Human Physiology I, Ahfad University for Women, 2024, PDF

Ahfad University for Women School of Health Sciences Human Physiology I 2nd Year /Semester 1 Dr: Nisreen Osman Assistant Professor AUW Contents Cell physiology Body fluid Blood component and function Excitable tissues Nervous system Cardiovasc...

Ahfad University for Women School of Health Sciences Human Physiology I 2nd Year /Semester 1 Dr: Nisreen Osman Assistant Professor AUW Contents Cell physiology Body fluid Blood component and function Excitable tissues Nervous system Cardiovascular system 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 2 Course Learning out come By the end of the course students should be able to:- Explain how the different systems participate in homeostasis. Define the Excitable tissues and their function. Discus the organization of the nervous system. Describe component of cardiovascular system and their function. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 3  Course Policy Students are expected to be punctual. Students are expected to attend all lectures and submit the assignment on 16/12/2024 Late submission of assignment beyond 16/12/2024 will be evaluated out of 8 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 4 Evaluation 40 % final exam 20%Mid term exam 10% Assignment 10% Test 20 % Practical 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 5  Learning out come :- Describe cell physiology. Describe cell membrane (chemical composition, structure, and function) Describe cell transport across the membrane ( active and passive transport) 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 6  Human physiology explain the specific characteristics and mechanisms of the human body that make it a living being. In fact, human remain alive as a result of complex control systems. Example Sensations of cold make us look for warmth. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 7  The term homeostasis 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. E.g the lungs provide oxygen ; gastrointestinal system provides nutrients. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 8  Composition of the cell:- Plasma membrane ,cytoplasm ,organelles and nucleus Plasma membrane:- Is a flexible, sturdy barrier that surrounds and contains the cytoplasm of a cell. it appears as a trilaminar structure Consist of 1.lipid bilayer 2. Membrane proteins are attached to or inserted within the lipid bilayer 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 9  1. The Lipid Bilayer Made up of three types of lipid molecules 75%phospholipids, 20%cholesterol, and 5%glycolipids Functions of lipid bilayer:- It forms the basic structure of the membrane. Its hydrophobic interior serves as a barrier to passage of water-soluble substances between the ICF and ECF. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 10  Maintain different mixtures and concentrations of solutes inside and outside the cell. It is responsible for the fluidity of the membrane. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 11  2. Membrane Proteins classified in to Integral protein extend into or through the lipid bilayer among the fatty acid tails and are firmly embedded in it..(transmembrane proteins) (glycoproteins) Peripheral protein Are not as firmly embedded in the membrane. They are attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 12 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 13 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 14  Functions of Membrane Proteins:- 1. Ion channels Most ion channels are selective; They allow only a single type of ion to pass through e.g potassium ions (K) 2. Carriers which transfer specific substances across the membrane that are unable to cross on their own Selectively moving a polar substance or ion from one side of the membrane to the other (transporters) 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 15  3. Receptors Serve as cellular recognition sites. Each type of receptor recognizes and binds a specific type of molecule. E.g hormones, can influence only the specific cells that have receptors for a given messenger 4. Enzymes Catalyze specific chemical reactions at the inside or outside surface of the cell. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 16  5. linkers Anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside and outside the cell. 6. Cell identity markers ABO blood type 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 17  Membrane Permeability The plasma membranes have selective permeability. Two properties of particles influence permeability;- 1. The solubility of the particle in lipid. Highly lipid-soluble particles can dissolve in the lipid bilayer and pass through the membrane. Uncharged or nonpolar molecules (such as O2, CO2, and fatty acids 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 18  2. The size of the particle. Slightly permeable to small, uncharged polar molecules such as water and urea Transmembrane proteins permeable to a variety of ions and uncharged polar molecules. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 19  Transport across the plasma membrane:- Substances generally move across cellular membranes via 1. Passive Processes 2. Active Processes (Need ATP) 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 20  Passive Processes Does not require cell energy Examples: 1. Diffusion 2. Osmosis 1. Diffusion:- Means “to spread out” Is a passive process in which the random movement of particles of a solute from an area of higher to lower concentration area. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 21  Factors influence the diffusion:- 1.Sharpness of the concentration gradient. 2. Temperature. The higher the temperature, the faster the rate of diffusion. 