Lecture 3: Body Fluid Comp PART 1

Question 1

These are? What do they contain

Answer 1

Red: The renal cortex = renal corpuscles and portions of the proximal and distal tubules

Orange: Medullary pyramid = collecting ducts and loops of Henle.

Therefore nephrons lie from deep to outer locations.

Question 2

What happens to the millions of collecting ducts within a lobe?

Answer 2

They fuse to form larger diameter ducts, that open at the renal papillae. (ensure a higher volume)

Question 3

Medullary Rays

Answer 3

Straight bundles containing a collecting duct, prox and distal tubules going to and from the medulla. Collecting duct is the centre of lobule, and the tubules arranged around it and drain into it. These all bundle together in parallel, and create a medullary ray.

Question 4

A lobule or lobe can be defined by?

Answer 4

Interlobular or interlobar vessels lining it. (not the entire way around though!)

Question 5

List the journey of the urine

Answer 5

Through corpuscle
Proximal tubule
down and up loop of Henle
Distal tubule into collecting duct
Down collecting duct, these fuse and run into renal papillae
Runs into minor calyx > Major Calyx > Ureter > bladder > urethra

Question 6

Arterial Blood Supply to the Kidney

Answer 6

Renal artery enters Renal Hila and branches into interlobar arteries (between the lobes). When they reach the medullary pyramid they arch over as ‘Arcuate arteries’ and sends shoots up to the outer kidney which are interlobular arteries (between the lobules). These send off shoots to nephrons, afferent arterioles

Question 7

What happens to the afferent arteriole after it has been through the renal corpuscle and exited as an efferent arteriole?

Answer 7

It all depends on where the Renal Corpuscle is located.

Outer Renal Corpuscles: efferent arterioles forms a peritubular capillary bed (wrap around the proximal tubule in the cortex, and are vital for reabsorbtion of nutrients). Drain into a venous capillary bed, drains into a interlobular vein, arcuate vein > interlobar vein

Deep Renal Corpuscle: Close the the junction of cortex-medulla. Long straight vessels (arterial vasa recta) Bundled with the collecting duct and loops of Henle (in medulla). Branch to capillary beds around loops. Drain into venous vasa recta that fuse with the arcute vein

Question 8

Note* how is the vascular actually orientated (different to pictures)?

Answer 8

All bundled together, around the nephron, you couldn’t tell it apart.

Question 9

What is the point of the looping of tubules

Answer 9

To maintain a gradient of salt concentration that ensure that [salt] is overall maintained.

Question 10

The Histology of the Ureter. (5x layers)

Answer 10

Transitional Epithelium: Layer of transitional epithelium, starshaped during relaxation to allow for swelling of urine (expansioncontration)

Mucus membrane: produces mucus; lubrication and protection against pathogens and from the urine itself (acidic).

Subepithelial CT/Lamina propria: elastic layer allowing opening/closing

Smooth Muscle Layers: 2x Contractile; inner longitudinal and outer circular, alows peristaltic movements of ureter to mve urine.

Outside layer of Adventitia: elastic and harbours Blood supply

Question 11

The Histology of the Bladder.

Answer 11

Continuation of the ureter but on a much larger scale.

Epithelial Layer: with relaxed state (3-4 layers high) and stretched state (1 layer)

Question 12

Histology of the Urethra

Answer 12

Changes as you go along it!
Transitional epithelium > stratified columnar > stratified squamous

This reflects the more protective layer of SS as you get closer to the outside of the body.