21. Create a 3-way T chart to compare and contrast skeletal, smooth and cardiac muscle. Include locations, functions, structures and special characteristics. (BLM 1, 2) 22. Describe the general locations, functions and characteristics of nervous tissues. (BLM 1, 2)

 Histology is defined as the study of the microanatomy of animal and plant tissues  A tissue is a group of like cells of similar specialized structure which carry out similar specific functions.

 A tissue is a group of like cells of similar specialized structure which carry out specific functions.  Groups of tissues compose and work together to form organs.  All organs are composed of two or more types of tissues.  There are four major tissue types: 1. Epithelial 2. Connective 3. Muscle 4. Nervous

 Muscle tissue is composed of cells which have the ability to contract (shorten) and relax (lengthen).  Muscle tissue is highly vascularized and dense tissue.  Muscle tissue can not regenerate itself once it has been destroyed.

 Muscle cells are called muscle fibers.  There are three types of muscle tissues: I. Striated or skeletal muscle II. Cardiac muscle or myocardial tissue III. Smooth or visceral muscle

 Striated or skeletal muscle: This muscle is composed of long, cylindrical, parallel fibers.  There are bands or striations present which run across the width of the fiber.  These fibers are multinucleated (more than one nucleus present per cell).

 This type of muscle tissue is under conscious or voluntary control.  This muscle has the greatest strength of contraction but tires most rapidly.  Functions are movement and facial expressions.

 Cardiac muscle fibers are branched at the end with striations present,  Usually only one nucleus is present per cell.  The branches of each fiber come into contact at specialized junctions called intercalated discs.

 Involuntarily controlled by the autonomic nervous system and hormones.  Contractions are short, but the muscle fibers are constantly contracting.  Function is to create the pump which propels the blood throughout the body.

 Smooth or visceral muscle: These cells are spindle-shaped (tapered on the ends) and lack striations.  They have one nucleus present.  They produce weaker contractions, however they contract for extended periods of time.

 They are involuntarily controlled by the autonomic nervous system or hormones.  Their contractions propels (moves) substances or objects from one location to another.

 They are found in the digestive organs, arteries and veins, the trachea and bronchiole tubes, and the urogenital tract.

 3 Muscle Types: 6:20  bMMaM bMMaM

 These tissues have the ability of excitability.  They respond to environmental stimuli.  They relay messages in the form of electrical and chemical signals.  They do not have the ability to regenerate when damaged.

 They can reach great lengths even though they are microscopic  There are two major cell types: 1. Neurons which relay the message. 2. Neuroglial cells which insulate and support the neurons.

 Nervous tissue: This tissue composes the brain, spinal cord, and the peripheral nervous system.

 Transmit electrical signals from sensory receptors to the integration center and then from the integration center to the effector organ.

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