PET3323 Exam 4 Study Guide Lecture Acid Base Balance Acid Base pH levels pH is the measure of acidity in a solution relative concentration of H in body fluids o Greater H Acidic Lower H Alkaline All functional proteins are influenced by H o So almost all reactions are influenced by pH of their fluid environ interstitial fluid blood H are by products of metabolism Lactate Also ketone bodies from ketosis due to a lack of CHO releases H ions into the blood pH balance in Body Fluids Arterial Blood 7 4 Venous Blood and Interstitial Fluid 7 35 pH falls when H increases and rises when H decreases Intracellular Fluid 7 0 is neutral o Arterial pH 7 45 alkalosis o Arterial pH 7 35 acidosis Lower pH that is in the blood demonstrates more acidic metabolites and CO2 How is H concentration regulated to maintain a neutral pH 1 Chemical Buffers 1st line of defense These act within a fraction of a second in an attempt to resist changes in pH Muscle Carnosine 2 Brain Stem Respiratory Centers Act within 1 3 minutes to counteract acidosis or alkalosis Respiratory Buffer 3 Renal Mechanisms Kidneys Require hours or even a day or more to act on changes in blood pH Chemical Buffer Systems Definition A system of one or more compounds that acts to resist changes in pH when a strong acid or base is added o Compounds bind to H when pH drops o Release H when pH rises A shift in H concentration in one fluid compartment is compensated by a shift in another compartment if 2 or more compounds o Therefore there are 3 Chemical Buffer Systems Strong Acid HCL Dissociates completely b c acids are proton donors which releases all of its H individually into the water Weak Acid H2CO3 Only dissociates partly Note Acidity of a solution is reflected by FREE H and not those bound to anions thus a weak acid is efficient at preventing a change in pH Strong Base Dissociates easily and accepts H Hydroxides Weak Base Bicarbonate ammonia Four types of chemical buffer systems 1 Bicarbonate Buffer System a H2CO3 and NaHCO3 2 Phosphate Buffer System a H2PO4 and HPO4 2 3 Protein Buffer System a Example Hemoglobin NOTE Chemical buffers can only tie up acids or bases temporarily only kidneys can remove excess from the body Bicarbonate Buffer Substances o H2CO3 Carbonic Acid Weak Acid o NaHCO3 Sodium Bicarbonate Weak Base o HCL Strong Acid o NaOH Sodium Hydroxide Strong Base The Only important buffer in extracellular fluid ECF H2CO3 and NaHCO3 Carbonic Acid and Sodium Bicarbonate Salt Carbonic Weak Acid Salt Weak Base HCL s interaction w Bicarbonate o Carbonic Acid weak acid doesn t dissociate completely o HCL does strong acid o Bicarbonate weak base which ties up H from HCL Now pH is only slightly lowered o If a strong base is now added sodium hydroxide it causes Carbonic acid to dissociate a little more making H to tie up with OH released by the strong base Now pH is slightly elevated Buffering Power is related to concentration of substances Phosphate Buffer System Similar to that of the Bicarbonate Buffer Sodium dihydrogen phosphate NaH2PO4 and monohydrogen phosphate NaHPO4 o NaH2PO4 Weak Acid NaHPO4 Weak Base Phosphate concentrations are low in the blood so this is very effective buffer in urine and intracellular fluid ICF Excretion of Titratable acid 1 Titratable acid refers to the process by which the kidney eliminates H with urinary buffers 2 The monobasic phosphate ion the buffer is filtered 3 As pH decreases in tubular lumen the monobasic phosphate ion becomes a more effective buffer and is converted to titratable acid Protein Buffer System of buffering power of all bodily fluids are in the cells and this mostly reflects the buffering capabilities of intracellular proteins Amino Group Carbon Group COOH Organic Acid o COOH is a strong acid which releases H when pH rises to counteract o Amino Group NH2 binds w H to become NH3 This removes H to prevent the solution from becoming too it acidic Amphoteric Molecules A single protein which can act as an acid or base depending on the pH of its environment Hemoglobin is charged after releasing O2 o H dissociates from Carbonic Acid but H rapidly binds to Hb so pH changes are minimal release of O2 Note this rapid binding is because of Hb s charge due to the Respiratory Buffer System Acts more slowly than the chemical buffers 2X s the buffering power of all of the chemical buffers combined As CO2 expelled from lungs Carbonic acid is formed and dissociated in H Hypercapnia drop in cerebrospinal fluid activates medulla chemoreceptors which Respiratory rate o Chemoreceptors will also increase plasma H to counteract alkalosis Acidosis increase in respiratory rate and depth Alkalosis decrease in respiratory rate and depth Respiratory Compensations Compensate for metabolic acid base imbalances Metabolic acidosis increased respiratory rate and depth Metabolic alkalosis decreased respiratory rate and depth CO2 H2O H2CO3 H HCO 3 as the Alveolar ventilation increases the pH of arterial blood becomes more basic raises in numbers 7 0 7 1 ect Renal Buffer System buffers i e nitrogen Only the kidneys can rid the body of metabolic acids not chemical Only the kidneys can regulate blood levels of alkaline substances and renew chemical buffers that are used up o H is proportional to CO2 in ECF and CO2 is inversely proportional to blood pH HCO3 is lost when CO2 leaves lungs H is retained as HCO3 is secreted which increases H shifting equation to the right Na is reabsorbed from filtrate to maintain balance Need to replenish HCO3 to counteract H retention Reabsorption of Filtered HCO3 1 Carbonic acid production in tubule lumen and CO2 diffusion 2 Bicarb production in cell 3 Na and Bicarb reabsorption into ECF with no net acid secretion decreases luminal pH from 7 4 to 6 7 Acid Base Disorders Acid Base Imbalances Lecture Male Reproductive Male reproductive system Primary Sex Organs o Testes Produce gametes Secrete sex hormones Accessory Sex Organs o Epididymis o Ductus Deferens o Ejaculatory Duct o Urethra o Seminal Vesicles o Prostate o Bulbourethral Glands Anatomy Testes Produce Sperm o which follows this path o Epididymis o Ductus Deferens o Ejaculatory Duct o Urethra opens to outside of body Sex glands empty their secretions into these ducts o Seminal vesicles prostate bulbourethral glands Male Sexual Response Erection Ejaculation the propulsion of semen from the male duct system o PNS stimulates increase in NO o Relaxation and vasodilation of arterioles o Erectile bodies fill with blood o SNS stimulation
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