Introduction to Physiology PDF

Introduction to Physiology Faculty of Nursing By/ Dr. Marwa Taha  What is Physiology? Physiology is the study of the functions of living things. Specifically, it focuses on how the human body works  The Cell The cell is the basi...

Introduction to Physiology Faculty of Nursing By/ Dr. Marwa Taha  What is Physiology? Physiology is the study of the functions of living things. Specifically, it focuses on how the human body works  The Cell The cell is the basic structural and functional unit of the body. It is microscopic in size. The body is composed of billions of cells that vary in size and shape.  STRUCTURE OF THE CELL Each cell is formed by: Cell membrane Nucleus Cytoplasm  The Cell Membrane The cell membrane envelops the cell, separating the cell’s contents from the surrounding. The fluid inside the cell is called intracellular fluid (ICF), and the fluid outside the cell is extracellular fluid (ECF). is a thin, flexible, and elastic structure. It is semipermeable, allowing some substances to pass through it and excluding others.  The Cell Membrane The cell membrane is composed of three types of substances: Proteins (55%) Lipids (42%) (phospholipid & Cholesterol) Carbohydrates (3%) Its basic structure is a phospholipid bilayer, which is a thin, double-layered film of lipids. Interspersed in this lipid film are large globular protein molecules.  Membrane protein Channels Carriers Pumps Receptors Enzymes Integral Peripheral  Membrane transport ENERGY ENERGY 1- Passive 2- Active transport 3- Bulk transport transport Simple diffusion. Primary Endocytosis Osmosis. Secondary Exocytosis Facilitated diffusion.  1- Passive transport a- Simple Diffusion: It is the transport of small substances from high concentration to low concentration (with concentration gradient). It is a passive process: no need for energy or carrier. e.g. CO2, O2 The rate of diffusion of a substance depends on: Concentration gradient of the substance. Surface area. Temperature: Increased temperature increase diffusion rate. Solubility of the substance: Increased solubility increase diffusion rate. Molecular weight of diffusing substances: Increased M.W decreases diffusion rate. Thickness of the membrane: Increase thickness decrease diffusion rate.  1- Passive transport b- Osmosis: It is a simple diffusion of water across a semipermeable membrane from high water concentration to low water concentration.  1- Passive transport c- Facilitated diffusion It a passive transport down concentration gradient (from high to low concentration) for large molecules. No need for energy, but it needs for carrier. i.e. glucose.  2- Active transport The transport of substances across the cell membrane against an electrochemical gradient. From lower concentration to higher concentration. Need specific carrier proteins and need for energy (as ATP).  A- Primary active transport: B-Secondary active transport: against an electrochemical gradient. Need for energy but not provided From lower to higher concentration directly by ATP but by the gradient, Need specific carrier proteins supplied by other. Need for energy (as ATP) e.g, absorption of glucose with sodium E.g Na-K pump (antiport) in the intestine (symport).  Carriers They are of 3 types: a) Uniport: a carrier that transports one substance in one direction e.g. Ca++ b) Symport: a carrier that transports two substances simultaneously in the same direction, e.g. carriers of glucose and Na+. c) Antiport: a carrier that transports one substance in one direction and another substance in the opposite direction e.g. Na+ - K+ pump  3- Bulk transport It Is the movement of macromolecules. It is of two types: A- Endocytosis: the movement from outside the cell to the inside, molecules can enter the cells as small invaginating vesicles. B- Exocytosis: The movement from inside the cell to the outside, as glands secretion.  ENERGY Passive Transport Movement from High Low concentration Simple Diffusion Osmosis Facilitated Diffusion Need carrier protein  ENERGY Active Transport Movement from low high concentration Primary Secondary  ENERGY Bulk Transport Large molecules that cannot pass through the cell membrane pores or via carriers. Endocytosis Exocytosis To inside To outside  What is Homeostasis? (Homeo = same / Stasis = staying) It is the maintenance of constant conditions in the internal environment of the body It is essential to maintain constant conditions in this internal environment since normal cell function depends upon this constancy For example: If you decide to go for a run, different body organs cooperate to maintain homeostasis (stable internal environment) regarding:  Body Compartments The body of normal adult male is composed of: 1- 18 % proteins 2- 15 % fat 3- 7 % minerals 4- 60 % water (Total Body Water) (TBW).  Body Water TBW constitutes 60% of body weight in adult males. TBW is 70-80% in infants. 50% in adult females and obese people due to high content of fat.  Body Water TBW is present in 2 compartments: 1. The intracellular fluid (I.C.F.): 2. The extracellular fluid (E.C.F.): a) Constitutes (2/3 TBW). a) Constitutes (1/3 TBW). b) Presents inside the cells. b) Presents outside the cells. c) Equals 40% of Total Body Weight. c) Equals 20% of Total Body Weight. d) It contains More K+ and less d) It contains less K+ and More Na+, CL- Na+, CL- and HCO3 and HCO3-  Body compartments The extracellular fluid is distributed as follows: a. 5% inside the blood vessels is called intravascular fluid (Plasma) b. 15% outside the blood vessels called the interstitial fluid (ISF) 40% 15% 20% 5%  Significance of Body Fluids 1. Constitutional: it represents 60% of total Body Weight. 2. Transport mechanism 3. Metabolic reactions 4. Regulation of body temperature