Genitourinary A&P (6) Flashcards
What are the parts of the urinary system
Kidneys - make urine
Ureters - transport urine to bladder
Bladder - store urine
Urethra - get rid of urine
What are the 10 functions of the kidneys
- Maintain Water balance
- Maintain osmolarity of body fluids
- Regulate quantity and amount of ECF ions (Na, K, Cl, H, Bicarbonate)
- Maintain plasma volume/blood pressure
- maintain acid base balancne (H and bicarbonate)
- excreating waste (urea, uric acid, creatine)
- Excrete foreign compounds
- produce erythropoietin
- produce renin
- convert vitamin D to active form
What is acute kidney failure
sudden loss of kidney function
What is cystitis
inflammation of bladder
What is Hematuria
blood in the urine
What is Hemodialysis
a method of clearing waste products from the blood
What is nocturia
night urination
what is polyuria
excessive urination
what is uremia
retention of urinary constituants in the blood
What is hydronephrosis
water in the kidney
what are the parts of the nephron
glomerulus glomerular capsule (bowmans) Proximal convoluted tubule Loop of henle Distal convoluted tubule collecting duct
What are the vascular components of the nephron
afferent arteriole (carries blood to glomerulus) glomerulus (filters protein free plasma to tubular component) efferent arteriole (carries blood from the glomerulus) pertibular capillaries (supply renal tissues, does exchanges with the tubular lumen)
What are the tubular components of the nephron
bowmans capsule (collects glomerular filtrate)
proximal tubule (uncontrolled reabsorption and secretion)
Loop of henle (establishes osmotic gradient in the renal medulla allowing for different concentrations of urine)
distal tubule and collecting duct (controlled reabsorption of Na+, H2O, and secretion of K and H)
What is the combined vascular/tubular component of the nephron
juxtaglomerular apparatus (produces substances involved in control of kidney function)
What is the glomerulus
a network of about 50 capillaries with an endothelial lining that has circular fenestrations (pores) that make it 100 to 1000 times more permeable than normal capillaries
What percent of blood passes through the glomerulus into the kidney tubule through bowmans capsule
20%
What is the structure of the glomerular capsule (bowmans)
its a double walled structure of squamous epithelium, the outer layer is continuous with the epithelium of the proximal tubule, the inner layer is composed of podocytes that are closely associated with the glomerular capillaries
What are the three layers that the filtrate must pass through in the glomerulus and capsule
- capillary endothelium (fenestrations)
- basement membrane (thick, with type IV collagen)
- podocytes (primary and secondary processes with a uniform width of 40 nm)
What does glomerular filtration prevent and permit
it prevents the passage of blood cells and most plasma proteins
it permits the movement of water, metabolic wastes, ions, glucose, fatty acids, amino acids, vitamins, and other solutes
What is the proximal convoluted tubule
the tubule that receives the filtrate from the glomerulus its epithelium is continuous with the glomerular capsule
and is asingle layer of cuboidal cells with microvili,
it also has many mitochondria for active transport
What are the parts of the nephron loop
descending and ascending thin limbs made of flat squamous cells without microvili
ascending thick limb made of cuboidal cells without microvili
Where does the distal convoluted tubule start
at the macula densa
What are the three major functions of the nephron
glomerular filtration (from capillaries to kidney tubule) tubular reabsorption (from tubule into blood) tubular secretion (from blood into tubule)
What is the “formula” for whats in urine
Urine = materials filtered - materials reasborbed + materials secreted
What is the glomerular filtrate, and how much is there per day
the portion of blood plasma the enters the glomerular capsule,
about 45 gallons per day
What are the mechanisms that cause fluid filtrate
high hydrostatic pressure of the blood in the glomerulus
and the large quantities of pores
what is found in the glomerular filtrate, and what isn’t passed in the filtrate
water, electrolytes and glucose is in the filtrate
plasma proteins, RBCs, WBCs, and platelets are too large to be filtered
What is the cutoff for size of particles in the filtrate
less than 60000 MW
what is filtrate
protein free plasma
What is the average BP in the glomerulus, and what is the average GFR
55 mm Hg = BP
120 ml/min = GFR
What affect does vasodilation and vasoconstriction have on GFR
vasodilation increases GFR (increased BP, increase Filtration pressure)
vasoconstriction decreases GFR (decreased BP, decreased filtration pressure)
what regulates GFR
extrinsic (sympathetic) and intrinsic (local chemicals) regulate GFR
How do you find GFR
