Cellular Physiology , lec. 1.pdf

Al-Hadba University Collage of Pharmacy General Physiology I (2024-2025) Lec.1 Dr. Mohammed Al-Khaffaf Mon. 16.09.2024 Specialist Trauma Surgeon Human Physiology: The specific...

Al-Hadba University Collage of Pharmacy General Physiology I (2024-2025) Lec.1 Dr. Mohammed Al-Khaffaf Mon. 16.09.2024 Specialist Trauma Surgeon Human Physiology: The specific characteristics and mechanisms the human body that make it a living being. The fact that we remain alive is the result of complex control systems, e.g.: Hunger makes us seek food. Sensations of cold make us look for warmth. Why do we study Physiology? Understand the physical and chemical principle underlie normal, in sin as the impairments. function in order to cure 6 of of many different cells held together by  Each organ is an aggregate intercellular supporting structures. is to perform one or a few  Each type of cell is specially adapted particular functions.  The entire body contains about 100 trillion cells.  Almost all cells also have the ability to reproduce additional cells of their own kind. IT Flm 1m  Cell—tissue---tissues to organ -----organs to systems and from systems to organism. The human body has thousands of control systems: 1. Genetic control systems help control intracellular and extracellular functions. 2. Control systems operate within the organs. 3. Throughout the entire body.  EXAMPLES OF CONTROL MECHANISMS: mKSÑ Regulation of Oxygen and Carbon Dioxide Concentrations in the Extracellular Fluid. Regulation of Arterial Blood Pressure. 1  Feedback Systems Negative Feedback Nature of Most Control Systems: eg: A high concentration of carbon dioxide in the extracellular fluid increases pulmonary ventilation. Item Pulmonaryventilation This payment in turn, decreases the extracellular fluid carbon dioxide concentration because the lungs expire greater amounts of carbon Joint temkin's dioxide from the body. In general, if some factor becomes excessive or deficient, a control it's system initiates negative feedback mechanism. Jett m sensor 1,1 control effector Positive Feedback  A way as to increase the intensity of the change in the same direction.  Positive feedback can sometimes be useful. If  Blood clotting is an example of a valuable use of positive feedback Some time cause formation of unwanted clots.{Heart attack}. sÉf echanism a Childbirth is another e g. in which positive feedback is valuable.  Positive feedback leads to instability rather than stability and in some cases, can cause death. 2  Homeostasis I If eM Homeostasis is defined as a self-regulating process by which an organism can IImaintain internal stability while adjusting to changing external conditions. Eif Homeostasis is an important characteristic of living things maintaining a stable internal environment which requires adjustments as conditions change inside and outside the cell. The maintenance of systems within a cell is called homeostatic I L É regulation. ma Tmk The maintenanceofsystem I ma a Homeostaticregulation 12 Q The maintenance of systemwithin a cell is called A Hemostaticregulation B Homeostaticregulation c feedback mechanism D Control mechanism 3  Physiology of the Cell idiot The basic living unit of the body is the cell. Each organ is an aggregate of many different cells held together by intercellular supporting structures. A typical cell contains nucleus and the cytoplasm. The nucleus is separated from the cytoplasm by a nuclear membrane, and the cytoplasm is separated from the surrounding fluids by a cell membrane. _a The different substances that make up the cell are collectively called protoplasm Protoplasm is composed mainly of five basic substances: water, electrolytes, proteins, lipids, and carbohydrates. Water: is the principal fluid medium of the cell, it is present in most cells in a concentration of 70 to 85 % Many cellular chemicals are dissolved in the water. Ions: The most important ions in the cell are potassium, 8 magnesium, phosphate, sulphate, bicarbonate, and smaller quantities of sodium & chloride. Proteins: normally constitute 10 to 20 % of the cell mass divided IF Protoplasm into two types: structural proteins and functional proteins. Lipids: The important lipids are phospholipids and cholesterol, which together constitute only about 2 % of the total cell mass. In the fat cells, lipids often account for as much as 95 % of the cell mass. They represent the body’s main storehouse of energy. The significance of lipid is insoluble in water and used to form the cell membrane and intracellular membrane. Carbohydrates: Carbohydrates play a major role in nutrition of the cell, their total amount about 1 % of cell total mass, 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. III t.cl 70 85 161s 4 EE jjj.tatce  The Cell Membrane (Plasma Membrane) Envelops the cell as a thin elastic structure. 