Excretion (liver, kidneys, osmoregulation)

Question 1

What do the pyramids in the kidney represent?

Answer 1

The pointed ends of the renal pelvis.

Question 2

What does the renal artery carry?

Answer 2

Oxygenated blood with high urea concentration.

Question 3

What does the renal vein carry?

Answer 3

Deoxygenated, filtered blood with low urea.

Question 4

What is included when cutting open a kidney?

Answer 4

Pelvis, ureter, blood vessels.

Question 5

How many nephrons are there per kidney?

Answer 5

About 1 million nephrons.

Question 6

Where does ultrafiltration take place in the nephron?

Answer 6

From the glomerulus to Bowman’s capsule.

Question 7

What is the purpose of the PCT in the nephron?

Answer 7

Reabsorbs sugars, water, and ions.

Question 8

How does the loop of Henle contribute to osmoregulation?

Answer 8

Creates a medullary gradient to concentrate urine.

Question 9

What happens in the descending limb of the loop of Henle?

Answer 9

Water diffuses out, ions diffuse in.

Question 10

What happens in the ascending limb of the loop of Henle?

Answer 10

Ions are actively transported out; impermeable to water.

Question 11

What does the DCT do?

Answer 11

Regulates pH and responds to hormones.

Question 12

What happens in the collecting duct?

Answer 12

Water diffuses out, producing concentrated urine.

Question 13

Why is the afferent arteriole wider than the efferent?

Answer 13

To build high hydrostatic pressure in the glomerulus.

Question 14

What structures form the ultrafiltration barrier?

Answer 14

Capillary endothelium, basement membrane, podocytes.

Question 15

What do podocytes do?

Answer 15

Provide filtration slits to allow small molecules through.

Question 16

What does the basement membrane do in filtration?

Answer 16

Blocks large molecules >69,000 Mr, like proteins.

Question 17

What substances are present in the glomerular filtrate?

Answer 17

Water, glucose, urea, amino acids, ions.

Question 18

What substances are not filtered into the nephron?

Answer 18

Blood cells and plasma proteins.

Question 19

Why is plasma protein retention important?

Answer 19

Maintains low blood water potential to aid reabsorption.

Question 20

How often is the whole blood volume filtered by kidneys?

Answer 20

Every 4–5 minutes.

Question 21

What percentage of reabsorption happens in the PCT?

Answer 21

About 85%.

Question 22

What adaptations does the PCT have for reabsorption?

Answer 22

Microvilli, mitochondria, tight junctions.

Question 23

How is glucose reabsorbed in the PCT?

Answer 23

By co-transport with sodium ions.

Question 24

What creates the sodium ion gradient in PCT cells?

Answer 24

Na⁺/K⁺ pumps in the basolateral membrane.

Question 25

What percentage of water is reabsorbed in the PCT?

Answer 25

About 65% by osmosis.

Question 26

How is urea reabsorbed?

Answer 26

By passive diffusion.

Question 27

How are small proteins reabsorbed?

Answer 27

By endocytosis.

Question 28

What does the countercurrent multiplier do?

Answer 28

Maintains ion gradient in the medulla for water reabsorption.

Question 29

Which part of the loop of Henle is impermeable to water?

Answer 29

Ascending limb.

Question 30

Which part of the loop of Henle is permeable to water?

Answer 30

Descending limb.

Question 31

What hormones affect the DCT and collecting duct?

Answer 31

ADH and aldosterone.

Question 32

How does the DCT help regulate pH?

Answer 32

Excretes H⁺ and reabsorbs HCO₃⁻ based on need.

Question 33

What triggers ADH release?

Answer 33

Osmoreceptors shrink when water potential is low.

Question 34

Where is ADH released from?

Answer 34

Posterior pituitary gland.

Question 35

What is the function of ADH?

Answer 35

Inserts aquaporins into collecting duct to reabsorb water.

Question 36

How long does ADH stay active?

Answer 36

Half-life of about 20 minutes.

Question 37

How is water balance maintained?

Answer 37

By osmoregulation involving the kidneys and ADH.

Question 38

What are the sources of water loss in the body?

Answer 38

Sweating, urine, breathing.

Question 39

What does high blood osmolarity indicate?

Answer 39

Low water potential → triggers ADH release.

Question 40

What does low blood osmolarity indicate?

Answer 40

High water potential → inhibits ADH release.

Question 41

What are three things urine tests can detect?

Answer 41

Metabolites, hormones (e.g. hCG), and drugs.

Question 42

What hormone does a pregnancy test detect?

Answer 42

hCG (human chorionic gonadotropin).

Question 43

What type of antibodies are used in pregnancy tests?

Answer 43

Monoclonal antibodies specific to hCG.

Question 44

What do two lines on a pregnancy test mean?

Answer 44

hCG detected → positive result.

Question 45

What technique detects anabolic steroids?

Answer 45

Gas chromatography–mass spectrometry (GC-MS).

Question 46

How are drug tests performed in athletes?

Answer 46

Random urine testing, 2 samples taken.

Question 47

What happens if an athlete misses 3 tests?

Answer 47

They receive a ban.

Question 48

What happens in acute kidney failure?

Answer 48

Sudden, usually reversible loss of kidney function.

Question 49

What are some causes of chronic kidney failure?

Answer 49

Diabetes, hypertension, infections.

Question 50

What are symptoms of kidney failure?

Answer 50

Toxin build-up, fluid retention, ion imbalance.

Question 51

What is haemodialysis?

Answer 51

Blood pumped through a dialyser with a semi-permeable membrane.

Question 52

Why is a countercurrent flow used in haemodialysis?

Answer 52

Maximises concentration gradient for diffusion.

Question 53

Why is heparin used during dialysis?

Answer 53

To prevent clotting.

Question 54

How often is haemodialysis done?

Answer 54

3 times a week, ~4 hours per session.

Question 55

What is peritoneal dialysis?

Answer 55

Dialysis fluid fills abdominal cavity; waste diffuses into it.

Question 56

What acts as the dialysis membrane in peritoneal dialysis?

Answer 56

The peritoneum (lining of the abdomen).

Question 57

What is ambulatory peritoneal dialysis?

Answer 57

Allows mobility while dialysis fluid is in abdomen.

Question 58

Which ions are regulated by the kidneys?

Answer 58

Potassium, sodium, magnesium, and others.

Question 59

What can high potassium levels cause?

Answer 59

Muscle cramps, weakness, cardiac arrest.

Question 60

What can high sodium levels cause?

Answer 60

Confusion, twitching, high blood pressure.

Question 61

What can high magnesium levels cause?

Answer 61

CNS, muscle, and heart dysfunction.