Anatomy and Physiology 1: Cell and Tissue (Part 1) PDF

RNB10603 ANATOMY AND PHYSIOLOGY 1 TOPIC 2 THE CELL AND TISSUE (PART 1) Y.S. PEK  SIX LEVELS OF ORGANIZATION OF THE BODY 1 2 3 5 4 6...

RNB10603 ANATOMY AND PHYSIOLOGY 1 TOPIC 2 THE CELL AND TISSUE (PART 1) Y.S. PEK  SIX LEVELS OF ORGANIZATION OF THE BODY 1 2 3 5 4 6 2 CELL STRUCTURE 3  LEARNING OUTCOMES At the end of the topic, you should be able to: 1. list various functions of cells 2. differentiate between the types of microscope used to view cells 3. identify the basic characteristics of a typical human cell 4. describe the main components of a typical human cell 4  INTRODUCTION All living organisms are composed of cells. Cells are the basic structural and functional units of our bodies. Our body is made up of trillions of cells and contains about 200 distinct types of cells. Each cell is unique with important characteristics and functions. 5 Generalized View of Cell Structure 6 THE SIMPLE CELL 7  FUNCTIONS OF CELLS Cells are like “little factories”, constantly active in carrying out specific tasks. Generally, the functions of cells are: 1. Basic unit of life ▪ Cells are the building blocks of living organisms 2. Inheritance ▪ Genetic blueprint: they are the reproductive cells 3. Cellular metabolism and energy release 4. Protection and support, e.g. bone cells 5. Communication ▪ Produce or receive chemical or electrical signals in body 6. Movement, e.g. muscle cells 8 9 VISUALISING CELLS – THE USE OF MICROSCOPES & STAINING 10 VISUALISING CELLS – THE USE OF MICROSCOPES & STAINING 11 12 CHARACTERISTICS OF CELLS 13 COMPONENTS OF A CELL 14  COMPONENTS OF A CELL Although each cell may show different characteristics for the different functions performed; cells do have some fundamental/basic characteristics. Divided into 3 main parts: ✓ Plasma membrane ✓ Cytoplasm: cytosol + organelles ✓ Nucleus 15 THE SIMPLE CELL 16  PLASMA MEMBRANE ▪ Surrounds and contains the cytoplasm of a cell ▪ Phospholipid bilayer (back to back) ▪ Cholesterol ▪ Proteins (integral and peripheral) ▪ Attached carbohydrates (in the form of glycolipids and glycoproteins) ▪ Head of phospholipid molecule – hydrophilic ▪ Tail - hydrophobic 17 PLASMA MEMBRANE 18  FUNCTIONS OF PLASMA MEMBRANE Barrier between inside and outside of cell Controls entry of materials: transport through a selective semi-permeable membrane ▪ The simple sugar, amino acids, potassium ions and water can pass through the membrane rapidly; but sodium ions and other substances cannot. Maintain cell integrity Proteins receptor sites (recognition sites) 19 CYTOPLASM - CYTOSOL 20  CYTOPLASM: ORGANELLES  Specialized cellular structures inside cells  Specific functions and characteristic shapes ✓ Mitochondria ✓ Ribosomes ✓ Endoplasmic reticulum ✓ Golgi apparatus ✓ Lysosome ✓ Nucleus & nucleolus 21  MITOCHONDRIA Structure: ✓ Sausage-shaped with many folded membranes (cristae) and liquid matrix containing enzymes ✓ Have some DNA, ribosomes (can make proteins) Function: ✓ Nutrient energy is released and trapped in ATP; so known as “power houses of cell” 22 MITOCHONDRIA 23  RIBOSOMES They are spherical bodies. Consist of ribosomal ribonucleic acids (rRNA) + proteins Sites of protein synthesis Contain large and small subunits Can be attached to endoplasmic reticulum or freely within cytosol 24 RIBOSOMES 25 RIBOSOMES Complete functional ribosome 26  ENDOPLASMIC RETICULUM (E.R.)  Structure: ✓ network of folded membranes that extends from the nuclear envelope  Two Types of E.R. i. Rough E.R. ii. Smooth E.R. 27  ENDOPLASMIC RETICULUM (E.R.) i. Rough E.R. ✓ studded with ribosomes (sites of protein synthesis) ✓ Protein synthesized on the ribosomes enter rough E.R. for processing, sorting and transporting ✓ Factory for synthesizing secretory proteins and membrane molecules 28  ENDOPLASMIC RETICULUM (E.R.) ii. Smooth E.R. ✓ Lack ribosomes ✓ Lipid synthesis ✓ Release of glucose in liver cells into bloodstream ✓ Drug detoxification (especially in liver cells) ✓ Storage and release of Ca2+ in muscle cells 29 ENDOPLASMIC RETICULUM (E.R.) 30  GOLGI COMPLEX Flattened membranes (cisterns) with bulging edges Communicate with ER and cell surface Most cells have several Golgi complex 31  GOLGI COMPLEX Functions: ✓ Modifies, sort, packages and transport proteins received from rough ER ✓ Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid ✓ Forms membrane vesicles that ferry new molecules to the plasma membrane ✓ Forms transport vesicles that carry molecules to other organelles, such as lysosomes 32  LYSOSOMES Membrane-enclosed vesicles that contain digestive enzymes. Functions: ✓ Help in final processes of digestion within cells ✓ Carry out autophagy (destruction of worn-out parts of cell) and ✓ Digestion of dead and old cells (autolysis) Autolysis occur in some pathological condition and occurs just after death. 33  CENTROSOME Structure: ▪ Two centrioles arranged perpendicular to each other ▪ Composed of microtubules: 9 clusters of 3 (triplets) ▪ Pericentriolar material ▪ Composed of tubulin that grows the mitotic spindle Function: ▪ moves chromosomes to ends of cell during cell division 34 CENTROSOME 35  NUCLEUS Spherical or oval structure surrounded by a nuclear envelope with nuclear pores. Generally, occupies a central position in the cell. All cells in the human body have a nucleus, except the mature erythrocyte (RBC). It contains nucleolus (nuclei –plural) ▪ makes ribosomes (ribosome synthesis) that pass into cytoplasm through nuclear pores ▪ RNA processing 36  NUCLEUS ▪ Nucleus stores genetic material (DNA), the chemical basis of genes, arranged in 46 chromosomes ▪ The very long DNA molecules are complexed with proteins to form chromatin and are further organised into chromosomes. ▪ DNA replication and RNA synthesis (transcription) occur inside the nucleus. 37 NUCLEUS 38 NUCLEUS 39 40 SUMMARY 41 42 43