Types of acids and bases Strong acids – Release large amount of Hydrogen ions Weak acids – Release small amount of Hydrogen ions Strong bases – Accept large amount of Hydrogen ions Weak bases – Accept small amount of Hydrogen ions
What Is Buffer ??? A buffer is a solution (or a substance) that has the ability to maintain pH and bring it back to its optimal value by addition or removal of hydrogen ions Buffer + H H buffer
Contd…. When Hydrogen ion conc. Increases – Reaction shifts towards right When Hydrogen ion conc. Decreases – Reaction shifts towards left In this way hydrogen ion concentration is maintained
Types of chemical buffer– Carbonic acid-bicarbonate –– Buffering changes caused by organic and fixed acids– Protein buffer system-Amino acids– Minor buffering system-– Phosphate –Buffer pH in the ICF
Bicarbonate buffer- Has the following limitations: – Cannot protect the ECF from pH changes due to increased or depressed CO2 levels – Only functions when respiratory system and control centers are working normally – It is limited by availability of bicarbonate ions (bicarbonate reserve).
Phosphate buffer system- Main elements of phosphate buffer system- - H2PO4, and HPO4 Phosphoric acid changes pretty quickly into dihydrogen phosphate, or H2PO4-. This dihydrogen phosphate is an efficient buffer.
Contd…. Phosphate buffer system in the ECF is low compared to the bicarbonate buffer. Its buffering power is less compared to the bicarbonate buffer. It has its importance in the renal tubules of kidneys for two reasons..
Contd 1.Conc. of phosphate is more in tubules. 2. Tubular fluid has lower pH. Conc. of phosphate is more in ICF compared to ECF.
Protein buffer system Proteins are made up of amino acids Amino acids have a central carbon with four groups off of it:1.a carboxyl group (COOH)2.an amino group (NH2)3.a hydrogen atom4.an R group.
Contd… The carboxyl and amino groups are what enable proteins to act as buffers. Carboxyl group is attached to the amino acid central carbon: C - COOH Carboxyl group consists of a double bond to one of the oxygens and a single bond to the hydroxyl group.
Contd... At neutral pH the carboxyl ion is present as COO instead of COOH. Acidic medium – becomes COOH Basic medium – becomes COO.
Contd… Amino group is attached to the amino acid central carbon: C - NH2. Neutral pH, the amino group is actually- NH3+ rather than just NH2. Acidic medium – becomes NH3+ Basic medium- becomes NH2
Respiratory regulationWhen alveolar ventilation increases CO2 conc. In ECF decreases H+ conc. decreases Or vice versa.......
Respiratory regulation Contd… Pulmonary expiration of CO2 balances metabolic formation of CO2 – 1.2 mol/L of dissolved CO2 is present in the ECF corresponding to pCO2 of 40 mm/hg – Rate of pulmonary ventilation is inversely proportional to CO2 & pCO2 – So either pulmonary ventilation rate of CO2 – or its formation by tissues can change pCO2 in ECF.
Contd… Increasing alveolar ventilation decreases ECF hydrogen ion conc. And raises pH– If alveolar ventilation increases the pCO2 decreases.– If alveolar ventilation decreases the pCO2 increases.– Twice rise of AV--rises pH of ECF by about 0.23– Decrease of AV to ¼ -- decreases pH by 0.45
Contd… Increased Hydrogen ion conc. Stimulates alveolar ventilation Change in alveolar ventilation rate is much greater in reduced levels of pH than in increased levels of pH
ReasonAlveolar ventilation rate decreases Increases pH O2 added in blood reduces Demand of O2 in blood increases pO2 also decreases Stimulates ventilation
Feedback control of Hydrogen ion conc. By RS H conc. Falls below normal Respiration is depressed Alveolar ventilation decreases H increases back to normal
Bufffering power of RS The kidneys work in elimination of hydrogen ion conc. and control imbalance. Its capacity is 1-2 times as much as other chemical buffers.
Impairment of lungs function: Impairment of lung function leads to emphysema and respiratory disorders. Kidneys play a major physiologic mechanism for returning pH to normal
Renal mechanism of acid-base regulation Kidneys regulate the blood pH by 1. maintaining alkali reserves 2. excreting / reabsorbing acid/base. Urine pH is lower than blood pH Kidneys- Acidification of urine.
Contd… Excretion of hydrogen ions Reabsorption of bicarbonate ion Excretion of ammonium ions
Disorders of acid-base regulation MAY LEAD TO--------- ALKALOSIS-- OR ACIDOSIS--
Contd… Respiratory acid-base disorders are initiated by an increase or decrease in partial pressure of carbondioxide whereas metabolic disorders are initiated by an increase or decrease in bicarbonate ion.
Contd… Alkalosis - Partial pressure of oxygen increases. Acidosis – Partial pressure of carbondioxide increases.
Contd…Respiratory acidosis- Decrease in rate of pulmonary ventilation- Increased pCO2 of ECF.Respiratory alkalosis- Increased rate of ventilation- Decrease the pCO2
Contd… Metabolic acidosis- Decreased ECF bicarbonate ion conc. Metabolic alkalosis- Increased ECF bicarbonate ion conc.
