Unit 1: Urinary System; Anatomy and Functions of the Kidney (Module 3)

kidneys

urinary structure that filters blood and produces urine

filter blood (waste, toxins), produce urine, secrete hormones, regulate pH, electrolyte levels, and fluid levels

functions of the kidneys

ureters

carries urine to the urinary bladder

bladder

store urine

urethra

allows urine to exit the body

hillus/hillum

concave region of the kidney, where blood vessels enter and exit and the ureter drains the kidney

cortex

outer portion of the kidney

medulla

inner portion of the kidney

nephron

small functional units of the kidney

renal corpuscle

part of the nephron that includes the glomerulus and bowman’s capsule

glomerulus

capillary network under pressure in the nephron

bowman’s capsule

receives filtered fluid (filtrate) in the nephron

renal tubes

includes the PCT, LOH, DCT, and CD

proximal convoluted tubule

PCT; first tube exiting the kidney

loop of henle

LOH; contains a descending and ascending limp as well as a thick and thin portion; off of the PCT

distal convoluted tubule

DCT; comes off of the LOH

collecting duct (CD)

receives filtrate from many DCTs

many CDs → one papillary duct → minor calices → ureter

pathway from the CDs to the ureter

peritubular capillaries

surround the entire renal tubule/nephron

filtration, reabsorption, secretion

3 major functions of the nephron

filtrate

fluids and solutes that leave the glomerulus and enter Bowman’s capsule

endothelial cells; basal lamina; podocytes

3 parts of the filtration membrane

fenestrations

what structure in endothelial cells of the filtration membrane allow solutes through?

basal lamina

made of collagen fibers, glycoproteins and proteoglycans; prevents passage of large proteins/formed elements

podocytes

cells of Bowman’s capsule that wrap around endothelial cells; form pedicels

pedicels

wrap around endothelial cells

allow small molecules such as water, glucose, amino acids, vitamins, urea, and ions to pass through

what do the filtration slits between pedicels do?

fenestrations and pressure

filtration occurs due to…

glomerular blood hydrostatic pressure (GBHP), capsular hydrostatic pressure (CHP), blood colloid osmotic pressure (BCOP)

three pressures in the kidneys

glomerular blood hydrostatic pressure

blood pressure in glomerular capillaries; increases filtration

capsular hydrostatic pressure

hydrostatic pressure pushing back on glomerular membrane; caused by existing fluid in Bowman’s capsule, opposes filtration

blood colloid osmotic pressure

type of pressure where proteins in blood oppose filtration

capsular hydrostatic pressure and blood colloid osmotic pressure

what 2 things oppose filtration

fenestrations and glomerular blood hydrostatic pressure

what two things increase/promote filtration?

glomerular filtration rate (GFR)

volume of filtrate formed by both kidneys in one minute; any change in this will alter urine formation; measured to determine kidney function

1. change in blood flow to glomerulus

2. change in glomerular capillary surface area

what two things can alter/change GFR?

True

True or False: changes in GFR will alter urine formation

reabsorption

solutes leave the filtrate and enter the peritubular capillaries (which cling to all parts of the nephron).

secretion

solutes leave the peritubular capillaries and enter the filtrate of the nephron to be excreted in urine

vitamins, glucose, a.a., H2O, Na, HCO3-, Cl, K

what are some things that are reabsorbed in the PCT?

H2O

what is reabsorbed in the thin decending LOH?

Cl and Na

what is reabsorbed in the thick ascending LOH?

Ca, K, Cl, Na, H2O

what is reabsorbed in the DCT?

Na, K, HCO3-, H2O

what can be reabsorbed by the CD?

toxins, H+, HCO3-, creatinine, drugs

what things are secreted into the PCT?

urea

what can be secreted into the LOH?

H+ and toxins

what can be secreted into the DCT?

H+

what can be secreted into the CD?