1. proteins 55 % 2. phospholipids 25 % 3. cholesterol 13 % 4. other lipids 4 % 5. and carbohydrates 3 % The lipid of cell membrane: is bilayer phospholipid molecules. a) Its phosphate end of each phospholipid molecule is soluble in water, it is hydrophilic which constitute the two surfaces of the complete cell membrane (two outer surface). b) The fatty acid portion is soluble only in fats; that is, it is hydrophobic. The lipid layer in the middle of the membrane and it is is impermeable to the water-soluble substances. c) Conversely, fat-soluble substances, such as oxygen, carbon am this portion of the membrane. dioxide, and alcohol, can penetrate 5 Cell Membrane Proteins: Globular masses floating in the lipid bilayer usually are glycoproteins. I all the way through the membrane A-Integral proteins: that protrude form channels (or pores) through which water molecules and water- soluble substances can diffuse. B-Peripheral protein: is often attached to the integral proteins. These peripheral proteins function as enzymes or as controllers of transport to of substances through the cell membrane. 5 Membrane Carbohydrates Membrane carbohydrates occur almost in the form of glycoproteins or glycolipids. The entire outside surface of the cell often has a loose carbohydrate coat called the glycocalyx have several important functions: 1-Many of them have a negative electrical charge that repels other negative objects. 2- The glycocalyx of some cells attaches to the glycocalyx of other cells, thus attaching cells to one another. 3-Many of the carbohydrates act as receptor substances for binding hormones, such as insulin. miss 4- Some enter in to immune reactions. The Cytoplasmic Organelles Endoplasmic Reticulum his  It is network of tubular and flat vesicular structures. Their walls are similar to the cell membrane. 1) Granular Endoplasmic Reticulum is part of the endoplasmic reticulum has an attachment of granular particles called ribosomes they synthesize new protein molecules in the cell. 2) Agranular (smooth) Endoplasmic Reticulum is part of the endoplasmic reticulum has no attached ribosomes. The agranular reticulum synthesis of lipid substances.  Golgi Apparatus 1) The Golgi apparatus functions in association with the endoplasmic em reticulum as a small transport vesicles continually pinchin off from the endoplasmic reticulum and fuse with the Golgi apparatus. 2) The transported substances are processed in the Golgi apparatus to form lysosomes, secretory vesicles and others.  Lysosomes They lipid bilayer membrane organelle is found in most cells. They are s.sioff from the Golgi apparatus and spherical vesicles that form by breaking contain hydrolytic enzymes from protein aggregation (hydrolase enzyme), so its provide an intracellular digestive system.  lysosom digest: 1) damaged cellular structures. 2) food particles. 3) bacteria. 6   Peroxisomes are similar physically to lysosomes, but they contain oxidases enzyme rather than hydrolases.  Mitochondria i. The mitochondria are self-replicative and called the “powerhouses” of the cell. ii. Without them cells would be unable to extract enough energy from the nutrients and essentially all cellular functions would cease. iii. The liberated I energy is used to synthesize a “high-energy” substance called adenosine triphosphate (ATP). Nucleus  The nucleus is the control centre of the cell.  Briefly, the nucleus contains large quantities of DNA, which are the genes. Cell Function  Ingestion by the Cell Very large particles enter the cell by endocytosis. The principal forms of endocytosis are :- a) Pinocytosis. docytosis E's b) Phagocytosis. oximal of the cell membrane to form a pocket, it adf.tl Pinocytosis is the invagination is Pinocytosis off in to the cell to form a vesicle filled which then pinches with a large volume of extracellular fluid and molecules within it. This process requires energy from within the cell; this is supplied by ATP, as protein absorption inside cell after its attachment to cell membrane receptor. 7  t nl  Phagocytosis The cell membrane receptors attach to the surface ligands of the particle (as antibody of bacteria). in of the membrane around the points of attachment  The edges evaginate outward to surround the entire particle; to form a closed phagocytic vesicle. Ek  Cytoplasm actin surround the phagocytic vesicle and contract around its outer edge, pinch the vesicle and pushing the vesicle to w the interior of the cell.  Ingestion of large particles, such as bacteria is by phagocytosis. Only certain cells have the capability of phagocytosis, like the white blood cells. Exocytosis: In a highly secretory cell, the vesicles formed by the Golgi apparatus are mainly secretory vesicles containing protein substances that are to be secreted through the surface of the cell membrane.①These secretory vesicles first diffuse to the cell membrane, then②fuse with it and empty their substances to the exterior by the mechanism called exocytosis. Uses of ATP for Cellular Function. (1) Transport of substances through multiple membranes in the cell as sf the transport of sodium through the cell membrane. EE (2) Synthesis of chemical compounds throughout the cell as protein synthesis by the ribosomes. (3) Mechanical as work as muscle contraction. 8