Introduction to Physiology and Fluid Balance 2024 PDF

Introduction to Physiology and Fluid Balance Assoc. Prof. Dr. Radiah Abdul Ghani Human Structure & Function 1  Learning Objectives 2  Understand the concept of physiology.  Explain the body fluid compartments.  Describe the movement...

Introduction to Physiology and Fluid Balance Assoc. Prof. Dr. Radiah Abdul Ghani Human Structure & Function 1  Learning Objectives 2  Understand the concept of physiology.  Explain the body fluid compartments.  Describe the movement across the membranes such as passive transport, diffusion, mediated transport, facilitated diffusion, active transport.  Describe the significance of balance in distribution of water and solutes in the body.  Describe examples of physiological regulation known as homeostasis.  What is Physiology? 3  The study of the normal functioning a living organism and its component parts, including chemical and functional process.  Physiology ➔ knowledge of nature.  Aristotle : functioning of all living organisms.  Hippocrates : the healing power of nature and associated with medicine.  Integrative science that examine many functions at many level of organism complexity.  From Oxford Dictionary 4  Physiology is defined as the branch of biology that deals with the homeostasis of living organisms and their parts  From Philosophy of Islamic Medicine 5  Physiology or ‘ilm umur tabi’iyyah’ which is literally means the science of natural affairs.  It is concerned with the functioning of all structures and organs of the human body.  Muslim physiology also is based on the humoral theory which is fundamentally different in many respects from modern physiology (Bakar, 2008).  Humoral Physiology 6  is based on the idea that four major fluids dominate the human body: blood, phlegm, choler (yellow bile) and black bile.  Each one is composed of two elements: Heat, cold, dryness and moisture  Each individual, however, was also said to have his or her own natural “complexion” or constitution in which one humor dominated, and this distinctive makeup determined the nature of bodily functions, character, and intelligence (Bakar, 2008).  Image result for humoral physiology When the body is in a state of health, the four humors were said to be balanced, or in the correct proportion. An imbalance of humors was seen as the origin of sickness and disease. 7 8 The relationship between clinical manifestation, physiology and molecular level interaction 9  LEVELS OF STRUCTURAL ORGANIZATION AND BODY SYSTEMS  Exploration of the human body will extend from atoms and molecules to the whole person.  From the smallest to the largest.  6 levels of organization  Chemical  Cellular  Tissue  Organ  System  Organismal levels  CHEMICAL LEVEL  Basic level - includes atoms, the smallest units of matter that participate in chemical reactions, and molecules, two or more atoms joined together.  Eg atoms - C, H, O, N, P, Ca - essential for maintaining life.  Eg molecules -DNA, glucose.  CELLULAR LEVEL  Molecules combine to form cells  basic structural and functional units of an organism that are composed of chemicals.  the smallest living units in the human body.  Eg: muscle cells, nerve cells, and epithelial cells.  TISSUE & ORGAN LEVEL  Tissues are groups of cells and the materials surrounding them that work together to perform a particular function.  4 basic types of tissues in the body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue.  Organs are structures that are composed of two or more different types of tissues; they have specific functions and usually have recognizable shapes.  Eg: stomach, skin, bones, heart, liver, lungs, and brain.  SYSTEM (ORGAN-SYSTEM) LEVEL  Consists of related organs with a common function.  Eg: The digestive system - Its organs include the mouth, salivary glands, pharynx (throat), esophagus (food tube), stomach, small intestine, large intestine, liver, gallbladder, and pancreas.  An organ can be part of more than one system.  Eg: The pancreas – digestive system, endocrine system.  PHYSIOLOGY IS AN INTEGRATIVE SCIENCE  All body systems influence one another.  They work together to maintain health, provide protection from disease, and allow for reproduction of the human species. 17  Image result for water Ion and molecules movement  PLASMA MEMBRANE  A flexible yet sturdy barrier that surrounds and contains the cytoplasm of a cell.  Best described by using a structural model called the fluid mosaic model.  MEMBRANE PERMEABILITY  Permeable ➔ permits the passage of substances through it  impermeable ➔?  Plasma membranes permit some substances to pass more readily than others  termed selective permeability.  MEMBRANE PERMEABILITY  The lipid bilayer portion is permeable to  Nonpolar, uncharged molecules  Eg: O2, CO2, steroids  Impermeable to  ions  large, uncharged polar molecules eg: glucose.  Slightly permeable to  small, uncharged polar molecules such as water & urea  MEMBRANE PERMEABILITY  Transmembrane proteins  Channels  carriers  increase the plasma membrane’s permeability to a variety of ions and uncharged polar molecules.  Macromolecules – eg: proteins, so large - unable to pass across the plasma membrane except by endocytosis and exocytosis.  GRADIENTS ACROSS THE PLASMA  The selective permeability  Allows a living cell to maintain different concentrations of certain substances on either side of the plasma membrane.  A concentration gradient  a difference in the concentration of a chemical from one place to another, such as from the inside to the outside of the plasma membrane.  