarboxylations B2 - made into FAD B3 - made into NAD+ B6 - protein metabolism B12 - reduction of NTs to deoxyNTs C - collagen formation Biotin - transport of CO2 groups in rxn Folate - synthesis of nitrogenous bases, and for fetal nervous system develop
macula densa
sense blood osmolarity. When low, they dilate aff arteriole to increase urine production
