Biology 235 Physiology - Exam #2 Questions
With Verified Answers
What are the three types of muscle tissue?
1) Skeletal muscle
2) Cardiac muscle
3) Smooth muscle
What are the characteristics of skeletal muscle?
- Long, cylindrical cells
- Multinucleate
- Striated with numerous fine bands
- Voluntary
- Neurogenic, it requires a nerve to stimulate it
What are the characteristics of smooth muscle?
- Spindle shapes
- Flat and unstriated
- Single nucleus
- Involuntary
- No sarcomeres, t-tubules or troponin
- Tropomyosin is present
- Poorly developed SR
- Two types, single and motor unit
- Contain actin and myosin
- Slower, less forceful contraction
- Myogenic (doesn't need an outside source to stimulate)
Where is smooth muscle found?
It is found in the reproductive tract, urinary tract (bladder), respiratory tract (bronchioles),
cardiovascular tract, integumentary tract (skin, arrestor pili).
What is smooth muscle and membrane depolarization triggered by?
Mechanical stimulation, autonomic stimulation, and hormonal stimulation.
What are the characteristics of cardiac muscle?
- Found only in the heart
- Uninucleate
- Striated with branching fibers
- Intercalated disks which are specialized cell junctions that contain gap junctions
- Have desmosomes which allow for stability
- Creates syncytium (moves as one)
- Myogenic
- Involuntary
Why are gap junctions important?
They allow information to spread from one heart cell to the next heart cell.
Hierarchal Organization of Skeletal Muscle
1) Muscle
, 2) Fascicle
3) Muscle cell (muscle fiber)
4) Myofibril
5) Myofilaments
Muscle
A collection of muscle cells (example, deltoids, biceps). A muscle is made up of many fascicles.
Fascicle
A bundle of muscle fibers. Each fascicle is made up of many muscle cells.
Muscle cell (muscle fiber)
Multinucleate and have many myofibrils. Within a muscle cell we have many myofibrils.
Myofibril
A tube inside a muscle cell. Bundles of contractile and elastic proteins responsible for muscle
contraction (where actual contraction occurs). Myofibrils contain sarcomeres and are composed of
two main protein units, myosin and actin.
Myofilament
Another name for thick and thin filaments.
What are the three layers of connective tissue in a skeletal muscle?
1) Epimysium
2) Perimysium
3) Endomysium
Epimysium
Surround a whole muscle.
Perimysium
Surrounds a bundle of muscle fibers also known as fascicles.
Endomysium
Surrounds individual muscle cells.
What is a sarcomere?
- The contractile unit of a myofibril
- Basic functional unit of contraction
- From Z line to Z line
- A and I bands are responsible for striations
Define and explain the five elements of a sarcomere.
1) M line: Cytoskeleton proteins that stabilize myosin. Protein fibers that connect to neighboring thick
filaments.
With Verified Answers
What are the three types of muscle tissue?
1) Skeletal muscle
2) Cardiac muscle
3) Smooth muscle
What are the characteristics of skeletal muscle?
- Long, cylindrical cells
- Multinucleate
- Striated with numerous fine bands
- Voluntary
- Neurogenic, it requires a nerve to stimulate it
What are the characteristics of smooth muscle?
- Spindle shapes
- Flat and unstriated
- Single nucleus
- Involuntary
- No sarcomeres, t-tubules or troponin
- Tropomyosin is present
- Poorly developed SR
- Two types, single and motor unit
- Contain actin and myosin
- Slower, less forceful contraction
- Myogenic (doesn't need an outside source to stimulate)
Where is smooth muscle found?
It is found in the reproductive tract, urinary tract (bladder), respiratory tract (bronchioles),
cardiovascular tract, integumentary tract (skin, arrestor pili).
What is smooth muscle and membrane depolarization triggered by?
Mechanical stimulation, autonomic stimulation, and hormonal stimulation.
What are the characteristics of cardiac muscle?
- Found only in the heart
- Uninucleate
- Striated with branching fibers
- Intercalated disks which are specialized cell junctions that contain gap junctions
- Have desmosomes which allow for stability
- Creates syncytium (moves as one)
- Myogenic
- Involuntary
Why are gap junctions important?
They allow information to spread from one heart cell to the next heart cell.
Hierarchal Organization of Skeletal Muscle
1) Muscle
, 2) Fascicle
3) Muscle cell (muscle fiber)
4) Myofibril
5) Myofilaments
Muscle
A collection of muscle cells (example, deltoids, biceps). A muscle is made up of many fascicles.
Fascicle
A bundle of muscle fibers. Each fascicle is made up of many muscle cells.
Muscle cell (muscle fiber)
Multinucleate and have many myofibrils. Within a muscle cell we have many myofibrils.
Myofibril
A tube inside a muscle cell. Bundles of contractile and elastic proteins responsible for muscle
contraction (where actual contraction occurs). Myofibrils contain sarcomeres and are composed of
two main protein units, myosin and actin.
Myofilament
Another name for thick and thin filaments.
What are the three layers of connective tissue in a skeletal muscle?
1) Epimysium
2) Perimysium
3) Endomysium
Epimysium
Surround a whole muscle.
Perimysium
Surrounds a bundle of muscle fibers also known as fascicles.
Endomysium
Surrounds individual muscle cells.
What is a sarcomere?
- The contractile unit of a myofibril
- Basic functional unit of contraction
- From Z line to Z line
- A and I bands are responsible for striations
Define and explain the five elements of a sarcomere.
1) M line: Cytoskeleton proteins that stabilize myosin. Protein fibers that connect to neighboring thick
filaments.
