Filter 200 liters of blood daily, allowing toxins, metabolic wastes and excess ions to leave body in urine

regulate volume  and chemical makeup of blood

maintain proper balance between water and salts, acids and bases

Glucogenesis during prologned fasting

production of renin(enzyme to regulate blood pressure)  and erythropoietin  (red blood cell production)

Metabolizing vitamin D to active form  

leads to renal sinus

where ureters, renal blood vessels, lymphatics and nerves enter and exit  

renal capsule - fibrous capsule - prevents infection

adipose capsule - fatty mass which cushions and helps attach kidney to body wall

renal fascia - outer layer of dense fibrous connective tissue that anchors kidney  

structural and functional unit - form urine

Consists of:

glomerulus: tuft of capillaries associated with renal tubule  

Bowman's Capsule: surrounds tubule

renal corpuscle - glomerulus + bowman's capsule  

glomerular endothelium - fenestrated epithelium that allows solute-rich virtually protein free filtrate to pass from blood into glomerulus

external parietal layer = simple squamous (structural)

visceral layer = epithelial podocytes with foot processes

Filtration slits are openings between podocytes' foot processes that allow filtrate to pass into capsular space 

PCT - composed of cuboidal cells with numerous microvilli (absoprtion!) and mitochondria (ATP) --> reabsorbs water and solutes from filtrate and secretes substances into it

Loop of Henle - loop of renal tube

proximal part similar to PCT

followed by thin segment (simple squamous cells) and thick segment (cuboidal to columnar cells)

DCT - cuboidal cells without microvilli that function more in secretion than absorption  

connect the DCT with the collecting ducts 

IMPORTANT CELL TYPES

intercalated cells: cuboidal cells with microvilli

Function:  maintaining acid-base ballance of body

Principal cells: cuboidal without microvilli

Function: maintain body's water and salt balance

Cortical nephrons - 85% of nephrons - located in cortex

juxamedullary nephrons: located at cortex-medulla junction, have extensive thin segments that extend deep into medulla

involved in production of concentrated urine (so therefore a LOT more water is reabsorbed in these) 

each has two capillary beds: glomerulus, peritubular capillaries

Each glomerulus is fed by an afferent arteriole and drained be an efferent tubule

Blood pressure in golmerulus is high b/c arterioles are high-resisitance vessles, afferent arteriolse have larger diameters than effernt artieruols

peritubular beds - low pressure, pourous capillaries adopted for absorption

arise from efferent arterioles

cling to adjacent tubules

empty into renal venous system

Vasa recta - long straing efferent arterioles of juxtamedullary  nephrons

afferent and efferent arteiroles = hifh resistance to blood flow

Resistance in afferent - protects glomeruli from fluctuations in systemic blood pressure

Resistance in efferent - reinforces high glomerulus blood pressure and reduces hydrostatic pressure in peritubular capillaries  

where distal tubule lies against afferent (sometimes effernt) arteriole

arteriole walls have JG cells = enlarged smooth muscle cells that have secretory granules containing renin - act as mechanoreceptors (Sense blood pressure in afferent 

Macula Densa celles - tall, closely packed distal tubule cells and lie adjacent to JG cells - function as chemoreceptors and monitor changes in NaCl content of filtrate 

Etraglomerular mesangial cells - phagocytic and contracile properties - influence capillary function  

filter that lies between blood and interior of glomerular capsule

composed of three layers

fenestrated endothelium of glomerular capsule

visceral membrane of glomerular capsule (podocytes)

basement membrane composed of fused basal cells