urinary system

Question 1

functions of the liver

Answer 1

breaks down exogenous toxins

Question 2

functions of kidneys

Answer 2

excrete toxins

Question 3

nephron

Answer 3

smallest funtional unit of the kidney

Question 4

fluid movement through the nephron

Answer 4

1. Renal corpuscle (glomerulus + Bowman’s capsule)
2. Proximal tubule
3. Descending loop of Henle
4. Ascending loop of Henle
5. Distal tubule
6. Collecting ducts

Question 5

the loop of henle sepertes

Answer 5

the proximal from distal tubules

Question 6

nephron functions (fluid movement)

Answer 6

• Nephron functions (fluid movement):
  1. Filtration: from blood into Bowman’s capsule
  2. Reabsorption: from tubule back to bloodstream
  3. Secretion: from bloodstream (capillaries around
  tubules) into the tubules except for Bowman’s capsule

Question 7

excretion:

Answer 7

expelling urine from the bladder through urethra

Question 8

amount excreted equatuation

Answer 8

Amount excreted = amount filtered – amount resorbed
+ amount secreted

Question 9

what substances are totally reabsorbed after filtration

Answer 9

glucose and amino acids

Question 10

what substances are partially reabsorbed

Answer 10

sodium

Question 11

what substances are totally excreted

Answer 11

medications and toxins

Question 12

what are the hormones affecting the distal tubule and collecting duct

Answer 12

• Parathyroid hormone (PTH) increases Ca++ reabsorption
• Antidiuretic hormone (ADH) increases water reabsorption
• Aldosterone increases Na+ reabsorption the nephron (and thus increases water reabsorption) but also increases K+ secretion

Question 13

how much of water is reabsorbed

Answer 13

alomst 100% only 1% goes to urine

Question 14

how much urine do we make a day

Answer 14

1-2 L a day

Question 15

molecules passing into or out of nephron tubules must move through

Answer 15

the cuboidal epithelial cells lining the tubule

Question 16

The side facing the tubule lumen (inside) is called the

Answer 16

apical or luminal membrane

Question 17

the side NOT facing the tubule lumen is the

Answer 17

basolateral membrane

Question 18

Tight junctions between epithelial cells prevent

Answer 18

most molecules from moving between the cells, so they must go through the epithelial cells
This means the cells can regulate which molecules move back to the bloodstream by using membrane proteins (channels and transporters)
(the rest of the water molecules become urine)

Question 19

Like in intestines, water can be reabsorbed by:

Answer 19

1. Osmosis
2. Through aquaporins (upregulated by ADH),
3. Paracellular transport (tight junctions can’t completely stop water)
   As more ions are reabsorbed, more water is reabsorbed (same as small intestine)

Question 20

Transport mechanisms vary depending on the molecule:

Answer 20

simple diffusion, osmosis (water), facilitated diffusion, coupled transport and active transport

Question 21

Glucose and amino acids are completely reabsorbed by the

Answer 21

proximal tubule – co-transport with Na+ (apical membrane), then GLUT (basolateral) in healthy people.

Question 22

The Na+ from glucose/amino acid co-transport needs to be

Answer 22

emoved from the cell, so the Na+/K+ pump on the basolateral side pumps it back into the circulation

Question 23

Angiotensin II effects (all increase BP):

Answer 23

1. Stimulates adrenal cortex to produce aldosterone
2. Vasoconstriction
3. Posterior pituitary to release antidiuretic hormone
4. Sympathetic nervous system increase blood pressure
5. Reabsorption of Na+ and Cl- (and so water)
6. Causes thirst and salt craving

Question 24

(renin-antogensin system) Decreased blood pressure causes

Answer 24

decreased stretch of baroreceptors in the afferent arterioles (entering glomerulus)

Question 25

RAS signal

Answer 25

juxtaglomerluar cells to secrete renin into the bloodstream

Question 26

renin cleaves angiotensinogen into

Answer 26

angiotensin I

Question 27

angiotensin I is cleaved into

Answer 27

angiotensin II (by ACE

Question 28

low blood sodium decreases

Answer 28

the glomerular filtration rate (GFR) as well as causing renin production and release

Question 29

what is GFR

Answer 29

the amount of blood filtered by the glomeruli each minute.

Question 30

Macula densa cells signal smooth muscle cells in the

Answer 30

afferent arteriole to constrict, thus decreasing pressure and reducing filtration and so urinary output
They also signal juxtaglomerular cells which store renin and secrete it when blood pressure is low

Question 31

low blood sodium or water causes blood pressure to

Answer 31

decrease

Question 32

low sodium is detected by

Answer 32

the macula densa cells in the upper ascedning loop of henle