Eg: Na+ are more concentrated in the extracellular fluid than in the cytosol  GRADIENTS ACROSS THE PLASMA  Different distribution of positively and negatively charged ions between the two sides of the plasma membrane  The inner surface is more negatively charged  the outer surface is more positively charged.  GRADIENTS ACROSS THE PLASMA  A difference in electrical charges between two regions  electrical gradient.  It occurs across the plasma membrane, this charge difference is termed the membrane potential.  The concentration gradient and electrical gradient help move substances across the plasma membrane.  TRANSPORT ACROSS THE PLASMA MEMBRANE  Essential to the life of a cell.  Substances must move into the cell - support metabolic reactions.  Products/waste by the cell must move out.  Type of membranes transport  - passive or active  depending on whether they require cellular energy.  TRANSPORT ACROSS THE PLASMA MEMBRANE Passive processes  Substance moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy (energy of motion).  Eg: simple diffusion. In active processes, cellular energy is used to drive the substance “uphill” against its concentration or electrical gradient.  The cellular energy used is usually in the form of ATP.  Eg: active transport, vesicles (endocytosis, exocytosis).  ACTIVE TRANSPORT primary active transport  Energy obtained from hydrolysis of adenosine triphosphate (ATP). secondary active transport  Use energy stored in an ionic concentration gradient. PRIMARY ACTIVE TRANSPORT: SODIUM- POTASSIUM PUMP  Expels Na+ and brings K+ in.  A part of the pump acts as an ATPase, an enzyme that hydrolyzes ATP  Thus - another name - Na/K ATPase.  PRIMARY ACTIVE TRANSPORT: SODIUM- POTASSIUM PUMP  K and Na slowly leak back across the plasma membrane  down their electrochemical gradients— passive transport or secondary active transport  sodium-potassium pumps must work nonstop to maintain the concentration gradient. SECONDARY ACTIVE TRANSPORT  The energy stored in a Na or H concentration gradient is used to drive other substances across the membrane.  Na or H gradient is established by primary active transport. SECONDARY ACTIVE TRANSPORT  Involve a carrier protein  Simultaneously binds to Na and another substance  Move both substances across the membrane.  Symporters - move in the same direction  Antiporters -move in opposite directions across the membrane.  TRANSPORT IN VESICLES  A vesicle - a small, spherical sac.  Function:  Transport materials from one structure to another within cells.  import materials from and release materials into extracellular fluid.  Endocytosis (endo- within), materials move into a cell in a vesicle formed from the plasma membrane.  In exocytosis (exo- out), materials move out of a cell by the fusion with the plasma membrane of vesicles formed inside the cell.  Energy supplied by ATP.  EXOCYTOSIS  Secretory cells that liberate digestive enzymes, hormones, mucus, or other secretions.  Nerve cells that release neurotransmitters.  Remove wastes.  Membrane-enclosed vesicles called secretory vesicles form inside the cell, fuse with the plasma membrane, and release their contents.  Image result for water Distribution and compartment of body fluids  Body fluid 45  Cell membrane divide the inside of the body into different compartments.  Most cells are not in direct contact with the outside of the world. Instead, they are surrounding by fluid. 46 47  Body Fluid Compartments 48  In lean adults, body fluids constitute 55% of female and 60% of male total body mass  Intracellular fluid (ICF) inside cells  About 2/3 of body fluid  Extracellular fluid (ECF) outside cells  Interstitial fluid between cell is 80% of ECF  Plasma in blood is 20% of ECF (intravascular fluid)  Also includes lymph, cerebrospinal fluid, synovial fluid, aqueous humor, vitreous body, endolymph, perilymph, and pleural, pericardial, and peritoneal fluids Body Fluid Compartments 49 50  Composition of Body Fluids 51  The compositions of the two components of the ECF— plasma and IF—are more similar to each other than either is to the ICF.  Blood plasma has high concentrations of sodium, chloride, bicarbonate, and protein.  The IF has high concentrations of sodium, chloride, and bicarbonate, but a relatively lower concentration of protein.  In contrast, the ICF has elevated amounts of potassium, phosphate, magnesium, and protein. Overall, the ICF contains high concentrations of potassium and phosphate ( HPO42−HPO42− ), whereas both plasma and the ECF contain high concentrations of sodium and chloride. The graph shows the composition of the ICF, IF, and plasma. The compositions of plasma and IF are similar to one another but are quite different from the composition of the ICF. 52  Image result for water Water and electrolyte balance: How it is important? 54  Fluid Balance 55  2 barriers separate ICF, interstitial fluid and plasma  Plasma membrane separates ICF from surrounding interstitial fluid  Blood vessel wall divide interstitial fluid from plasma  Body is in fluid balance when required amounts of water and solutes are present and correctly proportioned among compartments  Water is by far the largest single component of the body making up 45-75% of total body mass  Although many materials move freely between blood and the interstitial space, the cell membrane is an effective barrier.  