Monday, July 24, 2006
KIDNEYS
Kidneys-filtration, reabsorption, secretion
-are retroperitoneal in superior lumbar region
-consists of a renal fascia, adipose capsule and renal capsule (from outside in)
-has a superficial cortex, medulla with pyramids, and medial pelvis
-receive 25% of total cardiac output/minute
Kidney (renal) functions:
1) gluconogenesis during prolonged fasting
2) produce rennin which regulates BP and kidney function
3) produce EPO which stimulates RBC production
4) metabolizing vit D to active form
Adrenal gland sits on top of each kidney
The ureters, renal blood vessels, lymphatics and nerves all join the kidney at the renal hilus which leads into the renal sinuses.
The apex of the pyramids are the papilla which means nipple – contain bundles of collecting tubules (inside the pyramids).
Columns separate the pyramids
Seven lobes of a kidney
Major calyx and minor calyx are where urine is collected and is emptied into the renal pelvis which goes to the ureter to the bladder.
Know drawing and the movement into and out of the kidneys
No lobar or segmented veins in the kidneys
Renal plexus is a network of nerve fibers and ganglia and is supplied by the parasympathetic fibers from the 12th thoracic and the 1st lumber splanchic nerves
Nephrons
-consists of a glomerulus and renal tubule (glomerular capsule (Bowman’s capsule), PCT, loop of Henle, DCT) Peritubular capillary is associated with the renal tubule of each nephron.
PCTThere are microvilli (Brush Border) in the PCT and cubodial cells. And many mitochondria. Reabsorb nutrients and water.
Descending limb of the loop of Henle-thin segment-permeable to water
Ascending limb of the loop of Henle-thick segment
DCT
Cells are cubodial but are thinner and no microvilli
Secrete solutes into filtrate rather than reabsorb as much
Toward the collecting tubule, the DCT becomes more like the collecting tubules
Intercalated cells, cubodial cells w/microvilli and principal cells
Intercalated cells maintain acid-base balance of blood
Principle cells maintain body water and Na+ balance.
Cortical nephrons – 85% of nephrons in kidney-located in the cortex
Juxtamedullary nephrons – 15% of nephrons in kidney-located close to cortex-medulla junction – produce concentrated urine
-Vasa recta-capillaries that supply loop of Henle in the medulla region of the kidney
Nephron Capillary Beds --Glomerulus and Peritubular capillaries
Glomerulus –specialized for filtration
Afferent arterioles-high BP, larger diameter, forces fluids and solutes into glomerulus
Efferent arterioles-break into the peritubular capillaries,
low BP, fenestrated capillaries, absorb solutes and water from the tubule cells from the filtrate and return to blood in the peritubular capillary beds
Efferent arterioles serving the juxtamedullary nephrons do not break into the peritubular capillaries-form bundles of long straight vessels called Vasa recta-form concentrated urine
Renal BP goes from 85 mg in the renal arteries to 8 mg in the renal veins Net filtration pressure is 10 mg.
Efferent arterioles-peritubular capillaries
Juxtaglomerlar cells – acts as mechanoreceptors that send BP in the afferent arterioles in the arteriole walls
Macula densa-group of closely packed DCT cells that respond to changes in the solute content of the filtrate.
These two groups of cells regulate rate of filtrate formation and systemic BP
Filtration Membrane-allows for free passage of water and solutes
Layers: 1) fenestrated epithelium of glomerular capillaries-allows passage of plasma components but not blood
2) visceral memberane in glomerular capsule of PODOCYTES
3) basement membrane
Three major mechanisms by which the kidneys adjust plasma composition:
1) glomerular filtration
2) tubular reabsorption
3) tubular secretion
Glomerular Filtration: Filtrate and urine: filtrate contains everything in blood plasma except proteins Urine is mostly metabolic wastes Kidneys produce 180 liters of filtrate per day Plasma Proteins and blood cells stay in the capillaries
Tubular reabsorption Glucose and AA are reabsorbed (passively or actively)
PCT – absorbs Na+, all nutrients (glucose, AA K+, Ca2+, Mg2+), Cl-, H20, urea and lipid-soluble solutes, small proteins
(active transport with Na+, passive transport with Cations, osmosis with H2O, passive diffusion with urea and lipid-soluble solutes
Loop of Henle – absorbs H20, Na+, Cl-, K+ Ca2+, Mg2+
DCT – absorbs Na+, Ca2+, Cl-, H2O
(active transport with aldosterone for the Na+ ion, diffusion and osmosis)
Collecting duct –absorbs all of the above (DCT) plus urea
Tubular secretion; As the blood becomes more acidic, the renal tubule cells secrete more H+ into the filtrate and retain more HCO3- and K+ and H+ goes into the urine
As blood becomes more alkaline, the renal tubule cells will absorb more Cl- and HCO3- is secreted into the urine.
