urinary system

components of urinary system

kidneys, ureters, urinary bladder, urethra\####urine travels from \___ to \____ by the \___ and then excreted through the \___

bladder

ureters

urethra\####urine contains

metabolic wastes\####kidneys are the main functional components for

-regulates Na, Ca, K, Cl and phosphates\####how do the kidneys regulate blood ph?

excrete hydrogen ions and conserve bicarbonate ions\####how do the kidneys regulate blood volume?

-secrete renin; activates RAAS

-increased renin causes increased blood pressure\####how do kidneys maintain blood osmolarity?

separately regulating loss of water and loss of solutes in urine\####osmolarity

erythropoietin- stimulates production of RBCs\####how do the kidneys regulate blood glucose level?

gluconeogenesis -uses amino acid glutamine\####what do the kidneys do to excrete wastes?

reddish in colour

kidney bean shaped\####Why is the right kidney lower than the left?

because of the liver\####how is the kidney protected?

adipose capsule

renal fascia\####renal capsule

transparent membrane maintains organ shape

-continuous with ureter and serves as a barrier for protection\####adipose capsule

helps protect from trauma\####renal fascia

-renal papilla\####renal papilla

points toward center of kidneys\####drainage system fills

ureter\####the kidney is abundantely supplied with \___

blood vessels

-20-25% of cardiac output

-normal adult average: ~1 L /min\####blood enters the kidney through \___ and leaves via \____

renal artery

renal vein\####3 capillary beds of kidney

glomerular capillaries

peritubular capillaries

vasa recta\####glomerular capillaries

where filtration of blood occurs

-between afferent and efferent arterioles\####peritubular capillaries supply the

cortex\####vasa recta supply the

-chemical exchange with tissue (O2/CO2)

-resorption\####nerves that supply the kidneys

renal nerves

-vasomotor\####blood flow through the kidneys

renal artery

cortical radiate arteries

afferent arterioles

glomerular capillaries

efferent arterioles

peritubular capillaries/ vasa recta

cortical radiate vein

renal vein\####nephron

functional unit of the kidney

-over 1 million per kidney -\> 145km\####nephrons are present at birth and

grow with age

- no more formed

-terminally differentiated\####3 functions of nephron

filtration, reabsorption, secretion\####nephron made of 2 parts

tubule\####renal corpuscle

glomerulus and bowman's capsule

-filters blood

-site of plasma filtration\####renal tubule

space into which the filtrate passes\####glomerulus

PCT

desc loop

asc loop

DCT

distal collecting tubule

collecting duct

papillary duct

minor calyx

major calyx

renal pelvis

ureter

bladder\####2 types of nephrons

cortical and juxtamedullary\####cortical nephrons

-renal corpuscle in outer portion of cortex

-short loops of henle extend only into outer region of medulla

-receive blood from peritubular capillaries (cause they supply the cortex)

-create urine with osmolarity similar to blood\####juxtamedullary nephrons

Renal corpuscle deep in cortex with long nephron loops

Receive blood from peritubular capillaries and vasa recta

Ascending limb has thick and thin regions

Enable kidney to secrete very concentrated urine\####blood from glomerular capillaries is filtered into

glomerular capsule\####what gives rise to peritubular capillaries and vasa recta?

-visceral layer:

-parietal layer:

v: modified simple squamous epithelial cells-podocytes

p:simple squamous epi- forms outer wall of capsule\####capsular space

separates the two layers of Bowman capsule

-continuous with PCT\####podocytes

its processes (pedicels) wrap around the capillaries of the glomerulus

-leaky barrier\####renal tubule and collecting duct histology

single layer of epi cells forms entire tube\####function of microvilli in PCT

aldosterone

principal cels of DCT and CD\####where does the ascending loop contact the afferent arteriole?

macula densa\####juxtaglomerular cells

where? what?

wall of afferent arteriole

-smooth muscle cells\####juxtaglomerular apparatus

regulates BP in the kidney in conjunction with the ANS\####How does the juxtaglomerular apparatus regulate BP?

99% reabsorbed into blood\####how much of the filtrate is secreted as urine?

~1-2 L\####filtration

-regulated by mesengial cells

2. filtration membrane thin and porous

3. glomerular pressure is high (hydrostatic pressure)\####what is the filtering unit of a nephron?

endothelial-capsular membrane\####what does the endothelial-capsular membrane permit?

basal lamina

filtration slit formed by podocyte\####glomerular endothelial cells are leaky because

they have fenestrations-

permits solutes in blood plasma to exit capillaries

prevents filtration of blood cells and platelets\####mesengial cells

contractile cells which increase glomerular filtration when relaxed

-located among glomerular capillaries and in cleft between afferent and efferent arterioles.\####basal lamina

layer of acellular material between endothelial cells and podocytes

-collagen fibers and proteoglycans in glycoprotein matrix\####what does the basal lamina prevent?

prevents filtration of larger protein molecules\####filtration slit formed by podocyte

-slit membrane\####where are the filtration slits?

spaces between the pedicels\####slit membrane

-1 promotes

2 oppose\####Net filtration pressure

total of all pressure\####Glomerular blood hydrostatic pressure (GBHP)

the BP in the glomerular capillaries\####what does the Glomerular blood hydrostatic pressure (GBHP) do?

PROMOTES filtration by pushing water and solutes out of capillaries through filtration membrane\####Capsular hydrostatic pressure (CHP)

~15mmHg\####Blood colloid osmotic pressure (BCOP)

due to presence of proteins in blood plasma

-albumins, globulins, fibrinogen\####what does Blood colloid osmotic pressure (BCOP) do?

OPPOSES filtration

-tends to pull fluid back into blood

~30mmHg\####What is net filtration pressure?

NFP\= GBHP - (CHP + BCOP)

55-(15+30)\=10 mmHg\####what will happen to the net filtration pressure when one of the ureters is obstructed by a tumor?

If you cannot drain fluid, CHP will increase eliminating NFP. Blocks capability of filtration

-\>might get poisoning since you can't get rid of metabolic wastes\####Glomerular filtration rate (GFR)

amount of filtrate formed in all the renal corpuscles of both kidneys each minute

-average: 105-125 mL/min\####Homeostasis requires fairly constant __

GFR\####If GFR is too high

-change the amount of surface area available for filtration\####GFR increases when blood flow into glomerular capillaries \___

increases\####3 mechanisms for controlling blood flow through glomeruli

-myogenic mechanism

-tubuloglomerular feedback

2. hormonal regulation (kidneys)

3. neural (autonomic) regulation (sympathetic)\####kidneys have 2 \___ mechanisms that maintain a constant GFR despite changes in arterial BP

negative feedback\####myogenic mechanism

-reduces the diameter of arteriole -\> decrease in GFR in seconds

-CAN WORK OTHER WAY (for low BP)\####myogenic mechanism: relaxation of smooth muscle occurs with \_______ arterial blood pressure thereby increasing \____

decreased

renal blood flow\####tubuloglomerular feedback

with elevated systemic BP -\> raised GFR

fluid flows more rapidly through PCT and Loop

-Na,Cl,H20 not properly reabsorbed

-macula densa cells detect excess ^

-cells inhibit release of nitric oxide from juxtaglomerular apparatus\####faster: myogenic or tubuloglomerular?

myogenic\####tubuloglomerular feedback: what does inhibiting nitric oxide do?

-decreased level of it constricts afferent arteriole constricting blood flow into glomerular capillaries

-\> reduces GFR