Session 2- Glomerulus

Question 1

Osmolality

Answer 1

Is solute per kg of solvent

Question 2

OsmolaRity

Answer 2

Number of osmoles of solute per litRe

Question 3

What is the average GFR

Answer 3

125 ml/min

Question 4

RBF

Answer 4

Renal blood flow

Flow of blood through renal artery

Question 5

RPF

Answer 5

RPF = RBF x (1- haemocrit)

Question 6

How is GFR regulated

Answer 6

• Arterial smooth muscle responds to
increases and decreases in
vascular wall tension 
• It contributes to total auto-
regulatory mechanism 
 • It is a property predominantly of the
preglomerular resistance vessels
• Accurate 
• Interlobular 
• Afferent arteriole

Question 7

FF

Answer 7

The filtration fraction - represents the proportion of the fluid reaching the kidneys that passses into the renal tubules

Question 8

How can you distinguish between the PCT and DCT

Answer 8

PCT has debris within which is the brush border which is the main site of reabsorption

DCT has a large lumen no brush border

Question 9

What 2 mechanisms are involved in auto regulation

Answer 9

Myogenic mechanism

Tubuloglomerular feedback

Question 10

What is JXA

Answer 10

Juxtoglomerular apparatus which is the DCT nestled up with the glomerulus this allows the golmerulys to determine what’s going on in the DCT and respond accordingly

Question 11

What are macular does a cells

Answer 11

Detect ow much NaCl is arriving in the cell

Question 12

How does the afferent arteriolar respond to increase in BP

Answer 12

Vasoconstriction
This prevents the transmission of high BP to glomerular capillary and maintains normal glomerular capillary pressure which maintains GFR and RBF

Question 13

How does the efferent arteriolar respond to blood pressure

Answer 13

If BP increases i vasoconstricts to increase GFR

Question 14

Tubuloglomerular feedback mechanism- High Tubular flow

Answer 14

Macula dense cells of the DCT epithelium detect osmolality or the rate of movement of Na and Cl into the cells.

A signal is ent via the JGA cells triggered by an increase in NaCl conc of distal tubular fluid

ATP is released concerted to adenosine binds with A1 receptor o afferent arteriolar

Further vasoconstriction of th smooth muscle of the adjacent afferent arterioles and therefore decreased RPF which decreased GFR

Question 15

Tubuloglomerular feedback mechanism - low BP

Answer 15

Release prostaglandins- attenuate constriction of afferent arteriolar

Renin released by JGA cells.

RENIN causes the release of angiotensin 2 which acts om efferent arteriole and causes vasoconstriction

Question 16

what stimulates renin release

Answer 16

stimuli responsible for release 
-sympathetic nerve stimulation 
-decease stretch of afferent arteriolar 
-signals generated by macula densa cells in response to 
decrease in NaCl delivered