L11 Renal System

Question 1

What is the role of juxtamedullary nephrons?

Answer 1

Involved in making concentrated urine

Question 2

Outline the vascular supply to the nephrons

Answer 2

Afferent arterioles feed into the glomeri
-> efferent arterioles leave the glomeruli and wrap around the nephron
-> peritubular capillaries or vasa recta
-> renal veins
-> inferior vena cava

Question 3

Name 3 functions of the kidney

Answer 3

1) homeostatic regulation of water and ion content of blood

2) excretion of metabolic waste products and foreign substances

3) production of hormones

Question 4

What does the kidney regulate?

Answer 4

Regulation of osmolarity - maintenance of ion balance

Regulation of extracellular fluid volume - blood pressure

Regulation of pH

Question 5

Which hormones does the kidney produce?

Answer 5

Erythropoietin - red blood cell synthesis

Renin - sodium balance

Activation of vitamin D - calcium ion balance

Prostaglandins and kinins - renal blood flow

Question 6

What is glomeralur filtration?

Answer 6

Blood is filtered at the glomerulus

Question 7

What is tubular reabsorption?

Answer 7

Fluid and solutes are reabsorbed from the filtrate and returned to the blood

Question 8

What is tubular secretion?

Answer 8

Substances are secreted from the blood and into the filtrate

Question 9

What is filtered during glomerular filtration and why?

Answer 9

All plasma constrituents except proteins
- filtration barrier restricts solute movement on basis of size and charge

Question 10

What structures make up the filtration barrier?

Answer 10

Capillary
Endothelial cell
Basement membrane
Podocyte
Podocyte foot process
Fenestration pore
Filtration slit

Question 11

What can pass through filtration slits?

Answer 11

Formed elements and most proteins in the blood are too large to fit through
- however, water and small solutes can pass through and enter the filtrate

Question 12

Which pressures control filtration?

Answer 12

1) Hydrostatic pressure of blood flowing through the glomerular capillaries - promotes movement of fluid into capsule

2) Colloid osmotic pressure caused by proteins in blood - favours fluid retention in/movement back into capillaries

3) Hydrostatic pressure of fluid into Bowman’s space - opposes movement of fluid into capsule

Question 13

How does increased resistance influence renal blood flow?

Answer 13

• increased resistance of afferent arteriole reduces blood flow to glomerulus
• increased resistance to efferent arteriole increases blood flow/pressure in the glomerulus

Question 14

How does decreased resistance influence renal blood flow?

Answer 14

• decreased resistance of afferent arteriole increases blood flow to glomerulus
• decreased resistance of efferent arteriole increases blood flow out of/decreases pressure in glomerulus

Question 15

Outline the myogenic response in autoregulation

Answer 15

1) myogenic response
- increased blood pressure leads to the stretch of smooth muscle cells, vasoconstriction, decreased RBF, decreased Ph, decreased GFR
- important in afferent arteriole

Question 16

Outline the tubuloglomerular feedback response in autoregulation

Answer 16

Fluid flow through tubule influences arteriole resistance and GFR
1) GFR increases
2) Flow through tubule increases
3) Flow past macula densa increases
4) Paracrine factors released from macula densa
5) Afferent arteriole constricts
6) Resistance in afferent arteriole increases
7) Hydrostatic pressure in glomerulus decreases
8) GFR decreases

Question 17

What is the role of autoregulation?

Answer 17

Maintains RBF and GFR within narrow limits during fluctuations in mean arterial blood pressure

Question 18

What is the role of autoregulation?

Answer 18

Maintains RBF and GFR within narrow limits during fluctuations in mean arterial blood pressure via local control mechanisms

Question 19

What’s the role of macula densa cells?

Answer 19

They sense distal tubule flow and release paracrines that affect afferent arteriole diameter

Question 20

How are GFR (glomerular filtration rate) and RBF ( renal blood flow) maintained?

Answer 20

By autoregulation, neural control and tubuloglomerular feedback

Question 21

What is the filtrate?

Answer 21

Solution entering the proximal convoluted tubule
- contains H2O, Na ions, K ions, Ca ions, Cl ions, HCO ions, glucose
- no blood cells, no serum proteins

Question 22

What structures does the nephron cortex include?

Answer 22

Proximal tubule
Distal tubule
Collecting tubules
Bowman’s capsule
Descending limb of loop begins
Ascending limb of loop ends

Question 23

What structures does the nephron medulla include?

Answer 23

Collecting duct to the bladder
Loop of Henle
Descending limb
Ascending limb

Question 24

Why doPCT have interdigitations on their basolateral membrane?

Answer 24

They shorten the distance between the mitochondria and basolateral carrier proteins used for active transport