W21 Renal system & osmoregulation

Question 1

Define osmolarity

Answer 1

concentration, in terms of amount of solutes per litre of solution

Question 2

By controlling the _____ of the ECF, we control _____ between ECF and ICF

Answer 2

osmolarity

osmosis

Question 3

In which ways does water leave the body?

Answer 3

Urine, sweat, GI tract as water/bile, lungs

Question 4

How is the rate of filtration in the glomerulus balanced?

Answer 4

With the Hydtrostatic pressure (blood) and Oncotic pressure (osmotic pressure by large molcules that are not filtered)

Question 5

Where does most reabsorption of water, ions, and all glucose occur?

Answer 5

In the proximal convoluted tubule and is absorbed into the blood

Question 6

How does water get reabsorbed?

Answer 6

Due to the osmotic effect. The buildup of solutes in interstitial fluid is the reason.

Question 7

How does glucose get reabsorbed?

Answer 7

Secondary active transport, symport or antiport, of ions (Na and K)

Question 8

What does tubular secretion ential?

Answer 8

Drugs, acids, bases secreted FROM blood INTO proximal convoluted tubule to then be disposed of :)

Question 9

Briefly describe how urine gets more concentrated in the loop of henle

Answer 9

Water continously diffuses out of descending limb due to it’s high osmolality (saltyness), more and more the further down you go (eventually into the medulla).
Then, up the ascending limb, the osmolality is so high compared to the interstitial fluid that the ions (or salts) diffuse out again. Urea remains and voila, you have concentrated urine.
*Remember water CAN’T Exit the ascending limb. This happens in the next step, the collecting duct.

Question 10

Briefly explain what role the collecting duct has in osmoregulation

Answer 10

Collecting duct is impermeable to water and NaCl, however ADH can increase/decrease the permeability to water (only).
The high osmolality in the medulla causes water to diffuse out of collecting duct, concentrating urine eveb further

Question 11

What is micturition? Describe the process

Answer 11

Urination.

* Urine composition remains the same when leaving renal pelvis (in the kidney)
* Urine travels along ureters - "peristaltic" contractions of smooth muscle does this
* When bladder is full, "detrusor muscle" contracts to expel urine via urethra

Internal & External sphincter open to allow urine to pass

Question 12

_____ is produced in the adrenal cortex in response to high levels of K+ in plasma.
In the kidney, _____ stimlautes Na _____ (into blood) and K _____ (out from blood).

Answer 12

Aldosterone

Aldosterone, reabsorbtion, secretion