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Chapter 3

ANAT 100 Chapter Notes - Chapter 3: Zygomaticus Major Muscle, Frontal Bone, Semispinalis Muscles

Anatomy and Cell Biology
Course Code
ANAT 100
Leslie W Mac Kenzie

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Muscular System
1. Smooth Muscle
- Is controlled by the nervous system or hormones
- Can be inactive until it responds to a stimulus (food in stomach) or be continually active
2. Skeletal Muscle
- Helps the body move by attaching to bones (using tendons)
3. Cardiac Muscle
- Found in the heart and contracts in a rhythm which changes speed and strength due to
neural activity (working out)
Morphological Characterization of Muscle
- Found in blood vessels, digestive system and other viscera
- These muscles have thin oval shaped cells with no ridges and the nucleus is found in the
very centre of the cell
- Marked with both light and dark bands in appearance
- Found in skeletal and cardiac muscles
Functional Characterization of Muscle
Voluntary Muscle
- These are the muscles that we consciously decide to move in order to performs a
desirable task (walking, speaking, etc.)
- Skeletal muscle is voluntarily controlled
- These muscles are not consciously controlled
- Smooth and cardiac muscle (digestive system, heart)
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Muscle Function (2 Basic Properties)
1. Excitability: when the muscle tissue receives electrical signals from nerves or from a
hormonal stimulus that tells it to contract
2. Contractility: when a nerve or hormonal stimulus activates the muscle cell to make
them shorten/contract (happens when excited)
- There are roughly 700 muscles attached to our skeletal system that make up for about
half of our body weight
- These muscles altogether are an organ made up of skeletal muscle tissue, epithelial,
connective and nervous tissue
- Most of these muscles are attached to 2 different bones by a joint so that when it
contracts it will cause the joint to change positions
- Functions: producing movement, maintaining posture, stabilize joints, control excretion
& swallowing, and produces fat
Organization of Skeletal Muscle Tissue
- Has connective tissue that surrounds the muscle tissue and attaches each end of a
muscle to the bone
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