Class 9- Urinary System

200 liters

amount of blood the kidney filters daily

kidney

filters blood to allow toxins, metabolic wastes, and excess ions to leave the body in urine

kidney

regulates volume and chemical makeup of blood

kidney

maintains ionic, salt, and acid-base balance

gluconeogenesis

formation of glucose from noncarbohydrate sources

kidney

carries out gluconeogenesis (makes glucose) during prolonged fasting

renin, erythropoietin

hormones produced by the kidney

vitamin D

vitamin that the kidney activates

cortical, juxtamedullary

2 types of nephrons

85%

percent of nephrons that are cortical

juxtamedullary

type of nephrons that have long loops of Henle that deeply invade the medulla and are involved in the production of concentrated urine; glomerulus is closer to the corticomedullary junction

nephron

part of the kidney responsible for filtration

renal cortex

where in the kidney nephrons are located

100 million

number of nephrons found in each kidney

parietal

layer of the glomerulus made up of squamous cells

visceral

layer of the glomerulus with a 3-layered filter (fenestrated endothelium, basement membrane, podocyte)

PCT

part of the nephron with many microvilli in its cells

DCT

part of the nephron with few microvilli in its cells

loop of Henle

part of the nephron made up of thin-segment cells

CD

part of the nephron made up of 2 types of cells: principal cells and intercalated cells

cortical

type of nephron that has a short loop of Henle and the glomerulus is further from the corticomedullary junction

cortical

type of nephron where the efferent arteriole supplies peritubular capillaries

juxtamedullary

type of nephrons where the efferent arteriole supplies vasa recta

wide

Is the afferent arteriole supplying a glomerulus wide or narrow?

narrow

Is the efferent arteriole draining a glomerulus wide or narrow?

juxtaglomerular apparatus (JGA)

contact point between the afferent arteriole of the glomerulus and the distal convoluted tubule of the nephron; involved in regulating blood pressure and GFR

glomerular filtration, tubular reabsorption, tubular secretion

3 major renal processes

capillary endothelium (fenestrated), basement membrane, foot processes of podocyte

3 layers of the glomerular filtration membrane

60

The kidneys filter the body's entire plasma volume how many times per day?

urine

contains metabolic wastes and unneeded substances

proteins

filtrate in the kidney contains all elements found in plasma except for this

95, 8

blood pressure declines from ______mmHg in renal arteries to _______mmHg in renal veins

afferent and efferent arterioles

vessels in the nephron that offer high resistance to blood flow

afferent arteriole

resistance in this vessel protects the glomerulus from fluctuations in systemic blood pressure

efferent arteriole

resistance in this vessel reinforces high glomerular pressure and reduces hydrostatic pressure in peritubular capillaries

glomerular filtration rate (GFR)

the total amount of filtrate formed per minute by the kidneys

total surface area available for filtration, filtration membrane permeability, net filtration pressure

factors that govern filtration rate at the capillary bed

net filtration pressure (NFP)

the pressure responsible for filtrate formation; pressure of filtrate as it exits glomerulus and enters PCT

proportional

GFR is directly ________________ to NFP

glomerular blood hydrostatic pressure

changes in GFR normally result from changes in this

55 mmHg

normal glomerular blood hydrostatic pressure

30 mmHg

normal blood colloid osmotic pressure

15 mmHg

normal capsular hydrostatic pressure

NFP = HPg - (OPg + HPc)

equation for NFP

10 mmHg

normal NFP

glomerular blood hydrostatic pressure

blood pressure in the glomerular capillaries that drives fluid out of the capillaries

blood colloid osmotic pressure

force on the glomerular capillaries that pushes fluid into the capillaries

capsular hydrostatic pressure

pressure exerted by fluid in the glomerular capsule against the fluids coming out of the glomerulus

high

if GFR rate is too ________, needed substances cannot be reabsorbed quickly enough and are lost in the urine

low

if GFR is too ______, everything is reabsorbed, including wastes that are usually disposed

intrinsic, extrinsic

controls that regulate (keep constant) GFR

intrinsic

control that regulates GFR via renal autoregulation entails; myogenic mechanisms and tubuloglomerular feedback

extrinsic

control that regulates GFR via neural and hormonal entails; sympathetic control and the renin-angiotensin system

intrinsic

control that directly regulates GFR despite moderate changes in blood pressure (between 80 and 180 mmHg mean arterial pressure)

extrinsic

control that indirectly regulates GFR by maintaining systemic blood pressure, which drives filtration in the kidneys

