Urinary Flashcards
Functions of Urinary System (3)
1) Regulate volume, composition, pH of body fluids
2) Eliminate drugs/food additives/urea
3) Endocrine ( release of compounds into blood to regulate Ca++ absorbtion, blood pressure, RBC formation)
Kidney Facts
-1/5 of blood flow to kidney
- Reconditions blood to return to system, removes waste
- Hard capsule surrounding kidney prevents overfilling
- 750mL of urine produced daily
- smallest functional unit = nephron
What percent of nephrons are Cortical?
Main function?
85%
-Re-absorption of “good” blood components
What percent of nephrons are juxtamedullary?
Main function?
15%
-H2O reabsorption
Body produces how many liters of filtrate per day?
80 LITERS!!!!!!!!!!!!!!!!
PCT Function
Reclaims “good” blood components and about 65% of H2O follows
- Including 100% of GLUCOSE
- Pumps solutes and H2O follows
Filtration system of Bowman’s Capsule/glomerulus
Fluid is driven into the capsule via net pressure of 10mmHg outward from the glomerulus (125mL per min moved)
Brush Border
Cilia on inside of PCT to increase SA for reabsorption.
Is there a high or low mitochondria concentration in PCT cells?
HIGH
Descending Loop Permeability
Very H2O permeable
NOT permeable to Na+ or Cl-
Ascending Loop Permeability
Not H2O permeable
-Cells actively pump Na+ out
Concentration of solutes at top of loop of henle?
Concentration of solutes on bottom of loop of henle?
300mmHG
1200mmHg
Aldosterone
- Adrenal cortex steroid
- Causes increased Na+ reabsorption = increased H2O retention (activates additional sodium pumps)
- Causes DCT to become H2O permeable
Juxta-Glomerular Apparatas
Maintains/regulates pressure within glomerulus via JG cells and the Macula Densa
JG cell
“Juxta Medullary Cell”
- stimulated when BP in glomerulus is too low
- Releases rennin into blood
Macula Densa
- Activated when blood pressure in glomerulus is too HIGH
- Causes paracrine secretion, which stimulates SM cells on afferent arteriole to contract, reducing flow = reduced pressure
Rennin/Angiotensin Activation
Rennin is released by JG cells when glomerulus BP is too low.
- Rennin is enzyme that is released to blood stream where Angoiotensin is present (INACTIVE)
- Rennin activates angiotensin to become Angiotensin 1
- When Angiotensin 1 reaches lungs, ACE enzyme converts Angiotensin 1 to Angiotensin 2 (MOST POTENT VASOCONSTRICTOR)
Angiotensin 2 Effects
- ADH release causing “thirstyness” (causes fluid retention = increased BP)
- Vasoconstriction of vessels
- AT KIDNEY, afferent & efferent arterioles constricted.
External sphinctor of urethra becomes controllable at what age?
2
Micturation
Urination
Sphinctors of Urethra
Internal = SM = autonomic External = skeletal muscle = voluntary
