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TISSUE - a group of similar cells that function
together to perform a specialized activity
There are four kinds of tissues:
1. Epithelial tissue = covers body surfaces; lines body cavities, hollow organs (protection), and ducts; and forms glands (secretion).
2. Connective tissue = supports the body and binds its organs; binds organs together, stores energy reserves as fat, and provides immunity.
3. Muscular tissue = for contraction (movement)
4. Nervous tissue = initiates and transmits nerve impulses that
coordinate body activities.
MUSCLE TISSUE
General Features:
● Function: facilitates movement of the animal by contraction of individual muscle cells (referred to as muscle fibers)
● has sarcomere as its functional unit
● each sarcomere having thick and thin filaments
(2) Cardiac muscle – found in the heart – striated – involuntary– contains intercalated discs for quick conduction
of nerve impulses through the cardiac muscle tissue during muscle contraction
(3) Smooth (visceral) muscle – found in a variety of locations such as the digestive
tract, the reproductive tract, the ureters, and around some blood vessels
– involuntary & autonomic movements
NERVOUS TISSUE
General Features:
• Function: integration of stimulus and control of response to that stimulus.
• Nerve cells are called neurons. Each neuron has a cell body, an axon, and many dendrites.
• Nervous tissue consists of two kinds of cells: neurons and neuroglia
• Neurons conduct nerve impulses, while the different kinds of neuroglial cells nourish and support the neurons.
• The different kinds of neuroglial cells nourish and support the neurons. There are several types of glial cells present in the nervous system of humans:
• Astrocytes. Found in the brain's capillaries and form the blood-brain barrier that restricts what substances can enter the brain.
• Microglia are extremely small cells of the central nervous system that remove cellular waste and protect against microorganisms.
• Oligodendrocytes are central nervous system structures that wrap some neuronal axons to form an insulating coat known as the myelin sheath.
Ependymal cells – neuroglial cells that cover choroid plexuses and produce cerebrospinal fluid (CSF); they also line ventricles of the brain