Renal System

Question 1

What are the functions of the kidney?

Answer 1

Homeostatic regulation of H2O + ion content in blood
Excretion of metabolic waste products
Production of hormones

Question 2

What is the overall structure of the kidney?

Answer 2

Cortex (outer)
Medulla (inner)
Nephrons 
Cortical nephrons = cortex 
Juxtamedullary nephrons = medulla

Question 3

Describe nephron structure

Answer 3

Bowman's capsule 
Proximal tubule 
Loop of Henle
Distal tubule 
Collecting duct

Question 4

What is the bowman’s capsule surrounded by?

Answer 4

Glomerulus

Question 5

What happens at the bowman’s capsule?

Answer 5

Ultrafiltration

Question 6

Describe blood flow around bowman’s capsule

Answer 6

Blood flows from afferent arteriole into glomerulus + leaves through efferent arteriole

Question 7

What surrounds the arterioles?

Answer 7

Peritubular capillaries

Question 8

What are the role of the renal capillaries?

Answer 8

Form venules = conduct blood out of the kidney

Question 9

What is the function of renal portal system?

Answer 9

Filter blood + into lumen of nephron

Question 10

Where are fluid reabsorbed?

Answer 10

From tubule back into blood at peritubular capillaries

Question 11

What processes happen at the nephron?

Answer 11

Filtration
Excretion
Reabsorption
Secretion

Question 12

What is filtration?

Answer 12

Movement of fluid from blood into lumen

Question 13

What is excretion?

Answer 13

Anything filtered from renal capsule

Question 14

What is reabsorption?

Answer 14

Movement of filtrate from lumen of tubule back into blood through peritubular capillaries

Question 15

What is secretion?

Answer 15

Removes selected molecules from blood + adds them to filtrate in tubule lumen

Question 16

How do you calculate the amount of urine?

Answer 16

(amount filtered) - (amount reabsorbed) + (amount secreted)

Question 17

What are the two mechanisms in autoregulation of GFR?

Answer 17

Myogenic mechanism of regulation

Tubuloglomerular feedback

Question 18

Describe myogenic mechanism of regulation

Answer 18

Afferent + efferent have smooth muscles
Contraction = blood pressure + = smooth muscle contracts = reduce diameter = oppose flow
Relaxation = bp - = relaxes = + diameter = facilitate flow

Question 19

Describe tubuloglomerular feedback

Answer 19

GFR +
Flow through tubule +
Paracrine factors released
Afferent constricts 
Resistance +
Hydrostatic pressure in glomerulus -
GFR -

Question 20

What is clearance?

Answer 20

Vol of plasma from which a substance has been removed + excreted into urine per unit time

Question 21

What is the equation for clearance?

Answer 21

         Plasma Conc

Question 22

What is clearance used as an index for?

Answer 22

Kidney function

Question 23

Describe the structure of glomerulus

Answer 23

Capillary endothelium has pores
Basal lamina
Podocytes with long cytoplasmic extensions

Question 24

What is the significance of capillary endothelium in glomerulus?

Answer 24

Pore surface negatively charged = negatively charged proteins = repulse negatively charged proteins

Question 25

What is the significance of basal lamina in glomerulus?

Answer 25

Layer of extracellular matric that separates capillary + endothelium of Bowman's capsule Negatively charged = exclude plasma proteins from filtration

Question 26

What is the significance of podocytes in glomerulus?

Answer 26

Form narrow filtration slits

Question 27

Describe what happens in glomerulus

Answer 27

Proteins excluded from filtration based on charge + molecular weight H2O, Na+, K+, Ca2+, glucose + urate = YES Blood plasma = NO

Question 28

What happens in proximal tubule?

Answer 28

Glucose + amino acid reabsorption | = co-transport

Question 29

What is the descending limb?

Answer 29

H2O permeable

Question 30

What is the ascending limb?

Answer 30

H2O impermeable

Question 31

What happens in the descending limb?

Answer 31

Impermeable to NaCl = no active transport | = osmolarity + = reach max at loop

Question 32

What happens in ascending limb?

Answer 32

Reabsorbed NaCl passively = active transport by NaK = osmolarity - = min at top

Question 33

Describe what happens overall in Loop of Henle

Answer 33

Isosmotic fluid leave proximal tubule = more concentrated as descends limb Removal of solute in ascending limb = hypoosmotic fluid Permeability of H2O + solutes in DT + CD regulated by hormones Final urine osmolarity depends on reabsorption in CD

Question 34

Describe the transport of solutes out of Loop of Henle

Answer 34

Transport out of ascending limb dilutes filtrate + helps concentrate interstitial fluid in medulla BUT H2O leaving descending limb DOESNT do this

Question 35

Describe the transport of solutes into Loop of Henle

Answer 35

Solute reabsorbed by ascending limb moves into descending limb of vasa recta = + blood osmolarity H2O reabsorbed by descending limb moves into ascending limb of vasa recta = - blood osmolarity

Question 36

Describe what happens in the initial segment of DT

Answer 36

NaCl reabsorbed by Na+/Cl- co-transporter H2O impermeable Osmolarity falls further

Question 37

Describe what happens in last segment of DT + CD

Answer 37

Principle cells recover more than Na+ + H2O via channels α- intercalated cells reabsorb K+ + secrete H+ Through K+/H+ transporter Reabsorbs HCO3- = regulate pH β- intercalated cells = secrete HCO3- + reabsorb Cl- Through Cl-/HCO3-

Question 38

What is the last segment of DT + CD composed of?

Answer 38

Principle cells + intercalated cells

Question 39

What are the processes that form urine?

Answer 39

Filtration Reabsorption Secretion

Question 40

What does Na+ balance + blood pressure do?

Answer 40

Increase osmolarity

Question 41

What is vasopressin?

Answer 41

Anti-diuretic hormone (ADH)

Question 42

What does vasopressin do?

Answer 42

Stimulate H2O recovery via aquaporin at CD | = concentrates urine

Question 43

What does aldosterone do?

Answer 43

Control Na+ balance

Question 44

How does aldosterone control Na+ balance? | Physiological modulation

Answer 44

Physiological modulation = + extracellular K+ + - BP = stimulates aldosterone secretion by adrenal cortex

Question 45

How does aldosterone control Na+ balance? | Pathological modulation

Answer 45

+ in ECF osmolarity = inhibit aldosterone release from adrenal cortex = abnormal - in Na+ = stimulate aldosterone secretion

Question 46

What happens when there is an increase in Na+?

Answer 46

+ BP = Na+ retention increases osmolarity = + thirst | = drinking + ECF, blood vol + = BP +

Question 47

What happens aldosterone acts on principle cells in DT + CD?

Answer 47

More Na+ reabsorbed due to insertion of more ENaC on membrane = urine dilutes

Question 48

Why does a decrease in blood pressure increase H2O retention?

Answer 48

ANG II activates release of aldosterone = BUT high osmolarity = blood aldosterone = - reabsorption of Na+ = BUT high osmolarity = release vasopressin = + reabsorption of H2O = + BP + H2O retention = - osmolarity

Question 49

What are diuretic drugs used for?

Answer 49

High blood pressure

Question 50

What do loop acting diuretics do?

Answer 50

Inhibit transport system in ascending limb

Question 51

What do thiazide diuretics do?

Answer 51

Inhibit transport system in DT

Question 52

What do K+ sparing diuretics do?

Answer 52

Inhibit ENaC in CD | Block effects of aldosterone on channels