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Chapter 10

Anatomy and Physiology HAP101 Chapter Notes - Chapter 10: Abdominopelvic Cavity, Cardiac Muscle, Smooth Muscle Tissue


Department
Anatomy and Physiology
Course Code
Anatomy and Physiology HAP101
Professor
Tania Killian
Chapter
10

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HAP101 Week 6/Chapter 10: Muscular Tissue
Overview of Muscular Tissue
There are three types of muscular tissue
1) Skeletal Muscle Tissue: is named as such since most skeletal muscles move the bones of the
skeleton. This type of tissue is striated, meaning it has alternating light and dark protein bands when
examined under the microscope. It works mainly in a voluntary manner, i.e. its activity can be
controlled by neurons of the somatic division of the NS.
2) Cardiac Muscle Tissue: present only in the heart to form most of the heart wall. This type of tissue
is also striated, but it is involuntary, i.e. the contractions and reactions of the heart are not
consciously controlled.
3) Smooth Muscle Tissue: found in the walls of hollow internal structures, e.g. blood vessels, most
organs in the abdominopelvic cavity, airways, etc. This type of tissue lacks striations, thus it looks
nonstriated. Its actions are involuntary and are controlled by neurons of the autonomic division of
the NS.
There are four functions of muscular tissue
1) Producing Body Movements: an integrated functioning of skeletal muscles, bones and joints allows
for the movement of the whole body, as well as localized movement (e.g. picking up a pencil)
2) Stabilizing Body Positions: contractions of the skeletal muscle tissue stabilize joints and help
maintain body positions
3) Storing and Moving Substances Within the Body: sphincters prevent overflow of the contents of
a hallow organ to ensure storage is accomplished. For example, cardiac muscle contract to pump
blood through blood vessels, but smooth muscle tissue in the walls of those vessels adjust the vessel
diameter, regulating the rate of blood glow; skeletal muscle contractions promote the flow of lymph
and help return blood from veins to heart.
4) Generating Heat: thermogenesis is when muscle contractions produce heat that helps maintain
normal body temperature.
The muscular tissue has four properties that contribute towards function and homeostasis
1) Electrical Excitability: the ability to respond to certain stimuli by producing electrical signals
called action potentials (impulses), referred to muscle action potentials in muscles and those in
nerve cells are called nerve action potentials. In muscle cells, there are two types of stimuli
triggering action potentials: (1) autorhythmic electrical signals that arise in the muscle tissue itself
and (2) chemical stimuli, e.g. NTs released by neurons, even local changes in pH, or hormones
distributed by the blood
2) Contractility: the ability of the muscular tissue to contract forcefully when stimulated by an action
potential. When a skeletal muscle contracts, tension is generating when pulling on its attachment
points; in some the muscle does not shorten when tension is developed.
3) Extensibility: the ability of muscular tissue to stretch, within limits and without being damaged. The
range of extensibility is limited due to the connective tissue within the muscles that keep the
contractile range of muscle cells. Smooth muscle is usually subjected to the greatest amount of
stretch.
4) Elasticity: the ability of the muscular tissue to return to its original length and shape after being
contracted or extended.
Skeletal Muscle Tissue (main focus of chapter)
Skeletal muscle contains connective tissues surrounding muscle fibres and whole muscles, blood vessels
and nerves.
Connective Tissue (CT) Components: the subQ layer (separates muscle from skin) is composed of
areolar CT and adipose tissue; its provides pathways for nerves, blood vessels, lymphatic vessels, etc. to
enter/exist muscles. An important part of CT is fascia, a dense sheet of irregular CT that lines the body
wall/limbs and supports/surrounds muscles of organs. It holds muscles with similar functions and allows
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