Both of these result in the regulation of blood pH.
Osmolarity-
Loop of Henle – descending limb is impermeable to solutes and permeable to water. Water is reabsorbed thru the descending limb
Ascending limb is impermeable to water but permeable to salt. NaCl is reabsorbed into the ascending loop of Henle. The use of co-transport occurs here (co-transport = picks up Na+ and a glucose comes with it) (active transport with pumper)
Albumin in filtrate -DON”T WANT THIS may find albumin in urine in pregnant women and when BP is high during vigorous exercise
Urea is a useless waste product but 50% diffused back into blood as a standard for negative feedback system(passive transport)
Uric acid (is a useless substance but retrieve 90% back into blood (active transport
Aldosterone regulates Na+ and tells K+ to get out
Parathormone regulates PO4 H+ combines with PO4 to become H2PO4
This gets H+ out of the PCT regulates pH of blood
Acidosis – H+ ions are produced by the body- more acidic blood (Bohr Effect- O2 less likely to jump off Hb) pH drops too much – you pickle
ADH release from supra optic release a lot of ADH – urine becomes concentrated
Release a little ADH, the urine becomes diluted
Diuretics include the following: Lasix or other types of diuretic drugs, caffeine-based drinks like coffee, tea, and colas, and alcohol
Normal Urine contains the following:
Urea, uric acid, creatine, Na+, K+, PO4, SO4
The bladder
Has three layers: mucosa epithelium, muscular layer called the detrusor muscle, and the fibrous adventitia layer. The smooth triangular area is called the trigone and this is where most infections occur (at the base of the bladder)
Bladder contains rugae and can stretch.
Urethra
Thickening of the detrusor muscle forms the internal urethral sphincter which keeps the urine in.
The external urethral sphincter is skeletal muscle and is voluntary
Male urethra carries urine and semen out
Micturition = urination
Because the external sphincter muscle is voluntarily controlled, micturition can be delayed temporarily.
Gather 125 mg of filtrate/minute but only collect 1-3 mg /minute for excretion
Kidneys-filtration, reabsorption, secretion
-are retroperitoneal in superior lumbar region
-consists of a renal fascia, adipose capsule and renal capsule (from outside in)
-has a superficial cortex, medulla with pyramids, and medial pelvis
-receive 25% of total cardiac output/minute
Kidney (renal) functions:
1) gluconogenesis during prolonged fasting
2) produce rennin which regulates BP and kidney function
3) produce EPO which stimulates RBC production
4) metabolizing vit D to active form
Adrenal gland sits on top of each kidney
The ureters, renal blood vessels, lymphatics and nerves all join the kidney at the renal hilus which leads into the renal sinuses.
The apex of the pyramids are the papilla which means nipple – contain bundles of collecting tubules (inside the pyramids).
Columns separate the pyramids
Seven lobes of a kidney
Major calyx and minor calyx are where urine is collected and is emptied into the renal pelvis which goes to the ureter to the bladder.
Know drawing and the movement into and out of the kidneys
No lobar or segmented veins in the kidneys
Renal plexus is a network of nerve fibers and ganglia and is supplied by the parasympathetic fibers from the 12th thoracic and the 1st lumber splanchic nerves
Nephrons
-consists of a glomerulus and renal tubule (glomerular capsule (Bowman’s capsule), PCT, loop of Henle, DCT) Peritubular capillary is associated with the renal tubule of each nephron.
PCTThere are microvilli (Brush Border) in the PCT and cubodial cells. And many mitochondria. Reabsorb nutrients and water.
Descending limb of the loop of Henle-thin segment-permeable to water
Ascending limb of the loop of Henle-thick segment
DCT
Cells are cubodial but are thinner and no microvilli
Secrete solutes into filtrate rather than reabsorb as much
Toward the collecting tubule, the DCT becomes more like the collecting tubules
Intercalated cells, cubodial cells w/microvilli and principal cells
Intercalated cells maintain acid-base balance of blood
Principle cells maintain body water and Na+ balance.
