Internal Environment Physiology PDF

INTERNAL ENVIRONMENT HOMEOSTASIS BODY FLUIDS ACID-BASE BALANCE BLOOD  INTERNAL ENVIRONMENT PHYSIOLOGY – the study of the the normal functioning of a living organism and its component parts KEY PRINCIPLES OF PHYSIOLOGY – homeostasis and the regulation of th...

INTERNAL ENVIRONMENT HOMEOSTASIS BODY FLUIDS ACID-BASE BALANCE BLOOD  INTERNAL ENVIRONMENT PHYSIOLOGY – the study of the the normal functioning of a living organism and its component parts KEY PRINCIPLES OF PHYSIOLOGY – homeostasis and the regulation of the internal environment HOMEOSTASIS (homeo – similar; stasis – condition; Claude Bernard) – an ability to keep the internal environment relatively stable /a dynamic steady state/ (body temp., heart rate, blood pressure and pH, osmolarity) The human body ☛open system → exchanges heat and materials with the outside environment. To maintain homeostatasis, the body must maintain mass balance.  INTERNAL ENVIRONMENT Mass balance is an open system – to maintain balance, input into the system must match output The law of mass balance – says that if the amount of a substance in the body is to remain constant, any gain must be offset by an equal loss.  The body’s internal and external environments INTERNAL ENVIRONMENT Most cells are completely surrounded by the body’s internal environment, composed of the extracellular fluid (ECF). A box diagram of the body represents the body’s fluid compartments, the extracellular fluid that exchanges material with the outside world and the fluid inside cells, or intracellular fluid (ICF)  INTERNAL ENVIRONMENT LEVELS OF ORGANIZATION: BODY COMPARTMENTS The general functions of the cell membrane include: 1. physical isolation 2. regulation of exchange with the environment 3. communication between the cell and its environment 4. structural support  INTERNAL ENVIRONMENT BODY FLUID COMPARTMENTS Cations and anions are not distributed equally between the body compartments, creating a state of electrical disequilibrium  INTERNAL ENVIRONMENT Water moves freely between the cells and extracellular fluid  INTERNAL ENVIRONMENT Osmosis – the flow of water across a semipermeable membrane from a solution with low solute concentration to a solution with high solute concentration Osmolarity (mOsM/L) – the number of particles per liter of solution Tonicity – describes a solution and how that solution would affect cell volume if the cell were placed in the solution and allowed to come to equilibrium Diffusion – the passive movement of molecules down a chemical gradient (Fick’s law of diffusion) TRANSPORT PROCESSES INTERNAL ENVIRONMENT cell membrane are selectively permeable movement of substances across cell membranes can be classified either by the energy requirements of transport or according to whether transport occurs by diffusion, a membrane protein, or a INTERNAL ENVIRONMENT INTERNAL ENVIRONMENT  INTERNAL ENVIRONMENT -Blood Total blood volume (70 kg man) – 7%; 0.07 x 70 kg = 4,9 kg→ 5L of blood INTERNAL ENVIRONMENT - BLOOD INTERNAL ENVIRONMENT - BLOOD INTERNAL ENVIRONMENT – RED BLOOD CELLS INTERNAL ENVIRONMENT - HEMOGLOBIN Globin proteins isoforms of : alpha, beta, gamma, delta→adult hemoglobin (HbA – 2⍺+2β; HbA2/2,5%/ -2⍺+2𝜹) RBCs live – 120 days hemoglobin and hyperglycemia – hemoglobin A1C INTERNAL ENVIRONMENT - HEMOGLOBIN  INTERNAL ENVIRONMENT - HEMOGLOBIN Bohr effect – pH Haldane effect – CO2 INTERNAL ENVIRONMENT - HEMOGLOBIN INTERNAL ENVIRONMENT - HEMOGLOBIN INTERNAL ENVIRONMENT - HEMOGLOBIN INTERNAL ENVIRONMENT- HEMOGLOBIN  INTERNAL ENVIRONMENT - HEMOGLOBIN polycythemia vera (vera, true) – a stem cell dysfunction; relative polycythemia – low plasma