7.3 - The Kidneys

list what these are

A - renal pyramid

B - renal column

C - renal vein

D - renal artery

E - renal pelvis

F - ureter

G - renal capsule

H - renal cortex

List what these are

A - branch of renal vein

B - branch of renal artery

C - glomerulus

D - glomerular capsule

E - renal capsule

F - afferent arteriole

G - efferent arteriole

H - proximal convoluted tubule

I - descending limb

J - loop of henle

K - ascending limb

L - distal convoluted tubule

M - collections duct

N - peritubular capillaries

what do the nephrons do

remove waste from the blood and regulate blood composition

how does blood enter and travel through the nephrons

enters kidney through renal artery

artery divides into arterioles

afferent arteriole forms glomerulus

efferent arteriole passes out renal capsule

efferent arteriole splits into peritubular capillaries that surround nephron

blood leaves kidneys out of renal vein

what are the three major processes involved in the production of urine

glomerular filtration

selective reabsorption

secretion by tubules

how is high blood pressure maintained in glomerular filtration

afferent arteriole is wider then efferent arteriole

how does the glomerular capsule’s wall help with filtration

it is only one cell thick so pressure forces fluid through semi permeable membrane into capsule

what is leftover after glomerular filtration

filtrate - no red/white blood cells or plasma but does contain

water, salt, amino acids, fatty acids, glucose, urea, uric acid, creatine, and hormones

why isnt all of the plasma filtered out in glomerular filtration

only 20% is filtered because there is continuous bloodflow

why do we need selective reabsorption and where does it occur

some filtered components are useful so selective reabsorption must take place in the cells lining the renal tubule

what are materials reabsorbed in selective reabsorption

water

glucose

amino acids

ions (sodium, potassium ect)

some wastes are partially reabsorbed (urea)

how does selective reabsorption change depending on the body’s needs

the permeability of the membrane can be changed to absorb more or lass water

this is an active process under hormonal control called facilitative reabsorption

what is tubular secretion

adding of materials to filtrate from blood, can be active or passive

what things are tubularly-secreted

penicillin, creatine, potassium, hydrogen ions

what does tubular secretion help maintain

blood pH of 7.4-7.5 be removing hydrogen and ammonium

urine pH

what happens during excretion

substances not reabsorbed drain from collecting ducts into renal pelvis

urine drains into ureters and is pushed by muscles into bladder

urethra carries urine from bladder to exterior of body

how is the formation of urine maximized by the kidney/nephrons (6)

• glomerular capsules surround glomerulus to collect fluid filtered out blood capillaries

• only two cells for filtrate to pass through

• large volume of blood and continual flow maintains concentration gradient

• efferent arteriole has smaller diameter to raise blook pressure

• each tubule has a large SA due to two sets of convolutions and long loop

• each kidney has over a million nephrons

why is a lot of water lost in urine

excreted substances have to be dissolved in a solution so half a liter minimum must be lost daily

how is uric acid produced

the metabolism of purines that come from food and the breakdown of nucleic acids

how is creatine produced

in muscles from breakdown of creatine phosphate

what can we observe from excreted substances

• 99% of water entering nephrons is reabsorbed

• urine doesn’t contain much protein

• urine doesn’t contain any glucose

• main materials are urea, ions, uric acid, and creatine