Urinary System

Question 1

What organs comprise the urinary system?

Answer 1

kidney
ureters - transports urine from the kidneys to the bladder
urinary bladder - stores urine
urethra - from bladder to outside the body

Question 2

Identify the 6 functions of the urinary system.

Answer 2

1. produce urine
2. depose of metabolic wastes
3. maintenance of proper electrolyte concentrations and acid-base balance in the blood/body fluids
4. produce and secrete renin
5. produce and secrete erythropoietin (EPO) - increate RBC production
6. metabolize vitamin D in its active form

Question 3

Describe the location and external anatomy of a kidney.

Answer 3

3 distinct regions
1. renal cortex
2. renal medulla
3. renal pelvis

renal pyramid - minor calyx - major calyx — renal pelvis – ureter

below rib cage on side of spine

Question 4

Identify and describe the three layers of tissue that surround the kidney.

Answer 4

Renal fascia - An outer layer of dense fibrous CT that anchors the kidney and the adrenal gland to surrounding structure

Perirenal fat capsule- fatty mass that surrounds the kidney and cushions it against blows

fibrous capsule- a transparent capsule that prevents infections in surrounding regions from spreading to the kidney

Question 5

What is the primary neural innervation of the kidney? How does the nervous system
help regulate renal function?

Answer 5

the renal plexus - network of autonomic nerve fibers and ganglia, provides nerve supply to the kidney and its ureter.

branches off the celiac plexus, the renal plexus is largely supplied by sympathetic fibers.

the sympathetic vasomotor fibers regulate renal blood flow by adjusting the fainter of renal arterioles to influence the formation of urine by the nephron

Question 6

Name the vessels that carry blood into and out of a glomerulus.

Answer 6

afferent arterioles
efferent arterioles

Question 7

What are the two main parts of a nephron?

Answer 7

renal corpuscle
renal tubule and ducts

Question 8

Describe the structure of the renal corpuscle.

Answer 8

made of the Bowmans capsule (glomerular capsule)
- double layers, forms a cup around the glomerulus
outer layer: simple squamous ET
visceral : modified simple squamous ET, had podocytes (blinds to glomerulus walls)

glomerulus

Question 9

Identify the regions of the renal tubule and describe the basic histological characteristics
of each.

Answer 9

proximal convoluted tubule -
- simple cuboidal ET
- brush border of luminal surface of cells increases surface area
- cells contain lots of mitochondria to fuel solute pumps important in tubular reabsorption

loop of henle -
- divided in descending and ascending limb
- each limb contains a thick segment (cuboidal or low columnar ET) and thin segment (squamous ET)

distal convoluted tubule -
mostly cuboidal ET , have few microvilli

Question 10

Trace the tubular system of a nephron from Bowman’s capsule to the renal pelvis.

Answer 10

Bowmans capsule — proximal convoluted tubule —- descending limb of LOH — ascending limb of LOH — DCT — collecting duct — papillary duct — minor calyx — major calyx — renal pelvis

Question 11

Trace the circulatory pathway of a kidney from the renal artery to the renal vein.

Answer 11

renal artery
segmentary artery
interlobar artery
arcuate artery
interlobular artery
afferent arteriole
glomerulus
efferent arteriole
peritubulalr capillaries
interlobular vein
arcuate vein
interloper vein
renal vein
inferior vena cava

Question 12

Describe the location and function of the peritubular capillaries and the vasa recta.

Answer 12

peritubular capillaries: surround tubular portions of nephrons.

adapted for reabsorption not filtration. closer to the cortex and other tubules.

Vasa recta: surrounds loop of henle in juxtamedullary nephrons.

plays important role in forming concentrated urine

Question 13

Based on location and structure, what are the two types of nephrons?

Answer 13

cortical nephrons - located entirely in the cortex

juxtamedullary nephrons- in the cortex medulla junction

Question 14

Which type of nephron (#13) is most numerous? Which type plays the most important
role in regulating urine concentration? Which type performs most of the reabsorptive
and secretory functions of the kidney?

Answer 14

cortical is most numerous - 85%

juxtamedullary important in concentrated urine formation (conserves water).

cortical does most reabsorption and secretion

Question 15

Describe the location and general function of the juxtaglomerular apparatus (JGA).
[Note that Marieb calls this the juxtaglomerular complex (JGC).]

Answer 15

located at the point where the distal convoluted tubule lies against the afferent arteriole of its own nephron

regulate rate of filtration and blood pressure

Question 16

Where are the macula densa cells located? What is their function?

Answer 16

cells at the junction spot where the wall of the tubule and the afferent arteriole are modified at contact form macula dense which has chemoreceptors that monitors the sodium and chloride concentrations of the filtrate into the distal convoluted tubule

Question 17

Where are the juxtaglomerular (JG) cells located? [Note that Marieb calls these granular
cells.] What is their function?

Answer 17

in the smooth muscle cell walls of the afferent arteriole

-function as mechanoreceptors (sense bp)

• they sense bp in the arteriole and release renin from renin-containing granules in their cytoplasm

Question 18

Identify and define the three steps involved in urine formation.

Answer 18

glomerular filtration - glomerular blood hydrostatic P forces H20 and dissolved solutes across the filtration membrane

tubular reabsorption - return of water and useful solute molecules from the filtrate to the blood

tubular secretion - transport of wastes and excesses materials across tubular epithelium into the filtrate

Question 19

Describe the filtration membrane.

Answer 19

between the blood and capsular space

small molecules and ions (H20 , glucose, and amino acids) filter freely

consists of 3 layers:
- glomerular capillary endothelium (pours so components pass through)

• basement membrane
  (glycoproteins)
  negatively charged–> repels plasma proteins that may try and get filtered
  Fenestrations in membrane–> free passage of water and solute
• visceral membrane of the glomerular capsule
  (filters whatever is left)

Question 20

How does the structure of the filtration membrane contribute to the process of
glomerular filtration?

Answer 20

provides renal clearance

capillary pores that help with filtration
fused masement membrane creates a physical barrier that prevents everything but small solutes
podocyte projections with filtration slits that keep larger solutes form passing on

Question 21

What factors promote glomerular filtration? What factors oppose glomerular filtration?

Answer 21

promote: glomerular hydrostatic pressure (55 mmHg)

oppose: blood colloid osmotic pressure (30 mmHg)

Question 22

Why is net filtration pressure (NFP) so much higher in the glomerulus than in the
systemic capillaries?

Answer 22

to push the solutes into the Bowmans capsule

Question 23

How does NFP affect the glomerular filtration rate (GFR)?

Question 24

What effect does a change in glomerular hydrostatic pressure have on GFR?

Question 25

What is the effect on GFR of vasoconstriction/vasodilation of the afferent arterioles?
the efferent arterioles?

Question 26

What effect does a change in plasma colloid osmotic pressure have on GFR?

Question 27

Describe the composition and osmolarity of glomerular filtrate.