Urinary System

Question 1

urinary system components

Answer 1

kidney
ureter
urinary bladder
urethra

Question 2

functions of kidneys

Answer 2

1. excretion: removal of wastes from body fluids in urine

2. regulation of blood: ions, pH, and pressure and volume

Question 3

kidneys accomplish functions with these 3 processes

Answer 3

1. filtration of water, ions, nutrients and wast products from blood
2. reabsorption of most of the water, ion, and nutrients back into the blood
3. excretion of metabolic wastes into the urine

Question 4

position of kidneys

Answer 4

located on either side of vertebral column

partly protected by rib cage

Question 5

divisions of kidney

Answer 5

1. renal cortex: outer portion
2. renal medulla: inner portion
   - separated into renal pyramids by renal columns

Question 6

blood supply to kidneys

Answer 6

receives blood from renal artery which continually break down until they become glomerulus

Question 7

kidney histology

Answer 7

kidney is composed of nephrons and a collecting system

Question 8

nephron

Answer 8

• functional unit of kidney
• urine production begins here
• composed of renal corpuscle and renal tubule

Question 9

renal corpuscle

Answer 9

spherical structure composed of glomerulus, bowman’s capsule, and urinary space

Question 10

glomerulus portion of renal corpuscle

Answer 10

• intertwining network of capillaries
• receives blood from the afferent arteriole
• blood leaves thru the efferent arteriole

Question 11

bowman’s capsule portion of renal corpuscle

Answer 11

• composed of squamous epithelial cells
• sac-like structure that surrounds the glomerulus
• encloses the urinary space

Question 12

urinary space

Answer 12

space between the inner layer lining of the glomerulus and the outer layer of the capsule

Question 13

filtration of fluid from blood into the nephron

Answer 13

• occurs in renal corpuscle
• contributes to blood pressure
  
  • forces water out of glomerulus into urinary space
  • produces filtrate (protein free)

Question 14

3 layers of filtration

Answer 14

1. glomerulus: endothelial cell layer
2. middle connective tissue layer
3. inner lining of bowman’s capsule: epithelial cell layer

Question 15

role of glomerular endothelial layer

Answer 15

small pores in the endothelial lining prevent passage of blood cells into the filtrate but do allow some proteins to get thru (so no blood in urine)

Question 16

role of podocyte layer of inner lining of bowman’s capsule

Answer 16

1. podocytes, which are epithelial cells on the inner lining of bowman’s capsule, surround the glomerular capillaries
   - composed of foot processes called pedicels
2. very small filtration slits between pedicels only allow water from the blood into the urinary space (so no protein in urine)

Question 17

renal tubule

Answer 17

• long “U” shaped tube extending from the cortex into the medulla and back into the cortex
• begins at renal corpuscle
• composed of proximal convoluted tube, loop of Henle, and distal convoluted tube
• ends at collecting duct

Question 18

composition of wall of tubule

Answer 18

composed of epithelial cells

-both squamous and columnar (depending on degree of activity)

Question 19

return of filtrate from nephron back into the blood

Answer 19

renal tubule cells:

1. reabsorb nutrients from filtrate
2. returns them to blood
3. reabsorb water from filtrate
4. returns it to blood
5. what is left in tube is excreted in urine

Question 20

peritubular capillaries and vasa recta

Answer 20

return reabsorbed water and solutes from the filtrate in the tube to the blood

• both are branches of the efferent arteriole leaving the kidney
• drain blood into venous system and back to heart

Question 21

proximal convoluted tube (PCT)

Answer 21

• 1st segment of renal tubule
• bulk reabsorption of filtrate occurs here (60-70%)
  
  • microvilli increase surface area for absorption

Question 22

loop of henle

Answer 22

• middle segment of renal tubule
• composed of descending limb (fluid flows down)
• ascending limb (fluid flows up into cortex)

Question 23

distal convoluted tubule

Answer 23

• last segment of renal tubule
• epithelial cells that line segment are:
  
  • smaller and have no microvilli
  • less active
  • more specialized
• selective reabsorption of filtrate occurs here in response to hormones in order to REGULATE BLOOD PRESSURE, VOLUME, AND PH

Question 24

juxtaglomerular apparatus

Answer 24

endocrine structure composed of:

• macula densa (specialized epithelial cells)
• juxtaglomerular (JG) cells (specialized smooth muscle cells)

Question 25

how the DCT regulates blood pressure and volume

Answer 25

1. if decr. BP is sensed by JG cells, they release renin 2. renin activates angiotensin 3. angiotensin causes vasoconstriction and secretion of aldosterone 4. aldosterone causes DCT cells to incr. sodium and water reabsorption 5. both are returned to blood 6. this causes incr. BP and volume

Question 26

decreased BP leads to...

Answer 26

``` renin -> angiostensin -> aldosterone -> -incr. Na and water reabsorption at DCT -incr. blood volume and pressure -less water in urine …so urine is more concentrated ```

Question 27

increased BP leads to...

Answer 27

``` ANP -> -decr. Na and water reabsorption at DCT -decr. blood volume and pressure -more water in urine …so urine is more dilute ```

Question 28

how the DCT regulates blood pH

Answer 28

controls is by 1. H+ excretion into urine 2. HCO3 production and reabsorption into blood

Question 29

the collecting ducts

Answer 29

- determine final urine composition and volume - hypothalamic neurons are stimulated by decr. BP or incr. Na/Cl concentration - neurons then release ADH - causes incr. water reabsorption at collecting duct

Question 30

aldosterone binding at DCT causes...

Answer 30

Na reabsorption (then water follows)

Question 31

ADH binding at collecting duct causes...

Answer 31

only water reabsorption

Question 32

functions of components of nephron and collecting duct

Answer 32

1. renal corpuscle: filtration 2. PCT: bulk reabsorption 3. loop of henle: concentration 4. DCT: fine tuning 5. collecting duct: fine tuning

Question 33

after the filtrate's final composition is determined by collecting duct...

Answer 33

the ducts empty into a minor calyx, which ends at the renal papilla of each renal pyramid

Question 34

minor calyx

Answer 34

- surrounds each renal pyramid - collects urine form each renal pyramid - several join to form major calyx

Question 35

major calyx

Answer 35

- collects urine from minor calyces | - join to form renal pelvis

Question 36

renal pelvis

Answer 36

acts as funnel to drain urine from kidney to ureter

Question 37

ureters

Answer 37

- smooth muscle tubes that collect urine from renal pelvis and empties into the urinary bladder - pass thru bladder at an angle to prevent backflow

Question 38

urinary bladder

Answer 38

hollow, muscular organ made of smooth muscle | -temporary reservoir for urine storage

Question 39

urothelium

Answer 39

aka transitional epithelium that lines the bladder and ureters -cells are impermeable to water and can rearrange themselves as bladder expands/contracts

Question 40

male urethra

Answer 40

- 7 to 8 inches long - begins at inferior pole of bladder - passes thru prostate gland and penis

Question 41

female urethra

Answer 41

- 1 to 2 inches long | - therefore female is more prone to frequent infections

Question 42

external urethral sphincter

Answer 42

skeletal muscle that surrounds the urethra | -relaxations permits micturition (urination)