Week 1 Body Fluid PDF

BODY FLUID Week1 A.L.Asma Ayaz ABOUT THIS CHAPTER I. Introduction human physiology II. The extracellular fluid and the intracellular fluid III. Definition of Homeostatic IV. Ways to transport substances into and out of the cell  Human Physiology....

BODY FLUID Week1 A.L.Asma Ayaz ABOUT THIS CHAPTER I. Introduction human physiology II. The extracellular fluid and the intracellular fluid III. Definition of Homeostatic IV. Ways to transport substances into and out of the cell  Human Physiology. 3 Human physiology is the branch of biology that focuses on the functions and processes of the human body. It seeks to understand how the various systems, organs, and tissues work together to maintain health and sustain life. In human physiology, we attempt to explain the specific characteristics and mechanisms of the human body that make it a living being. HUMAN PHYSIOLOGY. The very fact that we remain alive is the result of complex control systems, for hunger makes us seek food and fear makes us seek refuge. Sensations of cold make us look for warmth. Other forces cause us to seek fellowship and to reproduce. Thus, the human being is, in many ways, like an automaton, and the fact that we are sensing, feeling, and knowledgeable beings is part of this automatic sequence of life; these special attributes allow us to exist under widely varying conditions. 4  WHAT IS THE EXTRACELLULAR FLUID— THE “INTERNAL EXTRACELLULAR FLUID ENVIRONMENT” Approximately 60% of the adult human body 6 is comprised of fluid, predominantly a water solution containing ions and various substances. While the majority of this fluid is found within cells (intracellular fluid), about one third is located outside cells in what is known as extracellular fluid. This fluid is dynamic, circulating rapidly through the body via the bloodstream and diffusing through capillary walls to mix with tissue fluids.  The extracellular fluid serves as a crucial environment 7 for cells, housing essential ions and nutrients necessary for maintaining cell life. All cells essentially share this external environment, referred to as the internal environment or "milieu interior," a term coined by the 19th-century French physiologist Claude Bernard.  Cells thrive, grow, and execute their specialized functions as long as the proper concentrations of oxygen, glucose, ions, amino acids, fatty substances, and other constituents are maintained within this internal environment.  8 THE DIFFERENCES BETWEEN “ EXTRACELLULAR AND INTRACELLULAR FLUIDS ARE SIGNIFICANT. ”  9 Extracellular fluid comprises abundant sodium, chloride, and bicarbonate ions, along with essential nutrients like oxygen, glucose, fatty acids, and amino acids. It also contains carbon dioxide, being transported from cells to the lungs for excretion, and other cellular waste products destined for excretion by the kidneys.  10 intracellular fluid exhibits notable distinctions. It contains elevated levels of potassium, magnesium, and phosphate ions, deviating from the sodium and chloride ions predominant in extracellular fluid. Special mechanisms :operate within cell membranes to transport ions, ensuring the maintenance of concentration differences between extracellular and intracellular fluids. 11  12 CALLED INTRACELLULAR ORGANELLES. Figure 2-2 Reconstruction of a typical cell, showing the internal organelles in the cytoplasm and in the nucleus. “HOMEOSTATIC” MECHANISMS OF THE MAJOR FUNCTIONAL SYSTEMS The term homeostasis is used by physiologists to mean maintenance of nearly constant conditions in the internal environment. Essentially all organs and tissues of the body perform functions that help maintain these relatively constant conditions.  Lungs provide oxygen, kidneys regulate ion concentrations, and the gastrointestinal system supplies nutrients.  WATER 14 The principal fluid medium of the cell is water, which is present in most cells, except for fat cells, in a concentration of 70 to 85 percent. Many cellular chemicals are dissolved in the water. Others are suspended in the water as solid particulates. Chemical reactions take place among the dissolved chemicals or at the surfaces of the suspended particles or membranes.  15 WATER MOLECULE  Polarity of H20 allows H bonding  Water disassociates into H+ and OH-  Imbalance of H+ and OH- give rise to “acids and bases” - Measured by the pH pH influence charges of amino acid groups on protein, causing a specific activity Buffering systems maintain intracellular and extracellular pH the pH of the human body ranges between 7.35 to 7.45, with the average at 7.40.  Water Molecule 16 Hydrophobic “Water-fearing” Molecule is not polar, cannot form H bonds and is “repelled” from water Insoluble Hydrophilic “Water-loving” Molecule is polar, forms H bonds with water Soluble  17 IONS Important ions in the cell include potassium, magnesium, phosphate, sulfate, bicarbonate, and smaller quantities of sodium, chloride, and calcium. which considers the interrelations between the intracellular and extracellular fluids. The ions provide inorganic chemicals for cellular reactions. Also, they are necessary for operation of some of the cellular control mechanisms. For instance, ions acting at the cell membrane are required for transmission of electrochemical impulses in nerve and muscle fibers.  Proteins After water, the most abundant substances in most cells are proteins, which normally constitute 10 to 20 percent of the cell mass. two types: structural proteins functional proteins.  