you measure a substance that is freely filtered, but isn’t reabsorbed or secreted (INULIN)
What is the equation of GFR
Inulin conc in plasma
how do you find filtration fraction
GFR/Plasma flow rate = Filtration fraction
What is tubular reabsorption
the transfer of fluid and solutes out of the lumen into the interstitial space then into the peritubular capillaries
what percent of the filtrate is reabsorbed from the renal tubules
99%
Where does most of the tubular reabsorption occur
in the proximal convoluted tubule, but it does occur throughout
Where does passive tubular reabsorption occur, and what substances
PCT - H2O, Cl, Urea
DCT - H2O
Renal Tubule - Urea, H20
Where does active tubular reabsorption occur, and what substances
PCT - Glucose, Na, AA
loop of henle - Na, Cl
DCT - Na
How much of H2O, Na, and Urea are reabsorbed
99% of H2O, 99.5% of Na, and 50% urea
Of the 99.5% of Na reabsorbed, how much of it is reabsorbed in the PCT, Loop of Henle, and DCT
67% in the PCT (used for Glucose and AA reabsorption)
25% in loop of Henle (moves out with Cl-)
7% in the DCT (controlled by aldosterone)
how much of the glucose in the filtrate is reabsorbed
100% except for when the levels of glucose have exceeded their transport maximum (Tm), then any glucose above that is left in the urine
What is the Tm of glucose
375 mg/min (normal glucose concentration in plasma is 100 mg/ml of plasma)
how do you determine if glucose will be in the urine
take the concentration of glucose times it by the GFR, if it is above 375 mg/min then glucose will be in the urine
What is tubular secretion
movement of substances from the peritubular capillaries into the lumen of the kidney tubule
Where does active tubular secretion take place, and what substances move
PCT - H+ and penicillin
DCT - H+ and K+
What is acidosis
acidic blood plasma/high Co2 to HCO3 ratio (increased H+)
What is the kidneys response to acidosis
- increased CO2 enters the kidney tubule
- increased H+ enter the kidney tubule some combines to make HCO3. with each H+ that enters an Na leaves
- HCO3 and Na is reabsorbed, H+ is excreted
what is alkalosis
basic blood plasma, high HCO3 ratio
What is the kidneys response to alkalosis
- decreased CO2 enters the kidney tubule
- decreased H+ enters the kidney tubule, less H+ combines to form HCO3
- H+ is retained, HCO3 is excreted
What is the concentration of fluids in the kidney going from the cortex down deeper into the medulla
it is 300mosm/ liter in the cortex (average for the whole body) and it increases the deeper you go into the medulla
What are the mechanisms of urine concentrtation regulation
- Cl- is actively transported out of the ascending limb (Na goes with it)
- Ascending limb is impermeable to water, causing the urine to become more dilute
- urea diffuses out of the collecting duct
- ADH causes the distal tubule and collecting duct to become permeable to water, which causes the water to leave, concentrating the urine, and decreasing urine amount
What is a plasma clearance analysis used for
it is a test to determine the ability of the kidneys to “clear” the plasma of substances for a certain length of time. It tests if the kidneys are working right
how is the plasma clearance found
the amount of urine formed times the concentration of a substance in the urine all over the concentration of the substance in the blood still
what are the clearance rates of inulin and glucose
glucose should have a 0 clearance rate as long as the concentration isn’t above the Tm. Inulin’s clearance rate will equal the GFR
What is the function of the Juxtaglomerular apparatus
to produce renin
What causes the juxtaglomerular apparatus to release renin
low BP or blood volume, as well as high NaCl conc. This is sensed by the macula densaw
what is the macula Densa
it marks the start of the DCT, and is a group of tall, densley packed cells, that sense blood osmotic pressure
What are the Renin-secretin juxtaglomerular cells (J)
modified smooth muscle cells with mechanoreceptors
What are the 7 steps of renal function
- Glomerulus (filtrate = plasma - protein)
- PCT (permeable, water flow out)
- PCT and Descending limb (high conc. H2O reabsorp.)
- Thick ascending limb (NaCl out, low conc.)
- DCT and collecting ducts
- ADH at DCT and collecting ducts
- Vasa Recta (maintains concentration gradient)
What are the steps of micturition
- bladder fills
- stretch receptors send impulses to sacral spinal cord
- sensory neurons send impulse to brain
- PNS stimulates detrusor and internal urethral sphincter
- detrusor contracts, internal urethral sphincter relaxes
- need to urinate intensifies
- voluntary contraction of external urethral spincter, (relaxation = peeing)
- detrusor contracts and pushes urine through the urethra
What is the response of the juxtaglomerular apparatus to high NaCl
it secretes adenosine, which is a vasoconstrictor to the afferent arteriole, causing decreased GFR