Nutrition and Metabolism 2 PDF

24.3 Role of Metabolism Anabolism and Catabolism  Anabolism: synthesis of large molecules from small ones (example: synthesis of proteins from amino acids Always wild  Catabolism: hydrolysis of complex structures to simpler on...

24.3 Role of Metabolism Anabolism and Catabolism  Anabolism: synthesis of large molecules from small ones (example: synthesis of proteins from amino acids Always wild  Catabolism: hydrolysis of complex structures to simpler ones (example: breakdown of proteins into amino acids) same root as stastroph hydrolysis hydrolyze breaking down polymers Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Anabolism and Catabolism (cont.)  Cellular respiration: catabolic breakdown of food fuels whereby energy from food is captured to form ATP in cells Goal of cellular respiration is to trap chemical energy in ATP ― Energy can also be stored in glycogen and fats, which can be broken down later  Phosphorylation: enzymes shift high-energy phosphate groups of ATP to other molecules Phosphorylated molecules become activated to perform cellular functions of making ATP D quick Bio 202 A&P ASU DPC T. Penkrot dirty way © 2016 Pea rs on Education, Inc.  Anabolism and Catabolism (cont.)  Three stages in processing nutrients Stage 1: Digestion, absorption, and transport to tissues Stage 2: Cellular processing (in cytoplasm) ― Synthesis of lipids, proteins, and glycogen, or ― Catabolism (glycolysis) into pyruvic acid and acetyl CoA Stage 3: Oxidative breakdown of intermediates into CO2, water, and ATP ― Occurs in mitochondria  Cellular respiration consists of glycolysis of stage 2 and all of stage 3 Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.3 Three stages of metabolism of energy-containing nutrients. Stage 1: GI Tract Nutrients are: Digested into absorbable units. Absorbed into the blood and transported to tissue cells. PROTEINS CARBOHYDRATES FATS Amino acids Glucose and other sugars Glycerol Fatty acids Stage 2: Tissue Cells Anabolism or catabolism: Proteins Glucose Glycogen Triglycerides In anabolism, nutrients are Glycolysis built into macromolecules. In catabolism, nutrients are broken down to pyruvic acid and acetyl CoA. Glycolysis is the major catabolic pathway. NH 3 Pyruvic acid all eventually converge into this Acetyl CoA Stage 3: Mitochondria Oxidative breakdown of stage 2 products: Citric SEYEmedia CO2 is released. acid The H atoms removed are ultimately Infrequent cycle CO2 delivered to molecular oxygen, forming water. Some of the energy released is used O2 are used to form ATP. The citric acid cycle and oxidative phoshorylation are the major pathways. Oxidative phosphorylation H H 2O (in electron transport chain) Catabolic reactions Anabolic reactions key ATP ATP ATP Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Oxidation-Reduction Reactions and the Role of Coenzymes  Oxidation reactions: involve the gain of oxygen or loss of hydrogen atoms (and their electrons)  Oxidation-reduction (redox) reactions Oxidized substances lose electrons and energy Reduced substances gain electrons and energy Redox reactions are catalyzed by enzymes that usually require a B vitamin coenzyme Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  ATP Synthesis  Two mechanisms are used to make ATP from captured energy that is liberated during cellular respiration direct phosphorylation 1. Substrate-level phosphorylation ― High-energy phosphate groups are directly transferred from phosphorylated substrates to ADP ― Ex.= phosphagen system in skeletal muscle Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.4a Mechanisms of phosphorylation. Substrate-level phosphorylation A high-energy phosphate group is transferred directly from a substrate to ADP to form ATP. Occurs in the cytosol and mitochondrial matrix. source molecule P of phosphate ADP Substrate group Enzyme ex creatine phosphate Catalysis I per substrate molecule ATP Product product waste catalyzes Enzyme reaction ex creatin Bio 202 A&P ASU DPC T. Penkrot kinase © 2016 Pea rs on Education, Inc.  