10.1 HY The Excretory System (Kidneys)

Question 1

What are four functions of the kidney?

Answer 1

1. Regulation of blood pressure
2. blood osmolarity
3. Acid-base balance
4. Removal of nitrogenous wastes

Question 2

What are the following areas of the kidney:
Cortex:
Medulla:
Hilum:

Answer 2

Cortex: outer most layer
Medulla: inside of kidney
Hilum: deep medial surface

Question 3

What’s the difference between the afferent and efferent arteriole? (renal)

Answer 3

Afferent: brings blood towards the glomerulus
Efferent: brings blood away from the glomerulus

Question 4

What is the Bowman’s Capsule?

Answer 4

It is a cup-like structure that surrounds the glomerulus.

Question 5

What is the Bowman’s Capsule?

Answer 5

It is a cup-like structure that surrounds the glomerulus.

Question 6

What is the detrusor muscle?
What innervates it?

Answer 6

it is the muscular lining of the bladder

It is innervated by the parasympathetic system.

Question 7

What type of muscle controls the:
External urethral sphincter?
Internal urethral sphincter?

Answer 7

External: skeletal, under voluntary control
Internal: smooth muscle, involuntary control

Question 8

What is the micturition reflex?

Answer 8

It lets the person know that it is time to pee.
When the bladder is full, stretch receptors tell the nervous system that it is time to pee, the bladder contracts and the internal urethral sphincter opens.
The person can either keep the external sphincter closed or can open it to pee.

Question 9

What is the primary job of the kidney? (x2)
What three functions can this be divided up into?

Answer 9

regulate blood volume and osmolarity.

1. Filtration- movement of solutes from blood to filtrate at Bowman’s capsule
2. Secretion- movement of solutes from the blood to filtrate anywhere besides bowman’s capsule
3. Reabsorption: movements of solutes from filtrate

Question 10

What pressures or force regulate the movement of fluid into the bowman’s capsule?

Answer 10

Starlings forces (this is a misnomer because it is really the pressure differential that causes the movement of fluids)

1. Hydrostatic pressure in the glomerulus is significantly higher than in Bowman’s space.
2. However, osmolarity of blood is higher than in bowman’s space.

Question 11

What is secretion?
What is secreted in the kidney?

Answer 11

Secretion- movement of solutes from the blood to filtrate anywhere besides bowman’s capsule

The nephron can secrete salts, acids, and bases into the tubule through active or passive transport. Also can secrete urea

Question 12

How does a protein go from meat to urea?

Answer 12

Meat –> nitrogen –> ammonia –> urea (ammonia converts to urea by liver)

Question 13

What is reabsorption? What is reabsorbed?

Answer 13

Reabsorption: movements of solutes from filtrate

Certain substances like glucose, and amino acids, and vitamins are reabsorbed.

Water is reabsorbed to maintain blood pressure, and is governed by ADH and aldosterone.

Question 14

What happens in the proximal convoluted tubule?

Answer 14

Reabsorbed: Amino acids, glucose, and water-soluble vitamins, water, salt

Secretion: hydrogen ions, potassium ions, ammonia, and urea.
Dump the HUNK (hydrogen urea, nitrogen, potassium)

The filtrate remains isotonic to the interstitium. .

Question 15

What does the descending limb of the loop of Henle do?

Answer 15

Only absorbs water (tubule –> interstitcium)

As it goes down, the interstitium is more and more concentrated. This causes water to exit the loop of Henle.

Question 16

What is the countercurrent multiplier system?

Answer 16

This is made up of the vasa recta and nephron.

This means that the flow of the filtrate through the loop of Henle is in the opposite direction from the flow of blood through the vasa recta.

The opposite direction is important. If they flowed in the same direction, they would quickly reach equilibrium, and the kidney would be unable to reabsorb as much water.

Question 17

What does the Ascending limb of the loop of Henle do?

Answer 17

It is only permeable to salts. It is impermeable to water.
Actively reabsorbs NaCl only, via active transport

Because only salt is absorbed, not water, inside the ascending loop becomes hypertonic

The medullary is less tonic.

Question 18

What is the diluting segment of the loop of Henle?

Answer 18

This is in the ascending loop of Henle, at the transition from the medulla to cortex.

Question 19

What is the diluting segment of the loop of Henle?
Diluting segment= ascending loop

Answer 19

Diluting segment= ascending loop

The cells are larger here, causing the loop to be thicker. This occurs in the transition from the inner to outer medulla.

They contain a large amount of mitochondria, which allow for reabsorption of sodium and chloride by active transport. This causes the filtrate to by hypotonic.

This is an important part because it can create fluid that is more dilute than the blood.

This is important because it can eliminate excess water with overhydration.

Question 20

What happens at the distal convoluted tubule?

Answer 20

Responds to aldosterone, which promotes the reabsorption of sodium. Here, the water may follow, decreasing the volume and increasing the concentration of the filtrate.

Question 21

What happens in the collecting duct?

Answer 21

Responds to both aldosterone and ADH.
Water may be further reaborbed here

Anything that is not absorbed by the end of the collecting duct will be secreted in urine.

Question 22

How does aldosterone work?

Answer 22

Aldosterone works by altering the ability of the distal convoluted tubule and collecting duct to reabsorb sodium.

By absorbing more sodium, the water follows, and you increase blood pressure.

Question 23

How does ADH work?

Answer 23

increases absorption of water only.
Alcohol and caffeine both inhibit ADH release, and cause extretion of dilute urine.

Question 24

What will vasoconstriction do in the kidney?

Answer 24

Will lead to lower pressure of blood reaching the glomeruli, which will cause the juxtularglomerular cells to release renin, also increasing blood pressure.

Question 25

How does the kidney effect the pH?

Answer 25

The kidneys can selectively increase or decrease the secretion of hydrogen ions and bicarbonate.

For example, when the pH is too high, the kidneys can excrete more bicarbonate and increase the reabsorption of hydrogen ions.

It is slower than the respiratory response, but highly effective.