Nephrons

Question 1

Nephron functions

Answer 1

• basic structural + functional unit of kidney
• controls concentration of water and soluble materials in blood stream via: filtering blood, reabsorbing needed materials, excreting rest (waste)
• -> regulates blood volume/pH/BP, controls electrolyte

Question 2

of nephrons in each kidney

Answer 2

~ 1 million

Question 3

2 main parts of nephron

Answer 3

1. glomerular capsule

2. renal tubule

Question 4

glomerular capsule

Answer 4

aka renal corpuscle

• composed of (bowman’s) capsule + glomerulus (network of tiny blood capillaries)
• filters blood

Question 5

renal tubule

Answer 5

reabsorbs necessary materials back into blood stream (99% of filtrate reabsorbed)

Question 6

collecting ducts

Answer 6

carry remaining filtrate away from nephron as urine (to be excreted)

Question 7

glomerular capillaries

Answer 7

aka glomerulus

• lie between afferent + efferent arterioles
• highly coiled + specialized for filtration
• epithelium contains fenestration that allow certain materials to exit the capillaries (while proteins + blood cells stay inside)

Question 8

fenestration

Answer 8

pores

Question 9

afferent arteriole

Answer 9

• fed by interlobular artery
• much bigger of the 2 arterioles
• responsible for high blood pressure in glomerular capillaries, which is what forces substances out of capillaries and into renal tubule for filtration

Question 10

efferent arteriole

Answer 10

• smaller of the 2 arterioles

- on other side of glomerulus capillary bed

Question 11

filtrate

Answer 11

water and solutes forced out of glomerulus into the renal tubule

Question 12

2 types of nephrons

Answer 12

1. cortical (85% of nephrons, located in cortex / some are in loop of henle)
2. juxtamedullary (deep in medulla)

Question 13

3 sections of renal tubule

Answer 13

1. proximal convoluted tubule (PCT)
2. loop of Henle
3. distal convoluted tubule (DCT)

Question 14

PCT

Answer 14

proximal convoluted tubule

• first part of renal tubule
• specialized to reabsorb water + many solutes from filtrate back into peritubular capillaries
• can secrete certain unwanted substances

Question 15

loop of Henle

Answer 15

• middle section of renal tubule
• 2 limbs connected w/hairpin loop
• descending limb: allows water loss from filtrate (to be reabsorbed into bloodstream)
• ascending limb: allows salt (NaCl) loss from filtrate (to be reabsorbed into bloodstream)

Question 16

DCT

Answer 16

distal convoluted tubule

• final section of renal tubule (leads into collecting ducts)
• mostly responsible for secretion of unwanted substances (will become urine)

Question 17

peritubular capillaries

Answer 17

• arise from efferent arterioles as leave glomerulus
• closely follow renal tubules and drain into interlobular vein
• porous + low-pressure –> how filtrate (water + solutes) is returned to bloodstream if not meant for excretion