Anatomy and Histology for Nursing: The Cell PDF

Anatomy and Histology for Nursing The cell Lecturer: Rima Altaweel Introduction The cell: is the basic structural and functional unit of the body/life. There are two types of cells Prokaryotes Eukaryotes...

Anatomy and Histology for Nursing The cell Lecturer: Rima Altaweel Introduction The cell: is the basic structural and functional unit of the body/life. There are two types of cells Prokaryotes Eukaryotes lack a nuclear envelope Contain a nucleus  Cells can be divided into 3 groups: Somatic cells are all the cells in the Stem cells body that aren’t sex are cells, like blood cells, undifferentiate neurons, and d or partially osteocytes(bone cells). differentiated cells that can change into Germ cells various types of are cells that develops cells into a reproductive cell, which is an egg in females and a sperm in males Introduction The cell: is the basic structural and functional unit of the body/life. Structure of the cell: The cell has three principle parts as follows: 1. Nucleus 2. Plasma membrane 3. Cytoplasm  1. Nucleus The nucleus frequently appears as a rounded or oval structure, usually in the center of the cell. Within the nucleus are most of the cell’s hereditary units, called genes, which control cellular structure and direct cellular activities.  1. Nucleus Human somatic (body) cells have 46 chromosomes, 23 inherited from each parent. Each chromosome is a long molecule of DNA that is coiled together with several proteins This complex of DNA, proteins, and some RNA is called chromatin. The DNA replicates (duplicates) and the loops condense even more, forming a pair of chromatids. A pair of chromatids form a chromosome  Nucleus COMPONENTS OF THE NUCLEUS Nucleolus Nuclear envelope Chromatin (DNA and proteins)  2. Plasma membrane Plasma membrane: it is the cell’s flexible outer surface. Function: Surrounds the cell and separates its internal environment from the external environment. - It has a selective permeability; that is it regulates the flow of materials into and out of a cell. - Cellular communication Plasma membrane Structure: 1. Bilayer of phospholipid Phospholipid 2. Protein: bilayer Integral: protrude into both the cytosol and extracellular fluid Peripheral: are attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane. Plasma membrane Movement of materials across the plasma membrane can be divided according to energy requirements as follows: Passive transfer: no energy needed. Depends on the difference in concentration and osmotic pressure. Active transfer: needs energy. Either through pumps like sodium pump or by phagocytosis. 3. Cytoplasm It consists of all the cellular contents within the plasma membrane except for the nucleus. It has two components: 1. Cytosol: is the intracellular semifluid complex that surrounds organelles. It is composed of water plus various other components such as proteins, lipid, carbohydrate and inorganic substance. 2. Organelles and inclusion: Organelles are vital and have an activity. Inclusions are not active and are only a site of storage. Cytoplasm Ribosomes Tiny granules consisting of ribosomal RNA and ribosomal proteins. They are either free or attached to the endoplasmic reticulum. It is the site of protein synthesis using the nuclear information carried by the messenger RNA coming from the nucleus. Endoplasmic Reticulum Network of membrane enclosed channels that connects the nuclear membrane and the cytoplasm. If ribosomes are attached to the endoplasmic reticulum it is called rough endoplasmic reticulum If no ribosomes are attached it is called smooth endoplasmic reticulum. Endoplasmic Reticulum Function Rough ER Functions: synthesizes glycoproteins and phospholipids detoxify certain drugs. Smooth ER synthesizes fatty acids and steroids, such as estrogens and testosterone Endoplasmic Reticulum also transport substances to the Golgi apparatus Golgi complex Consists of several stacked and flattened membranous sacs: cis, medial, and trans. Function: Process, sort and deliver proteins and lipids to the plasma membrane as secretory vesicles.  Mitochondria Has a double membrane; outer smooth and inner irregular folded membrane (Cristae). Function: Site of oxidation and energy production. Most of the ATP is produced in the mitochondria (power house of the cell). Cytoskeleton It is a network of protein filaments that extends throughout the cytosol. Three types of filaments contribute to the cytoskeleton structure: (1) Microtubules: help determine cell shape. (2) Intermediate filament (3) Microfilament: they are composed of the proteins ACTIN AND MYOSIN Cytoskeleton Function Facilitates movement and gives mechanical support. It provides organization for chemical reactions. Assists movement of chemicals and organelles in the cytosol.  Centrosome and Centriole The centrosome is the microtubule-organizing center for the mitotic spindle and consists of paired centrioles. Centrosomes serve as centers for organizing centers for growth during the cell division, and for microtubules formation.  Lysosomes Lysosomes are membrane-enclosed vesicles that form from the golgi complex. They contain many kinds of digestive enzymes that are capable of breaking down a wide variety of molecules.  Cell Inclusions Chemical substances produced by the cell. Usually organic and have recognizable shape. Ex: melanin, glycogen, triglycerides. Identify?  Cell division Cell division is a very important process in all living organisms. Cell division is the process by which cells replicate in order to replace cell loss, repair tissue damage and reproduce the organism. The cell cycle, or cell-division cycle, is the sequential series of events that take place in a cell that causes it to divide into two daughter cells. Two types of cell division are encountered in the human cell: Mitosis and Meiosis  Mitosis Mitosis: the process by which a cell divides into two daughter cells that are genetically identical to the parent cell, and each one has 46 chromosomes. All cells of the body with the exception of the fully differentiated nerve cells undergo mitotic division.  Meiosis In Meiosis, two genetically none identical daughter cells are produced from the mother cell. Meiosis is the reproductive cell division that occurs on the gonads (ovaries and testes), produces gametes with half number of chromosomes (23 chromosomes) Mitosis and Meiosis proceed in two phases: nuclear division in which genetic materials are shared and cytoplasmic division (Cytokinesis) in which other organelles of the cell are shared.