Urinary System Physiology 1

Question 1

What vasculature of the kidney controls glomerular blood flow?

Answer 1

Afferent arteriole

Question 2

What controls blood flow through peritubular capillaries?

Answer 2

Efferent arteriole

Question 3

What happens with vasoconstriction of efferent arterioles?

Answer 3

Increased volume of blood into glomerulus –> increased glomerular hydrostatic pressure –> increase in filtration

Question 4

What is the major role of peritubular capillaries?

Answer 4

Reabsorption

Question 5

What is the tissue that regulates the concentration of the urine?

Answer 5

Vasa recta

Question 6

What blood vessels bring blood back to circulation?

Answer 6

Renal venules

Question 7

What collects the filtrate?

Answer 7

Bowman’s capsule

Question 8

What part of the nephron is responsible for the majority of reabsorption?

Answer 8

The proximal tubule

Question 9

Along with the vasa recta this part of nephron is important in controlling the concentration of urine?

Answer 9

The loop of Henle

Question 10

Where in the nephron is filtrate monitored by osmoreceptors?

Answer 10

Late (convoluted) distal tubule

Question 11

Which part of the nephron is impermeable to water?

Answer 11

Early/straight distal tuule

Question 12

Which part of the nephron regulates body sodium and potassium?

Answer 12

Late/convoluted distal tubule

Question 13

How does the body react to low Glomerular filtration rate?

Answer 13

(1) By causing vasodilation of the Afferent arteriole with release of vasodilator substances that bind to the afferent arteriole.

(2) By causing vasoconstriction of efferent arteriole by release of renin which leads to angiotensin II that binds to and causes vasoconstriction of the efferent arteriole.

Question 14

What are the effects of angiotensin II?

Answer 14

(1) Local vasoconstrictor

(2) Promotes release of aldosterone

Question 15

What stimulates renin production?

Answer 15

Decrease in Renal Blood Flow

Decrease in concentration of sodium. Renin is produced by the kidney to convert angiotensinogen to angiotensin II.

Question 16

An indication of how effectively the kidneys clear or excrete individual substances in the blood is known as what?

Answer 16

Plasma clearance

Question 17

What gives us a good estimate of GFR?

Answer 17

Plasma clearance of inulin. These substances are not secreted or reabsorbed by the kidney’s nephrons. Thus, GFR (liters of fluid filtered by the kidneys per minute) can be calculated.

Question 18

Substances moving passively from blood into nephron is known as what?

Answer 18

Filtration

Question 19

Substances moving actively from blood into nephron is known as what?

Answer 19

Secretion

Question 20

Substances moving from nephron into blood is known as what?

Answer 20

Reabsorption

Question 21

How is water reabsorbed?

Answer 21

Via osmosis

Question 22

Where is most of the water reabsorbed?

Answer 22

Proximal tubule

Question 23

What follows when sodium is actively reabsorbed?

Answer 23

Chloride

Question 24

Where in the nephron does aldosterone exert its effect on potassium and sodium?

Answer 24

Convoluted/late distal tubule

Question 25

Where is the majority of Na+, Cl- and K+ resorbed?

Answer 25

Proximal tubule

Question 26

What injected substance is a good measure of Renal blood flow due to the fact that there is no resorption and 100% secretion?

Answer 26

PAH, para-aminohippuric acid

Question 27

What are the effects of aldosterone?

Answer 27

Increased potassium secretion

Increased Sodium reabsorption

H+ excretion

Aldosterone ultimately is trying to increase water volume. Water follows sodium.

Question 28

What are the major controls of aldosterone?

Answer 28

Angiotensin II

Increased Extracellular concentration of K+

Decreased Extracellular concentration of Na+

Question 29

Why does measuring creatinine clearance give us an overestimated estimate of GFR?

Answer 29

100% of creatinine that is filtered gets excreted, no reabsorption. But also a small amount gets secreted into the nephron. So final excretion is 110% of what was filtered.

Question 30

Where does ADH have its effect? What is its effect?

Answer 30

It acts on the late/convoluted distal tubule and collecting tubule by making them permeable to water by inserting water channels into the membrane.

Question 31

How is dilute urine made?

Answer 31

Blood osmolality is measured by osmoreceptors and the amounts of ADH are controlled accordingly. Low osmolarity and the less ADH released and the more water excreted.

Question 32

An increase in osmolarity causes what to be released?

Answer 32

ADH

Question 33

What controls blood osmolality?

Answer 33

The concentration of sodium. Antidiuretic hormone (aka vasopressin) acts on the kidneys to reabsorb water to control the tonicity of fluids in the body.

Question 34

How does the body respond to increase blood osmolality?

Answer 34

Increased blood osmolality is detected by osmoreceptors in the hypothalamus –> release of ADH and stimulation of thirst

Question 35

When do we get a craving for salt?

Answer 35

With low blood osmolality. Low blood osmolality means that there’s fewer substances dissolved in the blood. This could be dangerous for the blood cells because the body will try to balance the concentration of solutes with osmosis. This will change the volume and thus shape of the blood cells. Therefore, the body will send signals to ingest more salt to increase that concentration and prevent this damage.

Question 36

When do we get a desire to drink?

Answer 36

With increased blood osmolality