role of the kidneys
- regulate water and electrolytes
- act as an endocrine organ by producing chemical mediators
what is the hilus of the kidney?
deep fissure indented on the medial border where blood vessels and nerves enter and exit the kidney
describe the lobes of the kidney
- there are 8 to 18 lobes of each kidney
- lobes are composed of 800 000 to 1 000 000 nephrons
outer cortex
- reddish brown color
- contains glomeruli and convoluted tubules of the nephron, and blood vessels
medulla
- consists of light colored cone shaped masses called the renal pyramids
renal pelvis
wide, funnel-shaped structure at the end of the upper end of the ureter
what makes a nephron?
capillary structures, proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct
what is a cortical nephron?
- short, thick loops of Henle that penetrate only a short distance into the medulla
- make up about 85% of all nephrons
think CORTical = CORTex
what is a juxtamedullary nephron?
- originate deeper in the cortex and have longer loops of Henle that penetrate the entire length of the medulla
think juxtaMEDULLArry = MEDULLA
role of the afferent arteriole?
carries blood to the glomerulus
role of the efferent arteriole?
carries blood away from the glomerulus
what is Bowman capsule?
double-walled capsule encasing a tuft of afferent and efferent arterioles
what is Bowman space?
fluid-filled space within the Bowman capsule
describe what happens in Bowman capsule
- fluid and solutes from the blood are filtered through the capillary membrane into the Bowman space
- blood that is filtered is now called filtrate
what are the 3 layers of the glomerular capillary membrane?
- capillary endothelial layer
- basement membrane
- single-celled capsular epithelial layer
what does the basement membrane do?
- determines the permeability of the glomerular capillary membrane
- the size of the pores prevent red blood cells and plasma proteins from passing through
what are mesangial cells?
- produce intercellular substance similar to the basement membrane
- provide support for the glomerulus in areas where there is no basement membrane
- posses phagocytic properties the remove macromolecules that enter the inter-capillary spaces
what are the 2 components of urine formation?
- filtration of the blood through the glomerulus to form an ultrafiltrate of urine
- tubular reabsorption of electrolytes and nutrients needed to maintain hemostasis and elimination of waste materials
what is glomerular filtrate?
- similar to plasma
- contains almost no proteins
what is GFR?
glomerular filtration rate
- about 125 mL per minute
- about 1 mL is excreted in the urine
- 124 mL is reabsorbed in the tubules
what is the proximal tubule responsible for?
reabsorption and secretory processes (highly permeable to water)
- about 65% occurs here
