Physiology Lecture - The Cell and Its Function PDF

(001) THE CELL AND ITS FUNCTION DR. MELANI T. GALLERO-REBULDELA | 09/15/2020 - Principal fluid medium of the cell (70-85%) OUTLINE...

(001) THE CELL AND ITS FUNCTION DR. MELANI T. GALLERO-REBULDELA | 09/15/2020 - Principal fluid medium of the cell (70-85%) OUTLINE - Free water- for metabolic process I. THE CELL - Bound Water- attached to protein molecules II. ORGANIZATION OF THE CELL 2. Ions A. Protoplasm - K, Mg, PO4, SO4, HCO3, Na, Cl, Ca III. PHYSICAL & FUNCTIONAL STRUCTURE OF THE 3. Proteins - responsible for the structure of the cell (10- CELL 20%) A. Cell Membrane - 2 Types: B. Cytoplasm & Its Organelles = Structural or Peripheral or Fibrous IV. LOCOMOTION OF CELLS Protein: Present in the cell mainly in A. Amoeboid Movement the form of long filaments. Intracellular B. Cilia and Ciliary movement filaments are used to form Microtubules that provide I. THE CELL cytoskeletons of such cellular Basic living unit of the body organelles as cilia, nerve axons, mitotic Building blocks of the body providing structure for cells the body’s tissues and organs, ingesting nutrients = Functional or Globular or Enzymatic and converting them to energy and performing or Integral Proteins: Mainly the specialized functions enzymes of the cell Contains the body’s hereditary code that controls 4. Lipids (2%) the substances synthesized by the cells and - Soluble in fat solvents permits them to make copies of themselves. - Important Lipids: Phospholipids & Maintains homeostasis Cholesterol II. ORGANIZATION OF THE CELL = Mainly insoluble in water and therefore 2 Major Parts: are used to form the cell membrane and - Nucleus intracellular membrane barriers that - Cytoplasm separate the different cell Nuclear Membrane compartments - Separates nucleus from the cytoplasm 5. Carbohydrates Cell Membrane or Plasma Membrane - Major role in nutrition of the cell - Separates cytoplasm from the surrounding - Some enter immune reactions to be easily fluids detected by immune cells - Glycogen – storage form of nutrients in the cell III. PHYSICAL & FUNCTIONAL STRUCTURE OF THE CELL Membranous Structures of the Cell - Cell membrane - Nuclear membrane - Endoplasmic Reticulum - Mitochondria - Lysosomes - Golgi apparatus A. CELL MEMBRANE A. PROTOPLASM Thin, pliable elastic structure than envelops the Substances that make up the cell cell (gatekeeper) Functions: Composition - Regulates cellular transport (most important 1. Water cell function) - Present in almost cells except fat cells - Maintain the composition of ICF and ECF PREPARED AND EDITED BY: MACARAEG, E., MACNI, K., MAPALO, D., NITURA, A., PASCUA, C., PAYUMO, M., PINERO, D.  (001) THE CELL AND ITS FUNCTION DR. MELANI T. GALLERO-REBULDELA | 09/15/2020 - Cell communication B. Sphingolipids - Acts as an anchor for structural proteins - Sphingomyelin- type of sphingolipid o Anchors one cell to neighboring cells - Derived from amino alcohol sphingosine and to the basal lamina which also have hydrophobic and hydrophilic - Provide cellular stability groups and are present in small amounts in - Determination of cell shape by linking the the cell membrane especially nerve cells cytoskeleton to the plasma membrane C. Cholesterol - Enzymatic activity - Moderator molecule. Composition: - Present in the inner bilayer - Proteins- 55% - Provides mechanical stability as well as - Phospholipids-25% flexibility - Carbohydrates- 3% - Mainly help determine the degree of - Cholesterol- 13% permeability of the lipid bilayer to water - Other lipids- 4% soluble substances = Makes the cell membrane less I. LIPID BILAYER permeable to water - Controls much of the fluidity of the membrane - Prevents the crystallization of the lipid agents II. PROTEINS Mainly glycoproteins 2 types 1. Integral or transmembrane Proteins - Protrude all the way through the membrane - May act as carrier proteins for transporting substances that otherwise could not penetrate lipid bilayer - May act as enzyme - May serve as receptors for