Cortical nephrons – 85% of nephrons in kidney-located in the cortex
Juxtamedullary nephrons – 15% of nephrons in kidney-located close to cortex-medulla junction – produce concentrated urine
-Vasa recta-capillaries that supply loop of Henle in the medulla region of the kidney
Nephron Capillary Beds --Glomerulus and Peritubular capillaries
Glomerulus –specialized for filtration
Afferent arterioles-high BP, larger diameter, forces fluids and solutes into glomerulus
Efferent arterioles-break into the peritubular capillaries,
low BP, fenestrated capillaries, absorb solutes and water from the tubule cells from the filtrate and return to blood in the peritubular capillary beds
Efferent arterioles serving the juxtamedullary nephrons do not break into the peritubular capillaries-form bundles of long straight vessels called Vasa recta-form concentrated urine
Renal BP goes from 85 mg in the renal arteries to 8 mg in the renal veins Net filtration pressure is 10 mg.
Efferent arterioles-peritubular capillaries
Juxtaglomerlar cells – acts as mechanoreceptors that send BP in the afferent arterioles in the arteriole walls
Macula densa-group of closely packed DCT cells that respond to changes in the solute content of the filtrate.
These two groups of cells regulate rate of filtrate formation and systemic BP
Filtration Membrane-allows for free passage of water and solutes
Layers: 1) fenestrated epithelium of glomerular capillaries-allows passage of plasma components but not blood
2) visceral memberane in glomerular capsule of PODOCYTES
3) basement membrane
Three major mechanisms by which the kidneys adjust plasma composition:
1) glomerular filtration
2) tubular reabsorption
3) tubular secretion
Glomerular Filtration: Filtrate and urine: filtrate contains everything in blood plasma except proteins Urine is mostly metabolic wastes Kidneys produce 180 liters of filtrate per day Plasma Proteins and blood cells stay in the capillaries
Tubular reabsorption Glucose and AA are reabsorbed (passively or actively)
PCT – absorbs Na+, all nutrients (glucose, AA K+, Ca2+, Mg2+), Cl-, H20, urea and lipid-soluble solutes, small proteins
(active transport with Na+, passive transport with Cations, osmosis with H2O, passive diffusion with urea and lipid-soluble solutes
Loop of Henle – absorbs H20, Na+, Cl-, K+ Ca2+, Mg2+
DCT – absorbs Na+, Ca2+, Cl-, H2O
(active transport with aldosterone for the Na+ ion, diffusion and osmosis)
Collecting duct –absorbs all of the above (DCT) plus urea
Tubular secretion; As the blood becomes more acidic, the renal tubule cells secrete more H+ into the filtrate and retain more HCO3- and K+ and H+ goes into the urine
As blood becomes more alkaline, the renal tubule cells will absorb more Cl- and HCO3- is secreted into the urine.
Both of these result in the regulation of blood pH.
Osmolarity-
Loop of Henle – descending limb is impermeable to solutes and permeable to water. Water is reabsorbed thru the descending limb
Ascending limb is impermeable to water but permeable to salt. NaCl is reabsorbed into the ascending loop of Henle. The use of co-transport occurs here (co-transport = picks up Na+ and a glucose comes with it) (active transport with pumper)
Albumin in filtrate -DON”T WANT THIS may find albumin in urine in pregnant women and when BP is high during vigorous exercise
Urea is a useless waste product but 50% diffused back into blood as a standard for negative feedback system(passive transport)
Uric acid (is a useless substance but retrieve 90% back into blood (active transport
Aldosterone regulates Na+ and tells K+ to get out
Parathormone regulates PO4 H+ combines with PO4 to become H2PO4
This gets H+ out of the PCT regulates pH of blood
Acidosis – H+ ions are produced by the body- more acidic blood (Bohr Effect- O2 less likely to jump off Hb) pH drops too much – you pickle
ADH release from supra optic release a lot of ADH – urine becomes concentrated
Release a little ADH, the urine becomes diluted
Diuretics include the following: Lasix or other types of diuretic drugs, caffeine-based drinks like coffee, tea, and colas, and alcohol
Normal Urine contains the following:
Urea, uric acid, creatine, Na+, K+, PO4, SO4
The bladder
Has three layers: mucosa epithelium, muscular layer called the detrusor muscle, and the fibrous adventitia layer. The smooth triangular area is called the trigone and this is where most infections occur (at the base of the bladder)
Bladder contains rugae and can stretch.
Urethra
Thickening of the detrusor muscle forms the internal urethral sphincter which keeps the urine in.
The external urethral sphincter is skeletal muscle and is voluntary
Male urethra carries urine and semen out
Micturition = urination
Because the external sphincter muscle is voluntarily controlled, micturition can be delayed temporarily.
Gather 125 mg of filtrate/minute but only collect 1-3 mg /minute for excretion
