PPY Exam 5

What is the blood flow through the nephron?

afferent arterioles, glomerulus, efferent arterioles, pertubular capillaries, and back to the veins

What is filtration?

goes from the glomerulus into the Bowman's capsule

Filtration is the first step to make _____.

filtrate

What is reabsorption?

going from the lumen that is inside the tubules to the peritubular capillaries (means it gets back into the blood)

What is secretion?

going from the peritubular capillaries back into lumen in the tubules (going to end up in the urine)

_____ does secretion.

potassium

What does it mean to say a substance is freely filtered?

substance in the Bowmna's capsule has the same concentration as in the afferent arteriole/blood

_____ does not get through filtration.

protein

What is micturition?

urinating

What happens during micturition?

-bladder sends signal to spinal cord that connects to the parasympathetic that connects to the bladder
-contraction of bladder smooth muscle by parasympathetic and put urine out
-sympathetics are shut off by lumbar cord causing relaxation of internal sphinter
-somatic is shut of by brain causing relaxation of external sphincter by voluntary somatic relax

How is GFR maintained constant?

-regulated by myogenic (responds to stretch BP)
-juxtaglomerular autoregulation (responds to sodium flow past mascular densa cells)

What is myogenic?

stretch

If BP is up, there is an increase in GFR so afferents _____.

contract

If BP is low, there is a decrease in GFR so afferents _____.

relax

What do macular densa cells do if flow is too high?

send a paracrine signal to afferents to contract

What do macular densa cells do if flow is too low?

send a paracrine signal to afferents to relax

The loop of henle is the _____ multiplier.

countercurrent

What does the loop of henle countercurrent multiplier do

it sets up the osmotic gradient in the medulla

What is a countercurrent exchanger?

-peritubular capillaries going around the mulitplier
-vesa recta maintains the gradient

Why does osmolarity increase as we go down the descending loop?

-Na is pumped out at the ascending loop
-water moves osmotically from the descending loop
-no sodium movement in the descending loop
-no water movement in the ascending loop

Descending loop only has _____ channels.

water (no sodium channels)

The descending loop spits out water which...

increases concentration and filtrate

What are the tubules of the ascending loop spitting out?

sodium

As you move up the tubules of the ascending loop, osmolarity is _____.

decreasing

What happens if the loop of henle doesn't work? (No water channels in the descending loop and no sodium channels in the ascending loop)

the gradient wouldn't be set up so ADH would not function and you would not get water reabsorption in the collecting duct

If the loop of henle isn't functional, _____ won't work.

ADH

What is glucose reabsorption under normal conditions (blood glucose

all glucose that is freely filtered is reabsorbed in the proximal tubule

When does glucose appear in the urine?

only when blood levels exceed 180mg/dL

Reabsorption is linearly related to levels until 180, so if blood glucose doubles the reabsorption will ____.

double

_____ accounts for water reabsorption in the collecting duct.

ADH

What is ADH released in response to?

-increase in renin (respons to low BP and low sodium flow)
-increased osmolarity (because you want to reabsorb water so you can decrease osmolarity)

What changes override the GFR constant effect?

-sympathetic decreases GFR
-renin release decreases GFR
-ANP increases GFR

What stimulates aldosterone release?

-increase in renin
-increase in blood potassium (not dependent on renin)
-decrease in BP (dependent on renin release)

Angiotensinogen is produced in the _____.

liver

Low BP renin increases angiotensin II and angiotensin I _____.

directly

Angiotensin I is converted into angiotensin II by enzyme _____.

ACE

What does angiotensin II do?

-acts directly on blood vessles stimulating vasoconstriction (narrowing)
-acts on adrenal gland to stimulate release of aldosterone
-decreases GFR
-ADH release

A drop in BP and drop in fluid volume causes...

renin release from kidney

Renin acts on an angiotensinogen to form _____.

angiotensin I

ACE (angiotensin-converting enzyme) is released from the _____.

lungs

Aldosterone acts on the kidneys to stimulate...

reabsorption of salt (NaCl) and water

What increases renin?

-decrease in BP and low blood volume
-decrease in blood sodium and low sodium past macular densa cells
-sympathetics

Where does renin come from?

juxtaglomerular cells

What would happen with a decrease in blood volume?

-BP would decrease
-renin would be released and cause vasoconstriction of the arterioles
-decrease in GFR
-increase in sympathetic which decreases GFR

What happens when you increase ANP (atrial natriuretic peptide)?

-decrease in renin release (angiotensin II, aldosterone, ADH, Na and water reabsorption go down which causes increased urine volume)
-decreases sympathetic activity and vasoconstriction
-increases GFR

What does PTH do?

increases clacium reabsorption

How does PTH increase calcium reabsorption?