water- Cell Membrane lipid barrier impedes penetration soluble chemicals such as peptide by water- soluble substances. One end of each hormones that do not easily penetrate phospholipid molecule is: the cell membrane a. Hydrophilic / lipophobic (water soluble) - Mostly utilized as channels, pores or - phosphate end / polar end fenestrations b. Hydrophobic / lipophilic (fat soluble) = Mostly involved in transport of water - fatty acid portion / non polar end molecules and water soluble Composition substances 3 main types of lipid = Selective properties that allow A. Phospholipids - most abundant preferential diffusion of some 1. Lipid Soluble Particles/substances substances over others - Include: O2, CO2, Steroid hormones 2. Peripheral Proteins - Cross cell membrane because they - Attached only to one surface of the can dissolve in the hydrophobic lipid membrane and do not penetrate/ bilayer traverse all the way through 2. Water-soluble Particles/substances - NOT embedded in the cell membrane - Include: Na, Cl, glucose, H2O, urea - Often attached to the integral protein - Cannot dissolve in the lipid of the - Loosely attached to the cell membrane by membrane, but may cross through electrostatic interactions water-filled channels or pores or maybe transported by carriers PREPARED AND EDITED BY: MACARAEG, E., MACNI, K., MAPALO, D., NITURA, A., PASCUA, C., PAYUMO, M., PINERO, D.  (001) THE CELL AND ITS FUNCTION DR. MELANI T. GALLERO-REBULDELA | 09/15/2020 Functions: - Watery medium that is different from - Acts as channels/ carriers (integral proteins) the fluid in cytosol outside the Cell identity markers (antigens) endoplasmic reticulum is connected - Receptors (hormones/ neurotransmitters) with the space between the two - Source of enzymes membrane surfaces of the nuclear - Skeletal framework and adhesion membrane - Stability III. CARBOHYDRATES: GLYCOCALYX Not present in the inner surface Mostly incorporated with lipids (glycolipids) or proteins (glycoproteins) Glycocalyx - Loose carbohydrate coat the surrounds the entire outer surface if the cell Proteoglycans: - Mainly carbohydrate substances bound to small protein cores- are loosely attached to the outer surface of the cell Functions: - Gives most cells an overall negative surface charge that repels other negative objects B. Ribosomes - May attach to the glycocalyx of other cells Impart the rough appearance - Communication characteristic of this organelle = May act as receptor substances for Attached to the outer surface of the rER binding hormones such as insulin Made up of Ribonucleoprotein = Can sometimes function as channels Protein synthesis may also occur - Some carbohydrates moieties enter into immune reactions - Antigenic markers such as Trbc’s responsible for binding antibodies B. Cytoplasm and Its Organelles I. ENDOPLASMIC RETICULUM Helps process molecules made by the cell and transports them to their specific destinations inside and outside the cell Agranular /Smooth endopasmic reticulum: - Detoxify drugs - Lipid synthesis Granular / Rough Endoplasmic reticulum: Functions: - Ribosomes - Site translation of mRNA and - RNA posttranslational modification of proteins that Provide enzymes as well that are capable of are destined to be secreted from the cell or detoxifying substances such as drugs that are targeted to the plasma membrane or damage the cell. It achieves detoxification by other membranous organelles (rER) coagulation oxidation and hydrolysis - Carbohydrates and lipid synthesis, coagulation with glucuronic acid sequestration of calcium (Smooth ER) = Provides the enzymes that control A. Endoplasmic matrix glycogen breakdown for energy used - Space inside the tubules and vesicles PREPARED AND EDITED BY: MACARAEG, E., MACNI, K., MAPALO, D., NITURA, A., PASCUA, C., PAYUMO, M., PINERO, D.  (001) THE CELL AND ITS FUNCTION DR. MELANI T. GALLERO-REBULDELA | 09/15/2020 II. GOLGI APPARATUS - Degrade material that is brought into the Has membranes similar to those of agranular cell via the process of endocytosis and endoplasmic reticulum. phagocytosis Composed of 4 or more stacked layers of thin, - Degrade intracellular organelles flat, enclosed vesicles lying near one side of (autophagy) and some intracellular proteins the nucleus. Functions: IV. PEROXISOMES OR MICROBODIES - Sorts the proteins from the rER and Membrane bound organelles that contain packages them for delivery to other parts of various oxidative enzymes (e.g: catalase) the cell Similar physically to lysosomes, but they are - Synthesize certain carbohydrates that different in two important ways: cannot be formed in the ER - They are believed to be formed by self replication (or perhaps by budding off from ✔ The Membranous system of the Endoplasmic the smooth ER) rather from the golgi Reticulum and Golgi Apparatus represents a highly apparatus. metabolic organ capable of forming new - They contain oxidases rather than intracellular structures, as well as secretory hydrolases. substances to be extruded from the cell Function: - Detoxify a number of compounds and oxidize fatty acids V. SECRETORY VESICLES Formed by the endoplasmic reticulum – golgi apparatus system and are then released from the golgi apparatus into the cytoplasmic the form of storage vesicles. Digestive functions on the food in the intestinal tract VI. MITOCHONDRIA Powerhouse of the cell - without them, cells would be unable to extract enough energy from the nutrients and essentially all cellular functions would III. LYSOSOMES cease. Vesicular organelles that form by breaking off Contains their own DNA from the golgi apparatus and then dispersing The number of mitochondria reflects the energy throughout the cytoplasm requirements of the cell. Contain a number of digestive enzymes (e.g: - E.g: cardiomyocytes: use large amounts of proteases, nucleases, lipases, glycosidases) energy and have far more mitochondria Provide an intracellular digestive system that than do fat cells (adipocytes), which are allows the cell to digest: much less active and use less energy. - Damaged cellular structures The principal substances from which cells - Food particles that have been ingested by extract energy are foodstuffs that react the cell chemically with oxygen- carbohydrates, fats - Unwanted matter such as bacteria and proteins - Carbohydrates converted to glucose - Fats converted to fatty acids - Proteins converted to amino acids Functions: Function: PREPARED AND EDITED BY: MACARAEG, E., MACNI, K., MAPALO, D., NITURA, A., PASCUA, C., PAYUMO, M., PINERO, D.  (001) THE CELL AND ITS FUNCTION DR. MELANI T. GALLERO-REBULDELA | 09/15/2020 - Synthesize ATP (providing the energy - In other cells, they are involved in needed to power many vital cell functions) locomotion (e.g: macrophages) ATP - Also make up the core of microvilli and - energy currency of the cell links the interior of the cell to adjacent cells o energy that is released is used to form through some cell junctions the high energy compound Intermediate Filaments o spent and remade continually, having - Primarily structural in function turnover time of only a few minutes - Links the interior of the cell to adjacent - Nucleotide composed of: cells and the surrounding extracellular o Nitrogenous base adenosine matrix. o Pentose sugar ribose Microtubules o 3 phosphate radicals - Special type of stiff filament composed of - Almost all these reactions occur in polymerized tubulin molecules is used in all mitochondria and the energy that is cells to construct strong tubular structures. released is used to form the high energy - Primary function: acts as cytoskeleton compound, ATP - Cytoskeleton - The last 2 phosphate radicals are o provides rigid physical structures for connected with the remainder of the certain parts of cells molecule by so called high energy PO4 o not only determines the cell shape but bonds also participates in cell division - Each high energy bond contains 12, 000 o allows cells to move and provides calories of energy per mole of ATP track- like system that directs the movement