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65 Cards in this Set
- Front
- Back
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Function of Renal System
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Remove waste products like urea and creatinin
Regulate ion concentrations Secrete endocrine hormones |
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Capsule
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Surrounds kidney
Dense CT (dense regular and dense irregular collageous) |
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Renal Cortex
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periphery of the kidney
contains the glomeruli & renal corpuscles |
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Renal Medulla
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internal part of the kidney
striated appearance due to the presence of tubules Contains Pyramids and Rays |
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Afferent Arteriole
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Enters Glomerulus
Twice as big as efferent arterioles Has special cells responsible for regulating Blood Pressure Very thick wall because has elastic fibers, smooth muscle, CT fibers |
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Renal Corpuscle
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responsible for filtration through Glomerulus, Bowman's Capsule, and Space
Responsible for reabsorption through PCT, LoH, and DCT |
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Bowman's Capsule
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Two poles: Vascular and Urinary
Has parietal and visceral layers with Bowman's space in between Contains Podocyte cells in visceral layer Contains Intraglomerular Mesangial cells in basement membrane |
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Vascular Pole
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Where afferent arteriole enters and efferent arteriole exists Bowman's Capsule
Parietal and Visceral layers join here Contains Macula Densa of DCT to sense hormones and control blood pressure |
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Urinary Pole
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Where Bowman's Space becomes continuous with PCT
Where glomerular filtrate enters tubule system |
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Podocyte Cells
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Located within internal visceral layer of Bowman's Capsule
Produces Podocalyxin that gets deposited on top of slit membrane Functions in filtration |
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Intraglomerular Mesangial Cells
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Like a pericyte
Replace BM provides support Acts as a macrophage to eat things that leak out glomerulus Regenerates basal lamina Senses glomerular filtration rate and vasocontrictor/dilators and responds by expanding/contracting to change blood flow |
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Basement Membrane of Bowman's Capsule
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Many layers
Lamina Rara Externa is lighter region next to podocyte cells Lamina Dense is central darker region Lamina Rara Interna is lighter region next to endothelial cell |
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Filtration
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Passive Diffusion
1. materials leak out of the pores of the discontinuous endothelium RBC and large molecules blocked 2. Filtered by basal lamina Blocks molecules >150,000 MW 3. Filtered by slit membrane covered w/ podocalyxin Blocks molecules > 70,000 MW 4. Enters Bowman's space and becomes Globerular Filtrate |
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Resorption
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Active process that requires mitochondria and energy
Begins in PCT |
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PCT
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Longest most convulted portion of nephron
Most resorption here Low Columnar/Cuboidal w/ nucleus located away from base Basal striations of mitochondria Brush border/microvilli to increase surface area Lateral border interdigitates Conserves sodium and water |
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Loop of Henle
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establish an equilibrium in the surrounding tissue so that the DCT can complete the reabsorption process
modifies electrolyte balance via active transport and sodium pumps |
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Distal Convoluted Tubule
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Contains Macula Densa to regulate blood pressure
Site for urine acidification by absorption of sodium and release of H, ammonium, and K into filtrate Shorter, narrower than PCT Bigger lumen and thinner walls than PCT Cuboidal cells No brush border Lateral cell borders are smooth Less striations because less mitochondria Fluid is not URINE |
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Differences between PCT and DCT
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PCT
Longer, more convoluted Smaller lumen Thicker wall because Columnar cells Brush border Lateral borer interdigitation More striations DCT Shorter Less convoluted Bigger lumen Thinner wall because Cuboidal cells No brush border Lateral borders smooth Less striations |
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Collecting Ducts
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Principal site of urine acidification
Lines with simple columnar cells Ducts get very wide as it continues |
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What is the principle site of urine acidification
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Collecting Ducts
