renal failure

Question 1

what is the function of the kidneys

Answer 1

• electrolyte and fluid balance
• acid base balance
• elimination of metabolic waste
• regulation of blood pressure eg, renin angiotensin system
• endocrine functions: site of vitamin D synthesis which helps in calcium homeostasis
  -helps produce RBC as its the site of erythropoietin synthesis (hormone)
• 2nd major place for gluconeogenesis

Question 2

describe the kidneys

Answer 2

• dimensions (size)= 10-12cm long, 5-7cm wide, 3cm thick
• position= between 12th thoracic and 3rd lumber vertebrae and its retroperitoneal (back of ribcage)
• receives 20-25% of resting cardiac output
• weight= 135-150g
  1.2L of blood passes through the kidneys per minute

Question 3

describe the renal cortex

Answer 3

• outer part
• where glomerulus is located
• function is for filtration of primary urine

Question 4

describe renal medulla

Answer 4

• inner part
• structure has renal pyramids and columns
• function is to regulate concentration of urine as has tubules and collecting duct

Question 5

describe the nephron

Answer 5

• structural and functional unit if the kidney
• responsible for the filtration and formation of urine
• approx 1 million nephrons in each kidney
• consists of renal corpuscle and tubules

Question 6

describe the renal corpuscle

Answer 6

consists of the glomerulus and bowman’s capsule

Question 7

describe the structure glomerulus

Answer 7

• contains a network of capillaries
• lined with endothelial cells which have large pores (0.07-0.1 micrometers), they don’t allow RBCs to pass through
• have mesangial cells that contract and regulate the glomerular filtration rate
• has basal lamina which excludes large plasma proteins from going through
• podocytes consist of pedicels (small feet) which wrap around the capillaries. have slits that cut off molecules larger than 0.006-0.007micrometers

Question 8

describe the mechanism of the glomerulus

Answer 8

• the endothelial fenestrations let plasma but not RBCs to pass through
• the basal lamina doesn’t let large proteins pass through
• the podocytes don’t allow medium sized proteins through

Question 9

function of renal corpuscle

Answer 9

• maintains normal blood pressure (80-120mmHg) by=
  
  • the dialation of the afferent arteriole and glomerular capillaries
  • the constriction of efferent arterioles
  • the renin angiotensin-aldosterone system
• has glomerulus which filters 180L of cell and protein free urine per day

Question 10

describe the renal tubules

Answer 10

• consists of the proximal tubule, descending limb loop of henle, ascending limb and distal convoluted tubule
• these reabsorb electrolytes, nutrients and water back into the blood
• they secrete waste and toxins