Renal Fluiud Balance

Question 1

What are main body fluid compartments?

Answer 1

Intracellular Fluid (ICF) - K+, soluble proteins (3x more than in plasma). 40% TBW

ECF: 1.Interstitial fluid - Na+, Cl-. (16% TBW)

ECF: 2.Plasma - fluid portion of the blood - Na+, Cl-, proteins (more than interstitial fluid). (4% TBW)

Question 2

What is the structure and function of the cells of kidney @: 1. PCT? 2. Loop of Henle? 3. DCT?

Answer 2

1. Simple cuboidal epithelium, with villi. Increase surface area for absorption (most of absorption occurs here). Transport of solutes via active and passive transport eg. Na-K ATP pump, osmosis of H2O.
2. Simple squamous epithelium. Aquaporins present (descending limb). Thin layer to allow the easy movement of water by diffusion. Ascending limb: active transport.
3. Simple cuboidal epithelium (no villi). Some absorption and secretion.

Question 3

What are the 4 different ways water and solutes moves across the epithelium?

Answer 3

1. Para-cellular: in between cells mediated by gap/tight junctions
2. Diffusion: follows gradient (concentration/ionic), also osmotic and hydrostatic forces.
3. Transporters: (carrier-mediated) may be ACTIVE (primary/secondary) or PASSIVE eg. NaK ATP pump
4. Trans-cellular: Exo/endocytosis

Question 4

Describe the key structural features of the kidney?

Answer 4

Renal capsule
Cortex
Arcuate artery
Afferent/efferent arterioles
Medulla 
Renal pyramid
Renal column
Interlobar artery
Papilla of pyramid
Minor calyx
Major calyx 
Lobar artery
Renal pelvis
Renal artery
Renal vein 
Ureter

Question 5

How do proteins mediate the movement of water and solutes across the lipid bi-layer cell membrane?

Answer 5

1. Channel-mediated diffusion
2. Carrier mediated diffusion
3. Primary active transport (ATP used)
4. Secondary active transport (co-transport/symporter)

Question 6

List the components (layers) of the gut wall.

Answer 6

1. Mucosa (crypts/villi)
   - epithelium (simple columnar)
   - laminar propriety
   - muscularis mucosa
2. Submucosa
   - submucosa plexus
3. Muscularis
   - inner circular smooth muscle
   - myenteric plexus (neutrons)
   - outer longitudinal smooth muscle
4. Serousa / Adventitia