Muscular System Anatomy and Physiology Assignment
Chapter 9: Muscular System: Histology and Physiology
I. Functions of the Muscular System
A. List and describe the seven major functions of muscles:
1. Movement of the body. Contraction of skeletal muscles is responsible for the general movements and motions of the body (running, walking, bending, stretching etc.)
2. Maintenance of posture. Skeletal muscles constantly maintain tone, which keeps us sitting or standing erect.
3. Respiration. Muscles of the thorax perform the necessary respiration movements.
4. Production of body heat. Heat, released as a by-product due to contraction in skeletal muscles is critical to the maintenance of body temperature.
5. Communication. Skeletal muscles are involved in all aspects of communication, including speaking, writing, typing, gesturing, and facial expressions.
6. Constriction of organs and vessels. The contraction of smooth muscles in the walls of internal organs and vessels leads to the contraction of these structures, and this can stimulate and mix food and water in the digestive tract, cause secretions from organs and regulate blood flow through vessels.
7. Contraction of the heart. The contraction of cardiac muscle causes the heart to beat, propelling blood to all parts of the body.
II. General Functional Characteristics of Muscle
A. Properties of Muscle
1. Contractility is the ability of skeletal muscle to contract forcefully
a. Muscle shortens forcefully
b. Muscle lengthens passively
2. Excitability is the ability of skeletal muscle to respond to certain stimulus
a. Normally stimulation comes from nerves
b. Stimulation can also come from hormones
3. Extensibility means that skeletal muscles can stretch beyond their normal resting length
4. Elasticity is the ability of muscles to return to their original length and shape after they have been stretched
B. Types of Muscle Tissue (Use Table 9.1 as needed)
1. Skeletal Muscle
a. Where do you find skeletal muscle? Skeletal muscles are attached to bones
b. What shape are skeletal muscle cells? They are very long and cylindrical
c. How much of the body is composed of skeletal muscle? 40%
d. Functionally skeletal muscle is responsible for many actions including:
1. Locomotion
2. Facial expressions
3. Posture
4. Respiratory functions
2. Smooth Muscle
a. Where do you find smooth muscle? In the walls of hollow organs, blood vessels, eyes, skin and glands
b. What shape are smooth muscle cells? Small and spindle-shaped
c. Smooth muscle has a wide variety of functions including:
1. Propelling urine through the urinary tract
2. Mixing food in the stomach and the small intestine
3. Dilating and constricting the pupil of the eye
4. Regulating the flow of blood through blood vessels
3. Cardiac Muscle
a. Where do you find cardiac muscle? Cardiac muscle can be found only in the walls of the heart
b. What shape are cardiac muscle cells? Long, cylindrical, and branched
c. Functionally cardiac muscle is responsible for pumping the blood
d. What does autorhythmic mean? It means that muscles contract spontaneously at somewhat regular intervals
e. What does involuntary control mean? Involuntary control means unconsciously control
III. Skeletal Muscle Structure
A. General
1. Skeletal muscles are composed of:
a. Muscle fibers
b. Associated with:
1. Connective tissue
2. Blood vessels
3. Nerves
2. What is a skeletal muscle fiber? A single cell that has numerous myofibrils
3. Each fiber is a single long cylindrical cell containing several nuclei located …
