S S 10 Secretion Reabsorption Filtration

Test # 3 on Monday Lab next week: Urinalysis! Covers only Cardiovascular and Respiratory. Some short answer questions and draw and label questions. Lab next week: Urinalysis!

During intervals, diagram the negative feedback loops. Drink Test Beverage in 5 minutes or less Urinalysis Lab 800 ml tap water or 800 ml tap water + 7 g NaCl or 80 ml tap water + 7 g NaCl Drink plenty of water the day of lab; Avoid coffee, caffeine, salty foods 60 min 30 min 30 min 30 min 30 min 30 min 1 Hr before Lab Empty bladder; note time At 30 min intervals, collect urine measure V and [NaCl] During intervals, diagram the negative feedback loops. Beginning of Lab: Collect Urine, measure Volume and titrate [NaCl]

Renal Physiology Structures of the kidney Four fundamental renal mechanisms Filtration Reabsorption Secretion Metabolism Functions of the kidneys Homeostasis Fluid balance (blood pressure) Electrolyte balance (blood pressure, membrane excitability) Acid-base balance (in concert with lungs)

Special terms Filtration: movement of fluid from blood into the lumen of the nephron (renal tubule) Reabsorption: the movement of specific compounds from the tubular lumen back into the blood (peritubular capillaries) Secretion: the transport of specific compounds from blood into the tubular lumen Excretion: elimination from the body in urine Glomerular Filtration Rate = 120 ml/ min

Table 14.02

Lab: Extra 800 ml intake! Sidebar: some desert animals never drink and must obtain all their water in the diet.

Table 14.04 Lab: Extra 7 g intake!

Kidneys are source of 3 hormones: Renin, EPO, and Vit D. Kidneys are targets of 3 hormones: ADH, Aldosterone, ANH S 15 Nephron = tubule Tubular fluid vs urine Topics discussed: cortex, medulla, kidney stones, micturition (detrussor, internal and external urethra sphincters and innervation), incidence of bladder infections by gender, urethral sphincters

Renal artery = One way in Renal artery = One way in. Two ways out of kidney (renal vein or ureter) Enlarged on next page S 16

Juxtamedullary and Cortical Nephrons Fig. 14.02a Renal corpuscle Peritubular Capillaraies and branch thereof called vasa recta 14.02a.jpg A Portal System

S 20 The nephron

S 21 Fig. 14.03a 14.03a.jpg

Glomerular Filtration Rate is 120 ml/min = 180 L/day Fig. 14.05 Glomerular Filtration Rate is 120 ml/min = 180 L/day Three stimuli for secretion of renin from JGC 14.05.jpg

Ultrafiltrate of plasma enters Bowman’s space Composition same as plasma except no formed elements and no proteins and no substances bound to proteins Figure 14.03

Fig. 14.08 Starling Forces 14.08.jpg variable

What happens during hemorrhage? Fig. 14.09 Ways to alter GFR What substances can cause this constriction? 14.09.jpg What happens during hemorrhage?

Fig. 14.02a 14.02a.jpg

Figure 14.10 reabsorption Secret ion Membrane proteins are segregated into apical (luminal) and basolateral membranes. Figure 14.10 reabsorption Secret ion Amino acid glucose metabolism

Reabsorption and secretion in proximal tubule is NOT under hormonal control. Primary active transport of Na+ establishes a gradient for reabsorption of glucose, amino acids, etc. Reabsorption and secretion in DCT & CCD is under hormonal control. Hormones that act here: ANH, ADH, Aldosterone. Here, reabsorption of Na+ is linked to the secretion of K+.

Effect of ADH: insertion of more aquaporins in th the membranes Effect: Increase H2O reabsorption

Figure 14.31 Normally, all filtered bicarbonate is “reabsorbed”

Figure 14.10 reabsorption secretion Membrane proteins are segregated into apical (luminal) and basolateral membranes. Figure 14.10 reabsorption secretion Amino acid glucose metabolism

Filtration is controlled by aa and ea diameters!

Consider a substance that in filtered only, no reabsorption, no secretion. Excretion of this substance = GFR Clearance of this substance = GFR

Clearance = volume of plasma from which a substance is completely removed (cleared) by the kidneys per unit time. Clearance of Inulin is 120 ml/min Cinulin or Ccreatinine = Glomerular Filtration Rate

Renal Handling of Substances Filtration + complete Secretion Ex: Para AminoHippurate (PAH) Measure Renal Plasma Flow Filtration + partial reabsorption Ex: Sodium Ex: Water Filtration + 100 Reabsorption Ex: Glucose Ex: Amino Acids

Clearance of Inulin is 120 ml/min Clearance = volume of plasma from which a substance is completely removed (cleared) by the kidneys per unit time. Clearance of Inulin is 120 ml/min Cinulin or Ccreatinine = Glomerular Filtration Rate If C x is greater than GFR ( which is Cinulin) then that substance undergoes NET TUBULAR SECRETION If C x is less than GFR ( which is Cinulin) then that substance undergoes NET TUBULAR REABSORPTION

A little more on Clearance: Clearance of glucose = 0 ml/min which means…. Clearance of X = 120 ml/min which means…. Clearance of antibiotic XXX = 500 ml/min which means…

Calculating clearance Clearance of s = Urine concentration of s X Urine Volume Plasma concentration of s “24 hour urine catch” + blood sample Special cases: Clearance of Inulin and creatinine (filtered only; use to measure Glomerular Filtration Rate.) Para Amino Hippurate (filtered and completely secreted, use to measure Renal Plasma Flow)