paracrines

locally acting chemicals that affect cells other than those that secrete them

prostaglandins (PGE2, PGI2), nitrix oxide, intrarenal angiotensin II, adenosine, endothelin

paracrines produced by renal cells that affect glomerular filtration

PGE2

vasodilator that counteracts norepinephrine and angiotensin II, preventing renal damage when peripheral resistance is increased

nitric oxide

vasodilator produced by vascular endothelium

intrarenal angiotensin II

reinforces systemic angiotensin

adenosine

vasoconstrictor of renal vasculature

endothelin

a powerful vascoconstrictor secreted by tubule cells

anuria

abnormally low urine output indicative of low GFP (kidney fails)

increased

an increase in hydrostatic pressure of the glomerulus would result in an _______________ filtration rate

tubular reabsorption

when water and solutes move from the tubular fluid into the capillaries (blood)

ADH

in the absence of this hormone, there is no water reabsorption

ADH

this hormone increases the permeability of the CD to water by inserting aquaporins in the CD luminal membranes

aldosterone

a decrease in blood volume, hyperkalemia, hyponatremia, or BP causes this hormone to increase NA reabsorption in the principal cells of the CD and cells in the DCT

ANP

hormone that decreases blood volume and BP by inhibiting Na reabsorption in the CD

increased

an increase in ANP results in _____________ urinary output

transport maximum (Tm)

reflects the number of carriers in the renal tubules available; exists for nearly every substance that is actively reabsorbed

excreted

when all carriers for a substance are saturated, excess of that substance is ______________

lack carriers, are not lipid soluble, are too large to pass through membrane pores

3 instances where substances are not reabsorbed

urea, creatinine, uric acid

3 most important nonreabsorbed substances

tubular secretion

substances move from peritubular capillaries or tubule cells into filtrate; essentially reabsorption in reverse

disposing, urea, uric acid, potassium, pH

tubular secretion is important for ______________ of substances not already in the filtrate, eliminating undesirable substances such as _______ and _______, ridding the body of excess ____________ ions, and controlling blood ______

osmolality

the number of solute particles dissolved in 1L of water; reflects the solution's ability to cause osmosis

countercurrent mechanism

the kidneys keep the solute load of body fluids constant at 300 mOsm through this mechanism

large, dilute

if we were so overhydrated we had no ADH, a __________ volume of ___________ urine would be produced

small, concentrated

if we were so dehydrated we had maximal ADH, a __________ volume of __________ urine would be produced

increase

If BP increases, what happens to GFR and urine output?

65%

percent of filtrate volume reabsorbed in the PCT

PCT

part of nephron where Na+, glucose, amino acids, and other nutrients are actively transported; H2O and many ions follow passively; H+ and NH4- secretion and HCO3- reabsorption occur to maintain blood pH; some drugs are secreted

descending limb

part of loop of Henle that is freely permeable to H2O and impermeable to NaCl

descending limb

part of loop of Henle where filtrate becomes increasingly concentrated as H2O leaves by osmosis

ascending limb

part of loop of Henle that is impermeable to H2O and permeable to NaCl

ascending limb

part of loop of Henle where filtrate becomes increasingly dilute as salt is reabsorbed

DCT

part of nephron where Na+ reabsorption is regulated by aldosterone, Ca2+ reabsorption is regulated by PTH, and Cl- is cotransported with Na+

CD

part of nephron where H2O reabsorption through aquaporins is regulated by ADH, Na+ reabsorption and K+ secretion is regulated by aldosterone, H+ and HCO3- reabsorption or secretion occurs to maintain blood pH, and urea reabsorption is increased by ADH

diuretics

chemicals that enhance urinary output

diuretics

examples of this are any substance not reabsorbed (substances with high Tm), substances that inhibit Na+ reabsorption

high glucose levels, alcohol, caffeine and most diuretic drugs, loop diuretics

examples of osmotic diuretics

water

___________ is carried out with glucose, making high glucose levels a diuretic

ADH

alcohol inhibits the release of ________

sodium

caffeine and most diuretic drugs inhibit __________ ion reabsorption

Na+

loop diuretics (such as Lasix) inhibit ______

renal clearance (RC)

the volume of plasma that is cleared of a particular substance in 1 minute; tested to determine GFR which tracks glomerular damage and renal disease

15

a GFR of less than _______ml/min indicates renal failure

hemodialysis or kidney transplant

treatment for low GFR (renal failure)

clear, pale to deep yellow (concentrated urine has a deeper yellow color)

color/transparency of urine