Urinary System

Question 1

give the 2 functions of the urinary system

Answer 1

1. excretion

2. regulation of extracellular fluid

Question 2

list the 4 components of the mammalian urinary system

Answer 2

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

Question 3

describe the kidneys (3)

Answer 3

paired, separated from abdominal cavity by parietal peritoneum, have outer cortex and inner medulla

Question 4

why are the kidneys separated from the abdominal cavity by the parietal peritoneum?

Answer 4

so that if something goes wrong, the other organs are not contaminated

Question 5

list and describe 2 more components of the kidneys

Answer 5

1. renal hilus: indented area on kidney where blood vessels, nerves, and ureters enter and leave
2. renal pelvis: expanded origin of ureter within kidney, receives urine

Question 6

describe the ureter, including tissue type lining it

Answer 6

smooth muscular tube that transports urine from kidney to bladder, lined with transitional epithelium to expand to allow for passage of urine

Question 7

describe the urinary bladder, including the tissue type lining it

Answer 7

hollow, smooth muscular structure that holds urine, also lined with transitional epithelium

Question 8

what lines the urethra?

Answer 8

transitional epithelium

Question 9

how many sphincters does the urethra have and what state are they usually in?

Answer 9

2, usually contracted to keep urine in bladder, relax for urination

Question 10

list and describe the location and muscle types of the 2 sphincters in the urethra

Answer 10

1. internal sphincter: at exit of bladder, smooth muscle

2. external sphincter: at end of urethra, skeletal muscle

Question 11

why is the external sphincter of the urethra composed of skeletal muscle?

Answer 11

to allow for voluntary control of urination

Question 12

what are nephrons?

Answer 12

the functional unit of kidneys

Question 13

list the 4 components of a nephron

Answer 13

1. renal corpuscle
2. proximal tubule
3. loop of Henle
4. distal tubule

Question 14

list and describe the 2 structures within the renal corpuscle

Answer 14

1. glomerulus: network of capillaries, site of filtration, keeps blood cells in blood
2. Bowman capsule: collects filtrate from glomerulus

Question 15

what is the proximal tubule connected to?

Answer 15

the renal corpuscle

Question 16

what does the loop of Henle connect?

Answer 16

connects the proximal tubule to the distal tubule

Question 17

what does the distal tubule connect to?

Answer 17

connects to/leads to ureter

Question 18

what are the proximal tubule, loop of Henle, and distal tubule all lined with?

Answer 18

simple cuboidal epithelium

Question 19

list and describe the 3 steps of formation of urine

Answer 19

1. glomerular filtration: blood pressure nonselectively forces water and small molecules out of plasma, filtrate collects in Bowman capsule
2. tubular reabsorption: approx 99% of filtrates returned to blood, occurs via simple and facilitated diffusion, active transport, and osmosis
3. tubular secretion: movement of nonfiltered substances into filtrate, how drugs and K+ are removed from bloodstream

Question 20

which steps of urine formation occur at the same time?

Answer 20

tubular reabsorption and tubular secretion

Question 21

what 3 hormones regulate the formation of urine?

Answer 21

1. antidiuretic hormone (ADH)
2. aldosterone
3. parathyroid hormone

Question 22

how does ADH regulate the formation of urine and what is it secreted by?

Answer 22

secreted by the posterior pituitary gland, acts on renal tubules to increase their permeability for water, increases water reabsorption, allows for water retention

Question 23

how does aldosterone regulate urine formation and what is it secreted by?

Answer 23

a steroid hormone secreted by the adrenal cortex, increases tubular reabsorption of K+, indirectly increases tubular reabsorption of Na+

Question 24

how does parathyroid hormone regulate urine formation and what secretes it?

Answer 24

secreted by the parathyroid, increases tubular reabsorption of Ca2+ to increase blood Ca2+ levels

Question 25

what is micturition?

Answer 25

emptying of the bladder

Question 26

list the 4 steps of micturition

Answer 26

1. stretch receptors on wall of bladder sense filling of bladder and send signals to CNS
2. this results in contraction of bladder and relaxation of internal sphincter
3. this puts pressure on external sphincter
4. animal must voluntarily relax external sphincter to allow for bladder to empty

Question 27

what is urinalysis?

Answer 27

a diagnostic procedure to evaluate the physical and chemical properties of urine

Question 28

what 6 things can be determined by urinalysis?

Answer 28

1. composition
2. color
3. odor
4. consistency
5. Nitrogenous component
6. amount

Question 29

describe the composition of urine as revealed by urinalysis

Answer 29

reflects the composition of extracellular fluid, slightly different for each animal

Question 30

describe the color of urine and why?

Answer 30

usually yellow, from bilirubin

Question 31

describe the odor of urine?

Answer 31

specific to each species, influenced by diet

Question 32

describe what the consistency of urine reveals

Answer 32

amount of water, can range from aqueous to syrupy

Question 33

list the nitrogenous component of urine for mammals, birds, and fish

Answer 33

mammals: urea
birds: uric acid
fish: ammonia