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127 Cards in this Set
- Front
- Back
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What is the main function of the kidneys?
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Keep the blood in homeostatic balance
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What are the 4 functions of the kidneys?
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1. Remove nitrogenous wastes (urea)
2. Regulate blood pH 3. Maintain plasama osmolarity and electrolyte composition 4. Maintain blood volume and pressure |
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What do the kidneys filter and produce?
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Filter blood and produce urine
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What does the urinary bladder do?
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stores urine
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What does the urethra do?
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Carries urine out of the body
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What do the ureters do?
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Transport urine from kidneys to bladder
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The renal arteries branch off what?
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Abdominal aorta
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The renal veins drain into what?
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Inferior vena cava
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2 kidneys receive about how much of the cardiac output? How much blood per minute?
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1/4 of cardiac output = 1200 ml blood per minute
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How do the kidneys cleanse so much blood?
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Large surface area
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90% of blood goes where in the kidneys?
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90% of blood goes to the renal cortex which is the outer part of the kidney
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What are nephrons?
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They are the functional units of the kidney
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What is the functional unit of the kidney?
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Nephrons
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What do nephrons do?
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Filter blood and form urine
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Nephrons are where what two systems meet?
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Renal and Cardiovascular systems meet
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How many nephrons are there per kidney?
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Roughly 1 million
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What are the two main parts of the nephron?
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1. Glomerulus
2. Renal Tubule |
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What is the glomerulus?
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It is a ball of glomerular capillaries
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What are peritubular capillaries?
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Capillaries that intertwine with the renal tubule
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The renal tubule begins with what?
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Globerular or Bowman's Capsule which surrounds the glomerular capillaries
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The renal tubule continues into what 4 major things?
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1. Proximal convoluted tubule
2. Loop of Henle 3. Distal convoluted tubule 4. Collecting ducts |
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What makes the striations visible in the kidneys?
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The various collecting ducts
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Collecting ducts drain urine into what? Then what?
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Drains urine into the ureter then to the bladder
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What two capillary beds are associated with the nephron?
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Glomerular capillaries and the peritubular capillaries
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Glomerular capillaries are specialized to do what?
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Specialized to filter blood
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Blood enters the glomerular capillaries through what? It exits through what?
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Enters through the Afferent Arteriole and exits through the Efferent arteriole
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Both the afferent and efferent arterioles have what kind of muscle?
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Smooth muscle!
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Why do the afferent and efferent arterioles have smooth muscle?
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So they can vasoconstrict or vasodilate to regulate how fast or how slow blood is filtered
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What 3 characteristics does glomerular capillaries have?
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1. Smooth muscle
2. Under high pressure 3. Fenestrated, very leaky |
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Systemic capillaries start with what at one end and end with what on the other?
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Start with arteriole and end with venule
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Systemic capillaries are only somewhat permeable to what?
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Water and solutes
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In the kidneys, the efferent arteriole continues on to form what?
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The peritubular capillaries
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Peritubular capillaries intertwine with the renal tubule to allow what?
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The exchange of water and solutes (reabsorption and secretion)
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What are 3 main differences between peritubular capillaries and glomerular capillaries?
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1. P capillaries are under lower pressure
2. Not as leaky as G capillaries 3. P capillaries drain into a venule |
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What are the 3 major renal processes?
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1. glomerular filtration
2. Tubular reabsorption 3. Tubular secretion |
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During Glomerular Filtration, water and solutes are pushed FROM what INTO what?
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Water and solutes are pushed FROM the glomerular capillaries INTO the glomerular capsule
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During Glomerular Filtration, water and solutes become what?
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Filtrate
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After Glomerular Filtration, what must happen to the filtrate?
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Must be processed some more
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During Tubular Reabsorption, water and solutes move FROM what INTO what?
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Water and solutes move FROM renal tubule INTO peritubular capillaries
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During Tubular Secretion, solutes move FROM what INTO what?
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Solutes move FROM the peritubular capillaries INTO the renal tubule
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What is the purpose of Tubular Secretion?
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It is the body's second chance to remove solutes from the blood
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What is filtered in the blood? What are the exceptions?
