7: Physiology 2

Question 1

What are the homeostatic functions of the kidneys?

Answer 1

Water balance

Salt balance

Acid-base balance

Maintenance of plasma volume and osmolarity

Question 2

What do the kidneys excrete?

Answer 2

Toxic metabolites

Drugs and their metabolites

Question 3

What hormones do the kidneys secrete?

Answer 3

Renin

Erythropoietin

Question 4

What are the functions of

a) renin
b) erythropoeitin?

Answer 4

a) Maintenance of BP by RAAS

b) Protects RBC from damage and increases RBC production - used in doping

Question 5

What vitamin do the kidneys activate?

What is its active form called?

Answer 5

Vitamin D

Calcitriol

Question 6

What is the name and function of activated Vitamin D?

Answer 6

Calcitriol

Enables calcium absorption in GI tract

Question 7

At what levels are the

a) left kidney
b) right kidney

found?

Answer 7

a) T12 - L2 (not pushed inferiorly)

b) L1 - L3 (pushed inferiorly by liver)

Question 8

What process propels urine from the kidneys to the bladders through the ureters?

Answer 8

Peristalsis

Question 9

What appearances do the renal cortex and medulla have?

Answer 9

Cortex - granulated

Medulla - striated

Question 10

The renal medulla is arranged into ___ of nephrons.

Answer 10

pyramids

Question 11

How long is an adult kidney?

Answer 11

12 cm

Question 12

How much of the cardiac output do the kidneys account for?

Answer 12

25%

loads, understandable given they filter the blood

Question 13

What are the functional units of the kidneys?

Answer 13

Nephrons

arranged into pyramids in renal medulla

Question 14

Which four processes occur in nephrons?

Answer 14

FILTRATION of urine from blood

REABSORPTION of water, ions, glucose, AAs from tubules into capillaries

SECRETION of “” from capillaries to tubules

EXCRETION into ureters

Question 15

What blood vessels supply the nephrons?

Answer 15

Renal artery - splits into afferent and efferent arterioles

Stuff then reabsorbed into peritubular capillaries draining into Renal vein

Question 16

What structure is the glomerulus found inside?

Answer 16

Bowman’s capsule

Question 17

Where does filtration of blood occur?

Answer 17

Glomerulus

Blood is filtered into Bowman’s capsule

Question 18

Where does urine travel from the glomerulus to reach the collecting duct?

Answer 18

Proximal tubules

Loop of Henle

Distal tubules

Question 19

What part of the distal tubule passes by the glomerulus and alters renal function?

Answer 19

Juxtaglomerular apparatus

Question 20

Which structures does the juxtaglomerular apparatus pass between?

Answer 20

Afferent and efferent arterioles

Question 21

Nephrons are split between the renal ___ and ___.

Answer 21

renal cortex and medulla

Question 22

What are the two types of nephron found in the kidney?

Answer 22

Cortical

Juxtamedullary

Question 23

Which type of nephron is more common?

Answer 23

Cortical (80%)

Question 24

What is the difference between cortical and juxtamedullary nephrons?

Answer 24

Juxtamedullary nephrons have:

• Longer Loops of Henle
• One single peritubular capillary called the vasa recta which follows the Loop of Henle

Question 25

What type of capillaries do a) cortical b) juxtamedullary nephrons have?

Answer 25

**a) Loads of peritubular capillaries** **b) One vasa recta**

Question 26

Juxtamedullary nephrons produce more ___ urine.

Answer 26

**concentrated / hypertonic**

Question 27

Which arteriole has the wider diameter?

Answer 27

**Afferent arteriole**

Question 28

What are **podocytes**?

Answer 28

**Epithelial cells of Bowman's capsule**, have big processes called **filtration slits**

Question 29

What is found between the **endothelium** of glomerular capillaries and the **podocytes** of Bowman's capulse?

Answer 29

**Basement membrane** (no cells)

Question 30

Which layers make up the **glomerular membrane**?

Answer 30

**Endothelium** of glomerular capillary **Basement membrane** **Podocytes** of Bowman's capsule

Question 31

The **glomerular membrane** acts as a big \_\_\_.

Answer 31

**sieve** for filtrate

Question 32

Glomerular capillaries are more ___ than other capillaries.

Answer 32

**permeable** allows them to filter stuff

Question 33

Which cells of the JGA secrete renin?

Answer 33

**GRANULAR** or **JUXTAGLOMERULAR CELLS**

Question 34

Which cells of the JGA are sensitive to salt concentrations of the **(blood / tubular fluid)**?

Answer 34

**Macula densa** salt concentration of tubules

Question 35

What is urine?

Answer 35

**Modified filtrate of the blood**

Question 36

How much of the blood which enters a glomerulus is actually filtered?

Answer 36

**20%** Rest of it is filtered in the peritubular capillaries

Question 37

What processes occur to filtrate as it passes through the renal tubules?

Answer 37

**Reabsorption** back into capillaries **Secretion** from capillaries into tubules

Question 38

What is the **rate of filtration**?

Answer 38

**Mass of substance filtered into Bowman's capsule per unit time** Filtration rate = [substance]_plasma x glomerular filtration rate (GFR) GFR is usually 120 in healthy people

Question 39

What is the **rate of excretion**?

Answer 39

**Mass of substance excreted per unit time** Rate of excretion = [substance]_urine x urine excretion rate

Question 40

If a substance's **rate of filtration \> rate of excretion**, what has occurred?

Answer 40

**Reabsorption**

Question 41

If a substance's **rate of filtration \< rate of excretion**, what has occurred?

Answer 41

**Secretion** into tubules from capillaries

Question 42

How do you calculate the **rate of _secretion_**?

Answer 42

**Rate of secretion = rate of excretion - rate of filtration**