volume (dehydration) INTERNAL ENVIRONMENT – PLATES AND COAGULATION plates are small fragments of cells the typical life span – 10 days hemostasis – the process of keeping blood within a damaged blood vessel INTERNAL ENVIRONMENT – PLATES AND COAGULATION Three steps: 1. vasoconstriction, 2. temporary blockage of a break by a platelet plug, 3. coagulation, the formation of a clot that seals the hole until tissues are repaired INTERNAL ENVIRONMENT – PLATES AND COAGULATION Platelets adhere to collagen with the help of integrins, membrane receptor proteins that atre linked to the cytoskeleton→binding activates platelets to release serotonin, ADP, platelet-activating factor (PAF)→positive feedback loop and initiates convertion platelet membrane pfospholipids into thromboxane A2 INTERNAL ENVIRONMENT – PLATES AND COAGULATION INTERNAL ENVIRONMENT – PLATES AND COAGULATION An intrinsic pathway – begins when damage to the tissue exposes collagen; uses proteins already present in the plasma An extrinsic pathway – starts when damaged tissues expose tissue factor, also called tissue thromboplastin (III)  INTERNAL ENVIRONMENT – PLATES AND COAGULATION Clots are a temporary fix→fibrin is broken into fragments by the enzyme plasmin (plasminogen→plasmin by thrombin and tPA /tissue plasminogen activator/) Anticoagulants: from endothelial cells: 1.heparin, antithrombin III (block active factors IX, X, XI, XII; 2. protein C (blocks factor V, VIII) drugs: 1. streptokinase (bacteria), 2. tPA, 3. aspirin (inhibits the COX enzymes that promote synthesis of the platelet activator thromboxane A2), 4. the coumarin anticoagulants such as warfarin (blocks vitamin K→a cofactor in the synthesis of factors II, VII, IX, X) Hemophilia: A (VIII); B (IX) INTERNAL ENVIRONMENT – ACID-BASE BALANCE INTERNAL ENVIRONMENT – ACID-BASE BALANCE carbonic anhydrase pH homeostasis depends on buffers (a molecule that moderates but does not prevent changes in pH by combining with or releasing H+), lungs and kidneys Buffers: cellular proteins, phosphate ions, hemoglobin, bicarbonate the Henderson-Hasselbalch equation INTERNAL ENVIRONMENT – ACID-BASE BALANCE INTERNAL ENVIRONMENT – ACID-BASE BALANCE Ventilation can correct disturbances in acid-base balance because changes in plasma PCO2 affect both the H+ content and the HCO3- content of the blood. An increase in PCO2 stimulates central chemoreceptors. An increase in plasma H+ stimulates carotid and aortic chemoreceptors. Increased ventilation excretes CO2 and decreases plasma H+ In acidosis, the kidneys secrete H+ and reabsorb HCO3- In alkalosis, the kidneys secrete HCO3- and reabsorb H+ INTERNAL ENVIRONMENT – ACID-BASE BALANCE INTERNAL ENVIRONMENT – ACID-BASE BALANCE  INTERNAL ENVIRONMENT – ACID-BASE BALANCE Clinical causes of acid-base disorders: 1. Respiratory acidosis ↓ventilation and ↑PCO 2 3. Metabolic acidosis ↓ HCO3- damage of respiratory centers failure of the kidneys decrease the ability of the lungs to eliminate CO2 formation of excess quantities of metabolic acids (DM) obstruction of the passageways of the respiratory truct addition of metabolic acids to the body by ingestion pneumonia, emphysema loss of base from the body fluids (diarrhea) the compensatory response → kidney ↓ HCO3- excretion the compensatory response → ↑ ventilation 2. Respiratory alkalosis ↑ ventilation and ↓ PCO 2 4. Metabolic alkalosis ↑ HCO3- psychoneurosis administration of diuretics (except the carbonic person ascends to high altitude anhydrase inhibitors) the compensatory response → kidney ↑HCO3- excretion vomiting of gastric contents, ingestion of  INTERNAL ENVIRONMENT – ACID-BASE BALANCE Usually the anion gap ranges between 8-16 mEq/L