ATP Synthesis (cont.) Oz needed mitochondria 2. Oxidative phosphorylation ― More complex process, but produces most ATP ― Chemiosmotic process: couples movement of substances across membranes to chemical reactions  Energy released from oxidation of food is used to pump H+ across inner mitochondrial membrane, creating a steep H+ concentration gradient Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.4b Mechanisms of phosphorylation. Oxidative phosphorylation differ Electron transport proteins “pump” protons, creating a proton gradient. Protonsmem ATP synthase uses the energy of the proton gradient to bind phosphate groups to ADP. across Occurs only in the mitochondrial matrix. High H+ concentration in intermembrane space turbine Inner MY mitochondrial membrane water Proton pumps mill (electron transport chain) H+ stainlunt ATP synthase of lots Energy from food ADP + Pi ATP Low H+ concentration in mitochondrial matrix Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Oxidation of Glucose  Glucose is catabolized via following reaction: C6H12O6 + 6O2 6H2O + 6CO2 + 32 ATP + heat glucose offsettoewecteteer oxygen water carbon dioxide  Complete glucose catabolism requires three pathways in half 1. Glycolysis splitting glucose 2. Krebs cycle citric acid cycle making 3. Electron transport chain and oxidative phosphorylation Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.5 During cellular respiration, ATP is formed in the cytosol and in the mitochondria. Chemical energy (high-energy electrons) Chemical energy Electron transport O Glycolysis Pyruvic Citric acid chain and oxidative phosphorylation Glucose cycle acid Inner Mitochondrion Cytosol mitochondrial membrane (cristae) Via oxidative phosphorylation Via substrate-level phosphorylation Lots of ATP ATP ATP ATP 1 Glycolysis, in the cytosol, 2 The pyruvic acid then enters 3 Energy-rich electrons picked up breaks down each glucose the mitochondrial matrix, where by coenzymes are transferred to molecule into two molecules the citric acid cycle oxidizes it to the electron transport chain, built into of pyruvic acid. CO2. During glycolysis and the the inner mitochondrial membrane. The citric acid cycle, substrate-level electron transport chain carries out phosphorylation forms small oxidative phosphorylation, which amounts of ATP. generates most of the ATP in cellular Bio 202 A&P ASU DPC T. Penkrot respiration. © 2016 Pea rs on Education, Inc. Figure 24.7 Simplified version of the citric acid (Krebs) cycle. Glycolysis Citric acid cycle Electron transport chain and oxidative Carbon atom CO is important phosphorylation Pi Inorganic phosphate CoA Coenzyme A ATP ATP ATP Cytosol Pyruvic acid from glycolysis Mitochondrion CO2 NAD+ generate ATPtorun (matrix) Transitional NADH + H+ phase CoA Acetyl CoA electron transport Oxaloacetic acid Citric acid (pickup molecule) (initial reactant) NADH + H+ CoA NAD+ chain Malic acid Isocitric acid NAD+ Citric acid CO2 cycle NADH + H+ Fumaric acid a-Ketoglutaric acid CoA CO2 FADH2 NAD+ bit of Succinic acid Succinyl-CoA NADH + H+ FAD CoA GTP GDP + Pi little ATP ATP ADP Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Oxidation of Glucose (cont.)  Electron transport chain and oxidative phosphorylation Oxidative phosphorylation consists of two phases: Phase 1: Electron transport chain creates a proton (H+) gradient across mitochondrial membrane using high-energy electrons removed from H from food fuels Phase 2: Chemiosmosis uses the energy of the proton gradient to synthesize ATP ATP synthase driven by Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.11 Energy yield during cellular respiration. Mitochondrion Cytosol 2 NADH + H+ Electron 2 NADH + H+ 6 NADH + H+ 2 FADH2 shuttle across mitochondrial membrane Glycolysis 2 Citric Electron transport Acetyl acid chain and oxidative Pyruvic cycle phosphorylation Glucose CoA acid (4 ATP – 2 