Nephrology (Biology 20)

Question 1

Four functions of the kidney

Answer 1

1) removal of digestive waste products in blood
2) water balance
3) blood pH balance (moving HCO-3 or H+)
4) body salt balance (moving NaCl)

Question 2

Deamination

Answer 2

Occuring in the liver, this process takes amino acids and turns them into glucose the body can use, often happening at night. The byproduct is toxic ammonia gas, which the body mixes with CO2 to create a less toxic product, urea.

Question 3

Three steps in the kidneys urine production

Answer 3

1) filtration
2) reabsorption
3) secretion

Question 4

Aorta

Answer 4

Carries oxygenated blood to the body

Question 5

Renal artery

Answer 5

Branch of aorta which takes blood to kidneys

Question 6

Renal vein

Answer 6

Carries blood from kidney to inferior vena cava

Question 7

Inferior vena cava

Answer 7

Large vein which carries blood to the heart

Question 8

Ureter

Answer 8

Carries urine from kidney to bladder

Question 9

Urinary bladder

Answer 9

Stores urine until signalled to release from body (signals emptying at 200 ml; at 600 ml you lose control)

Question 10

Urethra

Answer 10

Tube which carries urine from bladder out of body

Question 11

Kidney

Answer 11

Site of blood filtration (cleaning) and urine (waste) production.

Question 12

Cortex

Answer 12

Outer layer of connective tissue where most of the functional unit, the nephron, is found.

Question 13

Medulla

Answer 13

Salty layer where the loop of Henle from nephron is found.

Question 14

Renal pelvis

Answer 14

Hollow chamber where kidney joins ureter. Collects urine and directs it towards the bladder.

Question 15

Afferent arteriole

Answer 15

Carries blood to the glomerulus.

Question 16

Efferent arteriole

Answer 16

Carries blood away from the glomerulus

Question 17

Glomerulus

Answer 17

Network of capillaries where filtration of blood occurs.

• Has small openings in the walls of capillaries that allows filtrate to pass through into nephron tubules
• Small molecules are forced through opening due to pressure created as blood passes through the small capillaries.
• Material that passes through are amino acids, glucose, salt ions, urea, uric acid, and of course, water (large blood proteins and blood cells are too large to cross)

Question 18

Collecting duct

Answer 18

• ADH also works here as the final chance for the body to reabsorb water if needed and causes urine to become more concentrated.
• Urine (water, salt, urea, uric acid, minerals) is carried to the renal pelvis to be moved into the bladder.
• A hormone called aldosterone from the adrenal gland causes the distal tubule and collecting duct to increase Na+ reabsorption by active transport (Cl- follows passively) to maintain the bodies salt balance.
• Also causes K+ to be secreted into the distal tubule if too high in blood.

Question 19

Proximal tubule

Answer 19

First part of tubule following Bowman’s capsule where 65% of filtrate is reabsorbed.

• Glucose, amino acids, NaCl, are immediately reabsorbed back into blood through active transport, and K+ by passive transport.
• Water moves by osmosis with these substances as it follows the osmotic gradient
• Bicarbonate ions (move out passively) and H+ (move in with active transport) move to help control blood pH.

Question 20

Bowman’s capsule

Answer 20

Funnel shaped part of nephron which surrounds glomerulus; collects filtrate from glomerulus and moves it to tubules.

Question 21

Descending loop Henle

Answer 21

Permeable to water, so reabsorption of water by osmosis here, which concentrates filtrate.

Question 22

Ascending loop of Henle

Answer 22

• Thin segment permeable to salt, so NaCl passively moves out of tubule and into medulla.
• Thick segment requires active transport to continue moving NaCl out of tubule and into medulla (Na+ moves by active transport and Cl- ions follow passively)
• 2/3 of Na+ and water is reabsorbed by now.

Question 23

Distal tubule

Answer 23

active transport used to regulate the amount of NaCl and K+ in the blood; if needed, NaCl can be moved out and K+ can be secreted into tubule (excess in blood) - both by active transport.

• pH of blood also controlled here by either secreting (active transport) H+ into the tubule, or reabsorbing (this time with active transport) bicarbonate ions (HCO3- out of tubule by osmosis (alchohol decreases ADH release, so more water is urinated out)
• Materials not normal to the body (penicillin, drugs) and excess of other (ammonia, uric acid, histamines) are secreted here.

Question 24

What systems regulate body fluid levels?

Answer 24

The nervous system and endocrine system.

Question 25

What receptors detect blood osmotic pressure?

Answer 25

Osmoreceptors in the hypothalamus

Question 26

ADH

Answer 26

Hypothalamus sends message to pituitary gland in brain to release the hormone, which causes the distal tubule and collecting duct to become more permeable to water.

Question 27

Aldeosterone

Answer 27

Responsible for regulating blood pressure - stimulates nephrons to reabsorb NaCl, which increases the osmotic gradient and causes more water to move out of the nephrons into the blood.