GRFC - renal system Flashcards
General functions of the renal system
- 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
RAAS
- 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)
Calcitriol
1,25-dihydroxylcholecalciferol
Active form of Vitamin D; for resorption of calcium
Erythropoeitin
Stimulation of new RBCs in the bone marrow
- 90% produced in kidneys
- 10% produced in liver
Kidneys
- 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)
External anatomy of kidneys
- 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
Internal anatomy of kidney
- Renal cortex - outer region
* Renal medulla - inner region; contains renal pyramids
Nephron
Functional unit of kidneys
Responsible for urine formation
*2 million nephrons in the body
2 main structures of a nephron
- Renal corpuscle: glomerulus + bowman’s capsule
* Renal tubule: PCT, LoH, DCT, CT
2 types of nephrons
- Cortical nephron: part of the nephron that lies in the renal cortex
- Juxtamedullary nephron: part of the nephron that lies in the renal medulla
Types of collecting ducts
- Cortical collecting duct: collecting duct on the renal cortex
- Meullary collecting duct: collecting duct on the renal medulla
Formation of urine
- Glomerular filtration
2. Tubular reabsorption
Glomerular filtration
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
Net filtration pressure
10 mmHg
Glomerular filtration rate
Amount of filtrate found in all renal corpuscles in both kidneys
- Male: 125 mL/min
- Female: 105 mL/min
Tubular reabsorption
- PCT (workhorse of nephron):
* Loves H2O: 65% reabsorption (most H2O reabsorption)
* 100% absorption of glucose
* Luminal fluid is concentrated (decreased H2O) - Thin descending LoH
* Loves H2O: Reabsorption of H2O
* Hates solutes: No reabsorption of Na, urea, and Cl
* Luminal fluid is concentrated - Thin ascending LoH
* Hates H2O: No absorption of H2O
* Loves Na and Cl: Reabsorption of Na and Cl
* Luminal fluid is diluted - Thick ascending LoH
* Hates H2O: No absorption if H2O
* Loves ions: Reabsorption of Na, Cl, K, other ions
* Luminal fluid: More diluted - DCT + CT
* No reabsorption of H2O
* Receives diluted luminal fluid
* If with ADH, with reabsorption of H2O (receives concentrated fluid)
From DCT and CT
To:
- Medullary collecting duct
- Minor calyx
- Major calyx
- Ureter
Urochrome/ urobilin
Responsible for urine color
Urine is diluted in nature (pale yellow to orange)
ADH/ vasopressin
Secreted by neurohypophysis
Attaches on DCT
Ureter
Composed of smooth muscles
25 - 30 cm long
Urinary bladder
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
Urethra
Terminal end organ of the renal system
- Male: ~20 cm
- Female: 3 - 4 cm
UTI
Females more than males
2 urethral sphincters
Internal urethral sphincter: involuntary
External urethral sphincter: voluntary sphincter