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Everything! Except large plasma proteins, blood cells, and platelets
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What are the main solutes that are filtered from the blood during Glomerular Filtration?
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Glucose and amino acids
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What are the main ions being filtered from the blood during Glomerular Filtration?
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Na+, K+, Ca2+, H+, Cl-, HCO3-
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What are the main waste products being filtered from the blood during glomerular filtration?
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Urea and uric acid
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Is glomerular filtration an active or passive process?
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PASSIVE
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Is glomerular filtration selective or not very selective?
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NOT VERY selective
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Glomerular filtration is the net result of what?
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Three pressures
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What are the three pressures that results in glomerular filtration?
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1. Glomerular Hydrostatic Pressure
2. Blood Colloid Osmotic Pressure 3. Capsular Hydrostatic Pressure |
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What is Glomerular Hydrostatic Pressure?
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It is the blood pressure that favors filtration
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What is Blood Colloid Osmotic Pressure?
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It is pressure caused by solutes drawing water back and opposes filtration
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What is Capsular Hydrostatic Pressure?
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It is the back pressure that opposes filtration
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What is the net filtration pressure in mm Hg?
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10
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What is Net Filtration Pressure?
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It is the Glomerular Hydrostatic pressure minus the osmotic pressure and capsule hydrostatic pressure
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Of the three pressures during Glomerular Filtration, which one favors filtration?
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Only the Glomerular Hydrostatic Pressure
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Which pressure is the back pressure that inhibits the Glomerular Filtration Rate?
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Blood Colloid Osmotic Pressure
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What is the Glomerular Filtration Rate?
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It is the rate at which filtrate forms
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NFP equals what?
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NFP equals GFR times resistance
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If pressure increases, what happens to flow?
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Flow increases as well
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How can changes in GFR occur?
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Any change in the 3 pressures can change the GFR
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Which pressure is the most likely to change?
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Glomerular hydrostatic pressure
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If BP increases, what happens to GFR?
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GFR increases as well
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How much blood is in the human body?
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Roughly 5 liters
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What is the typical GFR?
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180 liters filtrate per day or 125 ml/min
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Why must GFR be regulated?
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To allow adequate time for reabsorption and secretion
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What is the urine output per day?
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1.5 liters per day
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99% of filtrate is what?
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Reabsorbed!
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If GFR is too high, what happens?
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There is not enough time for reabsorption and you lose valuable solutes and ions in the urine
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If GFR is too low, what happens?
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There is too much time for reabsorption and you gain unwanted wastes in the blood
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Afferent and Efferent arterioles operate independently or dependently to control GFR?
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Independently!
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What is one way the body regulates the GFR?
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Through the Myogenic Mechanism
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What is the Myogenic Mechanism?
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It is a negative feedback mechanism where the smooth muscle in the afferent arteriole responds to moderate changes in blood pressure
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If systemic BP decreases, what happens?
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There is an immediate drop in GFR and less stretch on afferent arteriole.
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If the systemic BP decreases, what vasodilates?
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Afferent Arteriole vasodilates (relaxes)
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When the systemic BP decreases and the afferent arteriole vasodilates, what occurs?
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Blood flow and GFR increase back to normal
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If BP increases, what happens?
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GFR increases and more stretch on the afferent arteriole
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If the systemic BP increases, what vasoconstricts?
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The Afferent Arteriole vasoconstricts
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When the systemic BP increases and the afferent arteriole vasoconstricts, what occurs?
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Blood flow and GFR decrease back to normal
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What is the sympathetic effect on GFR?
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Extrinsic neural control where during an emergency sympathetic nerves fire and cause vasoconstriction of afferent arterioles and GFR decreases
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What happens to the blood when sympathetic nerves fire during an emergency?
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Blood is rerouted away from kidneys to other parts of the body like the brain and muscles
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What type of cells make up the walls of the renal tubule?
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Epithelial cells!
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Tubular reabsorption includes what types of transport?
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Active and Passive
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What are the two routes solutes and the like can take during tubular reabsorption?