Contd…DISTURBANCE pH PRIMARY RATIO SECONDARY CHANGE CHANGEMetabolic Acidosis Decreased Deficit of bi- <20 Decrease in PaCO2 carbonateMetabolic Increased Excess of >20 Increase in PaCO2Alkalosis bicarbonateRespiratory Decreased Excess of <20 Increase in bicarbonateacidosis carbonic acidRespiratory Increased Deficit of >20 Decrease in bicarbonatealkalosis carbonic acid
Contd… Causes- Metabolic alkalosis 1. Vomiting of gastric contents 2. Ingestion of alkaline drugs etc.
Correction by renal for… Acidosis- Increased excretion of hydrogen ions and addition of bicarbonate ions to the ECF. Alkalosis- Decreased tubular secretion of hydrogen ions and increased excretion of HCO3_
EAT MORE -- Alkaline (80%) AcidAlkaline food chartEAT LESS -- Acidic (20%)Highly Alkaline Moderately Alkaline Mildly Alkaline Neutral/ Mildly Acidic Moderately Highly Acidic AcidicpH 9.5 alkaline water Avocado Artichokes Black Beans Fresh, Natural Juice AlcoholHimalayan salt Beetroot Asparagus Chickpeas/Garbanzos Ketchup Coffee & Black TeaGrasses Capsicum/Pepper Brussels Sprouts Kidney Beans Mayonnaise Fruit JuiceCucumber Cabbage Cauliflower Seitan Butter (Sweetened)Kale Celery Carrot Cantaloupe Apple CocoaKelp Collard/Spring Greens Chives Currants Apricot HoneySpinach Endive Courgette/Zucchini Fresh Dates Banana JamParsley Garlic Leeks Nectarine Blackberry JellyBroccoli Ginger New Baby Potatoes Plum Blueberry Mustard MisoSprouts(soy, alfalfa etc) Green Beans Peas Sweet Cherry Cranberry Rice SyrupSea Vegetables (Kelp) Lettuce Rhubarb Watermelon Grapes Soy SauceGreen drinks Mustard Greens Swede Amaranth Mango VinegarAll Sprouted Beans/ Sprouts Okra Watercress Millet Mangosteen Yeast Onion Grapefruit Oats/Oatmeal Orange Dried Fruit Radish Coconut Spelt Peach Beef Red Onion Buckwheat Soybeans Papaya Chicken Rocket/Arugula Spelt Rice/Soy/Hemp Protein Pineapple Eggs Tomato Lentils Freshwater Wild Fish Strawberry Farmed Fish Lemon Tofu Rice & Soy Milk Brown Rice Pork Lime Other Beans & Legumes Brazil Nuts Oats Shellfish Butter Beans Goat & Almond Milk Pecan Nuts Rye Bread Cheese Soy Beans Most Herbs & Spices Hazel Nuts Wheat Dairy White Haricot Beans Avocado Oil Sunflower Oil Wholemeal Bread Artificial Sweeteners Chia/Salba Olive Oil Grapeseed Oil Wild Rice Syrup Quinoa Coconut Oil ` Wholemeal Pasta Mushroom Flax Oil/ Udo’s Oil Ocean Fish
SO WHY NOT CONTROL THEACID BASE BALANCE WITH FOOD…???
References Guytons medical physiology,(Buffer System) Ionic changes By Rudolf Jensen
The Central Role of the CarbonicAcid-Bicarbonate Buffer System in the Regulation of Plasma pH Figure 27.11a
The Central Role of the CarbonicAcid-Bicarbonate Buffer System in the Regulation of Plasma pH Figure 27.11b
Acid-Base Disorders Respiratory acid base disorders – Result when abnormal respiratory function causes rise or fall in CO2 in ECF Metabolic acid-base disorders – Generation of organic or fixed acids – Anything affecting concentration of bicarbonate ions in ECF
Respiratory acidosis Results from excessive levels of CO2 in body fluids
Respiratory alkalosis Relatively rare condition Associated with hyperventilation
Metabolic acidosis Major causes are: – Depletion of bicarbonate reserve – Inability to excrete hydrogen ions at kidneys – Production of large numbers of fixed / organic acids – Bicarbonate loss due to chronic diarrhea
Figure 27.13 The Response to Metabolic Acidosis Figure 27.13
Detection of acidosis and alkalosis Diagnostic blood tests – Blood pH – PCO2 – Bicarbonate levels Distinguish between respiratory and metabolic Animation: Acid-Base Homeostasis
Changes with age include Reduced total body water content Impaired ability to perform renal compensation Increased water demands – Reduced ability to concentrate urine – Reduced sensitivity to ADH/ aldosterone Net loss of minerals Inability to perform respiratory compensation Secondary conditions that affect fluid, electrolyte, acid- base balance
You should now be familiar with: What is meant by “fluid balance,” “electrolyte balance,” and “acid-base balance” The compositions of intracellular and extracellular fluids The hormones that play important roles in regulating fluid and electrolyte balance The movement of fluid that takes place within the ECF, between the ECF and the ICF, and between the ECF and the environment
You should now be familiar with: How sodium, potassium, calcium and chloride ions are regulated to maintain electrolyte balance The buffering systems that balance the pH of the intracellular and extracellular fluids The compensatory mechanisms involved in acid-base balance
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