Kidney

Question 1

Nephron

Answer 1

Functional unit of the kidney which begins at Bowman’s capsule
Contained in kidney cortex and medulla
Kidney has a million nephrons

Question 2

Urethra vs Ureters

Answer 2

Urethra takes urine out of the body and 2 ureters carry the urine from the kidney.

Question 3

Parts of the kidney

Answer 3

Bowman’s capsule- surrounds the glomerulus and collects filtrate
Glomerulus is capillaries where blood is filtered
Proximal tube reabsorption and secretion occurs
Descending loop is when water is reabsorbed
Ascending loop is when ion are reabsorbed
Distal tube reabsorption and secretion occurs
Collecting duct is where urine is received

Question 4

Nephron’s ability to exchange materials with the blood
Afferent vs Efferent

Answer 4

Afferent arteriole takes blood toward the kidney and the glomerulus, it decreases blood supply but it’s wider to maintain high blood pressure
Efferent arteriole goes out of the kidney, narrower to help pressure gradient

Question 5

Function of the kidney requires filtration, reabsorption and secretion

Answer 5

Filtration happens at the Bowman’s capsule with glomerulus
Reabsorption happens at proximal, loop of henle, distal and collecting duck
Secretion occurs at proximal, distal and collecting tube

Question 6

Less than 1% of the filtered plasma is secreted as urine

Answer 6

1-100% of plasma volume enters afferent arteriole from and gets filtered
80% goes out of the efferent arteriole to peritubular capillaries
-20% falls into bowman’s capsule and is filtered through the tubule
-19% is reabsorbed
-more than 99% of plasma entering kidney returns to systemic circulation
-less than 1% is excreted

Question 7

Glucosuria

Answer 7

Glucosuria is when glucose appears in urine
Glucose has to be transported back into the peritubular capsule

Question 8

GFR based on time

Answer 8

How fast material moves from the plasma to the urine the 2.75 L
(excretion rate)/ X concentration in plasma
-Hydrostatic pressure is the blood pressure
-Colloid osmotic pressure is due to proteins in plasma but not the Bowman’s capsule
-Fluid pressure is the filtrate in the Bowman’s capsule

Question 9

Net filtration

Answer 9

Hydrostatic pressure- colloid osmotic pressure- pressure of fluid

Question 10

How many times per day is plasma filtered?

Answer 10

Every 20 minutes or 72x/Day

Question 11

Vasocontraction and vasodilation in the afferent arteriole vs efferent arteriole

Answer 11

Vasoconstriction in the afferent arteriole decreases renal blood flow, capillary blood pressure and GFR while increasing resistance in the afferent arteriole.
Vasodilation in the afferent arteriole increases renal blood flow, capillary blood pressure and GFR while decreasing resistance in the afferent arteriole.
Vasoconstriction in the efferent arteriole increases resistance while increasing the hydrostatic blood pressure, GFR and lowers the renal blood flow
Vasodilation in the efferent arteriole increases renal blood flow while decreasing GFR, hydrostatic blood pressure and resistance.

Question 12

Explain how an increase in hydrostatic pressure in the Bowman’s capsule would affect GFR?

Answer 12

An increase in hydrostatic pressure in the bowman’s capsule would decrease GFR because it opposes the filtration pressure gradient from the glomerulus into Bowman’s capsule.
It will make it harder for fluids and solute to fall into the Bowman’s capsule.

Question 13

How would you increase GFR at the two arterioles

Answer 13

In the Afferent arteriole, vasodilation would increase GFR by increasing renal blood flow and hydrostatic blood pressure.
In the Efferent arteriole, vasoconstriction would increase GFR by decreasing the renal blood flow but increasing hydrostatic blood pressure.

Question 14

GFR is the standard for measuring kidney efficiency
What are the formula

Answer 14

Clearance refers to rate at which material is removed from blood and appears in the urine.
-Filtration rate of X= X in plasma X GFR
-Excretion rate of X= urine flow X X in urine
-Clearance rate of X= Excretion rate of X mg/min / X in plasma mg/ml

Question 15

What factors affect GFR

Answer 15

-Changes in renal blood flow, blood pressure
-Arteriole constriction (afferent vs efferent)
-Changes in protein concentration, dehydration, osmolarity
-Changes in hydrostatic pressure within Bowman’s capsule

Question 16

Clearance rate of inulin vs glucose

Answer 16

Inulin clearance is equal to GFR because with inulin, the filtration and excretion rate are the same which means that there is no net reabsorption or secretion.
With glucose, all of it is absorbed which means that the filtration rate is higher than the excretion rate so there is a net reabsorption rate which means that glucose is filtered and reabsorbed

Question 17

What is the normal glucose clearance rate

Answer 17

It’s zero because glucose should not be secreted

Question 18

Penicilin vs urea

Answer 18

Penicillin is cleared from the plasma and into urine faster than inulin
It is secreted and excreted while urea is reabsorbed and excreted.

Question 19

What happens when filtration is higher than excretion or of excretion is higher than filtra

Answer 19

If filtration rate is higher than excretion rate then there is a net reabsorption
If Excretion rate is greater than the filtration rate then there is a net secretion.

Question 20

Osmoregulation involves the digestion, integument and respiratory systems as well as the kidney

Answer 20

Volume is gained by ingestion and IV which makes the GFR keep happening and it can be adjusted through afferent or efferent arteriole.
Volume is loss in the urine and vasopressin regulates water reabsorption and kidneys only conserve volume not replace it.
Volume is also loss from lungs, skin, digestive tract.

Question 21

Osmolarity changes as the filtrate moves through the loop of Henle.

Answer 21

-At the descending limb, isosmotic fluid leaving leaving the proximal tubule becomes more concentrated. Water leaves due to osmolarity of blood, it’s salty outside.
-At the ascending limb, solute leave the tubule and create an hyposmotic fluid.
-At the distal tubule, permeability to water and solute is regulated by hormones as well as in the collecting duct.
-Final urine osmolarity depends on reabsorption in the collecting duct.

Question 22

Cortex vs medulla osmolarity

Answer 22

The cortex top part is isosmotic to plasma but the medulla becomes progressively more concentrated

Question 23

Nephron tubules are interwoven with a set of peritubular capillaries which form a portal system

Answer 23

Vasa recta allows transfer from tubule to blood

Question 24

Renal countercurrent multiplier increases the efficiency of of water absorption

Answer 24

The vaso recta is more hypertonic at the descending limb which increases water leaving the tubule and casing a hypertonic filtrate. At the ascending limb water doesn’t leave because the channel is impermeable to water no aquaporins channels, ions leave and are reabsorbed leaving a hypoosmotic filtrate.

Question 25

ADH or vasopressin effect on water retention

Answer 25

Vasopressin binds to membrane receptor and that activated camp and cells insets aquaporins channels AQP2 which leads to water reabsorption

Question 26

Hormones affecting BP and Calcium homeostasis

Answer 26

Atrial natriuretic peptide
Angiotensin II
Parathyroid hormone
Aldosterone
ADH (vasopressin)

Question 27

Vasopressin

Answer 27

It’s released by the pituitary and hypothalamus to increase water retention and blood pressure

Question 28

RAAS, renin angiotensin system

Answer 28

Increases blood pressure though the release of aldosterone
Low renal pressure leads to the secretion of renin which f

Question 29

Aldosterone salt

Answer 29

Increases blood pressure by the reabsorption of Na in the tubule
Na retention helps increase blood pressure and volume because water will follow sodium back into the blood
Potassium is secreted which can lead to hypokalemia and the the hyperpolarization of cells less likely to have action potential occur.