Excretory System

Question 1

urinary artery vs vein:

Answer 1

Artery: blood supply to kidney
Vein: blood supply away

Question 2

Functional unit of the kidney

Answer 2

Nephron

Question 3

part of the nephron located in the renal cortex:

What is its role?

Answer 3

Renal corpuscle

• filters blood from afferent arterial, diffusion to glomerular capillaries of bowman’s capsule
• Reabsorb substances back into peritubular capillary
• Secrete substances back into corpuscle
• Out towards` urinary excretion

Question 4

Part of nephron located partially in cortex and medulla:

- how does it extend

Answer 4

Renal tubule: cortex, deep into medulla, back up into cortex

- Filtrate travels through until reaching the collecting duct for drainage

Question 5

Pathway of urine:

Answer 5

• renal corpuscle > renal tubule > collecting duct > medullary pyramids > minor and. Major calyx > renal pelvis > ureter > urethra

Question 6

Control of urine release from the body:

Answer 6

Internal and external urethral sphincters

• internal: smooth, autonomic control
• external: skeletal, voluntary control

Question 7

What soluble mixture is called and includes and occurs by:

Answer 7

Filtrate
- water, salt, vitamins, glucose, amino acids

NOT: proteins, blood cells

Occurs via hydrostatic pressure

Question 8

Parts of the renal tubule

Answer 8

Proximal convoluted tubule (PCT): reabsorb small nutrients, glucose in large quantities (virtually all)

Loop of Henle: descending and ascending > retention of water and solutes (sodium)
- reduce volume of urine without change concentration

Distal

Overall:
- adjust volume filtrate, reabsorbs valuable nutrients, expels waste

Question 9

What is hypertonicity? And what part of the nephron is hypertonic?

Answer 9

Solute rich: more concentrated?

• Medulla > cortex hypertonicity
• mostly Sodium

Question 10

Descending vs Ascending loop of Henle:

Answer 10

Descending: permeable to water but not ions
- water down concentration gradient > vasa recta

Bottom of loop: very concentrated

Ascending: permeable to ions (na/K) - but now after

• ions out to vasa recta
• active transport required the higher up the ascending limb

Question 11

opposite direction of filtrate and blood in loop of henle is defined as:
- what direction is each

Answer 11

Countercurrent multiplier system

• filtrate down loop of henle
• blood up the vasa recta

Question 12

Part of the nephron where ADH works to reabsorb what?

Answer 12

Collecting duct, promote water reabsorption

Question 13

Ions, urea, and water are reabsorbed in this part of the nephron:
- this effectively does what

Answer 13

Collecting duct: reduces filtrate volume and increases osmolarity

Question 14

This hormone acts on what part of the nephron(s) to promote reabsorption of sodium?

Answer 14

Aldosterone:

- acts on collecting duct and DTC

Question 15

This hormone works to reabsorb calcium in what part of the nephron?

Answer 15

PTH in the DTC

Question 16

How does ADH influence osmolarity?

Answer 16

• works on collecting duct
• promotes aquaporin insertion to reabsorb water
• Thus promotes water retention > reduce osmolarity

Osmolarity = solute (ions) / solvent
- incr solvent without changing solute reabsorption will decr osmolarity

Question 17

How does excretory system regulate blood pH?

Answer 17

• reabsorb/excrete H+ protons in the urine

- Sodium proton exchanger

Question 18

What is the structure of urea? How is urea created?

Answer 18

(NH2)2C=O

• carbo containing carrier of excess amine groups
• Ammonia is byproduct of protein breakdown > liver convert ammonia to urea

Question 19

Kidney failure during severe dehydration is most likely due to:

Answer 19

Inadequate blood volume for effective filtration

• Dehydration reduces filtrate through nephrons of kidney
• fluid volume drastically reduced, kidney unable to effectively do job of filtering and maintaining homeostasis and bodily fluids

Question 20

In the tropics, someone without sweat glands is more likely due die of heat stroke. What about vasodilation might cause this?

Answer 20

• Rely solely on vasodilation, radiation of heat, to respond to elevated external temperatures
• radiation alone is ineffective
• may actually gain heat by absorbing radiation from the sun, leading to further elevation in body temp

Question 21

What will osmolarity look like if someone is dehydrated?

Answer 21

Blood and urine osmolarity would be similar