ATP 10 NADH + H+  2.5 ATP used for activation 2 FADH2  1.5 ATP energy) Net +2 ATP +2 ATP + about 28 ATP by substrate-level by substrate-level by oxidative phosphorylation phosphorylation phosphorylation –2 ATP (average shuttle cost) 80 Typical About ATP yield 30 ATP per glucose Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Glycogenesis, Glycogenolysis, and Gluconeogensis  Cells cannot store large amounts of ATP  Glycogenesis stores glucose by making Glycogen can be formed with excess glucoseglycogen to store Mostly occurs in liver and skeletal muscle cells  Glycogenolysis Ginb meas Breakdown of glycogen via glycogen phosphorylase in p response to low blood glucose breakdown glycogen Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.13 Glycogenesis and glycogenolysis. Glycogenesis Glycogenolysis Synthesizes glycogen from Breaks down glycogen to glucose release glucose Occurs when glucose Stimulated by low blood supplies exceed demand glucose for ATP Cell Blood glucose exterior Hexokinase (present in all cells) Glucose-6-phosphatase Pi (present in liver, kidney, and intestinal cells) ATP ADP Glucose-6-phosphate Glucose-1-phosphate Pi Glycogen Glycogen phosphorylase synthase Pi Glycogen Cell interior Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Glycogenesis, Glycogenolysis, and Gluconeogensis (cont.) new neo  Gluconeogenesis genesis build Process of forming new (neo) glucose from noncarbohydrate sources fats proteins Occurs in the liver triglycerides Glucose can be formed from glycerol and amino acids when blood glucose levels drop Protects against damaging effects of hypoglycemia ― Especially important for nervous system Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.12 Quick summary of carbohydrate reactions. Glycolysis: Converts glucose to pyruvic acid Glycogenesis: Polymerizes glucose to form glycogen Glycogenolysis: Hydrolyzes glycogen to glucose monomers Gluconeogenesis: Forms glucose from noncarbohydrate precursors on exam Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  24.5 Lipid Metabolism  Lipids provide a greater energy yield than from glucose or protein catabolism Fat catabolism yields 9 kcal per gram versus 4 kcal per gram of carbohydrate or protein fatathas  So, why don’t we *mainly* use fats to get our energy…?  Only triglycerides are routinely oxidized for energy  Two building blocks of triglycerides are oxidized separately 1. Glycerol breakdown treat it as glucose 2. Fatty acid breakdown ― Fatty acids undergo beta oxidation in mitochondria Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Tetones Figure 24.15 Lipid oxidation. store fat dietary fat Triglycerides Lipase main Masically reated same 0 Glycerol 0 Fatty acids as glucose H2 O ATP Coenzyme A Glyceraldehyde NAD+ Beta oxidation in the mitochondria 3-phosphate generates (a glycolysis intermediate) NADH + H+ Glycolysis FAD ketones Pyruvic acid FADH2 Cleavage enzyme snips off 2C fragments Acetyl CoA Citric acid cycle Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Lipogenesis  Lipogenesis: triglyceride synthesis that occurs when cellular ATP and glucose levels are high stores extra calories  Dietary glycerol and fatty acids not needed for energy are stored as triglycerides 50% is stored in adipose tissue; other 50% is deposited in other areas  Glucose is easily converted to fat because acetyl CoA is an intermediate in glucose catabolism and the starting point for fatty acid synthesis easy to convert between fuel sources Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Lipolysis (cont.)  Lipolysis: breakdown of stored fats into glycerol and fatty acids; reverse of lipogenesis Fatty acids are actually preferred by liver, cardiac muscle, resting skeletal muscle for fuel Lipolysis is accelerated when carbohydrate intake is inadequate  Lipolysis (cont.) ― Accumulated acetyl CoA can be converted by ketogenesis in liver to ketone bodies (ketones) ― So, what’s the issue with ketone bodies?? Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Lipogenesis (cont.)  Lipolysis (cont.) ― Accumulated acetyl CoA can be converted by ketogenesis in liver to ketone bodies (ketones) ― So, what’s the issue with ketone bodies?? I leads to metabolic acidosis Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.16 Lipid metabolism. know beta oxidation step is what causes ketone Glycolysis bodies Ap Glucose Stored fats in Glycerol adipose tissue Lipogenesis Triglycerides Glyceraldehyde 3-phosphate o Dietary fats Fatty acids Pyruvic acid Certain amino acids Ketone Ketogenesis (in liver) Acetyl CoA bodies Steroids Electron ATP Cholesterol Bile salts Citric transport acid chain + Catabolic reactions cycle CO2 + H2 O Anabolic reactions Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 24.14 Quick summary of lipid reactions. Beta oxidation: Converts fatty acids to acetyl CoA Lipolysis: Breaks down lipids to fatty acids and glycerol Lipogenesis: Forms lipids from acetyl CoA and glyceraldehyde 3-phosphate Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Water, ARIZONA STATE UNIVERSITY College of Integrative Sciences & Arts Electrolyte, & iIiiiirfr hp.im Acid-Base Balance Bio 202 BID 2h22 WAI MY & A natomy Physiology PEPSI II I GRIT Tonya na A. Penkrot, 307 t Ph.D. 7  26.1 Body Fluid Compartments Body Water Content  Infants are 73% or more water (low body fat, low bone mass)  Adult males: ~60% water C Adult females: ~50% water (higher fat content, less skeletal muscle mass) Adipose tissue is least hydrated tissue of all Total body water in adults averages ~40 L  Water content declines to ~45% in old age © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Figure 26.1 The major fluid compartments of the body. Total body water Volume = 40 L 60% of body weight Volume = 3 L, 20% of ECF Plasma Intracellular fluid (ICF) Interstitial fluid (IF) Volume = 25 L Volume = 12 L 40% of body weight 80% of ECF Extracellular fluid (ECF) Volume = 15 L 20% of body weight © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Composition of Body Fluids (cont.) Electrolytes ― Dissociate into ions in water  Examples: inorganic salts, all acids and bases, some proteins ― Ions conduct electrical current ― Greater osmotic power than nonelectrolytes  Greater ability to cause fluid shifts due to ability to dissociate into two or more ions  NaCl Na+ + Cl− (electrolyte; 2 particles)  MgCl2 Mg2+ + 2Cl− (electrolyte; 3 particles)  glucose glucose (nonelectrolyte; 1 particle) © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Figure 26.2 Electrolyte composition 160 of blood plasma, interstitial fluid, and intracellular fluid. sniper superabundant abundant ICF 140 in ECF 120 Natis Total solute concentration (mEq/L) IN Blood plasma Interstitial fluid 100 WY Intracellular fluid Ktis Na+ Sodium 80 K+ Potassium Ktis Ca2+ Calcium OUT Mg2+ Magnesium Bicarbonatesuper 60  HCO3 CI Chloride abund HPO4 2  Hydrogen phosphate in ICF 40 SO4 2  Sulfate Where is Na 20 kt most abundant know this 0 DO   Na+ K+ Ca2+ Mg2+ HCO3 CI HPO42 SO42 Protein © 2016 Pea rs on Education, Inc. anions Bio 202 A&P ASU DPC T. Penkrot  Figure 26.3 Exchange of gases, nutrients, water, and wastes between the three fluid compartments of the body. Lungs Gastrointestinal Kidneys tract Blood O2 CO2 Nutrients H2O, H2O, Nitrogenous plasma Ions Ions wastes O2 CO2 Nutrients H2O Ions Nitrogenous Interstitial wastes fluid Intracellular fluid in tissue cells © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  26.2 Water Balance and ECF Osmolality  Water intake must equal water output: ~2500 ml/day  Water intake: most water is taken in via ingested foods and beverages, but small amount from metabolism Tehydration Metabolic water (water of oxidation): water produced by cellular metabolism synthesis  Water output: urine (60%), insensible water loss (lost through skin and lungs), perspiration, and feces © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot 26.2 Water Balance and ECF Osmolality  Osmolality is maintained around 280–300 mOsm  Rise in osmolality 1 Change Stimulates thirst Causes ADH release triggers  Decrease in osmolality Causes thirst inhibition Causes ADH inhibition © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Figure 26.4 Major sources of water intake and output. 