Introduction to Cell Physiology PDF

Introduction to Cell Physiology Prepared by: Yvette M. Batar, RN, MAN, DM Source: Focus on Nursing Pharmacology by Karch, 9th edition (Chapter 7) Learning Objectives Upon completion of this chapter, learners will be able to: 1. Identify the parts of the human ce...

Introduction to Cell Physiology Prepared by: Yvette M. Batar, RN, MAN, DM Source: Focus on Nursing Pharmacology by Karch, 9th edition (Chapter 7) Learning Objectives Upon completion of this chapter, learners will be able to: 1. Identify the parts of the human cell. 2. Describe the role of each organelle found within the cell cytoplasm. 3. Explain the unique properties of the cell membrane. 4. Describe three processes used by the cell to move things across the cell membrane. 5. Outline the cell cycle, including the activities going on within the cell in each phase. THE CELL CELL NUCLEUS o Basic structural unit of the body. o Programmed” by genes (sequences of DNA found in o Each with nucleus, a cell chromatin), allow cell division. membrane, and cytoplasm, w/c contains a variety of organelles. o Produce proteins that allow cell to carry out its functions & maintain cell homeostasis. o Genetic material necessary for cell reproduction & regulation of cellular production of proteins. o Nucleolus (w/in nucleus), become ribosomes, the sites of protein synthesis within the cell. o Genes - responsible for the formation & transcription of messenger RNA.  THE CELL CELL MEMBRANE (a lipoprotein) LIPOPROTEINS o Separates intracellular fluid from o Monitors substances passing in extracellular fluid. and out of the cell. o Essential for cellular integrity & is o Bipolar in nature: polar regions equipped with mechanisms for mix well with water, nonpolar maintaining cell homeostasis. region repels water. o Bipolarity allow membrane to act as barrier to regulate what can enter the cell. o Cholesterol - found in large quantities, works to keep phospholipids in place & the cell membrane stable.  THE CELL RECEPTOR SITES IDENTIFYING MARKERS o One type of protein located on o Are proteins called cell membrane. histocompatibility antigens or o Reacts with specific chemicals human leukocyte antigens, which outside the cell to stimulate a the body uses to identify a cell as reaction within the cell. a self-cell. o Play a very important role in o Immune system recognizes these clinical pharmacology. proteins and acts to protect self- cells and to destroy nonself- cells. CHANNEL (or PORES) o Immune system may attack cells, o Allow passage of small substances leading to problems associated in or out of the cell. with autoimmune disorders and o Specific channels have been chronic inflammatory conditions. identified for sodium, potassium, calcium, chloride, bicarbonate, & water; other channels may exist.  THE CELL CYTOPLASM ENDOPLASMIC RETICULUM (ER) o Gelatinous liquid within the cell o A network of interconnected membrane & outside the nucleus. channels (cisternae) within the o Site of activities of cellular cytoplasm. metabolism and special cellular o Rough ER – production of functions. proteins, phospholipids, and MITOCHONDRIA cholesterol takes place. o Are rod-shaped “power plants” o Smooth ER - site of further lipid within each cell that produce and cholesterol production and energy in the form of ATP. the production of cell products, such as hormones; breakdown of o Adenosine TriPhosphate (ATP) – many toxic substances. source of energy which allows the cell to function.  THE CELL FREE RIBOSOMES LYSOSOMES o Are free-floating ribosomes that o Membrane-covered organelles produce proteins that are that contain specific digestive important to the structure of the enzymes that break down cell & some enzymes necessary proteins, nucleic acids, for cellular activity. carbohydrates, & lipids GOLGI APPARATUS o Responsible for digesting worn or o Prepare hormones or other damaged sections of a cell when substances for secretion by membrane ruptures & cell dies. processing them & packaging o Form a membrane around any them in vesicles to be moved to substance that needs to be cell membrane for excretion. digested & secrete digestive o Produce lysosomes & store enzymes directly into the isolated other synthesized proteins & area, protecting the rest of the enzymes until they are needed. cytoplasm from injury.  