urinary system

what are the functions of the kidneys

filter blood and excrete toxic metabolic waste

blood volume, pressure, osmolarity

secrete erythropoietin, reg electrolytes and acid base

regulate calcitrol synthesis and synthesize glucose

waste

any substance that is useless to the body or present in excess of the bodys needs

metabolic waste

waste substance produced by the body

urea formation

proteins - amino acids - NH2 removed - forms ammonia

*liver converts ammonia to urea

uric acid

product of nucleic acid catabolism

creatinine

product of creatine phosphate catabolism

blood urea nitrogen (BUN)

level of nitrogenous waste in blood

normal concentration is 10 to 20 mg/dL

uremia

toxicity of nitrogenous waste

syndrome of diarrhea, vomiting, dyspnea, cardiac arrhythmia

how do you treat uremia

hemodialysis or organ transplant

excretion

separating wastes from body fluids and eliminating them

how does the respiratory system carry out excretion

co2, small amounts of other gases, and water

how does the integumentary system carry out excretion

water, inorganic salts, lactic acid, urea in sweat

how does the digestive system carry out excretion

water, salts, co2, lipids, bile pigments, cholesterol, metabolic wastes

how does the urinary system carry out excretion

metabolic wastes, toxins, drugs, hormones, salts, H, water

how are the kidneys oriented in the body

posterior abdominal wall

which kidney is lower and why

right because of the liver

what is all in the retroperitoneal cavity

kidneys, ureters, urinary bladder, renal artery, renal vein, adrenal glands

what is the shape of the kidney

size of a bar of soap, lateral surface is convex and medial is concave

what is the hilum and what does it do

renal nerves, blood vessels, lymphatics, and ureter

renal fascia

binds kidney to abdominal wall

perirenal fat capsule

cushions kidney and holds it in place

fibrous capsule

protects from trauma and infection

*collagen fibers

renal parenchyma

glandular tissue that forms urine

encircles renal sinus, in middle

renal sinus

urine collecting structures

*adipose fills remaining cavity and holds structures in place

what is in the inner renal medulla

renal columns and renal pyramids

renal columns

extensions of the cortex that project inward toward sinus

renal pyramids

broad base facing cortex and renal papilla facing sinus

lobe of kidney

one pyramid and its overlaying cortex

minor calyx

collects urine of each pyramid

major calyx

formed by convergence of 2 or 3 minor calyx

renal pelvis

formed by convergence of 2 or 3 major calyx

ureter

tubular continuation of pelvis that drains urine down to urinary bladder

what are the parts of the renal artery

interlobar arteries, arcuate arteries, cortical radiate arteries

interlobar arteries

up renal columns, between pyramids

arcuate arteries

over pyramids

cortical radiate arteries

up cortex

how is blood drained from the glomerulus

efferent arterioles, then to peritubular capillaries

order from heart

aorta - renal artery - segmental artery - interlobar artery - arcuate artery - cortical radiate artery - afferent arteriole - glomerulus

order to heart

glomerulus - efferent arteriole - peritubular capillaries - cortical radiate vein - arcuate vein - interlobar vein - renal vein - inferior vena cava

* can use vasa recta to spread out blood

what happens in the cortex with blood

convoluted peritubular capillaries branch off efferent arterioles supplying tissue, proximal and distal ules

what happens in the medulla with blood

efferent arterioles give rise to vasa recta supplying nephron loop with blood

what is the urogenital system

shared embryonic development and adult anatomical relationship of the urinary system and reproductive/genital system

renal corpuscle

filters the blood plasma

renal tubule

long, coiled tube that coverts the filtrate into urine

what is the renal corpuscle has two glomerular layers

parietal - simple squamous epithelium

visceral - podocytes that wrap around capillaries

vascular pole

side of the corpuscle where the afferent arterial enters the corpuscle and the efferent arteriole leaves

urinary pole

the opposite side of the corpuscle where the renal tubule begins

renal tubule

duct leading away from the glomerular capsule and ending at the tip of the medullary pyramid

proximal convoluted tubule

longest and most coiled region

simple cuboidal epitehlium with microvilli for absorption

nephron loop

descending limb and ascending limb

thick segment of nephron loop

initial part of descending limb and majority of ascending limb

*active transport of salts and lots of mitochondria

thin segment of nephron loop

simple squamous epithelium

lower part of descending limb, very permeable to water

distal convoluted tubule

begins shortly after ascending limb, shorter and less coiled

cuboidal epithelium, end of a nephron

collecting duct

receives fluid from several nephrons

papillary duct

formed by merger of several collecting ducts

renal papilla

multiple papillary ducts merging

what is the renal tubule pathway

glomerular capsule - proximal convoluted tubule - nephron loop - distal convoluted tubule - collecting duct - papillary duct - minor calyx - major calyx - renal pelvis - ureter - urinary bladder - urethra

