NATIONAL REVIEW COURSE. Cells, Tissues, and Membranes

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1 NATIONAL REVIEW COURSE Cells, Tissues, and Membranes I. Cell Types A. Prokaryote bacteria cells; a cell that does not have a nucleus in which to store its genetic material. B. Eukaryote plant or animal cells; a cell with an enclosed nucleus in which the cell stores its genetic material. II. Eukaryotic Cell Structure and Organelles A. Cell membrane 1. Also known as plasma membrane, phospholipid bilayer. 2. The external structure that houses the cell s contents and regulates what moves into and out of the cell; separates the intracellular environment from the extracellular environment. B. Cytoplasm the intracellular environment; consists of cytosol (fluid) and organelles (solids). C. Organelles 1. Distinct structures inside the cytoplasm that each have their own function to keep the cell alive; the cell s organs. 2. Some important organelles to know: a. Nucleus the largest organelle; the cell s command center; contains the cell s genetic material, including: i. DNA (deoxyribonucleic acid) the genetic blueprint of the body containing all information for anatomical structures and physiological processes. ii. Chromatin the form DNA takes in the nucleus during the cell s growth phase. iii. Chromosomes the most compact form of DNA in the nucleus taken before cell division; human cells have 23 pairs of chromosomes. iv. Genes segments of chromosomes that carry the genetic code for a specific protein. v. RNA (ribonucleic acid) forms copies of DNA segments that are transferred from the nucleus to the cytoplasm. b. Ribosomes responsible for decoding RNA and using that information to build proteins. c. Endoplasmic reticulum (ER) network of stacked, flattened tubules located close to the nucleus; the location for molecule production and responsible for collecting, packaging and shipping. i. Rough ER rough appearance due to ribosomes found on its surface; location for protein production.

2 III. IV. ii. Smooth ER lacks ribosomes on its surface; location for non-protein production. d. Golgi apparatus network of stacked, flattened membranes located away from the nucleus; location for protein modification. e. Mitochondria the powerhouse of the cell; responsible for energy production in the form of ATP (adenosine triphosphate). f. Lysosome contains digestive enzymes used to clean-up the inside of the cell by digesting damaged or foreign particles (think Lysol ) g. Centrioles paired, spindle-like structures that organize the cell s DNA during cell division (mitosis). h. Cilia hair-like protrusions from the cell membrane used for moving substances across the surface of the cell. i. Flagellum tail-like projection from the cell membrane used for cell motility (e.g. sperm) Cellular Transport and Movement A. Diffusion movement of a substance from an area of high concentration to an area of low concentration to reach equilibrium. B. Osmosis diffusion of water through a semipermeable membrane. C. Filtration movement of a fluid through pores of a membrane that restrict movement of larger particles; based on pressure. D. Active transport movement of a substance from low concentration to high concentration; requires energy; opposite of diffusion. E. Phagocytosis solid particles engulfed by the cell membrane; cell eating. F. Pinocytosis fluid particles engulfed by the cell membrane; cell drinking. Tissues A. Histology the study of tissues B. Four primary tissue types in the body: 1. Epithelial tissue 2. Connective tissue 3. Muscle tissue 4. Nervous tissue V. Epithelial Tissue A. Forms all coverings and linings of the body. B. Named based on the shape of the cells and the number of cell layers. C. Cell shapes: 1. Squamous flat cells; adapted for diffusion, filtration, and protection. 2. Cuboidal cube-shaped cells; adapted for secretion and excretion. 3. Columnar column-shaped cells; adapted for protection and secretion.

