Excretory System

Question 1

Kidney portal system

Answer 1

2 capillary beds in series: vasa recta capillary bed for providing oxygen to kidneys, peritubular capillary bed for nutrients

Question 2

Bladder

Answer 2

has muscular lining (detrusor muscle); urine must pass through internal and external urethral sphincters

Question 3

Internal urethral sphincter

Answer 3

smooth muscle, involuntary control

Question 4

External urethral sphincter

Answer 4

skeletal muscles, voluntary control

Question 5

Micturition reflex

Answer 5

when bladder is full:

1) nervous system alerted-parasympathetic neurons fire-detrusor muscle contracts-internal sphincter relaxes
2) invididual must choose to relax external sphincter to urinate or maintain discomfort

Question 6

Filtration

Answer 6

• blood from glomerulus filtered as fluid into Bowman’s space
• fluid collected=filtrate
• movement of fluid due to Starling forces
• hydrostatic pressure much higher in glomerulus so net flow of fluid into nephron

Question 7

Kidney stones

Answer 7

obstruct ureter causing buildup of urine; high hydrostatic pressure in Bowman’s space so filtration can’t occur

Question 8

Secretion

Answer 8

Kidneys can secrete salts, acids, bases, and urea as needed in body, to be eliminated in urine, mechanism for excreting waste

Question 9

Reabsorption

Answer 9

Some compounds such as glucose, amino acids, and vitamins that are filtered are usually taken back up for use in the body; water is also reabsorbs depending on the blood pressure

Question 10

Interstitium

Answer 10

connective tissue surrounding nephrons where reabsorbed water and ions enter before being returned to circulation

Question 11

Descending limb of Henle

Answer 11

Water leaves due to increasing interstitial concentation after the release of substances in the proximal convoluted tubule

Question 12

Ascending limb of Henle

Answer 12

only permeable to salts; increasing amounts of salts removed as move up; filtrate becomes hypotonic

Question 13

Aldosterone mechanism

Answer 13

1) Low blood pressure stimulates release of renin from kidneys
2) renin cleaves angiotensinogen to form Ang I
3) Ang I metabolized by ACE in lungs to form Ang II- promotes release of aldosterone
4) Aldosterone causes reabsorption of Na+ which causes water to also be reabsorbed

Question 14

ACE inhibitors

Answer 14

Used to lower blood pressure by prohibiting conversion of Ang I into Ang II

Question 15

ADH/vasopressin

Answer 15

Released when high blood osmolarity to retain water in the body; alters permeability of collecting duct to allow more water to reabsorb; inhibited by caffeine and alcohol

Question 16

Acid-Base balance

Answer 16

kidneys can excrete bicarbonate and increase reabsorption of H+ if pH too high
If pH too low, excretes more H+ and increases reabsorption of bicarbonate

Question 17

Glomerulus

Answer 17

main site of filtration; blood enters through afferent arteriole, leaves through efferent arteriole; filtrate that is filtered out falls into Bowman’s capsule; acts like a sieve-small molecules dissolved in blood can go through pores, but large proteins and blood cells can’t

Question 18

Proximal convoluted tubule

Answer 18

filtrate from glomerulus enters; amino acids, glucose, and vitamins are reabsorbed with water here, as well as most of sodium; waste products such as hydrogen ions, potassium ions, ammonia and urea are secreted into the tubule

Question 19

distal convoluted tubule

Answer 19

responds to aldosterone, which promotes sodium reabsorption, causing water to follow; causes a lower volume of concentrated urine

Question 20

osmotic pressure

Answer 20

sucking pressure that draws water into the vasculature caused by concentration of dissolved solutes

Question 21

oncotic pressure

Answer 21

osmotic pressure that is due specifically to dissolved proteins

Question 22

osmolarity

Answer 22

concentration of a solution, in solute particles per volume

Question 23

when blood osmolarity is low

Answer 23

excess water is excreted and solutes reabsorbed in higher concentrations

Question 24

when blood osmolarity is high

Answer 24

increased water reabsorption and solute excretion increases