100 ml Feces 4% Metabolism 10% 250 ml Sweat 8% 200 ml Insensible loss Foods 30% via skin and 750 ml 700 ml lungs 28% 2500 ml 1500 ml Urine 60% Beverages 60% 1500 ml Average intake Average output per day per day © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Regulation of Water Intake  Thirst mechanism is driving force for water intake  Governed by hypothalamic thirst center Hypothalamic osmoreceptors detect ECF osmolality and are activated by: dehydration ― Increased plasma osmolality of 1–2% ― Dry mouth ― Decreased blood volume or pressure ― Angiotensin II or baroreceptor input © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Figure 26.5 The thirst mechanism for regulating water intake. ECF osmolality Plasma volume (5–10%) Blood pressure Osmoreceptors Saliva Granular cells in hypothalamus in kidney Renin-angiotensin- aldoster one Dry mouth mechanism Angiotensin II Hypothalamic thirst center Sensation of thirst; person takes a drink Water moistens mouth, throat; stretches stomach, intestine Water absorbed from GI tract Initial stimulus Physiological response ECF osmolality Result Plasma volume Increases, stimulates © 2016 Pea rs on Education, Inc. Reduces, inhibits Bio 202 A&P ASU DPC T. Penkrot  Figure 26.6 Mechanisms and consequences of ADH release. ECF osmolality Na+ concentration in plasma Plasma volume Stimulates (5–10%), BP Osmoreceptors Inhibits in hypothalamus Negative feedback inhibits Baroreceptors in atria and Stimulates large vessels Stimulates Posterior pituitary Releases ADH Antidiuretic more aquapuring hormone (ADH) Targets Collecting ducts added to of kidneys Effects collecting Water reabsorption Results in ducts ECF osmolality Scant urine Plasma volume © 2016 Pearson Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Disorders of Water Balance  Three principal abnormalities of water balance 1. Dehydration ― ECF water loss due to hemorrhage, severe burns, prolonged vomiting or diarrhea, profuse sweating, water deprivation, diuretic abuse, endocrine disturbances Sticky dry ― Signs and symptoms: “cottony” oral mucosa, thirst,dry flushed skin, oliguria evensuii.ie ― May lead to weight loss, fever, mental confusion, hypovolemic shock, and loss of electrolytes nausea © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Slide 1 Figure 26.7a Disturbances in water balance. 1 Excessive 2 ECF osmotic 3 Cells lose loss of H2O pressure rises H2O to ECF from ECF by osmosis; cells shrink Consequences of dehydration. If more water than solutes is lost, cells shrink. © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Disorders of Water Balance (cont.) 2. Hypotonic hydration ― Cellular overhydration, or water intoxication ― Occurs with renal insufficiency or rapid excess water ingestion ― ECF osmolality decreases, causing hyponatremia  Results in net osmosis of water into tissue cells and swelling of cells  Symptoms: severe metabolic disturbances, nausea, vomiting, muscular cramping, cerebral edema, and possible death 2x normal Saline Treated with hypertonic saline concentrated w © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot salt  Slide 1 Figure 26.7b Disturbances in water balance. 