Ch 8 Muscle Flashcards
(62 cards)
What is muscle?
Muscle is one of the four basic tissue types in the body.
What are the three types of muscle and what are some of the general characteristics of each type?
The three types of muscle are skeletal, smooth, and cardiac.
Skeletal muscle is controlled by the conscious mind and moves the bones of the skeleton.
Smooth muscle carries out most of the unconscious, internal movements of the body. Cardiac muscle is found only in the heart and makes up the structure of the heart.
What is the difference between a tendon and an aponeurosis?
A tendon is a band of fibrous connective tissue that attaches muscle to bone. An aponeuroses is a broad sheet of fibrous connective tissue. An example of it would be the linea alba.
What is the origin of a muscle?
The insertion?
The origin of a muscle is the most stable attachment site.
The insertion of a muscle is the site that undergoes the most movement when a muscle contracts.
Why might it be of clinical importance to know the origin and insertion of a muscle?
By knowing the origin and insertion of a muscle, you can predict the action of the muscle without seeing the muscle contract.
Describe a skeletal muscle cell in terms of cell size, shape, number of nuclei, and appearance under the microscope.
Skeletal muscle cells, also known as fibers, are large, long, and have multiple nuclei. Under a microscope the cells appear striated or striped.
What are the differences among a skeletal muscle fiber, a skeletal muscle myofibril, and a skeletal muscle protein filament?
A muscle fiber is one muscle cell. The muscle fiber is made up of many muscle myofibrils. The proteins myosin and actin can be found inside the myofibrils.
Which contractile protein filaments make up the dark bands of skeletal muscle cells? Which make up the light bands?
Myosin myofilaments are thick protein filaments that appear to float in the middle of the sarcomere.
Actin filaments are thin protein filaments that attach to the Z line and extend toward the center of the sarcomere.
What is a sarcomere and what are its components?
A sarcomere is the area from one Z line to the next Z line and is the basic contracting unit of skeletal muscle. Many sarcomeres lined up end-to-end form a myofibril. Each individual sarcomere in a myofibril only shortens slightly when the fiber is stimulated to contract, but when all the sarcomere contractions are added together, the muscle fiber shortens considerably.
What ion, released from the sarcoplasmic reticulum by a nerve impulse, starts the contraction process in a muscle fiber?
Calcium
What molecules in muscle act as the “batteries” to power the sliding of the actin and myosin filaments?
What molecules function as the “battery chargers”?
Adenosine triphosphate (ATP)
Creatine phosphate (CP)
If individual muscle fiber contractions obey the all-or-nothing principle how does an animal control the size and strength of its muscular movements?
The body carefully controls the number of muscle fibers that contract during each movement
What is myoglobin and why is it important?
Myoglobin is a large protein in muscle that can store oxygen for times, such as strenuous exercise, when more oxygen is needed by the muscle.
Why does an animal breathe heavily for a while after heavy exercise?
In order to increase their oxygen supply and help the liver convert the extra lactic acid into glucose.
Describe a cardiac muscle cell in terms of size, shape, number of nuclei, and appearance under the microscope.
Cardiac muscle is striated but smaller than skeletal muscle cells. These muscles have only one nucleus per cell. The cardiac muscle cells are longer than they are wide and have multiple branches. They are attached to each other by intercalated discs.
What are intercalated discs and why are they important to the functioning of cardiac muscle?
Intercalated discs are the attachments of the end of one cardiac muscle cell to the end of another cardiac muscle cell. They secure the cells together and transmit impulses from cell to cell, thus coordinating the contraction of large groups of cells.
Describe the effect of a cardiac muscle’s nerve supply on its functioning.
The nerve supply of the heart does not initiate cardiac muscle contraction, but it can modify the activity.
What is the general effect of sympathetic nervous system stimulation on cardiac muscle?
What is the effect of parasympathetic nervous system stimulation?
Sympathetic nerves cause the heart to beat harder and faster.
Parasympathetic nerves cause the heart to beat slower and with less force.
Describe a smooth muscle cell in terms of its size, shape, number of nuclei, and appearance under the microscope.
Smooth muscles are small, and spindle shaped. They are not striated nor are they voluntary. They would be classified as involuntary, nonstriated muscles. They have one nucleus per cell.
What are the main differences between visceral smooth muscle and multi-unit smooth muscle?
Visceral smooth muscle is found in the walls of internal soft organs (viscera). The muscle cells are linked to form large sheets. Fine movement is not possible because the contractions are strong and rhythmic. Multi-unit smooth muscles are small and delicate. They are made up of individual cells or small groups of cells. They are found where small, delicate contractions are needed, such as in the iris of the eye and the walls of small blood vessels.
Describe the effect of nerve stimulation on the functioning of visceral smooth muscle versus multi-unit smooth muscle.
Nerve stimulation does not initiate smooth muscle action; it modifies it.
What is the general effect of sympathetic nervous system stimulation on visceral smooth muscle? What is the effect of parasympathetic nervous system stimulation?
Parasympathetic nerve stimulation increases smooth muscle activity.
What are the main differences in the structures and functions of skeletal muscle, cardiac muscle, and smooth muscle?
Skeletal muscle is composed of long, multi-nucleated cells that are under conscious control. They are striated when viewed microscopically. They move the bones that move the animal’s body. Cardiac muscle is found only in the heart. It is made up of striated muscle cells that are not under conscious control. The cells have only one nucleus each. Intercalated discs join cardiac muscle cells end to end. Smooth muscle cells are nonstriated and have a single nucleus. They are not under conscious control. They are found in the walls of internal organs and locations, such as the eye, where delicate movements are necessary.
The more stable attachment of a muscle to bone is called.
Origin
