KIDNEYS

KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS

KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS KIDNEYS

FUNCTIONS• Excretion of wastes –

– ammonia and urea (breakdown of amino acids), broken down bilirubin (breakdown of hemoglobin), creatinine (breakdown of creatine phosphate in muscles), uric acid (breakdown of nucleic acids)

• Regulates blood levels of:– Ions (sodium, potassium, calcium, phosphate,

chloride)– pH – excrete H+; conserve bicarbonate ions (a

buffer of H+ in blood)– Water – maintains blood volume (bp)

What is urine?• Mostly water• wastes• NOT FOUND: glucose, proteins, rbc,

hemoglobin, wbc, and bile

LOCATION• Above waist• Protected by 11th and 12th pair of ribs

ANATOMICAL PARTS• Renal capsule: outer

covering of kidney• Renal cortex:

superficial • Renal medulla: inner

region containing renal pyramids: Apex (papilla) face the hilus– Renal column: part of

medulla between pyramids

More parts• minor calyx; major

calyces – collect urine from pyramid

• Renal pelvis – collect urine from calyces

• Nephrons – filter urine from blood

URINE FORMATION

• Occurs in nephrons: mostly in renal cortex

• Leaves through collecting ducts

1. Glomerular filtration• Water and small

solutes from blood• Glomerular capsule• Due to high bp

2. Tubular reabsorption• Returns useful nutrients to blood

– Ex: water, glucose, sodium, calcium• Both passive and active transport• ADH affects cell’s permeability to H20

3. Tubular secretion• Brings some substances into the urine that

are not already there.– Ex: ammonium ions, hydrogen, some drugs

blood supply

1. What is the difference between the renal cortex and the renal medulla?

2. What part of the kidney is the hilus?

3. What part of the kidney collects urine from a medullary pyramid?

4. What is the function of a nephron?

5. Which structure of the urinary system leaves the kidneys with urine?