biology 2 part 1

• Histology is the study of tissues.
• Tissues are groups of cells which are similar in structure and which perform common or related functions.
• Epithelial Tissue covers the body, lines the cavities, tubes, ducts and blood vessels inside the body, covers the organs inside body cavities, protects from physical & chemical injury, protects against microbial invasion, contains receptors which respond to stimuli, filters, secretes & reabsorbs materials, and secretes serous fluids to lubricate structures.
• Connective Tissue is the most abundant & widely distributed tissue, it includes a large group of different tissue characterized by having dispersed cells and a large extracellular space called Extracellular matrix.
• Extracellular matrix includes protein fibers such as collagen, elastic or reticular, is solid in bone, soft in connective tissue, and liquid in blood.
• Connective Tissue functions to connect, bind and support structures, tendons, ligaments, protects & cushions organs and tissues, insulates (fat) and transports substances (nutrients and waste), and is involved in repair of body parts and body defense.
• Muscle Tissue is associated with the bones of the skeleton, the heart and in the walls of the hollow organs of the body, it maintains posture, produces heat, and is involved in facial expressions, pumping blood, peristalsis, and nervous system function.
• Nervous Tissue is the main component of the nervous system, it regulates and controls body functions, generates and transmits nerve impulses, supports, insulates and protects impulse generating neurons.
• Epithelial Squamous Epithelium is simple, one cell thick, forms a solid layer of cells which line blood vessels, body cavities & cover organs in body cavities.
• Stratified Epithelium is multiple layers, forms epidermis.
• Cuboidal Epithelium is simple, one cell thick, lines ducts in kidneys, etc, where reabsorption and secretory activities take place.
• Columnar Epithelium is simple, one cell thick, lines digestive tract where reabsorption & secretion occurs.
• Pseudostratified Epithelium gives the appearance of more than one layer of columnar epithelial cells.
• Connective Tissue Types include Connective - Bone, which has a tree ring-like appearance, supports & protects, stores minerals and fat, and is involved in blood cell production, and Connective – Hyaline Cartilage which supports while providing flexibility, absorbs compression between bones in joints, holds open respiratory passages, and is the most abundant type of cartilage in the body.
• Muscle Tissue Types include Muscle - Skeletal which consists of muscle fibers (cells) long, parallel & cylindrical with many nuclei (multinucleate), produces voluntary movement, locomotion, maintains posture, produces heat, and is involved in facial expressions, pumping blood, peristalsis, and nervous system function, and Muscle - Cardiac which is found only in the walls of the heart, its contraction is involuntarily controlled, and it allows impulses to move freely from one muscle fiber to another.
• Smooth Muscle is not striated, spindle-shaped muscle that is involuntarily controlled, is found in a wall of the stomach, intestines, urinary bladder, uterus and blood vessels.
• Nervous Tissue consists of branching cells with many long processes, a large central nucleus, and transmits impulses from one area of the body to other areas.