GRFC - renal system

Question 1

General functions of the renal system

Answer 1

• Elimination of waste products (bilirubin, uric acid, urea)
• Controls plasma volume in the body
• Acid-base balance
• Controls BP (via renin through RAAS)
• Produces hormones

Question 2

RAAS

Answer 2

• Activated by renin in response to dehydration or excessive bleeding
• Decreased BP –> activation of juxtaglomerular cells –> kidneys produce renin
• Increased renin –> renin converts angiotensinogen to angiotensin I
• Increased angiotensin I –> as blood flows in the capillaries of the lungs –> ACE converts angiotensin I into angiotensin II

–Angiotensin II is a potent vasoconstrictor (increases BP)

–Angiotensin II stimulates adrenal cortex to produce aldosterone (resorption of H2O; normalize BP by increasing it)

Question 3

Calcitriol

Answer 3

1,25-dihydroxylcholecalciferol

Active form of Vitamin D; for resorption of calcium

Question 4

Erythropoeitin

Answer 4

Stimulation of new RBCs in the bone marrow

• 90% produced in kidneys
• 10% produced in liver

Question 5

Kidneys

Answer 5

• Bean-shaped
• Level of kidneys: T12 - L3
• Right kidney is lower d/t the presence of the liver
• Location: Retroperitoneal (thus protection by lower ribs)

Question 6

External anatomy of kidneys

Answer 6

• Renal capsule - barrier to trauma
• Adipose tissue - contains fats; middle layer of tissue (if decreased fats, kidney will fall [ptosis], called nephroptosis)
• Renal fascia - anchors the kidneys to the abdominal wall

Question 7

Internal anatomy of kidney

Answer 7

• Renal cortex - outer region

* Renal medulla - inner region; contains renal pyramids

Question 8

Nephron

Answer 8

Functional unit of kidneys

Responsible for urine formation
*2 million nephrons in the body

Question 9

2 main structures of a nephron

Answer 9

• Renal corpuscle: glomerulus + bowman’s capsule

* Renal tubule: PCT, LoH, DCT, CT

Question 10

2 types of nephrons

Answer 10

• Cortical nephron: part of the nephron that lies in the renal cortex
• Juxtamedullary nephron: part of the nephron that lies in the renal medulla

Question 11

Types of collecting ducts

Answer 11

• Cortical collecting duct: collecting duct on the renal cortex
• Meullary collecting duct: collecting duct on the renal medulla

Question 12

Formation of urine

Answer 12

1. Glomerular filtration

2. Tubular reabsorption

Question 13

Glomerular filtration

Answer 13

Filtered by filtration membrane composed of podocytes and endothelial cells

Allows H2O snd small solutes to pass through

Does not permit proteins, platelets, and blood cells to pass through

Question 14

Net filtration pressure

Answer 14

10 mmHg

Question 15

Glomerular filtration rate

Answer 15

Amount of filtrate found in all renal corpuscles in both kidneys

• Male: 125 mL/min
• Female: 105 mL/min

Question 16

Tubular reabsorption

Answer 16

1. PCT (workhorse of nephron):
   * Loves H2O: 65% reabsorption (most H2O reabsorption)
   * 100% absorption of glucose
   * Luminal fluid is concentrated (decreased H2O)
2. Thin descending LoH
   * Loves H2O: Reabsorption of H2O
   * Hates solutes: No reabsorption of Na, urea, and Cl
   * Luminal fluid is concentrated
3. Thin ascending LoH
   * Hates H2O: No absorption of H2O
   * Loves Na and Cl: Reabsorption of Na and Cl
   * Luminal fluid is diluted
4. Thick ascending LoH
   * Hates H2O: No absorption if H2O
   * Loves ions: Reabsorption of Na, Cl, K, other ions
   * Luminal fluid: More diluted
5. DCT + CT
   * No reabsorption of H2O
   * Receives diluted luminal fluid
   * If with ADH, with reabsorption of H2O (receives concentrated fluid)

Question 17

From DCT and CT

Answer 17

To:

• Medullary collecting duct
• Minor calyx
• Major calyx
• Ureter

Question 18

Urochrome/ urobilin

Answer 18

Responsible for urine color

Urine is diluted in nature (pale yellow to orange)

Question 19

ADH/ vasopressin

Answer 19

Secreted by neurohypophysis

Attaches on DCT

Question 20

Ureter

Answer 20

Composed of smooth muscles

25 - 30 cm long

Question 21

Urinary bladder

Answer 21

Has a smooth muscle called “detrusor muscle”

500 mL, normal storage

700 - 800 mL, dribbles

Innervated by S2, S3, S4 (or S2, S3)

At 200 - 300 mL, can be suppressed

Micturition reflex - voiding

Question 22

Urethra

Answer 22

Terminal end organ of the renal system

• Male: ~20 cm
• Female: 3 - 4 cm

Question 23

UTI

Answer 23

Females more than males

Question 24

2 urethral sphincters

Answer 24

Internal urethral sphincter: involuntary

External urethral sphincter: voluntary sphincter

Question 25

Overflow incontinence

Answer 25

Inability to empty completely

Caused by atonic bladder

(+) dribbles

Question 26

Stress incontinence

Answer 26

Normal bladder

Weakness of supporting structures

Increased abdominal pressure facilitates urination

Question 27

Urge incontinence

Answer 27

Caused by neurogenic bladder/ overactive bladder

Caused by damage to nerves, the urinary system, or the muscles

Bladder has involuntary contractures

Urinates >8 times a day

Question 28

Functional incontinence

Answer 28

Physical or mental problems preventing the person to reach the bathroom/ toilet in time

No nerve, urinary system, or muscle damage

Question 29

Mixed incontinence

Answer 29

Combination of stress and urge incontinence

Question 30

Transient incontinence

Answer 30

Temporary incontinence brought about by a short-lived medical condition or medications

Question 31

Total incontinence

Answer 31

Complete loss of urinary control (SCI, MS)

Question 32

Components of the renal system

Answer 32

• Kidneys
• Ureters
• Bladder
• Urethra