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Flashcards in Urinary Deck (46)
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organs of urinary system:

- 2 kidneys
- 2 ureters = carry urine from kidneys to bladder
- 1 bladder
- 1 urethra = carries urine from bladder to the outside of the body


1. kidneys are located:

behind the peritoneal membrane, near the lateral posts muscle


2. renal capsule

layer of adipose/fibrous connective tissue; cushions the kidneys against mechanical shock


3. parietal fat pad (adipose)

engulfs renal capsule acts as cushioning


4. renal fascia

thin connective tissue surrounds the adipose tissue and help anchor the kidneys to abdominal wall.


urine flow path

1. minor calyces
2. major calyces
3. renal pelvis
4. ureters
5. urinary bladder
6. urethra


afferent / efferent

affarent = sensory neurons that carry nerve impulses from sensory stimuli towards the central nervous system
efferent = motor neurons that carry neural impulse away from the central nervous system and towards muscle to cause movement


muscle in afferent and efferent arterioles

smooth muscle


external urinary sphinkter:

controls flow of urine through urethra


effect of ADH

- increase kidney reabsorption
- increase in number of aquaporins=membrane protein transfer water
- decrease in blood osmolarity


renal fraction

potion of total cardiac output flows through the kidneys


Function of Kidney

1. excretion
2. regulation of blood volume
3. regulation of the concentration of solutes in the blood: Na+, Cl-, K+, Ca2+, HCO3-, HPO4 2-
4. regulation of extracellular fluid pH = secrete variable amount of H+
5. regulation of red blood cell synthesis = secrete hormone erythropoietin which stimulate RBC in red bone marrow
6. regulation of vitamin D synthesis



Regulate concentration of water and substances (Na) by filtering blood, reabsorbing what is needed, excreting the rest as urine

consists of 4:
- renal corpuscle
- proximal convoluted tubule
- loop of Henle (nephron loop)
- distal convoluted tubule


major ions regulated by kidney:

- chloride Cl+
- bicarbonate HCO3-
- phosphate PO
- sodium Na+


renal pelvis

- major calyces converge to form enlarged chamber
- surrounded by renal sinus



locate in pelvic cavity posterior to the symphysis pubis
Store urine and drain into urethra


1. positively charged ions -
2. proteins less than 7nm -
3. most blood cells

1.pass freely into filtrate (dissolved ions)
2. small amounts may enter the filtrate but will ultimately be reabsorbed
3. cannot pass into filtrate


impermeable to filtration barrier:

- proteins
- blood cells


ADH on nephron water movement

1. ADH bind to its receptor
2. G-protein activates adenylate cyclase
3. aquaporin-2 containing vesicle
4. Cyclic AMP increase aquaporin-2 to increase permeability of the membrane to H2O
5. water exits the tubule cells and enters interstitial fluid through aquaporin-3 and aquaporin-4water channel in the basal mambranes


How ADH works

- stimulates water reabsorption stimulating insertion of “water channels” = aquaporins into membrane of kidney tubules
- these channels transport solute-free water through tubular cells and back into blood, leading to decrease in plasma osmolarity and increase osmolarity of urine
- leads vasoconstriction to increase arterial


hormones involved in urine concentration:

- Renin
- Aldosterone


Glomerulus (Bowman’s capsule)

- Parietal layer: simple squamous epithelium
- visceral layer: podocytes wrap around glomerular capillaries
- hydrostatic pressure = 10mmHg


glomerular filtration

blood pressure forces through the glomerular capitally walls into the glomerular capsule


glomerular capillary pressure (GCP)

- outward pressure from blood pressing capillary walls (BP)
- forces fluid and solutes out of the blood into Bowman’s capsule
- higher than other capillaries of body because efferent arteriole diameter is smaller


capsular hydrostatic pressure (CHP)

- inward pressure from the pressure of filtrate accumulation in Bowman capsule
- filtrate pressing on the walls of Bowman capsule creates CHP = 10mmHG


micturition reflex

1. urine stretches wall of the urinary bladder
2. action potentials transmitted from stretch receptors along pelvic nerves to the sacral region of the spinal cord
3. action potential transmitted from the spinal cord to the urinary bladder by pelvic nerves
4. contraction of detrusor muscle of the urinary bladder


blood colloid osmotic pressure (BCOP)
P.958see picture

- inward pressure due to the osmotic force of plasma proteins within the glomerular capillaries
- BCOP is greater at the end of glomerular capillary, because as fluid leaves capillary and enters Bowman capsule there is a higher protein concentration in th glomerular capillary = 30mmHg


ADH in order:

1. blood pressure greatly increases
2. ADH secretion is inhibited
3. reabsorption of water in kidney tubules is decreased
4. urine volume is increased
5. blood pressure and extracellular fluid volume is decreased


2 pressure in the glomerulus is determined by:

- colloid osmotic = plasma protein tends to pull water into the blood (opposite force to hydrostatic pressure)
- blood hydrostatic



- visceral layer of glomerular capsule
- contain negatively charged glycoproteins = repel negatively charged plasma proteins to prevent them from exiting the blood