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

Types of Muscle Tissue

(1) Skeletal muscle – attached to the skeleton – striated – voluntary

(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.

Organization of a neuron

• 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