UNIT 3: HISTOLOGY

ANATOMY AND PHYSIOLOGY

OBJECTIVES21. 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 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.

4 TYPES OF TISSUES 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. Epithelial2. Connective3. Muscle4. Nervous

3. MUSCLE TISSUE

MUSCULAR TISSUE 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.

MUSCULAR TISSUE: 3 TYPES

Muscle cells are called muscle fibers. There are three types of muscle

tissues:I. Striated or skeletal muscleII. Cardiac muscle or myocardial

tissueIII. Smooth or visceral muscle

I. SKELETAL MUSCLE:A. STRUCTURE 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).

I. SKELETAL MUSCLE:A. STRUCTURE

I. SKELETAL MUSCLEA. STRUCTURE

I. SKELETAL MUSCLEB. FUNCTION 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.

II. CARDIAC MUSCLEA. STRUCTURE 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.

II. CARDIAC MUSCLEA. STRUCTURE

II. CARDIAC MUSCLEA. STRUCTURE

II. CARDIAC MUSCLEB. FUNCTION 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.

III. SMOOTH MUSCLEA. STRUCTURE 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.

III. SMOOTH MUSCLEA. STRUCTURE

III. SMOOTH MUSCLEA. STRUCTURE

III. SMOOTH MUSCLEB. FUNCTION They are involuntarily controlled by the autonomic nervous system or hormones.

Their contractions propels (moves) substances or objects from one location to another.

III. SMOOTH MUSCLEC. LOCATIONS They are found in the digestive organs,

arteries and veins, the trachea and bronchiole tubes, and the urogenital tract.

VIDEO CLIP 3 Muscle Types: 6:20 https://

www.youtube.com/watch?v=WFQLFHbMMaM

4. NERVOUS TISSUE

NERVOUS TISSUE:A. GENERAL CHARACTERISTICS 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.

NERVOUS TISSUE:B. STRUCTURE 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.

NEURONS: STRUCTURE

NEUROGLIAL CELLS: STRUCTURE

NEURONS AND NEUROGLIAL CELLS

NERVOUS TISSUE:C. LOCATIONS

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

NERVOUS TISSUE:D. FUNCTION

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

VIDEO CLIP 4:51 min https://

www.youtube.com/watch?v=o9p2ou1IyC0