1 Excessive 2 ECF osmotic 3 H2O moves into H2O enters pressure falls cells by osmosis; the ECF cells swell Consequences of hypotonic hydration (water gain). If more water than solutes is gained, cells swell. © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Disorders of Water Balance (cont.) 3. Edema ― Atypical accumulation of IF, resulting in tissue swelling (not cell swelling)  Only volume of IF is increased, not of other compartments ― Can impair tissue function by increasing distance for diffusion of oxygen and nutrients from blood into cells Could be caused by increased fluid flow out of blood or decreased return of fluid to blood © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot Central Role of Sodium in Fluid and Electrolyte Balance  Sodium is most abundant cation in ECF 0  Only cation exerting significant osmotic pressure is Na+ Controls ECF volume and water distribution because water follows salt Changes in Na+ levels affects plasma volume, blood pressure, and ECF and IF volumes  There are no known receptors that monitor Na+ levels in body fluids macula densa cells  Na+-water balance is linked to blood pressure and blood volume control mechanisms  Changes in blood pressure or volume trigger neural and hormonal controls to regulate Na+ content © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Regulation of Sodium Balance (cont.) know the angiotensin renin mechanism  Influence of aldosterone and angiotensin II (cont.) Renin catalyzes production of angiotensin II exam ― Prompts aldosterone release from adrenal cortex ― Results in increased Na+ reabsorption by kidney tubules Aldosterone release is also triggered by elevated K+ levels in ECF c Aldosterone brings about its effects slowly (hours to days) © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Figure 26.8 Mechanisms and consequences of aldosterone release. Body Na+ content K+ concentration triggers renin release, in the ECF increasing angiotensin II Stimulates Adrenal cortex Releases Aldosterone Targets waterf y Kidney tubules Effects 00 Na+ reabsorption K+ secretion Restores Homeostatic plasma levels of Na+ and K+ © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Regulation of Sodium Balance (cont.) anti aldosterone  Influence of atrial natriuretic peptide (ANP) Released by atrial cellsJurine in response to stretch caused by increased blood pressure Effects ― Decreases blood pressure and blood volume  Inhibits ADH, renin, and aldosterone production  Increases excretion of Na+ and water Nat H2O loses opposite of © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot aldosterone  Figure 26.9 Mechanisms and consequences of ANP release. Stretch of atria of heart due to BP Releases Negative feedback Atrial natriuretic peptide (ANP) Targets Granular cells Hypothalamus and Adrenal cortex of the kidney posterior pituitary Effects Effects Renin release* ADH release Aldosterone release Angiotensin II Inhibits Inhibits Collecting ducts of kidneys Vasodilation Effects Na+ and H 2O reabsorption Results in Blood volume Results in Blood pressure © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Regulation of Sodium Balance (cont.) all steroids are similar  Influence of other hormones Female sex hormones to ― Estrogens: increase NaCl reabsorption (like aldosterone)  Leads to H2O retention during menstrual cycles and pregnancy ― Progesterone: decreases Na+ reabsorption (blocks aldosterone)  Promotes Na+ and H2O loss Glucocorticoids © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot scortisI ― Increase Na+ reabsorption and promote edema  Figure 26.10 Mechanisms regulating sodium and water balance help maintain blood pressure homeostasis. Systemic blood pressure/volume exam Stretch in afferent arterioles Filtrate NaCl concentration in ascending limb of nephron loop Inhibits baroreceptors in blood vessels Aft (+ ) (+ ) (+ ) (+ ) Sympathetic Granular cells of kidneys nervous system Release (+ ) Renin Systemic arterioles Catalyzes conversion Causes vapor Angiotensinogen Angiotensin I Vasoconstriction (from liver) Results in renin Converting enzyme (in lungs) Peripheral resistance (+ ) Angiotensin II Posterior pituitary (+ ) (+ ) G (+ ) Releases Systemic arterioles Adrenal cortex ADH (antidiuretic hormone) Causes Secretes (+ ) Vasoconstriction Aldosterone yg.gg Collecting ducts Results in Targets of kidneys Causes Peripheral resistance Distal kidney tubules H2O reabsorption Causes Na+ (and H2O) reabsorption Results in Blood volume (+ ) stimulates aldosterone Blood pressure Renin-angiotensin-aldosterone mechanism Neural regulation (sympathetic mechanism nervous system effects) ADH release and effects © 2016 Pearson Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Regulation of Potassium Balance  Importance of potassium Affects resting membrane potential (RMP) in neurons and muscle cells (especially cardiac muscle) ― Increases in ECF [K+] (hyperkalemia) cause decreased RMP, causing depolarization, followed by reduced excitability ― Decreases in ECF [K+] (hypokalemia) cause hyperpolarization and nonresponsiveness Disruption in [K+] (hyper- or hypokalemia) in heart can interfere with electrical conduction, leading to sudden death © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Regulation of Potassium Balance (cont.)  K+ is also part of body’s buffer system  H+ shifts in and out of cells in opposite direction of K+ to maintain cation balance, so: ECF K+ levels rise with acidosis same direct ECF K+ levels fall with alkalosis as Ht  Regulatory site: the DCT and collecting duct K+ balance is controlled in cortical collecting ducts by regulating amount secreted into filtrate aldosterone Kidneys have limited ability to retain K+, so most K+ is lost in urine; may lead to deficiency if not replaced in diet © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Figure 16.12 Effects of parathyroid hormone on bone, the kidneys, and the intestine. Hypocalcemia (low blood Ca2+) PTH release from H exam on hear calcium PTH parathyroid gland PTH lower blood Osteoclast activity Ca2+ reabsorption Activation of in bone causes Ca2+ in kidney tubule vitamin D by kidney and PO43– release Ca by into blood PTH Ca2+ absorption inhibition from food in small intestine Initial stimulus Physiological response Ca2+ in blood Result © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  Regulation of Anions  Cl– is major anion accompanying Na + in ECF Helps maintain osmotic pressure of blood 99% of Cl– is reabsorbed under normal pH ― Passively follows Na+ in PCT and is coupled to active transport of Na+ in other tubule segments  When acidosis occurs, fewer chloride ions are 0 reabsorbed in lieu of HCO3– © 2016 Pea rs on Education, Inc. Bio 202 A&P ASU DPC T. Penkrot  26.4 Acid-Base Balance  pH affects all functional proteins and biochemical reactions, so it is closely regulated by the body  Normal pH of body fluids to Arterial blood: pH 7.4 ON EXAM Venous blood and interstitial fluid: pH 7.35 ICF: pH 7.0 1  Alkalosis or alkalemia: arterial pH >7.45  Acidosis or acidemia: arterial pH 1 million per kidney  Two main parts Renal corpuscle filtration happens Renal tubule here reabsorption secretion happens here another chance to add Stuff to Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. filtrate Figure 25.6 Location and structure of nephrons. Renal cortex Renal medulla Renal pelvis Gl omerular ca psule: parietal layer Ureter Basement membrane Podocyte Kidney Fenestrated twisted endothelium LO Renal corpuscle Glomerular capsule of the glomerulus Glomerulus Gl omerular ca psule: vi sceral l ayer Di s tal convol uted Apical microvilli tubul e Mitochondria Highly Proxi ma l infolded convol uted basolateral tubul e membrane Proxi ma l convoluted tubule cells Cortex Apical side Medulla Basolateral side Thick segment Di s tal convoluted tubule cells Thin segment Nephron l oop Descending limb Ascending limb Col l ecting Nephron l oop (thin-segment) cells duct Principal cell Intercalated cell Col l ecting duct cells Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 25.12a The filtration membrane. Glomerular capsular space Collanderin Efferent arteriole small a kitchen sink omy smalles big stuff is filte through Afferent faucet drain arteriole Going Proximal tone convoluted Collander Glomerular capillary tubule covered by podocytes Parietal layer that form the visceral layer of glomerular everything is mall of glomerular capsule capsule that guesthru Renal