Homeostasis - Water Balance + Excretory System

Question 1

Hyperosmotic (hypertonic)

Answer 1

Property of solution on one side of selectively permeable membrane that has lower conc. of water (higher conc. of solute)

Water leaves cell, causing it to shrink + shrivel

Question 2

Hypoosmotic (hypotonic)

Answer 2

Property of solution on one side of selectively permeable membrane that has higher conc. of water (lower conc. of solute)

Water moves into cell, cell swells + can burst

Question 3

Isosmotic (isotonic)

Answer 3

Property of two solutions that have equal water conc. (equal solute conc.)

No net movement of water, cell’s volume remains stable

Question 4

Osmotic pressure

Answer 4

Pressure that results from difference in solute concentration between two sides of selectively permeable membrane

Pushes water to hypertonic side of membrane

Question 5

Hydrostatic pressure

Answer 5

Water pressure against cell membrane/wall

If hydrostatic and osmotic pressure is equal, there is no net flow of water

Hydrostatic pressure cannot build in animal cells because they do not have strong cell walls

Question 6

What is excretion?

Answer 6

The elimination of waste products + foreign matter from the body

Question 7

Why do humans excrete urea?

Answer 7

• Very soluble in water
• Minimally toxic
• Requires very little water to be eliminated from the body

Question 8

Structures of kidney + function

Answer 8

• Renal medulla: outer layer
• Renal cortex: inner layer
• Renal artery: supplies blood to kidney
• Renal vein: clean blood exits kidney
• Renal pelvis: connects kidney to ureter
• Ureter: passes urine to urinary bladder

Question 9

Bowman’s capsule

Answer 9

Small folded structure that encircles glomerulus

Question 10

Glomerulus

Answer 10

Network of capillaries within Bowman’s capsule that performs 1st step in blood filtration
- Filters water, ions, small nutrient molecules, + nitrogenous waste molecules into nephron

Question 11

Afferent arteriole

Answer 11

Vessel that supplies blood to nephron

Question 12

Efferent arteriole

Answer 12

Vessel that carries blood away from nephron

Question 13

Peritubular capillaries

Answer 13

Net of capillaries in nephron that reabsorb essential ions + minerals from filtered blood

Question 14

Proximal convoluted tubule

Answer 14

Duct portion of nephron that connects Bowman’s capsule to loop of Henle
- Active reabsorption: K+, Na+, Cl-, amino acids, glucose + other nutrients
- Passive reabsorption: water through aquaporins
- Secretion: H+ ions (actively)

Question 15

Loop of Henle

Answer 15

U-shaped part of duct that connects proximal convoluted tubule to distal convoluted tubule
- Descending reabsorption: water through aquaporins (passive)
- Ascending reabsorption: Na+ and Cl- (active)

Question 16

Distal convoluted tubule

Answer 16

Duct portion of nephron that connects loop of Henle to ducts that lead to renal pelvis
- Reabsorption: Na+ and Cl- (active)
- Secretion: K and Na+ (active), water sometimes (passive)

Question 17

Collecting ducts

Answer 17

Lead to renal pelvis
- Reabsorption: water (passive), some urea, H+ ions

Question 18

What is filtration?

Answer 18

Process in which blood and fluid pass through a selectively permeable membrane

Question 19

What is reabsorption?

Answer 19

Transfer of water, ions, + nutrients back into interstitial fluid via passive + active transport

Question 20

What is secretion?

Answer 20

Removal of waste materials from blood and intercellular fluid

Question 21

How can secretion be used to maintain blood pH?

Answer 21

Secretion of H+ ions into filtrate helps counteract the acidity constantly generated in the body by metabolic reactions

If too acidic, H+ ions are secreted into proximal convoluted tubule + collecting ducts