CELL PROPERTIES – allow cell to survive EXOCYTOSIS o Movement of substances (waste products, hormones, neurotransmitters) out of the cell. üPinocytosis - engulfing of specific substances that have reacted with a receptor site on the cell membrane. üPhagocytosis - allows cell, usually a neutrophil or macrophage, to engulf a bacterium or a foreign protein and destroy it within the cell by secreting digestive enzymes into the area.  CELL PROPERTIES - cont’d ENDOCYTOSIS o Destruction of engulfed proteins or bacteria. o Removing substances from a cell by pushing them through cell membrane. o Hormones, neurotransmitters, enzymes, & other substances produced within a cell are excreted into the body by this process. Homeostasis o The process of maintaining stable --- conditions inside a cell. o Main goal cell: to maintain homeostasis. o Active & Passive transport systems are used to achieve homeostasis. o Passive Transport - happens w/o expenditure of energy & can occur across any semipermeable membrane. o Active Transport – requires energy input from cell to move substance against its concentration gradient.  PASSIVE TRANSPORT DIFFUSION OSMOSIS (a form of diffusion) o Movement of substance from o Movement of water across a higher concentration to lower semipermeable membrane from concentration. an area that is low in dissolved o Substances that move by solutes to one that is high in diffusion include sodium, dissolved solutes. potassium, calcium, carbonate, o Osmotic Pressure – pressure oxygen, bicarbonate, & water. created when diffusion of water o Small substances & materials w/ across a cell membrane from an no ionic charge move most freely area of high concentration (of thru the channels. water) to an area of low concentration. o Substances w/ negative charge move more freely than o Water equalize dilution of the substances w/ positive charge. solutes. PASSIVE TRANSPORT OSMOSIS – cont’d o Isotonic Solution - fluid that contains the same concentration of solutes as human plasma. o Hypertonic Solution - fluid that contains a higher concentration of solutes than human plasma o Hypotonic Solution - fluid that contains a lower concentration of solutes than human plasma. PASSIVE TRANSPORT ACTIVE TRANSPORT FACILITATED DIFFUSION o Movement of substance from o Movement of substance from lower to higher concentration, higher concentration to lower requires energy. concentration assisted by a o Kidney cells use active transport carrier (no energy required). to excrete drugs from the body, as o Carriers may be hormones, well as to maintain electrolyte and enzymes, or proteins. acid–base balances. CELL CYCLE PHASES OF CELL CYCLE G0 OR RESTING PHASE o Most cells have ability to reproduce themselves thru o Cells are stable, basically dormant. mitosis. Just functioning to do whatever o Genetic makeup of cell they are supposed to do. determines the rate at which it o Cells in G0 phase cause problem in multiplies. some CA treatment. o Some cells reproduce very o CA chemotherapy usually works quickly (e.g., cells of GIT lining on active, dividing cells, leaving with generation time of 72 hours) resting cells fairly untouched. o Some reproduce very slowly (e.g., o When resting cells are stimulated cells in breast tissue with to become active & regenerate CA generation time of a few months). can return w/c is why a 5-year CA-free period is usually the basic guide for considering a CA to be cured.  PHASES OF CELL CYCLE – cont’d G1 OR GATHERING PHASE G2 PHASE- another gathering phase o When cells in resting phase is o After DNA has doubled G2 stimulated to emerge, it enters G1 phase begins. phase. o Cell produces all substances o Lasts from the time of stimulation required for the manufacture from the resting phase until the of the mitotic spindles. formation of DNA. M OR MITOSISPHASE o Cell synthesizes substances needed o After the cell has produced all for DNA formation. of the substances necessary S OR SYNTHESIS PHASE for formation of a new cell, or o Involves the actual synthesis of DNA, daughter cell, it undergoes cell which is an energy-consuming activity. division or mitosis. o Cell remains in this phase until the o Cell splits to form 2 identical amount of cellular DNA has doubled. daughter cells, a process called mitosis.