Though DCT has minor role |
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JG cells
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Cell of Juxtaglomerular Apparatus
Releases Renin Located in afferent arteriole |
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What releases Renin
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JG cells of Juxtaglomerular Apparatus
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Extraglomeular Mesangial Cells
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Component of Juxtaglomerular Apparatus
Outside Bowman Capsule's Vascular pole in between capillaries Receptors on cell respond to vasocontrictors/dilators |
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Macula Densa
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Component of Juxtaglomerular Apparatus
Has sensors to detect when blood pressure has dropped |
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How Renal increases blood pressure
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Macula densa sense drop in BP
Intraglomerular and Extraglomerula Mesangial cells receive signal from Macula Densa and stimulates JG cells JG cells secrete Renin and Angiotensinogen Angiotensinogen converts to Angiotensin-1 in lungs and then Angiotensin-2 (angiotonin) Angiotonin stimulates adrenal cortex to release Aldosterone to conserve water and sodium increases blood pressure Angiotonin also stimulates vasocontriction increases blood pressure |
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Angiotonin
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AKA Angiotensin-2
Increases blood pressure Formed in lungs Stimulates adrenal cortex to release Aldosterone Stimulates vasoconstriction of renal efferent arteriole |
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Aldosterone
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Released by adrenal cortex
Stimulated by Angiotonin Stimulates DCT to conserve water and sodium by regulating Na/K pump to increase blood pressure |
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How does Renal decrease blood pressure
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Medullary Interstitial cells secrete Medullipin-1 which is converted to Medullipin-2 to cause vasodilation
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Medullary Interstitial Cells
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Fibroblast like cells in Renal Interstitium of Medulla
Secrete steroid like hormone called Medullipin-1 to decrease blood pressure |
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Medullipin-2
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Converted from Medullipin-1 produced by Medullary Interstitial Cells
Causes vasodilation |
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Atrial Naturetic Peptides
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Produced by special cardiac myocytes
Causes vasodilation Decreases blood pressure |
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Ureter
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Transitional Epithelium
Dome cells Not attached by desmosomes |
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What happens in the Proximal Convoluted Tubule?
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2/3 of sodium, chloride, water get reabsorbed back into plasma
2/3 of potassium follows water out of filtrate through solvent drag Therefore 60L remaining (from 180L) |
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What happens in the Descending Loop of Henle?
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Water gets reabsorbed out due to the high interstitial osmolarity of medulla
Ions stay in filtrate Therefore, you have the same amount of solute but less water causing Filtrate to become Hypertonic and Osmolarity increases Therefore 36L remaining (from 60L from PCT) |
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Osmolarity of Cortex
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Isotonic
(310mos/kg of water) |
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Osmolarity of Medulla
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Osmolarity increases as you go deeper from isotonic to hypertonic (310 - 1200mos/kg of water)
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What happens in the Ascending Loop of Henle?
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Impermeable to water so no net movement of water
Remains 36L Sodium, Potassium and 2 Chlorides resorbed via facilitated transport Filtrate becomes hypotonic and osmolarity decreases (285mosm/kg water = less than cortex tissue which is 310) Creates medullary enviornment |
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What happens in the Distal Convoluted Tubule?
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Half of water and solutes from ALH gets resorbed
18L remaining (from 36L) |
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What occurs if glomerular filtrate is too high
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Means too much fluid going through too fast
Not enough time for efficient solute removal in ALH When it reaches Macula Densa in DCT, osmolarity is measured as too high (higher than 285mOs) Turns down Renin and dopamine secretion But you still get 2/3 resorption of water |
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What occurs if glomerular filtrate is too low
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Means too little fluid is going through too slow
Too much time for solute removal in ALH When it reaches Macula Densa in DCT, osmolarity is measured as too low (lower than 285mos) Secretes Renin to constrict efferent arteriole Secretes dopamine to dilate afferent arteriole |
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What happens in the Collecting Ducts?