Process of filtration, reabsorption, diffusion, and osmosis all continual exchange of water and solutes among compartments  Sources of Body Water Gain and Loss 56  Fluid balance related to electrolyte balance  Intake of water and electrolytes rarely proportional  Kidneys excrete excess water through dilute urine or excess electrolytes through concentrated urine  Body can gain water by  Ingestion of liquids and moist foods (2300mL/day)  Metabolic synthesis of water during cellular respiration and dehydration synthesis (200mL/day)  Body loses water through  Kidneys (1500mL/day)  Evaporation from skin (600mL/day)  Exhalation from lungs (300mL/day)  Feces (100mL/day) Daily Water Gain and Loss 57  58  Most body fluids are neutral in charge. Thus, cations, or positively charged ions, and anions, or negatively charged ions, are balanced in fluids.  As seen in the previous graph, sodium (Na+) ions and chloride (Cl–) ions are concentrated in the ECF of the body, whereas potassium (K+) ions are concentrated inside cells.  Although sodium and potassium can “leak” through “pores” into and out of cells, respectively, the high levels of potassium and low levels of sodium in the ICF are maintained by sodium-potassium pumps in the cell membranes.  These pumps use the energy supplied by ATP to pump sodium out of the cell and potassium into the cell. The sodium-potassium pump is powered by ATP to transfer sodium out of the cytoplasm and into the ECF. The pump also transfers potassium out of the ECF and into the cytoplasm. (credit: modification of work by Mariana Ruiz Villarreal) 59  Let’s Think! 60  When blood volume decreases due to sweating, from what source is water taken in by the blood?  Image result for water Fluid movement between compartments  The movement is due to this pressure 62  Hydrostatic pressure, the force exerted by a fluid against a wall, causes movement of fluid between compartments.  In capillaries, hydrostatic pressure (also known as capillary blood pressure) is higher than the opposing “colloid osmotic pressure” in blood—a “constant” pressure primarily produced by circulating albumin—at the arteriolar end of the capillary.  This pressure forces plasma and nutrients out of the capillaries and into surrounding tissues. Fluid and the cellular wastes in the tissues enter the capillaries at the venule end, where the hydrostatic pressure is less than the osmotic pressure in the vessel. Filtration pressure squeezes fluid from the plasma in the blood to the IF surrounding the tissue cells.  The surplus fluid in the interstitial space that is not returned directly back to the capillaries is drained from tissues by the lymphatic system, and then re-enters the vascular system at the subclavian veins. Net filtration occurs near the arterial end of the capillary since capillary hydrostatic pressure (CHP) is greater than blood colloidal osmotic pressure (BCOP). There is no net movement of fluid near the midpoint of the capillary since CHP = BCOP. Net reabsorption occurs near the venous end of the capillary since BCOPis greater than CHP. 63  Homeostasis The manifestation of the importance of fluid balance A STATE OF BALANCE AMONG ALL THE BODY SYSTEMS NEEDED FOR THE BODY TO SURVIVE AND FUNCTION CORRECTLY. 65  Let’s Think! 66  What happened to the movement of fluids inside the body in the event of sweating?  Regulation of body water gain 68  Mainly by volume of water intake/ how much you drink  Dehydration – when water loss is greater than gain  Decrease in volume, increase in osmolarity of body fluids  Stimulates thirst center in hypothalamus Regulation of water and solute loss 69  Elimination of excess body water through urine  Extent of urinary salt (NaCl) loss is the main factor that determines body fluid volume  Main factor that determines body fluid osmolarity is extent of urinary water loss  3 hormones regulate renal Na+ and Cl- reabsorption (or not)  Angiotensin II and aldosterone promote urinary Na+ and Cl- reabsorption of (and water by osmosis) when dehydrated  Atrial natriuretic peptide (ANP) promotes excretion of Na+ and Cl- followed by water excretion to decrease blood volume  Movement of water between compartments 70  Normally, cells neither shrink or swell because intracellular and interstitial fluids have the same osmolarity Increasing osmolarity of interstitial fluid draws water out of cells and cells shrink Decreasing osmolarity of interstitial fluid causes cells to swell  Changes in osmolarity most often result from changes in Na+ concentration Movement of water: Osmolarity 71 72  Water Intoxication 73  Water intoxication – drinking water faster than the kidneys can excrete it Can lead to convulsions, coma or death  also known as water poisoning or dilutional hyponatremia. 74 Would you be able to explain, how does it occurred? 75 Series of Events in Water Intoxication 76 Image result for water intoxication  Lesson to be learn? 77  What are the other option to reserve back the loss of electrolytes? 78 Electrolyte Imbalance – fail to back to normal 79  Edema 80 Edema is the accumulation of excess water in the tissues. An allergic reaction can cause capillaries in the hand to leak excess fluid that accumulates in the tissues. (credit: Jane Whitney)  81 Fluid is moved by a combination of osmotic and hydrostatic pressures. The osmotic pressure results from differences in solute concentrations across cell membranes. Hydrostatic pressure results from the pressure of blood as it enters a capillary system, forcing some fluid out of the vessel into the surrounding tissues.  Let’s Think! 82 How do you know that you are getting enough? 83  Other Examples 84 Three examples of homeostasis are: Body temperature regulation. Blood pressure regulation. Blood sugar regulation.  85 End of Lecture ☺