Tissues and muscles

• types of tissue in the human body: nervous, epithelial, muscle and connective.
• nervous tissue: brain, spinal cord, nerves.
• epithelial tissue: skin surface, lining of hollow organs and body cavities.
• connective tissue: fat and padding, bones, tendons.
• nervous tissue contains cells that convert stimuli to electrical impulses and conduct those messages.
• muscle tissue obtains cells specialised to contract and move parts of the body.
• epithelial tissue covers and lines free surfaces of the body.
• connective tissue holds structures together and provide support.
• smooth muscle: involuntary contraction and relaxation. Found in the walls of the digestive tract and blood vessels. These muscle cells are non-straited.
• cardiac muscle: involuntary contraction and relaxation. Found in the heart. It is striated and has a branched structure.
• skeletal muscle: voluntary contraction and relaxation. Biceps, abdominals etc. They are longer than typical cells, have more than one nucleus and are striated.
• examples of connective tissue: bones, cartilage, blood, tendons and ligaments.
• types of cartilage: hyaline, fibrous and elastic.
• hyaline forms the embryonic skeleton, covers the end of long bone, is in the nose, trachea and larynx.
• fibrous cartilage: discs between vertebrae, and the knee.
• elastic cartilage is found in the outer ear and epiglottis.
• phloem: consist of sieve tubes and companion cells, elongated cells end to end, allows movement between cells - companion cells, very metabolically active
• companion cells: they support sieve cells by carrying out cell metwb
• plant tissue categories: vascular, parenchyma, epidermal.
• the four main plant organs are flower, root, leaf, stem
• xylem transports water and dissolved mineral salts upwards through plants.