3 VI. 4. Transitional similar to squamous but able to stretch without tearing; transitions between shapes; adapted for stretching. D. Cell layers: 1. Simple one layer of cells. 2. Stratified more than one layer. E. Examples: 1. Simple squamous epithelium single layer of flat cells; alveoli of lungs, capillaries. 2. Stratified squamous epithelium many layers of flat cells; the outer skin, linings of body cavities. 3. Simple cuboidal epithelium single layer of cube-shaped cells; lines glands and ducts. 4. Stratified cuboidal epithelium rare. 5. Simple columnar epithelium single layer of column-shaped cells; lines digestive tract. 6. Pseudostratified columnar epithelium single layer of columnshaped cells that looks like many layers; lines respiratory tract, much is ciliated. 7. Stratified columnar epithelium rare. 8. Transitional epithelium found in urinary tract only, particularly the bladder. Connective Tissue A. Used for packaging, protecting, and supporting various organs B. Most abundant tissue in the body. C. Soft connective tissue (loose/areolar tissue): 1. Adipose tissue made of adipose cells that store fat molecules; used for insulation, protection, and energy storage. 2. Fascia forms the coverings around muscles, blood vessels, and nerves; connects structures to surrounding tissues to hold them in place. D. Dense fibrous connective tissue strong, flexible tissue due to its content of collagen fibers and elastic fibers. 1. Regular fiber orientation is along the long axis; found in tendons and ligaments. 2. Irregular fiber orientation is random; found in aponeuroses, retinacula, and scars. E. Reticular connective tissue fibers with embedded phagocytes for immune function; found in the spleen, lymph nodes, bone marrow. F. Hard connective tissue: 1. Bone rigid tissue providing structure and protection. 2. Cartilage semisolid tissue providing structure and shock absorption. G. Blood liquid connective tissue V. Muscle Tissue A. Responsible for movement of the body and movement in the body.

4 VI. VII. 1. Smooth muscle (visceral muscle) nonstriated, involuntary; located in hollow organs of the digestive tract, respiratory passages, arterial walls, etc. 2. Cardiac muscle striated, involuntary; located in the heart only. 3. Skeletal muscle striated, voluntary; attached to the skeleton for body movement. Nervous Tissue A. Nervous tissue responsible for conducting electrical nerve impulses (action potential) through the body allowing for communication. 1. Neuron nerve cell responsible for conducting the action potential. 2. Glia supporting cells of the nervous system. Membranes A. Cutaneous membrane (skin) epithelial tissue; covers the outer body and lines cavities exposed to the external environment. B. Mucous membranes (mucosa) epithelial tissue; secretes mucous; lines most of the cavities in the respiratory and digestive systems to protect and lubricate. C. Serous membranes (serosa) epithelial tissue; secretes serous fluid; covers the internal organs and lines the cavities not exposed to the external environment. 1. Visceral membrane covers an organ. 2. Parietal membrane lines a cavity. 3. Pleurae serous membranes associated with the lungs. a. Visceral pleurae covers the lungs. b. Parietal pleurae lines the pleural cavities. 4. Pericardium serous membrane surrounding the heart. a. Visceral pericardium (epicardium) - covers the heart. b. Parietal pericardium - lines the pericardial cavity. 5. Peritoneum serous membrane of the abdominal cavity. a. Visceral peritoneum covers the organs. b. Parietal peritoneum lines the cavity. D. Synovial membrane lines the inside of the joint capsule of synovial joints; secretes synovial fluid as a lubricant. Sample Questions Serous membranes: A. line the inside of blood vessels. B. are found in the organs of the digestive tract. C. cover the central nervous system. D. surround the internal organs and body cavities. What type of muscle cell is NOT striated? A. Smooth (visceral) B. Cardiac C. Skeletal D. Heart muscle

5 The lubricating fluid that is found in moveable joints is called: A. serous fluid. B. synovial fluid. C. arthropometric fluid. D. diarthrotic fluid. The most abundant and widely distributed tissue of the body is: A. connective tissue. B. epithelial tissue. C. serous tissue. D. tendons. Functions of the connective tissue include all of the following except: A. nutrient transportation. B. defense against disease. C. clotting mechanisms. D. neural transport. All of the following are functions of adipose tissue except: A. protection. B. thermal heat. C. movement. D. insulation.