Chapter 17 Physiology of the Kidneys

A. Kidney Function  Regulates  Volume of _______________, which contributes to BP  plasma & ________________ by formation of urine  Waste products in blood  Concentration of ___________________  Including Na +, K +, HC0 3 -, & others  Plasma ____

 kidneys located on either side of vertebral column below __________  About size of ____  Urine flows from kidneys into ________which empty into________ Fig 17.1 B. Kidney Structure

 ______ contains many capillaries & outer parts of ________  _____ consists of _________ separated by _____________  Pyramid contains ___________ which unite to form a _______________ Fig 17.2  ___________ join to form ________ which collects urine

C. Micturition Reflex (Urination)  Actions of _______ & __________________ are regulated by reflex center located in sacral part of cord Bladder fills __________________ activated Contraction of _____________ relaxes internal urethral _____________ voluntary control over external _________________

D. Nephron  functional unit of kidney responsible for forming __________  >1 million ___________/kidney  Is a long tube & has associated _______ ______ Fig 17.2

E. Renal Blood Vessels  Blood enters kidney through ____________  Which divides into ___________, then __________ then ______________, then ______________ which supply _____________ Fig 17.4

F. Nephron Tubules  Tubular part of nephron begins with _______________ which transitions into _________________ (PCT), then to ______________ & ___________________________ (LH), & _____________________ (DCT)  Tubule ends where it empties into _________________ (CD) Fig 17.2

G. Glomerular (Bowman's) Capsule  Surrounds glomerulus  Together they form ______________  Is where glomerular filtration occurs  Filtrate passes into ______ Glomerular capsule PCT Fig 17.6

H. Glomerular Filtration  Glomerular capillaries & ________________ form a filter for blood  Glomerular Caps are ____________--have large pores between its endothelial cells  times more permeable than other Caps  Small enough to keep RBCs, platelets, & WBCs from passing

 To enter tubule filtrate must pass through narrow ______________ H. Glomerular Filtration continued Fig 17.8

Glomerular Filtration Rate (GFR)  volume of filtrate produced by both kidneys/min  Averages ________ in women; 125 ml/min in men  Totals about 180L/day (____________)  So most filtered water must be reabsorbed or death would ensue from water lost through urination  controlled by extrinsic & intrinsic _______________) mechanisms  Vasoconstriction or dilation of afferent arterioles affects rate of blood flow to glomeruli & thus ________

I. Sympathetic Effects  Sympathetic activity constricts ____________  Helps maintain BP & shunts blood to ______ _____________ Fig 17.11

J. ______________ of Salt & H 2 0 by Glomerular Capsule  About 180 L/day of ultrafiltrate produced; only 1–2 L of urine excreted/24 hours  Minimum of 400 ml/day urine necessary to excrete metabolic wastes (________________ _________________) Return of filtered molecules is called _______________

 permeable to ___, salt Fig ______________ Impermeable to H20; permeable to ___ 1. ______________ K. Loop of _________

 Plays important role in _____ ________________  Is impermeable to salt in medulla  Permeability to H 2 0 depends on levels of _____ L. Collecting Duct (CD) Post pituitary ___________ __________ Water drawn out of ___________

 Refers to ability of kidney to remove substances from _______ & excrete them in ________  Occurs by filtration & by ___________ Fig M. Renal Clearance Many drugs, toxins, & metabolites are secreted by organic anion transporters of the PCT Thus 40-60% of filtered urea is always ___________ Only ______ of blood is filtered

 glucose & amino acids are _____________________  Occurs in ____ N. Glucose & Amino Acid Reabsorption ______________- presence of glucose in urine Occurs in ______________when exceed renal plasma threshold (> mg/100ml plasma) _________________ occurs when hyperglycemia results in _________________

O. Hormonal Effects 1. ________________  controls K+ secretion & ___ ____________ 90% filtered Na+ & K+ reabsorbed ______________ 80% of remaining Na+ is reabsorbed in DCT & cortical CD  only way K+ ends up in urine Control of plasma Na+ is important in regulation of _________________________ Control of plasma of K+ important in proper function of cardiac & skeletal muscles

 Located near Glomerulus Fig ____________________________ (JGA) – Activates alderosterone secretion Senses ___________________

Fig _______________________________ System Regulates _____ in blood

 Is produced by atria due to stretching of walls  Acts opposite to ____________________  Stimulates salt & H 2 0 excretion  Acts as an endogenous _________________ 2. ____________________________ (ANP) O. Hormonal Effects (cont.)

 Na + reabsorption creates electrical gradient for _____________ secretion  High extracellular H + = H + moves into cells causing K + to diffuse out & vice versa  ______________ can cause acidosis  In severe acidosis, H + is secreted at _________________ Insert fig Fig P. Na+, K+, & H+ Relationship

 Kidneys help regulate blood pH by excreting H + &/or reabsorbing HC0 3 -  Normal urine is _______________ (pH = 5-7) because kidneys reabsorb almost all HC0 3 - & excrete H + Q. Renal Acid-Base Regulation

 Nephron cannot produce urine with pH < 4.5  Excretes more H + by buffering H + s with HPO 4 -2 or NH 3 before excretion  Buffering reactions  HPO H +  H 2 PO 4 -  NH 3 + H +  NH 4 + (ammonium ion) R. Urinary Buffers

 _______________ ____ ________ prevent H 2 0 reabsorption in PCT when HC0 s - is reabsorbed  _____________ inhibit NaCl reabsorption in 1 st part of DCT  ____________ are most powerful; inhibit AT salt in thick ascending limb of LH  ____________ increase osmotic pressure of filtrate S. Clinical Aspects ____________ used to _________ blood volume due to ___________, congestive heart failure, or edema Increase volume of ________ by increasing proportion of glomerular filtrate that is excreted Fig 17.30

1. _____________________- kidneys fail to excrete wastes & regulate blood volume, pH  blood creatinine rises  Can result from atherosclerosis, inflammation of tubules, kidney ischemia, or overuse of NSAIDs T. Kidney Diseases 2. _________________________ - inflammation of glomeruli Autoimmune attack glomerular capillary basement membranes Causes leakage of protein into urine resulting

3. _________________________- nephrons have been destroyed as a result of a ____________  Observe salt & H 2 0 retention & ___________  high plasma H + & K + can cause uremic coma  Treatment includes ______________  Patient's blood is passed through a dialysis machine which separates molecules on basis of ability to diffuse through _______________ _______________________  Urea & other wastes are removed