Tissues + Structures - Muscles Flashcards
What are the types of muscles?
- Skeletal.
- Cardiac.
- Visceral (smooth).
What are the histological classifications of muscle?
- Striated (skeletal, cardiac).
- Non-striated (visceral).
What is the difference between muscle cell and fibre?
They are the same thing.
Describe the nuclei situation of the three types of muscle?
- Smooth - single nucleus.
- Cardiac - single nucleus.
- Skeletal - multiple nuclei.
What does smooth muscle consist of?
Narrow spindle shaped cells that lay parallel.
Describe smooth muscle in tubes that undergo peristalsis?
Arranged in longitudinal and circular fashion.
Describe smooth muscle fibres in viscera that undergo contraction without peristalsis (bladder and uterus)?
Fibres arranged in whorls and spirals.
What are gap junction?
These are nexuses that allow for contractile impulses to be transmitted from one smooth muscle cell to the next adjacent cell.
What innervates smooth muscle?
Autonomic nervous system. However, due to gap junctions many smooth fibres do not receive nerve fibres.
What does cardiac muscle consist of?
Broader short cells that branch.
How is cardiac muscle cells arranged?
Whorls and spirals.
How doe the cells connect with each other?
Interdigitations with one another, these help to increase the surface area for impulse conduction.
How does each chamber of the heart empty blood?
By mass contraction - no peristalsis involved.
What innervates cardiac muscle?
Autonomic nervous system.
What does skeletal muscle consist of?
Non-branching fibres bound together by loose aerolar tissue (containing macrophages and fibroblasts).
How is connective tissue made in skeletal muscle?
Condensed to create a epimysium.
Why is the epimysium important?
Helps to prevent the spread of fluid such as pus.
What are the types of skeletal muscle?
- Red.
- White.
All humans have a mixture of both muscles.
Describe red skeletal muscle fibres?
Slow twitch muscle fibres - aerobic.
What do the red skeletal muscle fibres contain structurally?
High content of the following:
1. Mitochondria.
2. Myoglobin.
3. Succinic dehydrogenase.
4. Oxidative enzymes.
Low content of:
1. Myosin ATPase.
Describe white skeletal muscle fibres?
Fast twitch muscles - anaerobic.
What do the white muscle fibres contain structurally?
Low content of following:
1. Mitochondria.
2. Myoglobin.
3. Succinic dehydrogenase.
4. Oxidative enzymes.
High content of following:
1. Glycogen.
2. Phosphorylase.
3. Myosin ATPase.
Describe the nervous supply of skeletal muscle?
Each individual fibre receives a motor nerve fibre.
What is a muscle spindle?
Group of individual fibres (up to 10).
Where can you find muscle spindle?
Embedded among the ordinary skeletal muscle.
What holds the muscle spindles together?
Connective tissue capsule. These fibres lay within a cigar-shaped or fusiform capsule.
What are fibres in muscle spindles called?
Intra-fusal.
What are ordinary skeletal muscle fibres called?
Extra-fusal.
Describe muscle spindles in muscles that do small movement?
These fibres are constantly in position and have high numbers of fibres relative to the seize of their muscle bulk e.g. 368 fibres in latiissimus dorsi and 80 fibres in abductor pollicis brevis.
What are intra-fusal muscle fibres innervated by?
Gamma motor neurons of the anterior horn.
What are extra-fusal muscle fibres innervated by?
Large A cells.
What is the function of muscle spindles?
To act as one type of sensory receptor that transmitts information on the state of the contraction of muscles in which they lie. They transmit this information to the central nervous system.