Week 11

Question 1

First part of the glomerulus

Answer 1

There is an arterial inflow of o2 and arterial outflow of o2, created high pressure environment

Question 2

What is special about the glomerulus

Answer 2

It is very porous - allows small molecules and fluid out of the blood
It is surrounded by cells called podocytes - allows further filtration

Question 3

Role of podocytes

Answer 3

Podocytes further filters and allows fluid passing into Bowman’s space

Question 4

What does/dosent get filtered

Answer 4

Small molecules such as na+, glucose and amino acids get filtered
Large molecules such as red blood cells dosent get filtered

Question 5

What surrounds the glomerulus

Answer 5

The bowmans capsule

Question 6

What happens at the proximal convoluted tubule

Answer 6

The start of the reabsorption via the cells lining the PCT
Happens via active transport (use of ATP)

Question 7

Fluid moves from PCT to..
What happens here

Answer 7

The Loop of henle
Crosses border of cortex and the medulla
Medulla is hypertonic (high electrolyte conc)
Descending loop of henle - reabsorption of h20 - filtrate is losing water so becoming more hypertonic
Acsending loop - reabsorption by body of na+, cl-, k+

Question 8

Functions of the kidneys

Answer 8

Regulation of water, inorganic ion balance, and acid-base balance
Removal of metabolic waste products from the blood and their exertion in the urine
Gluconeogenesis
Production of hormones/enzymes
-EPO
-Renin

Question 9

What happens after the loop of henle

Answer 9

Fluid moves to the distilled convoluted tubule
Filtrate is becoming more concentrated

Then it comes to the collecting duct - last stage where body can reabsorb anything it needs
Anti-diuretic hormones acting

Question 10

Nephrons

Answer 10

Nephrons are the structural and functional units of the kidney. Each kidney has over 1 milllion of these units
Each nephron consists of a renal corpuscle, which contains the glomerulus and a renal tubule
The tubule forms a cup shape around the glomerulus called the glomerular capsule (bowman’s capsule)

Question 11

Glomerular filtration (GFR)

Answer 11

The GFR is the amount of blood filtered by the glomeruli each minute
Factors influencing GFR:
Capilliary permeability
Surface area (size of capillary bed)
Hydrostatic pressure that drives fluid out of the capillaries
Osmotic forces within the capillaries, which oppose the exit of fluid

Question 12

Renal clearence (RC)

Answer 12

The amount of substance filtered per minute, divide by its plasma concentration
RC = (U*V) / P
U = conc of the substance in the urine
V = flow rate of urine formation
P = concentration of substance in the plasma

Question 13

Water and lean body weight

Answer 13

Water makes up 60% of our lean body weight
2/3 of our total body water is located within our cells - intracellular fluid
The remaining 1/3 is outside the cells - extracellular fluid

Question 14

Sodium reabsorption

Answer 14

It is an active process occuring in all tubular segments except the descending limb of the loop of henle and the medullary collecting duct

Question 15

Water reabsorption

Answer 15

This is by diffusion (i.e. osmosis)

Question 16

Key points of sodium reabsorption

Answer 16

Active transport out of cells into interstitial fluid
Transport achieved by Na+/K+ -ATPase pump
Keeps intracellular conc of Na+ low to allow downhill movement of Na+ from lumen

Question 17

Aquaporins

Answer 17

Water channels that are activated that move towards the cell walls to help transport water out of the tubules and back into the body.
They increase water reabsorption

Question 18

Anti-diuretic hormone (ADH)
What does it initiate

Answer 18

ADH (aka vasopressin) initiates a cascade of events within the collecting duct cells that leads to an increased number of AQP2 channels in luminal membrane. This allows increased passive diffusion of water into the cell

Question 19

ADH

Answer 19

It increases the insertion of aquaporins into the membrane of the collecting duct cells, meaning water can flow out of the collecting duct and be reabsorbed by the body
Stimulates through osmoreceptors and baroreceptors

Question 20

3 factors that deterine the rate of sodium reabsorption

Answer 20

1 - aldosterone
2 - atrial natriuretic peptide (ANP)
3 - local effect of the blood pressure on the tubules

Question 21

Diuretics

Answer 21

Substances that promote the loss of Na+ and H20.
Alcohol acts like a diuretic by inhibiting the release of vasopressin from the pituitary gland

Question 22

Basic Renal Process for Sodium and Water

Answer 22

The body gains H2O via ingestion and metabolism, it loses H2Ovia
urine, the gastrointestinal tract, and evaporation from the skin and
respiratory tract.
The body gains Na+ and Cl− by ingestion and loses them via the skin (in
sweat), the gastrointestinal tract, and urine
The renal system is the major homeostatic control point for controlling
H2Oand Na+

Question 23

Renal Na+ reabsorption

Answer 23

Baroreceptor regulation of blood pressure simultaneously regulates total-body Na+
Aldosterone controls tubular Na+ reabsorption The renin–angiotensin system is one of the two major controllers of aldosterone secretion
ANP also controls Na+ reabsorption

Question 24

Renal H2O reabsorption

Answer 24

Baroreceptor regulation of blood pressure simultaneously regulatesH2Oexcretion
Main controller of water reabsorption is ADH
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