STRUCTURAL PROTEINS 19 intracellular Structural proteins are present in the cell mainly in the form of long filaments that are polymers of many individual protein molecules. A prominent use of such intracellular filaments is to form microtubules that provide the “cytoskeletons” of such cellular organelles as cilia, nerve axons, the mitotic spindles of mitosing cells, and a tangled mass of thin filamentous tubules that hold the parts of the cytoplasm and nucleoplasm together in their respective compartments. Also, many of them are adherent to membranous structures inside the cell. 20  STRUCTURAL PROTEINS 21 Extracellularly, fibrillar protein the collagen and elastin fibers of connective tissue and in blood vessel walls, tendons, ligaments, and so forth.  22 FUNCTIONAL PROTEINS The functional proteins are an entirely different type of protein, usually composed of combinations of a few molecules in tubular-globular form. These proteins are mainly the enzymes of the cell and, in contrast to the fibrillar proteins, are often mobile in the cell fluid  LIPIDS 23 Lipids are several types of substances that are grouped together because of their common property of being soluble in fat solvents. important lipids are phospholipids and cholesterol, which together constitute only about 2 percent of the total cell mass. The significance of phospholipids and cholesterol is that they are mainly insoluble in water and, therefore, are used to form the cell membrane and intracellular membrane barriers that separate the different cell compartments.  24 Triglycerides, also called neutral fat. In the fat cells, triglycerides often account for as much as 95 percent of the cell mass. The fat stored in these cells represents the body’s main storehouse of energy-giving nutrients that can later be dissolute and used to provide energy wherever in the body it is needed. 25  CARBOHYDRATES 26 Carbohydrates have little structural function in the cell except as parts of glycoprotein molecules, but they play a major role in nutrition of the cell. Most human cells do not maintain large stores of carbohydrates; the amount usually averages about 1 percent of their total mass but increases to as much as 3 percent in muscle cells and, occasionally, 6 percent in liver cells. However, carbohydrate in the form of dissolved glucose is always present in the surrounding extracellular fluid so that it is readily available to the cell. Also, a small amount of carbohydrate is stored in the cells in the form of glycogen, which is an insoluble polymer of glucose that can be depolymerized and used rapidly to supply the cells’ energy needs. 27 28 Ways to transport substances into and out of the cell  30 Osmotic Properties of Cells  Osmosis (Greek, osmos “to push”) Movement of water down its concentration gradient  Hydrostatic pressure Movement of water causes fluid mechanical pressure. Pressure gradient across a semi-permeable membrane 31 Hydrostatic pressure 32  HYDROSTATIC PRESSURE 33 Hydrostatic pressure refers to the pressure P= pgh P = fluid pressure that is exerted, due to the force of gravity, g = acceleration due to gravity by a fluid at equilibrium at any particular h = fluid depth point of time  Cell Permeability 34 Passive transport is carrier mediated  Facilitated diffusion  Solute molecule combines with a “carrier” or transporter  Electrochemical gradients determines the direction  Integral membrane proteins form channels 35 Crossing the membrane 36  Simple or passive diffusion  Passive transport -Channels or pores  Facilitated transport -Assisted by membrane-floating proteins  Active transport pumps & carriers -ATP is required -Enzymes and reactions may be required MODES OF TRANSPORT 37  CARRIER-MEDIATED TRANSPORT 38 Integral protein binds to the solute and undergo a conformational change to transport the solute across the membrane  CHANNEL MEDIATED TRANSPORT 39 Proteins form aqueous pores allowing specific solutes to pass across the membrane Allow much faster transport than carrier proteins  COUPLED TRANSPORT 40 Some solutes “go along for the ride” with a carrier protein or an ionophore Can also be a Channel coupled transport ACTIVE TRANSPORT 41 Three main mechanisms:  coupled carriers: a solute is driven uphill compensated by a different solute being transported downhill (secondary)  ATP-driven pump: uphill transport is powered by ATP hydrolysis (primary)  Light-driven pump: uphill transport is powered by energy from photons (bacteriorhodopsin)  ACTIVE TRANSPORT 42 Energy is required  NA /K PUMP + + 43 Actively transport Na+ out of the cell and K+ into the cell Against their electrochemical gradients For every 3 ATP, 3 Na+ out, 2 K+ in NA+/K+ PUMP 44 Na+ exchange (symport) is also used in epithelial cells in the gut to drive the absorption of glucose from the lumen, and eventually into the bloodstream (by passive transport) 45  Na+/K+ Pump 46 About 1/3 of ATP in an animal cell is used to power sodium-potassium pumps In electrically active nerve cells, which use Na+ and K+ gradients to propagate electrical signals, up to 2/3 of the ATP is used to power these pumps  ENDO AND EXOCYTOSIS 47  Exocytosis - membrane vesicle fuses with cell membrane, releases enclosed material to extracellular space.  Endocytosis - cell membrane invaginates, pinches in, creates vesicle enclosing contents RECEPTOR MEDIATED ENDOCYTOSIS 48 THANK YOU