-increases number of transporters on apical membrane resulting in increase in transcellular transport

What does the kidney do if pH decreases?

-proximal tubules want to reabsorb bicarbonate that has been filtered
-proximal tubules want to make new bicarbonate

What happens when you make new bicarbonate in proximal tubules?

you also get NH3 and excrete it

How does the kidney handle nonvolatile acids?

production of HCO3 in alpha intercalated cells and then absorbed
-take Co2 and water and make H2CO3
-H2CO3 dissociates and makes H+ and HCO3
-take up HCO3
-excrete H+

Alpha intercalated cells are trying to correct _____.

acids

Beta intercalated cells are trying to correct _____.

bases

What is the cephalic phase?

just seeing, smelling, and tasting food

What is the migrating motor pattern?

-peristalsis sweeping in between meals (fasting)
-sweeps undigested food through the small intestine into the large intestine

What is the pharyngeal phase?

-under autonomic control of smooth muscle
-swallowing center of brain stem

What is the mucosa layer?

absorptive layer of GI

What does the submucosa fibrous contain?

blood vessels and lymphatic vessels

During the cephalic phase, the vagus nerve is _____.

parasympathetic

What does the vagus nerve stimulate?

-chief cells
-ECL cells
-G cells that excrete pepsinogen and gastric lipase

In the cephalic phase, HCl, pepsinogen, and gastric lipase is _____.

exocrine (going into the lumen)

In the cephalic phase, histamine and vagus are _____.

endocrine (going into the blood)

What does histamine stimulate in the cephalic phase?

parietal cells that excrete HCl

In the cephalic phase, HCl _____ protiens.

denatures

In the cephalic phase, pepsinogen _____ protiens.

breaks down

_____ stimulates stomach mobility.

vagus nerve

Cephalic phase contains...

vagus nerve and hormones

In the gastric phase...

food is the stomach

During the gastric phase, amino acids and peptide stimulates...

G cells to release gastrin

Gastrin is a _____.

hormone

Gastrin in blood stimulates:

-histamine from ECL
-pepsinogen from chief cells
-increase mobility of stomach and small intestine

Gastrin release is _____ when pH is at 1 or below.

inhibited

The intestinal phase is when...

chyme reaches the small intestine

What is it called when food is in the esophagus?

bowls???

What is it called when food is in the stomach?

chyme

Chyme reactes the small intestine in _____ amounts.

small

What happens during the intestinal phase?

-CCK is released
-secretin is released
-motilin is released
-glucagon-like-peptide 1 (GLP1) released

Glucagon-like-peptide 1's release is increased because of...

glucose in the diet

What does CCK do?

-stimulates small intestine motility
-slows gastric motility and secretions from pancreous
-contraction of gallbladder

Gastric phase _____ small intestine mobility and gastric mobility.

increases

What does contraction of gallbladder do?

releases bile

What does secretin stimulate?

HCO3 from pancreas

Where is HCO3 made?

-mucous cells in stomach
-brunner cells in small intestine
-pancrease duct cells

Why is there HCO3 in the stomach?

because we want it to be low pH

Why is HCO3 made by mucous cells?

they secrete mucous and HCO3 as a protection for the epithelial cells of the stomach

Why is HCO3 made by brunner cells and pancreas duct cells?

secrete HCO3 to neutralize chyme that enters small intestine from stomach

What does the liver synthesize?

-angiosinogen synthesis
-clotting factors, prothrombin, and fibrinogen

What does the liver do?

converts bilirubin to conjugated bilirubin

Converting conjugated bilirubin to urobilinogen occurs by...

bacteria in small intestine and large intestine

Urobilinogen is not made in the _____.

liver

Bacteria is in the...

small and large intestine

The large intestine absorbs water but _____ than the small intestine.

less

The large intestine contains...

-electrolytes (K+, NA+, Ca2+, Cl-)
-B vitamins
-vitamin K

_____ has no digestive functions.

large intestine

Where does aldosterone stimulate Na reabsorption?

kidney and large intestine (same mechanism)

Food is moved by _____ in the stomach.

peristalsis

Small intestine does _____.

segmentations (except the migrating motor pattern)

Stomach does _____.

peristalsis

Chyme sloshes back and forth between segments of the small intestine that forms when...

bands of circular muscle briefly contract

What does the parasympathetic nerves of the small intestine do?

increases both frequency and strength of contraction throughout the duodenum and ileum of the small intestine

_____ causes relaxation of smooth muscle in small intestine.

NO (nitric oxide)