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Absorbs most water remaining due to high osmolarity in medulla
2L remaining (from 18L) Not freely permeable to water. Requires ADH |
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Anti-Diuretic Hormone
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ADH AKA Vasopressin
Produced by hypothalamus (Secreted by Pars Nervosa of Pituitary) in response to low plasma sodium levels and water imbalance Causes more resorption of water in Collecting Ducts by making it more permeable It increases blood pressure Decreases urine excreted |
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Diabetes Insipidus
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caused by a lack of ADH due to pathology in the hypothalamus / pituitary gland
Prevents collecting duct to reabsorbed water therefore 18L of filtrate is excreted instead of 2L Causes Polydypsia (excessive pee) Causes polyuria (thirsty) |
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Glucose resorption
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Glucose is permeable through glomerulus
But 100% resorbed in PCT But if there is too much glucose in the blood, the carrier proteins reach saturation level and cannot absorb more Therefore most glucose in filtrate, causing water to flow into filtrate making more urine Leads to diabetes mellitus |
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What is clearance of glucose
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Zero
There should be no glucose in urine |
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Transport Maximum
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point no more glucose is reabsorbed
there is saturation of glucose carriers reabsorption can’t keep up with filtration |
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Diabetes Mellitus
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when glucose filtration exceeds glucose reabsorption, you have reached transport maximum
b/c there’s more solute (glucose) in the filtrate there is less osmotic pressure which causes less water reabsorption and leads to polyuria |
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Calcium resorption
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50% of Calcium bound to plasma so cannot enter glomerular filtrate
Remaining freely enters filtrate Strong interactions with cell membrane in PCT causes little resorption 90% is resorbed by proximal part of DCT PTH stimulates Calcium ATPase pumps in distal part of DCT for 100% resorption |
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Parathyroid Hormone
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PTH
Secreted by parathyroid glands in response to low Calcium plasma levels Stimulates Calcium ATPase in distal part of DCT for resorption of calcium from filtrate |
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Potassium resorption
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Enters glomerular filtrate freely
80% resorbed in PCT due to solvent drag Solvent drag continues resorption in DCT Distal portion of DCT uses Na/K ATPase to secrete 2K out for 3Na in This is regulated by Aldosterone for sodium reabsorption |
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Vasa Recta
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Special capiillaries in medulla
Water leaves vasa recta as it descends and reduces diameter of capillary As it ascends up, water from kidney enters which removing solutes of kidney |
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Clearance
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[(Concent of A in urine)(Urine Output Rate/Time)]/(Concent of A in plasma)
OR (excretion rate of A) + (Concent of A in plasma) |
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Inuline
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Used to measure clearance
Freely filterable in glomerulus but not resorbable therefore all exits urine inulin clearance = excretion rate of inulin / [inulin]plasma OR Inulin clearance = inulin GFR Figured GFR is 180L/day If clearance of molecule is greater than 180L/day, then it is getting secreted If clearance is less than 180L/day then its getting resorbed |
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Vit D
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Kidney converts 25-hydroxy Vit D from liver into activated 1,25-dihydroxy Vit D
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Hydrostatic pressure in afferent arteriole
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60mmHg
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Hydrostatic pressure in efferent arteriole
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20mmHg
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Where is MAP higher?
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In glomerulus capillary bed (60mmHg)
Higher than anywhere else in body Hydrostatic pressure drives process of glomerular filtration |
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Which arteriole has greater hematocrit levels
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Efferent hematocrit > afferent hematocrit because plasma is filtered out and RBC remain
Efferent hematocrit = 50% Afferent hematocrit = 40% |
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Filtration Fraction
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glomerular filtration rate ÷ afferent arteriole flow
20% of plasma entering afferent arteriole gets filtered 80% is returned to circulatory system via efferent arteriole |
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What is the major pH buffer in the body?
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Bicarbonate
Concentration of 24mM in plasma |
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What occurs if you increase CO2 through hypoventilation?
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Causes right shift of system (Respiratory acidosis)
Lower pH levels results Renal tries to compensate by increasing reabsorption of bicarbonate in filtrate in increase bicarbonate plasma concentration |
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What occurs if you decrease CO2 through hyperventilation?
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Leads to left shift of system (Respiratory alkalosis)
Higher pH levels results Renal tries to compensate by increasing urine excretion to lower bicarbonate concentrations in plasa |
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What occurs if you have excess acid levels because you are exercising and metabolizing faster causing neutralizationg of bicarbonate concentrations?
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Leads to down shift of system (Metabolic acidosis)
Lower pH levels results Lung tries to compensate by increasing breathing rate to lower CO2 levels (not to increase O2 levels!!) |
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What occurs if you over ingest alkaline medication like Tums and increase bicarbonate levels?
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Causes up shift in system (Metabolic Alkalosis)
Higher pH levels results Lung tries to compensate by decreasing breathing rate so levels of carbon dioxide increase |
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How to calculate pH levels due to bicarbonate buffering
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pH = pK + log (base/acid)
Base (bicarbonate) = HCO3- = 24 mM Acid (carbonic acid) = H2CO3 = (0.03) PCO2 = (0.03)(40mmHg) pK of bicarbonate = 6.1 SO pH = 6.1 + log (24/0.03 x 40) = 7.4 |