of organelles within the cells VIII. NUCLEUS Control center of the cell. - Sends messages to the cell to grow and mature, to replicate, or to die. Contain large quantities of DNA, which comprise the genes. Genes - Determine the characteristics of cell’s - When ATP releases its energy, a phosphoric proteins, including structural proteins, as acid radical is split away and ADP is formed. well as the intracellular enzymes that - To reconstitute the cellular ATP as it is used control cytoplasmic and nuclear activities. up, energy-derived from the cellular nutrients - Control and promote reproduction of the causes ADP and phosphoric acid to cell recombine to form new ATP and the entire Characteristic constituents: Nucleic acids, process is repeated over and over. DNA and RNA together with residual - When ATP releases its energy, a phosphoric proteins. radical acid radical is split away and ADP is Nucleolus formed. This released energy is usd to - Accumulation of large amounts of RNA and energize many of the cell’s other functions, proteins of types found in ribosomes. such as synthesis of substances and Function: muscular contraction. - regulates metabolic processes of the cells VII. CELL CYTOSKELETON including synthesis of proteins and other Actin Filaments (Microfilaments) substances - Maintains shape of the cell - Includes cell growth and reproduction - In muscle cells, they are critical component of the contractile apparatus III. LOCOMOTION OF CELLS A. AMOEBOID MOVEMENT PREPARED AND EDITED BY: MACARAEG, E., MACNI, K., MAPALO, D., NITURA, A., PASCUA, C., PAYUMO, M., PINERO, D.  (001) THE CELL AND ITS FUNCTION DR. MELANI T. GALLERO-REBULDELA | 09/15/2020 Movement of an entire cell in relation to its A. Carbohydrates surroundings B. Cholesterol - E.g: White blood cells, when they move C. Proteins out of the blood into the tissues to form D. Water macrophages 6. SITE TRANSLATION OF mRNA AND POST- B. CILIA AND CILIARY MOVEMENT TRANSLATIONAL MODIFICATION OF Ciliary Movement PROTEINS THAT ARE DESTINED TO BE - Whiplike movement of cilia on the surfaces SECRETED FROM THE CELL OR ARE of the cells TARGETED TO THE PLASMA MEMBRANE - Occurs mainly on the surfaces of the OR OTHER MEMBRANOUS ORGANELLES. respiratory airways and on the inside A. Mitochondria surfaces of the uterine tubes (fallopian B. Golgi Apparatus tube) C. Rough endoplasmic reticulum Cilia D. Smooth endoplasmic reticulum - Each cilium is an outgrowth of a structure 7. VESICULAR ORGANELLES THAT FORM BY that lies immediately beneath the cell BREAKING OFF FROM THE GOLGI membrane APPARATUS AND THEN DISPERSING TEST YOUR KNOWLEDGE THROUGHOUT THE CYTOPLASM. 1. BUILDING BLOCKS OF THE BODY A. Peroxisomes PROVIDING STRUCTURE FOR THE BODY’S B. Endoplasmic reticulum TISSUES AND ORGANS, INGESTING C. Lysosomes NUTRIENTS AND CONVERTING THEM TO D. Golgi apparatus ENERGY AND PERFORMING SPECIALIZED 8. DETOXIFY A NUMBER OF COMPOUNDS AND FUNCTIONS. OXIDIZE FATTY ACIDS A. DNA A. Lysosomes B. Cell B. Mitochondria C. Mitochondria C. Peroxisomes D. Golgi apparatus D. endoplasmic reticulum 2. INTRACELLULAR FILAMENTS ARE USED 9. POWERHOUSE OF THE CELL TO FORM MICROTUBULES THAT PROVIDE A. Microbodies CYTOSKELETONS TO SUCH ORGANELLES B. Golgi apparatus A. Structural Protein C. Mitochondria B. Integral Protein D. Endoplasmic reticulum C. Functional Protein 10. CONTROL CENTER OF THE CELL D. Globular Protein A. Cell wall 3. MAJOR NUTRITION OF THE CELL B. Cell membrane A. Water C. Nucleus B. Proteins D. ATP ANSWERS: B,A,D,A,B,C,C,C,C,C C. Lipids D. Carbohydrates 4. REGULATES CELLULAR TRANSPORT REFERENCES (MOST IMPORTANT CELL FUNCTION) 1. Guyton, A.C., Hall, J.E. (2006). Textbook of AND MAINTAINS THE COMPOSITION OF ICF Medical Physiology.11th Ed. AND ECF Mississippi. Elsevier Inc. A. Plasma Membrane B. Nuclear Membrane C. Both D. None 5. MAINLY HELP DETERMINE THE DEGREE OF PERMEABILITY OF THE LIPID BILAYER TO WATER SOLUBLE SUBSTANCES PREPARED AND EDITED BY: MACARAEG, E., MACNI, K., MAPALO, D., NITURA, A., PASCUA, C., PAYUMO, M., PINERO, D.