Cell physiology
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The document discusses the structure and function of cells, tissues, organs and systems in the human body. It begins by defining cells as the basic functional units that make up tissues like blood, muscle and bone. Tissues combine to form organs like the heart, stomach and brain. Organs work together in organ systems to carry out important body functions. The document then provides detailed descriptions of cell structures such as the cell membrane, cytoplasm, organelles, and the functions they perform. It also discusses how cells, tissues and organ systems are organized in the body.
Cell physiology
- 2. Cell-Introduction Smallest functional units of the body Grouped together to form tissues, each having a specialized function, e.g. blood, muscle, bone. Different tissues are grouped together to form organs, e.g. heart, stomach, brain. Organs are grouped together to form systems, that perform particular function that maintains homeostasis and contributes to the health of the individual. E.g. digestive system, cardiovascular system. By Gladys Stephen
- 3. TISSUE Tissue is defined as the group of cells having similar function. There are many types of tissues in the body. classified into four major types primary tissues that includes Muscle tissue (skeletal muscle, smooth muscle and cardiac muscle) Nervous tissue (neurons and supporting cells) Epithelial tissue (squamous, columnar and cuboidal epithelial cells) Connective tissue (connective tissue proper, cartilage, bone and blood). By Gladys Stephen
- 4. ORGAN a structure that is formed by two or more primary types of tissues, do a physiological function. Some organs are composed of all the four types of primary tissues. The organs are of two types, namely tubular/hollow organs compact or parenchymal organs. Some of the organs in the body are brain, heart, lungs, stomach, intestine, liver, gallbladder, pancreas, kidneys, endocrine glands, etc By Gladys Stephen
- 5. SYSTEM A group of organs that work together to carry out specific functions of the body. Each system performs a specific function. digestive system is concerned with digestion of food particles. Excretory system eliminates unwanted substances. Cardiovascular system is responsible for transport of substances between the organs. Respiratory system is concerned with the supply of oxygen and removal of carbon dioxide. Reproductive system is involved in the reproduction of species. Endocrine system is concerned with growth of the body and regulation and maintenance of normal life. Musculoskeletal system is responsible for stability and movements of the body. Nervous system controls the locomotion and other activities including the intellectual functions. By Gladys Stephen
- 6. The cell A cell consists of a cell (plasma) membrane inside which a nucleus and cytoplasm surrounding the nucleus is present Organelles are small organs of the cell embedded in the cytoplasm. Have individual and highly specialized functions Organelles are enclosed in their own membrane within the cytoplasm. Individual cells are too small to be seen through the naked eye. By Gladys Stephen
- 8. Cell (Plasma) membrane Also called as plasmalemma Separates outside fluid (extracellular fluid) and the intracellular fluid It is a semipermeable membrane The thickness of the cell membrane varies from 75- 111A By Gladys Stephen
- 9. Cell membrane Consists of 2 layers of phospholipids with protein and sugar molecule embedded in them. Those proteins molecules extend all the way through the membrane provides channels that allow the passage of e.g. electrolytes and non-lipid substances By Gladys Stephen
- 10. Membrane proteins The lipid bilayer forms the basis of the cell membrane, distributed throughout with various proteins. Two different types of proteins that are commonly associated with the cell membrane Integral proteins – embedded in the membrane e.g. cell adhesion protein. peripheral protein - selectively allows particular materials, such as certain ions, to pass into or out of the cell., e.g. channel protein By Gladys Stephen
- 11. Functions of membrane protein Cell membrane protects the cytoplasm and the organelles present in the cytoplasm Cell membrane acts as a semipermeable membrane, which allows only some substances to pass through it and acts as a barrier for other substances Nutrients are absorbed into the cell through the cell membrane Metabolites and other waste products from the cell are excreted out through the cell membrane Oxygen enters the cell from the blood and carbon dioxide leaves the cell and enters the blood through the cell membrane (exchange of gases) Cell membrane is responsible for the maintenance of shape and size of the cell. By Gladys Stephen
- 12. Cytoplasm Cytoplasm of the cell is the jellylike material formed by 80% of water. It contains a clear liquid portion called cytosol and various particles of different shape and size. These particles are proteins, carbohydrates, lipids or electrolytes in nature. Cytoplasm contains many organelles with distinct structure and function. Cytoplasm is made up of two zones: Ectoplasm: Peripheral part of cytoplasm, situated just beneath the cell membrane Endoplasm: Inner part of cytoplasm, interposed By Gladys Stephen
- 13. The organelles in the cytoplasm are: Nucleus Mitochondria Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes Peroxisome Centrosome and centrioles Secretory vesicles cytoskeleton By Gladys Stephen
