Urinary system

Kidneys

Major excretory organs that maintain internal environment

How do kidneys maintain internal enviornent

Regulation H20 volume and solute concentrations

regulate ion concentrations in ECF,

acid-base balance,

excreting metabolic wastes,

produce erythropeitin and renin

How much o2 do the kidneys use at rest

20-25%

how many times a day do kidneys filter entire plasma vol

60

filtrate

blood plasma minus proteins <1% urine

medial renal hilum

marks where vasculature nerves and urinary tract enter/exit kidneys

Ureters(ext kidney)

urine from kidney to bladder

urinary bladder(ext kidney)

temporary storage for urine

urethra(ext kidney)

carries urine out body

cardiac output

renal arteries deliver 25% CO to kidneys every min

what kidney sits lower due to liver

right

because kidney’s are protected by inferior ribs they are prone to

damage from blunt trauma(esp. right)

3 distinct regions of internal kidneys

renal cortex, renal medulla, renal pelvis

Renal cortex

superficial region

renal medulla

deep to cortex composed of cone-shaped renal pyramids

renal pelvis

continuous with ureter

structures in renal pelvis

minor calyces, major calyces

minor calyces

cup shaped, collect urine from pyramids

major calyces

collect from minor calyces and empty into renal pelvis

pyelonephritis

infection or inflammation of entire kidney(fecal bacteria into urinary tract)

what causes pyelonephritis

untreated UTI

symptoms of pyelonephritis

fever, back pain, chills, painful urination, bloody(hematuria) or cloudy urine

servere pyelonephritis

cause kidney to swell, abscess formation, pus may fill renal pelvis

nephron

structural and functional units responsible for urine formation( actual filtration unit)

how may nephron

more 1 million

cortical nephrons

entirely inside renal cortex space, 85% of nephrons

juxtamedullary nephrons

long, nephron loops of tubule network extend deep into renal medulla, important for formation of concentrated urine

Nephron structure

Renal corpuscle, renal tubule

What does the renal corpuscle consist of

Glomerulus, Glomerular capsule, afferent arteriole, efferent arteriole

Renal corpuscle process( what you cannot lose)

blood enters glomerulus through afferent arteriole, filtration begins, filtrate collects in glomerular capsule, blood exits glomerulus through effect arteriole to capillaries, filtrate goes to proximal convoluted tubule(PCT)

Renal tubule proximal convoluted tubule( could keep or lose(selective))

Gets filtrate from renal corpuscle

Renal tubule nephron loop

continue with PCT, perm with H20

renal tubule distal convoluted tubule

drains filtrate into collecting duct goes into renal medulla

Renal tubule peritubular capillaries

low pressure pours capillaries adept at h20 and solute absorption

juxtaglomerular apparatus

regulates rate of filtrate formation and blood pressure( each nephron has 1)

JGA made of of modified prtions of:

Distal convoluted tubule: refeeds afferent arteriole and glomerulus, contains macula densa Afferent arteriole renal corpuscle: contains granular cells, recpeptor monitor BP, contain and secrete renin triggering mechanism Extraglomerular mesangial cells: allow for communication between macula densa and granular cells

Glomerular filtration

1st step of urine formation and blood composition adjustment

Glomerular filtration process

passive, hydrostatic(pushing) pressure forces fluids and solutes through membrane into capsular space

What can pass glomerular filtration

h20, glucose, amino acids, and nitrogenous wastes

What can NOT pass glomerular filtration

Cells and proteins( exit glomerulus through efferent arteriole, peritublar capillaries, circulation)

Glomerular filtration rate(GFR)

vol. of filtrate formed per min by both kidneys( Normal=120-125 mL/min)

GFR is directly proportional to:

Net filtration pressure: change diameter of afferent arterioles, Total SA available for filtration: Glomerular cap. have huge SA, Filtration permeability membrane: Glom. cap. much more permeable that other capillaries

How is GFR measured

Renal clearence

Renal clearance

Vol. of plasma the kidneys can clear of a particular substance in a given time

Chronic renal disease

GFR<60 mL/min for 3 mos

Renal failure

GFR <15 mL/min

Tubular reabsorption

reclamation of contents from filtrate into particular capillaries, mostly organic nurtrients, h20 and ion reabsorption hormonally regulated

Tubular secretion

contents form peritubular capillaries are added to filtrate into tubules, important for waste disposal

Transport maximum

limit how much of a substance can be reabsorbed

Where does tubular reasoption and secretion mainly occur

PCTA

Atrial natriuretic peptide

increase Na secretion, results in decreased blood volume and BP

Parathyroid hormone

Increase Ca reapportion at DCT

Antidiuretic hormone

Increase water reabsorption at DCT and collecting duct

Renin-angiotensisn-aldosterone mechanism

main mechanism for increasing BP

Stimulates increased ion reabsorption for increased BV and BP

Renin mechanism steps

Renin secretion from kidney and angiotensinogen from liver

make angiotensin 1

ACE from lungs coverts ^ to angiotensin II

What does angiotensin II stimulate the release of

ADH= increased BV and BP

aldosterone release=Na reabsorption K secretion

Loop of Henle

Descending limb and ascending limb

water and solute reabsorption are not coupled

critical role in regulating urine concentration

Descending limb(loop)

Water CAN be reabsorbed (many aquaporins)

Solute CANNOT be reabsorbed

Ascending limb(loop)

Water CANNOT be reabsorbed (few aquaporins)

Solute CAN be reabsorbed

Urine make up

95% h20 5% solute

Solutes

nitrogenous wastes

Urea(solute)

from amino acid breakdown

most prevalent

Uric acid(solute)

from nucleic acid metabolism

Creatinine(solute)

metabolite from phosphocreatine breakdown

Excess or abnormal solutes=

diagnostically significant

Urine concentration

kidneys need to adjust urine concentration and volumes to maintain body fluids’ osmotic concentrations

Anuria

abnormally low urine output(<50mL day)

may indicate glomerular BP is too low for filtration

may arise from lack of nephron function(renal failure)

Diuretics

chemicals enhancing urine output

ADH inhibitors

Na reabsorption inhibitors

Osmotic diuretics: substances that don’t get reabsorbed

Urinalysis

examination of urine for signs of disease

Diabetes mellitus urine smell

acetone

urine pH

slightly acidic (4.5-8.0)

specific gravity

ratio of mass solute to mass of equal volume water (urine>water due to solutes)

used to assess hydration

passage of urine

ureters

urinary bladder

urethra

urinary bladder

storage vessel

collapses when empty

lined with rugae

male capacity> women

Internal urethral sphincter

bladder urethra junction

involuntary