corpuscle Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Big stuff stays in Bloodstream Figure 25.12b The filtration membrane. collander 3 things that Cytoplasmic extensions of podocytes this fluid has to go Filtration slits thru 1 Fenestrati Podocyte cell body 2 surroundin capillary 3 pudocyte fenestrated capillaries Fenestrations (pores) Glomerular capillary endothelium (podocyte covering and basement Foot processes membrane removed) D surrounding of podocyte capillary Glomerular capillary surrounded by podocytes Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 25.12c The filtration membrane. Filtration slits Podocyte cell body Foot processes Bio 202 A&P ASU DPCFiltration T. Penkrot slits between the podocyte foot processes © 2016 Pea rs on Education, Inc. Figure 25.7 Renal cortical tissue. Renal corpuscle Proximal Squamous epithelium convoluted of parietal layer of tubule (fuzzy glomerular capsule lumen due to long microvilli) Glomerular capsular space Distal convoluted Glomerulus tubule (clear lumen) merulus Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. Figure 25.8 Cortical and juxtamedullary nephrons, and their blood vessels. Cortical nephron Juxtamedullary nephron Short nephron loop Long nephron loop Glomerulus further from Glomerulus closer to the the cortex-medulla junction cortex-medulla junction Efferent arteriole Gl omerulus Efferent Cortical radiate vein Efferent arteriole supplies supplies peritubular (capillaries) a rteri ole Cortical radiate artery vasa recta capillaries Renal 20 Of corpuscle Glomerular Afferent arteriole capsule Collecting duct 80 Of nephrons Proximal Distal convoluted tubule convoluted Afferent arteriole tubule Efferent a rteri ole nephrons Peri tubular cortec on ca pi llaries Ascending limb of nephron loop Cortex-medulla junction Arcuate vein med Kidney Va s a recta Arcuate artery Nephron loop Descending Every long limb of nephron loop very loop increases Shortloop Water reabsorption Pott surrounds reabsorption surrounds nephron pct Bio 202 A&P ASU DPC T. Penkrot secretion loop water © 2016 Pea rs on Education, Inc. Figure 25.9 Blood vessels of the renal cortex. eabsurption Peritubular capillary bed Afferent arteriole Glomerulus Efferent arteriole Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc.  Juxtaglomerular Complex (JGC) (cont.) to glomerulus next  Each nephron has one juxtaglomerular complex (JGC): 1. Macula densa dense spot ― Contain chemoreceptors that sense NaCl content of filtrate how concentrated is filtrate 2. Granular cells (juxtaglomerular, or JG cells) ― Act as mechanoreceptors to sense blood pressure in afferent arteriole ― Contain secretory granules that contain enzyme renin BP 3. Extraglomerular mesangial cells May pass signals between macula densa and granular cells linesmouth muscle Bio 202 A&P ASU DPC T. Penkrot act © 2016 Pea rs on Education, Inc.  ra Figure 25.10 Juxtaglomerular complex (JGC) of a nephron. Glomerular Efferent arteriole capsule Glomerulus nephron Parietal layer Foot processes of glomerular of podocytes Podocyte cell body capsule (visceral layer) Capsular Red blood cell space loopasitenterscorte.gg Afferent Efferent arteriole I Proximal arteriole tubule cell Juxtaglomerular Complex: Macula densa cells of the ascending limb of nephron loop Extraglomerular Lumens of mesangial cells glomerular 8 capillaries Granular cells Endothelial cell Tsurround afferent Afferent arteriole of glomerular capillary Glomerular mesangial arteriole make renin cells helpsset Juxtaglomerular complex Renal corpuscle Bio 202 A&P ASU DPC T. Penkrot © 2016 Pea rs on Education, Inc. GFR  25.3 Physiology of Kidney  180 L of fluid processed daily, but only 1.5 L of urine is formed  Kidneys filter body’s entire plasma volume 60 times each day intensive energy  Consume 20–25% of oxygen used by body at rest  Filtrate (produced by glomerular filtration) is basically blood plasma minus proteins  Urine is produced from filtrate 991 or more has to be Urine ―