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Transcellular (through the cells) and Paracellular (between the cells)
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What is the usual route for solutes and the like to travel during tubular reabsorption?
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Transcellular
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What is transcellular?
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Through the cells
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What is Paracellular?
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Between the cells
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What are the 4 main movements via transcellular route?
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1. Transport across the luminal membrane
2. Diffusion through the cytosol 3. Transport across the basolateral membrane 4. Movement through interstitial fluid into the capillary |
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What is the main movement via the paracellular route?
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Movement through the leaky tight junctions between cells
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What is the site of the most reabsorption?
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The main site of reabsorption is the Proximal Tubule
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What three things normally get reabsorbed?
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Nutrients like glucose and amino acids, ions, and small proteins
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Does reabsorption at the PCT depend on hormones?
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NO!
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What is the main reason why Na+ reabsorption is so important?
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Couldn't depolarize a neuron or muscle cell without it
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What is the other reason why Na+ reabsorption is so important?
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It provides the energy and the means for reabsorbing most other substances
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With diabetes mellitus, carriers during the reabsorption at the proximal tubule become what?
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Overwhelmed to where it can't reabsorb all the glucose
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What results when the carriers are overwhelmed and can't reabsorb glucose?
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Glucosuria (glucose lost in urine) and polyuria (water follows glucose)
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Reabsorption of HCO3- depends on what ion to be reabsorbed as well?
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Na+!
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Reabsorption of HCO3- is coupled with what ion being secreted?
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H+
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When blood is too acidic, is more HCO3- reabsorbed or secreted?
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Reabsorbed!
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When blood is too acidic, is more H+ reabsorbed or secreted?
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Secreted!
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Why is water reabsorbed by osmosis?
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Water follows Na+ and other solutes
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What is Urea?
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It is a lipid soluble waste product
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Urea follows water by what?
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"Solvent Drag"
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Cl- passively follows what ion?
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Na+
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Other ions including K+ are passively reabsorbed down what?
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Their concentration gradients!
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Kidneys work hard to maintain what ion's concentration gradient?
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Na+!
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The DECENDING limb of the loop of Henle is freely permeable to what? What is it not permeable to?
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Permeable to H2O, NOT permeable to NaCl
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The Ascending limb of the loop of Henle is permeable to what? What is it not permeable to?
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Permeable to NaCl and NOT permeable to water
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The longer the loop of Henle is...
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The more concentrated the urine can be!
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Reabsorption and secretion at the Distal Convoluted Tubule and Collecting Duct is regulated by what?
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HORMONES!
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The loop of Henle sets up what?
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Sets up a mechanism to produce concentrated urine
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What are the two hormones that regulate reabsorption and secretion at the DCT and collecting Duct?
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Aldosterone and Antidiuretic Hormone (ADH)
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What does Aldosterone control?
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Aldosterone controls the final reabsorption of Na+
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What does Antidiuretic Hormone (ADH) control?
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Controls final reabsorption of water
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What is the stimulus for aldosterone secretion?
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Low Na+ or high K+
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Where is Aldosterone secreted from?
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Adrenal Cortex
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Aldosterone targets what?
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Distal part of DCT and collecting ducts
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Aldosterone stimulates what?
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Na+ reabsorption and K+ secretion
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Aldosterone causes what to occur?
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More Na+ returns to the blood and more K+ is lost in the urine
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What does ADH prevent?
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ADH prevents diuresis which is the large loss of water in the urine
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What is the stimulus for ADH secretion?
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Dehydration and or high plasma Na+
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ADH targets what?
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ADH targets the collecting ducts to make them more permeable to water
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ADH causes what to occur?
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ADH causes water reabsorption to increase which lowers the plasma osmolarity
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ADH causes what to occur to urine secretion?
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ADH causes urine secretion to be scant and concentrated
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What is the main site of secretion?
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PCT
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Tubular Secretion eliminates what substances that have been passively reabsorbed?
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Urea and uric acid
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Tubular Secretion also disposes of what kind of substances?
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substances like drugs that are too large to filter
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How does Tubular Secretion control blood pH?
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It controls pH by changing H+ secretion
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