glomerular filtration

capillary fluid exchange where water solutes from blood plasma pass from capillaries of glomerulus into the capsular space

fenestrated endothelium

filtration pores, highly permeable

basement membrane

proteoglycan gel, negative charge, excludes big molecules

*albumin repelled by negative charge

filtration slits

podocyte cell wrap around capillaries to form a barrier layer

negatively charged

what small molecules can pass freely through filtration membrane

water, electrolytes, glucose, fatty acids, amino acids, nitrogenous waste, ATP, vitamins

what low molecular weight are bound to plasma proteins and cannot pass the filtration membrane

calcium, iron, thyroid hormone

proteinuria

presence of protein in the urine

hematuria

presence of blood in the urine

why would we maybe see proteinuria or hematuria

prolonged strenuous exercise

glomerulus deteriorates under prolonged hypoxia

blood hydrostatic pressure

pushes across membrane from blood stream

afferent arterioles are larger than efferent arterioles

hydrostatic pressure in capsular space

produces little push back from filtrate pressure in capsule

colloid osmotic pressure of blood

pulls across membrane

what capillary is most susceptible to high blood pressure

glomerulus capillaries

what causes renal failure

nephrosclerosis, atherosclerosis

glomerular filtration rate

amount of filtrate formed per minute by the two kidneys combined

GFR = NFP x Kf

what is the average glomerular filtration rate for males and females

male = 180 L/day

female = 150 L/day

what percentage of filtrate is reabsorbed

99%

what happens if glomerular filtration rate is too high

fluid is too rapid for reabsorption

urine output rises

dehydration and electrolyte depletion

what happens if glomerular filtration rate is too low

wastes are reabsorbed

azotemia = build up of nitrogenous products

renal autoregulation

adjust own blood flow and glomerular filtration rate without external control

what are the two methods to autoregulate

myogenic mechanism and tubuloglomerular feedback

myogenic mechanism

smooth muscle contracts when stretched

what happens when arterial blood pressure increases

arteriole is stretched

arteriole constricts and prevents blood flow into the glomerulus

what happens when arterial blood pressure decreases

arteriole relaxes

arteriole dilates and allows blood to flow more easily into glomerulus

tubuloglomerular feedback

regulates filtrate composition, stabilizes kidney performance, compensates for fluctuations in blood pressure

macula densa

slender, closely spaced sensory cells in nephron loop

what do macula densa cells do during high blood pressure

GFR is high and filtrate contains more NaCl

macula densa absorbs more NaCl and secretes ATP

ATP metabolized into adenosine

adenosine stimulates granular cells

granular cells

smooth muscle cells

respond to adenosine by constricting afferent arterioles - reduces blood flow

renin

participates int the RAAs that controls blood volume and pressure

what is the full tubuloglomerular feedback loop

high GFR

increased NaCl

macula densa secretes ATP, mesangial cells metabolize ATP to adenosine

adenosine stimulates granular cells

afferent arterioles constrict and reduces GFR

what happens when the sympathetic nervous system and adrenal epinephrine constrict

reduces GFR and urine output

redirects blood to heart, brain, skeletal muscles

what is the point of the RAAs

upregulate blood pressure

what is the general process for the RAA system

decrease in BP, kidneys secrete renin into blood stream, meets angiotensinogen, becomes angiotension I, meets angiotension converting enzyme from lung, becomes angiotension II

what are the three main outcomes from angiotension II

hypothalamus stimulation = thirst response

cardiovascular = vascocontriction to reduce volume and increase bp

adrenal cortex = secretes aldosterone to absorb NaCl

what does an ACE inhibitor do

decreases blood pressure by blocking angiotension converting enzyme

*high blood pressure medication

what does the posterior pituitary gland do

stimulated by angiotension II to secrete ADH to promote water reabsorption by collecting ducts

when does glomerular filtration become urine

when it leaves the collecting ducts

what is important about the proximal convoluted tubules when reabsorbing

absorbs 65% of glomerular filtrate

prominent microvilli and in long, abundant ATP

tubular reabsorption

process of reclaiming water and solutes from tubular fluid and returning them to blood

what is special about proximal convoluted tubules

accounts for 6% of resting ATP and calorie consumption

transcellular route

pass through cytoplasm of proximal convoluted tubule epithelial cells and out their base

paracelluar route

between proximal convoluted tubule cells

sodium

creates osmotic and electrical gradient

most abundant cation in filtrate

favors its diffusion into epithelial cells