KAAP310 - Exam 3 - Set #2 (urinary system)

organs of the urinary system

2 kidneys, 2 ureters, urinary bladder, urethra

function of ureters

pass urine from the kidney to the bladder

function of the urinary bladder

store urine

function of urethra

connects bladder to exterior and expels urine

primary function of the kidneys

filter blood and excretion

other functions of the kidney

regulate water output, electrolyte balance, secrete erythropoietin, vitamin D synthesis, clear hormones and drugs, detoxify free radicals, gluconeogenesis

what do the kidneys filter

nitrogenous wastes

what is waste

any substance that is useless to the body or in excess to the body's needs

what is metabolic waste

waste made in the body

what form are metabolic wastes mostly in

nitrogenous wastes

nitrogenous wastes are

highly toxic

1/2 of the waste forms urea and is measured by

blood urea nitrogen (BUN)

azotemia

high BUN and is related to a decease in renal function where urea is not being filtered out

byproduct of urea cycle in protein breakdown

urea

what happens with ammonia

highly toxic and gets converted immediately to less toxic urea

uric acid

breakdown of nucleic acids

creatinine

breakdown of creatine phosphate

excretion definiton

process of separating waste from the body fluids and eliminating them from the body

4 organ systems involved in excretion

respiratory, integumentary, digestive, urinary

what is excreted in the respiratory system

CO2 and H2O

what is excreted in the integumentary system

sweat (H2O, salts, urea, lactate)

what is excreted in the digestive system

H2O, salts, CO2, lipids, cholesterol, bile pigments, metabolic wastes

what is excreted in the urinary system

metabolic wastes, toxins, drugs, hormones, salts, H20, H+

3 layers that protect the kidney (outermost to inner)

fibrous renal fascia, perirenal fat capsule, fibrous capsule

fibrous renal fascia

attaches to other organs, helps hold kidneys in place

perirenal fat capsule

provides cushioning (adipose tissue)

fibrous capsule

enclose kidney to protect from trauma and infection

look at slide 53 for where parts of the kidney are

renal cortex

contains parenchyma where nephrons are found

renal medulla

separated into pyramids and contains part of the nephron where urine goes to be collected

minor calyx

collect urine from associated pyramid

major calyx

where 2-3 minors converge to dump into sinus that goes to ureter

renal column

between pyramids, separates medulla into 6-10 pyramids

cortical radiate artery

90 degree angle to arcuate artery, permeate through cortex and branch

interlobar artery

segmental arteries separate, go through renal columns

segmental artery

move blood from renal artery to interlobar artery

arcuate artery and vein

wrap around wide portion of pyramids

renal circulation steps

nephron

functional unit of kidney

step 1 of renal circulation

afferent arteriole into glomerulus

step 2 of renal circulation

whole blood is filtered at the glomerulus

step 3 of renal circulation

filtered blood comes out of the efferent arteriole

step 4 of renal circulation

blood moves towards the renal tubule and forms capillary bed

step 5 of renal circulation

peritubular capillaries around renal tubule moves filtrate back into blood to return reabsorbed filtrate items to blood

efferent arteriole becomes

vasa recta

where most blood flow goes

into the cortex where the parenchyma are

percentage of blood that goes to the medulla

1-2% because the vasa recta are very small

what makes up the corticomedullary junction

arcuate artery and vein

type of nephron that is 85% of nephrons

cortical nephron

juxtamedullary nephron

15%, next to medulla and is responsible for maintaining osmotic gradient of medulla to conserve water

nephron make up

renal corpuscle and renal tubule

renal corpuscle

glomerulus surrounded by capsule

why the afferent arteriole is larger

more blood enters then leaving

parietal layer of glomerular capsule

outside layer, simple squamous

visceral layer of glomerular capsule

inner layer

Podocytes of visceral layer

wrap around arteries and filter the blood that runs through them and retain large molecules (ex. proteins)

urinary pole

filtrate foes to renal tubule to eventually become urine

mesangial cells

pack space around glomerular capillaries and support capillaries to help maintain blood flow and clean

mesangial cells are similar to

macrophages

4 regions of the renal tubule

PCT, Nephron loop, DCT, collecting duct

each nephron will have their own

PCT, nephron loop, and DCT

multiple nephrons share

collecting ducts

Proximal Convoluted Tubule (PCT)

Aries from renal corpuscle, most coiled, simple cuboidal with brush border

what is the PCT good at

reabsorption due to increased surface area

where the nephron loop is mostly found

medulla

thick segments of nephron loop location

1st part of descending limb and most of ascending limb,

thick segments nephron loop purpose

used for active transport of salts and has a high metabolic activity due to lots of mitochondria

thin segments of nephron loop location

ladder portion of descending limb made of simple squamous

thin segments of nephron loop purpose

have low metabolic activity which is highly permeable to water and good for water reabsorption

distal convoluted tubule (DCT)

less coiled, re enters cortex, no microvilli, passageway that moves filtrate to collecting duct

collecting duct make up

from multiple nephrons, numerous ducts converge at tip of papilla, drain into minor calyx, simple cuboidal

renal plexus defined

receives sympathies innervation from superior mesenteric and celiac ganglions

what the renal plexus does

decrease urine production and glomerular blood flow and stimulus release of renin to increase blood pressure

parasympathetic input from vagus nerve

no known function

4 stages from blood to urine

glomerular filtration, tubular reabsorption, tubular secretion, water conservation

what happens in glomerular filtration

create a plasma like filtrate in the blood that goes into the nephron

purpose of barriers in glomerular filtration membrane

prevents all protein from leaving the blood and small molecules get filtered out

fenestrated endothelia of capillary (barrier 1)

has large filtration pores that are highly permeable to small molecules

basement membrane (barrier 2)

made of proteoglycan gel that excludes molecules larger than 8nm

charge of basement membrane and what that does

negatively charged, repels anions that have a negative charge even if they are under 8nm

filtration slits (barrier 3)

within pedicles of podocytes and are negatively charged

size of molecules that can pass freely in glomerular filtration

less than 3nm

protein percentage in plasma

7%

protein percentage in filtrate

0.03%

proteinuria/albuminuria/hematuria

protein (typically albumin) in the urine, sign of kidney dysfunction

blood hydrostatic pressure in glomerulus

extremely high - 60mmHg out

colloid osmotic pressure in glomerulus

-32 mmHg in

capsular pressure in glomerulus

-18 mmHg in

net flitration pressyre in glomerulus

10 mmHg out

percentage of filtrate reabsorbed

99%

urine produced daily

1-2 L/day

why can't you rid of all filtrate

you would be in the bathroom all day

glomerular filtration rate equation

GFR = NFP x Kf

how to adjust glomerular filtration rate

change the glomerular blood pressure

3 mechanisms for changing glomerular filtration rate

renal auto regulation, sympathetic control, hormonal control

renal auto regulation

nephrons adjust own blood flow without external input

myogenic mechanism

glomerulus receives feedback on status of downstream fluid and rely on juxtaglomerular apparatus

what is the glomerular apparatus

next to the glomerulus at the very end of nephron loop as it re enters the cortex affecting the afferent arteriole

how renal auto regulation starts

cells of macula dense

tubuloglomerular feedback

glomerulus receives feedback on the status of downstream tubular fluid and adjusts filtration rate accordingly