Cytology Dr. Dina A. A. Hassan Associate Professor, Pharmacology Email: da.hassan@psau.edu.sa
Cells All living things are made up of cells Basic building blocks of life It is the smallest functional and structural unit of the living organism. All cells come from preexisting cells through cell division A cell may be an entire organism (in a unicellular organism) or it may be one of billions of cells that make up the organism (in a multicellular organism). Grow, reproduce, use energy, adapt, respond to their environment 2
A cell is the smallest unit that is capable of performing life functions. 3
Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell 4
Prokaryotic: E.g. Bacteria and Archaea First cell type on earth No membrane bound nucleus Nucleoid = region of DNA concentration Organelles not bound by membranes Eukaryotic: E.g. fungi, plant, and animal cells Nucleus bound by membrane Possess many organelles 5
Typical Animal Cell http://web.jjay.cuny.edu/~acarpi/nsc/images/cell.gif 6
Cytoplasm Gel-like mixture Surrounded by cell membrane It contains 1. Organelles ( living structures) 2. Nucleus (which contains hereditary material) 3. Inclusion ( non living structures): stored nutrients, secretory products, and pigment granules. Examples of inclusions are glycogen granules in the liver and muscle cells, lipid droplets in fat cells, pigment granules in certain cells of skin and hair, water-containing vacuoles, and crystals of various types. 7
Endoplasmic Reticulum Types : Smooth type: Lacks ribosomes & Rough type: Ribosomes embedded in surface Function: Moves materials around in cell Ribosomes Each cell contains thousands of ribosomes Types: Free ribosomes: Found on the outer surface of Rough ER & Attached ribosomes: floating throughout the cytoplasm of the cell. Function: Make proteins 8
Mitochondria Second largest organelle in the cell after nucleus Structure: Has a double layered outer membrane with inner folds called cristae Functions: Produces energy through chemical reactions (cellular respiration) breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates and forms urea. Golgi Bodies Functions: Protein 'packaging plant' Move materials within the cell Move materials out of the cell 9
Lysosome Contain digestive enzymes Functions: Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal Cell breaks down (cell lysis) if lysosome explodes Vacuoles Membrane-bound sacs contains water, food and waste. Functions: they are site for storage, digestion, and waste removal Help plants to maintain their shape 10
Nucleus The nucleus is a nearly spherical structure present inside the cytoplasm of the cell Separated from cytoplasm by nuclear membrane Functions: Directs cell activities Contains genetic material DNA Inside nucleus Contains RNA to build proteins Nuclear Membrane It Surrounds the nucleus It consists of two layers: the outer layer is connected to the membrane of rough endoplasmic reticulum, while the inner layer is connected to chromatin It contains (nuclear pores) which are openings in the nuclear membrane to allow material to enter and leave nucleus Chromosomes Present inside in nucleus It is made of DNA Contain instructions for characteristics & genetic material. 11
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Plasma Membrane Structure Outer membrane of cell that controls movement in and out of the cell Formed of double layers 13
Histology1 Tissue and their classification Dr. Dina A. A. Hassan Associate Professor, Pharmacology Email: da.hassan@psau.edu.sa
Tissue Histology: Microscopic study of cells, tissues and organs (microscopic anatomy) Tissues: Groups of closely associated cells that are similar in structure and function Similar cells and cell products arise from same region of embryo Between cells: nonliving extracellular material Four primary tissues types: Epithelial tissue Connective tissue Muscular tissue (covering) (support) (movement) Nervous tissue (control) 15
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Preparation of histological specimens Fixative prevents decay (formalin) Sliced into thin sections 1 or 2 cells thick Mounted on slides and colored with histological stain stains bind to different cellular components Sectioning reduces 3-dimensional structure to 2-dimensional slice 17
1 2 3 4 5 1 5 2 3 4 Sectioning a cell with a centrally located nucleus Some slices miss the cell nucleus (Slices 1 & 5) In some cell the nucleus is smaller (Slices 2 & 4) 18
Cross section of blood vessel, gut, or other tubular organ. Longitudinal section of a sweat gland. Notice what a single slice could look like. 19
Longitudinal section tissue cut along longest direction of organ Cross section tissue cut perpendicular to length of organ Oblique section tissue cut at an angle between cross and longitudinal section 20
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