3. Mass of the diffusing substance. The larger the mass of the diffusing particle, the slower its diffusion rate. Smaller molecules diffuse more rapidly than larger ones 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 22. 4. Surface area. The larger the membrane surface area available for diffusion, the faster is the diffusion rate. 5. Diffusion distance. Greater the distance over which diffusion must occur, the longer it takes 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 23 Diffusion 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 24 Diffusion divided in to :- 1. Simple diffusion Is a passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins. 2. Facilitated Diffusion:- In this process, an integral membrane protein assists a specific substance across the membrane. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 25  Carrier (transporter ) The solute binds to a specific carrier on one side of the membrane and is released on the other side after the carrier undergoes a change in shape. Example glucose--insulin 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 26 Type of diffusion 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 27  2. Osmosis:- Is a passive process in which there is a diffusion of water through a selectively permeable membrane from higher water concentration to an area of lower water concentration. Osmosis occurs only when a membrane is permeable to water but is not permeable to certain solutes. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 28  The osmotic pressure (is a measure of the tendency for water to move into solution) which is proportional to the concentration of the solute particles that cannot cross the membrane. Normally, the osmotic pressure of the cytosol is the same as the osmotic pressure of the interstitial fluid outside cells. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 29 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 30  A solution’s tonicity is a measure of the solution’s ability to change the volume of cells by altering their water content. Accordingly, solution divided into:- Isotonic solution The concentration of solute inside and outside of the cell is the same. Isotonic: Water in = Water out No net movement of water. Molecules in equilibrium. Cell in homeostasis. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 31  Hypotonic solution: the concentration of solute is lower outside the cell than inside the cell. Have more water outside the cell so water moves into the cell Causes an increase in pressure inside the cell. Increase in pressure in cells causes them to swell or even burst. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 32  Hypertonic solution:- The concentration of solute is higher outside the cell than inside the cell. Have more water inside the cell so water moves out of the cell Causes a drop in turgor or osmotic pressure: called plasmolysis. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 33 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 34  Active Processes Active Transport Requires energy in the form of ATP. Uses transport/carrier proteins (protein pumps) embedded in the plasma membrane. Primary active transport:- In which pump a substance across a plasma membrane against its concentration gradient. Example sodium-potassium pump 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 35  Sodium-Potassium Pump Pumps sodium ions outward through the cell membrane and at the same time pumps potassium ions from the outside to the inside. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 36 Sodium-Potassium Pump 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 37  Transport in Vesicles Transported in vesicles from one structure to another within cells. Vesicles also import materials from and release materials into extracellular fluid. Divided in to Endocytosis Exocytosis 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 38  Endocytosis a process of taking material into the cell by means of in folding, or pockets, of the cell membrane (usually putting them into a vacuole). There are three forms of endocytosis, depending on the nature of the material internalized: 1. Pinocytosis (nonselective uptake of ECF). 2. Receptor-mediated endocytosis (selective uptake of a large molecule) 3. Phagocytosis (selective uptake of a multi molecular particle). 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 39 1. Phagocytosis -“Cell eating” Nonspecific molecules ,Intake of solids Few specialized cells are capable of phagocytosis It extends surface projections known as pseudopods (“false feet”) that completely surround or engulf the particle and trap it within an internalized vesicle. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 40  A lysosome fuses with the membrane of the internalized vesicle and releases its hydrolytic enzymes. The enzymes largely break down the engulfed material into reusable raw ingredients 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 41 2. Receptor-mediated endocytosis:- Is a highly selective process that enables cells to import specific large molecules that it needs from its environment. Is triggered by the binding of a specific molecule such as a protein to a surface membrane receptor site specific for that protein. This binding causes the plasma membrane at that site to sink in, then seal at the surface, trapping the protein inside the cell. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 42 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 43 3. Pinocytosis –”Cell Drinking” Nonspecific molecules a small droplet of extracellular fluid is internalized. Intake of small droplets of liquid 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 44  Exocytosis (reverse endocytosis): A process in which the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell. 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 45 12/1/2024 Dr Nisreen Osman (Human PhysiologyI) 46