Genitourinary System Flashcards
What are the 4 functions of the kidneys?
- Excretion —> metabolic products: urea, uric acid,
creatinine
—> foreign substances: drugs - Homeostasis —> body fluids
—> electrolytes
—> acid-base balance - Regulate blood pressure
- Hormone secretion —> erythropoietin
—> renin
What are the 7 main components of the kidneys?
- Cortex - outside
- Medulla - inside
- Major calyx - join to ureter
- Minor calyx - branches of major calyx
- Renal artery
- Renal vein
- Ureter
What is the pathway of blood through the kidneys?
In:
Renal artery
Segmental artery
Interlobar artery
Arcuate artery
Interlobular artery
Afferent arteriole
Glomerular capillaries
Out:
Efferent arteriole
Peritubular capillaries —> supply kidney
Interlobular vein
Arcuate vein
Interlobar vein
Renal vein
Which blood vessels supply the kidney?
Peritubular capillaries
What are the 5 parts of the bladder?
- Detrusor muscle
- outside
—> contraction for urination
- outside
- Trigone
—> signals brain when bladder full (stretch) - Internal sphincter
- end of bladder
—> involuntary control to prevent urination
- end of bladder
- External sphincter
- urogenital diaphragm
—> voluntary control to prevent urination
- urogenital diaphragm
- Bulbourethral glands
- males only
- urogenital diaphragm
—> produce and secrete lubricant to semen for
sperm survival
What are the 6 parts of a nephron?
- Glomerulus
- Bowman’s capsule
- Proximal convoluted tubule
- Loop of Henle - ascending and descending
- Distal convoluted tubule
- Collecting duct
Where is mitochondria found in high vs low densities in a nephron?
High —> active transport:
1. PCT
2. DCT
3. Thick ascending loop of Henle
4. Intercalated cells of collecting duct
Low —> passive transport:
1. Thin descending loop of Henle
2. Thin ascending loop of Henle
3. Principal cells of collecting duct
What are the 2 types of cells that make up the collecting duct?
- Principle cells —> Na+ reabsorption and K+
secretion - Intercalated cells —> maintain acid-base balance
What are the 2 types of nephron?
- Superficial
- glomerulus in outer cortex
- loop of Henle trough at inner-outer medulla
border
- Juxtaglomerular
- glomerulus near cortex-medullar border
- loop of Henle trough deep in inner medulla
Nephron —> 10:1 (superficial : juxtaglomerular)
Why is the cortex granular and medulla striated?
Cortex —> contains many glomeruli (dots)
Medulla —> contains many tubules (lines)
What is the juxtaglomerular apparatus?
Where glomerulus is next to DCT
- Macula densa - cells of DCT that meet glomerulus
—> GFR regulation (tubulo-glomerular
feedback mechanism)
- Extraglomerular mesangial cells - between DCT and
efferent arteriole
- Juxtaglomerular cells - on afferent arteriole
—> secrete renin —> regulates
blood pressure
What are the 4 renal processes?
- Glomerular filtration
- Reabsorption
- Secretion
- Excretion
How does glomerular filtration occur?
- Blood plasma pushed through glomerular
fenestrae- due to heart’s hydrostatic pressure
- 70nm gaps in basement membrane —> sieve
- Through Bowman’s capsule space
- Through Bowman’s capsule membrane
- -ve proteins in membrane —> repel proteins
- Through slit diaphragm
- between epithelial podocytes
- thin and porous —> sieve
Which 4 pressures affect glomerular filtration?
Push fluid out:
1. Blood hydrostatic pressure
2. Fluid oncotic pressure
Pull fluid in:
1. Blood oncotic pressure
2. Fluid hydrostatic pressure
What are the 4 equations for renal action?
- Net Ultrafiltration Pressure:
Puf = HPgc - HPbw - πgc - Glomerular Filtration Rate:
GFR = Puf x Kf - Renal Clearance:
C = (U x V) / P - Filtration Flow:
FF = GFR / RPF
What is Puf and how is it calculated?
Net Ultrafiltration Pressure
- pressure exerted on blood to force fluid out at
glomerulus
Puf = HPgc - HPbw - πgc
- HPgc = hydrostatic pressure in glomerular capillaries
- HPgc = hydrostatic pressure in bowman’s capsule
- πgc = oncotic pressure of plasma proteins in
glomerular capillaries
What is GFR and how is it calculated?
Glomeruar Filtration Rate
- volume of fluid pushed filtered through the
glomeruli per unit time (indicative of renal failure)
- mL/min
- males —> 90-140
females —> 80-125
GFR = Puf x Kf
- Puf = net ultrafiltration pressure
- Kf = ultrafiltration coefficient
- depends on membrane permeability and surface
area
What are the 2 mechanisms for GFR regulation?
- Myogenic mechanism:
- arterial pressure inc —> afferent arteriole
contracts —> blood flow dec
- arterial pressure inc —> afferent arteriole
- Tubulo-glomerular feedback mechanism:
- GFR inc —> inc NaCl in loop of Henle —> macula
densa detects —> inc ATP and adenosine
secreted —> afferent arteriole contricts - GFR dec —> dec NaCl in loop of Henle —> macula
densa detects —> dec ATP and adenosine
secreted —> afferent arteriole dilates
- GFR inc —> inc NaCl in loop of Henle —> macula
What is C and how is it calculated?
Renal Clearance
- volume of plasma cleared of a specific substance via
the kidneys per unit time
- mL/min
C = (U x V) / P
- U = conc of substance in urine
- V = rate of urine production
- P = conc of substance in plasma
Which 2 substances are used to determine GFR and why?
- Inulin - must be transfused from plants —> less use
- Creatine - muscle metabolism waste —> common
- Freely filtered (no reabsorption or secretion)
- Non-toxic
What is FF and how is it calculated?
Filtration Factor
- proportion of filtered plasma fluid that reaches the
afferent arteriole
- 0.15-0.2 (15-20% filtered)
- use PAH to measure - all removed from plasma
through kidney
FF = GFR / RPF
- GFR = glomerular filtration rate
- RPF = renal plasma flow
Which substance is used to calculate FF and why?
PAH = Para AminoHippurate
- all removed from plasma —> amount entering
kidney = amount excreted —> RPF = C
What are the 5 transport mechanisms used in renal tubules?
Passive:
1. Diffusion
2. Osmosis
3. Electrochemical gradient
Active:
4. Primary —> Na+/K+ ATPase pump
—> endocytosis
5. Secondary (coupled) —> symport eg. Na+/glucose
—> antiport eg. Na+/H+
What are the 2 transport pathways used in renal tubules?
- Transcellular —> across basolateral membrane
cells via transport proteins - Paracellular —> via tight junctions between
basolateral membrane cells