- 14. Nucleus Every cell has a nucleus (except matured erythrocyte). Nucleus is the largest organelle inside a nuclear envelope (10-20 micron) Nucleus contains body’s genetic material (gene) The cells with nucleus are called eukaryotes – cell with nucleus Prokaryote - cell without nucleus Nucleolus is present within the nucleus which involves in the manufacture or synthesis and assembly of the components of ribosomes. By Gladys Stephen
- 15. Mitochondria Mitochondria are membranous, sausage-shaped structures in the cytoplasm It is called as power house of the cell Involves in aerobic respiration (energy is made available in cell) by synthesizing ATP Most active cell types have the greater number of mitochondria e.g. liver, muscle By Gladys Stephen
- 16. ribosomes Tiny granules composed of RNA and protein Present on the outer surface of the nuclear envelope and rough endoplasmic reticulum Make proteins for use within the cell such as enzymes required for metabolism By Gladys Stephen
- 17. Endoplasmic reticulum Interconnecting membranous canals in the cytoplasm Two types Smooth ER – synthesizes lipids and steroid hormones, and associated with the detoxification of some drugs. Rough ER – Studded with ribosomes and are site of synthesis of some proteins. By Gladys Stephen
- 18. Golgi apparatus Consists of stacks of closely folded flattened membranous sacs Proteins move from ER to GA where they are packed into membrane-bound vesicles called secretory granules. These vesicles move to the plasma membranes and fuse with it, when in need The contents then leave the cell by exocytosis By Gladys Stephen
- 19. lysosomes Type of secretory vesicle with membranous walls formed by GA. Contain a variety of enzymes involved in breaking down fragments of organelles and large moleculs (RNA, DNA, carbohydrates, proeins) inside the cell in to smaller particle Lysosomes in WBC contain enzymes that digest foreign material such as microbes By Gladys Stephen
- 20. cytoskeleton Consists of an extensive network of tiny protein fibers Microfilaments Smallest fibers Provides structural support Maintains characteristic shape of cell Permits contraction e.g. muscle cells Microtubules Larger contractile protein fibers that are involved in the movement of Organelles within the cells Chromosomes during cell division Cell extensions By Gladys Stephen
- 21. Centrosomes Directs organization of microtubules within the cell. Consists of a pair of centrioles Plays an important role in cell division Cell extensions Project from the plasma membrane Main components are microtubules which allow movement Types of cell extensions are Microvilli – tiny projections containing microfilaments Cilia – microscopic hair-like projections containing microtubules along the border of cells. Flagella – single, long whip-like projections containing microtubules forming tails of cells like spermatozoa By Gladys Stephen
- 22. Cell cycle The period between two cell divisions is known as the cell cycle. Has two phases that can be seen on light microscopy Mitosis (M phase) Interphase longer phase and 3 separate stages are recognized . First gap phase (G1) – the cell grows in size and volume. Synthesis of DNA (S phase) – the chromosomes replicate forming two identical copies of DNA. Therefore following this phase, the cell now has 92 chromosomes enough DNA for 2 cells and ready to divide by mitosis Second gap phase (G2) - further growth and preparation for cell division. By Gladys Stephen
- 23. Mitosis It is a continuous process involving 4 stages seen by light microscopy Prophase Replicated chromatin becomes tightly coiled (seen under microscope) 46 chromosomes is paired with its copy in a double chromosome unit 2 chromotids joined to each other at the centromere Mitotic apparatus appears – containing 2 centrioles separated by mitotic spindle Nuclear envelope disappears. Metaphase Chromatids align on the centre of the spindle, attached by their centromeres Anaphase Centromeres separate, each pair of sister chromatids (chromosomes) migrates to each end of the spindle Telophase Mitotic spindle disappears, chromosomes uncoil Nuclear envelope reforms By Gladys Stephen
- 24. Transport of substances across cell membranes Passive transport Diffusion Faciliated diffusion Osmosis Active transport The sodium-potassium pump Bulk transport By Gladys Stephen
- 25. Passive transport When substances can cross the semipermeable plasma and organelle membranes and does not require any energy. Move down the concentration gradient without using energy Diffusion Small molecules diffuse down the concentration gradient Lipid-soluble materials – oxygen, carbon dioxide, fatty acids and steroids cross the membrane by dissolving in the lipid part of membrane Water-soluble materials – sodium, potassium and calcium cross the membrane by passing through water-filled channels By Gladys Stephen
- 26. Different types of cells in the body (BASED ON TISSUE FORMATION) Bone cells (Osteocytes) Cartilage cells (chondrocytes) Nerve cells Epithelial cell Secretory cell Adipose cells Blood cells By Gladys Stephen
- 27. TYPES OF CELLS IN HUMAN BODY (BASED ON THEIR FUNCTION) Conductive cells Connective cells Glandular cells Storage cells Supportive cells By Gladys Stephen
- 28. Special types of cells are Sperms Oocytes Stem cells Rods and cones Ciliated cells Blood cells By Gladys Stephen