ch 10

Question 1

main organs of excretory

Answer 1

1. kidneys
2. ureters
3. bladder
4. urethra

Question 2

main functions of excretory: 4

Answer 2

1. excretion of metabolic wastes
   - nitrogenous wastes (ammonia: highly toxic and converted to urea in liver, urea, uric acid)
2. maintenance of water-salt balance
   - maintain appropriate levels of K+. HCO2- (bicarbonate), and Ca2+ in the blood
3. maintenance of acid-base balance
   - kidneys monitor and help keep blood pH at 7.4 by excreting H+ ions and reabsorbing HCO2- as needed
4. secretion of hormones
   - kidneys help endocrine in hormone secretion (secrete CALCITRIOL (active form of vitamin D: promotes Ca++ absorption from digestive tract) and ERYTHROPOIETIN (stimulates red blood cell production + is released in response to either increase oxygen demand/reduce oxygen-carrying capacity of blood)

Question 3

3 regions of kidneys

Answer 3

1. cortex (outer layer)
2. medulla (inner layer, beneath cortex, consists of renal pyramids: cone-shaped tissue masses)
3. renal pelvis (hollow chamber where collecting ducts join and empty into ureter)

Question 4

define nephrons

Answer 4

microscopic tube-like functional filtration units of kidneys (approx 1 million per kidney)
- each has its own blood supply provided by 2 capillary regions
- role: filter wastes while retaining/reabsorbing water and other vital materials

Question 5

3 main parts of nephrons anatomy

Answer 5

1. filter (glomerulus, afferent/efferent arterioles)
2. tubules (proximal convoluted tubule, loop of henle, distal convoluted tubule)
3. duct (collecting duct)

Question 6

3 main parts of nephrons anatomy: THE FILTER: glomerulus

Answer 6

knot of capillaries inside bowman’s capsule
- walls: filtration device, impermeable to proteins, other large molecs, and red blood cells (they remain in blood)
- waste of metabolism (water, small molecs, ions, urea) pass through walls and into nephron to eventually be excreted like blood in urine
- filtered fluid = filtrate (not yet urine)

Question 7

3 main parts of nephrons anatomy: THE FILTER: afferent arteriole

Answer 7

carries blood TO glomerulus

Question 8

3 main parts of nephrons anatomy: THE FILTER: efferent arteriole

Answer 8

• carries blood AWAY from glomerulus
• connects to the peritubular capillary network

Question 9

3 main parts of nephrons anatomy: THE TUBULES: proximal convoluted tubule

Answer 9

narrow region of nephron after the bowman’s capsule, found in renal cortex
- joins bowman’s capsule to loop of henle
- main function: water + solutes reabsorption
- involves both active and passive transport mechanisms

Question 10

3 main parts of nephrons anatomy: THE TUBULES: loop of henle

Answer 10

• as the tube narrows, a U-turn making a loop in the tubule
• consists of a descending limb (allows water to leave filtrate/reabsorbed) and an ascending limb where ions (Na+, Cl-, K+) leave filtrate (reabsorbed into bloodstream)
• found in renal medulla
• animals in desert have adapted to their environment: have extremely long loops of henle (longer path: more surface area to reabsorb more water)
• must reabsorb most of water from filtrate

Question 11

3 main parts of nephrons anatomy: THE TUBULES: distal (convoluted) tubule

Answer 11

last convoluted tubule following loop of henle
- function: reabsorption of water + solutes
- found in renal cortex

Question 12

3 main parts of nephrons anatomy: THE DUCT: collecting duct

Answer 12

water conservation device (reabsorbing water from filtrate)
- filtrate = now urine
- area where urine is collected in kidney
- dis. conv. tubules of several nephrons enter on collecting duct
- many collecting duct in each kidney
- carries urine to renal pelvis
- found in renal medulla

Question 13

general process + movement of urine

Answer 13

1. kidneys produce urine
2. ureters transport urine
3. urinary bladder stores urine
4. urethra passes urine to outside