Muscle Types and Characteristics

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Questions and Answers

Which muscle type is responsible for voluntary movements?

Cardiac muscle

Smooth muscle

Skeletal muscle (correct)

Involuntary muscle

What is a key characteristic of smooth muscle?

Spindle-shaped cells (correct)

Conscious control

Multinucleated cells

Striated appearance

What structure serves as a protective wrapping around a whole skeletal muscle?

Fascia

Perimysium

Epimysium (correct)

Endomysium

Where is cardiac muscle exclusively found?

In the heart Signup and view all the answers

What term refers to muscle tissue that is not under conscious control?

Involuntary muscle Signup and view all the answers

Which of the following prefixes refers specifically to muscle?

myo- Signup and view all the answers

What connective tissue surrounds a single muscle fiber?

Endomysium Signup and view all the answers

What feature distinguishes skeletal muscle cells under a microscope?

Striations Signup and view all the answers

What is the role of the sarcoplasmic reticulum in skeletal muscle?

Storage of calcium Signup and view all the answers

What happens at the neuromuscular junction?

Acetylcholine is released from the nerve Signup and view all the answers

Which property of skeletal muscle allows it to respond to stimuli?

Irritability Signup and view all the answers

What is the significance of the H zone in muscle fibers?

It is the region without actin filaments Signup and view all the answers

What is a motor unit comprised of?

One neuron and multiple muscle fibers Signup and view all the answers

What characteristic of the sarcolemma is crucial for muscle contraction initiation?

Its permeability to sodium Signup and view all the answers

Which chemical is identified as the neurotransmitter for skeletal muscle?

Acetylcholine Signup and view all the answers

What fills the synaptic cleft at the neuromuscular junction?

Interstitial fluid Signup and view all the answers

What is the primary role of skeletal muscles?

To produce movement Signup and view all the answers

Which of the following is true regarding the structure of skeletal muscle cells?

They are multinucleated Signup and view all the answers

What component of the skeletal muscle cell functions as a specialized plasma membrane?

Sarcolemma Signup and view all the answers

What structure is the contractile unit of a muscle fiber called?

Sarcomere Signup and view all the answers

Which filaments are primarily involved in muscle contraction?

Both actin and myosin filaments Signup and view all the answers

What is the role of the sarcoplasmic reticulum in skeletal muscles?

To store Ca for muscle contraction Signup and view all the answers

Which band in the myofibril is described as the light band consisting of actin filaments?

I band Signup and view all the answers

What feature of myosin filaments enables them to interact with actin during muscle contraction?

Their ATPase enzymes Signup and view all the answers

Study Notes

Muscle Types

Muscles are responsible for body movement.
Three types of muscle:
- Skeletal
- Cardiac
- Smooth

Muscle Characteristics

Muscle cells are elongated (muscle cells = muscle fibers).
Muscle contraction is due to the movement of microfilaments.
Terms associated with muscle:
- "myo"
- "mys"
- "sarco"

Skeletal Muscles

Attached to bones via tendons.
Multinucleated cells.
Striated appearance due to banding.
Voluntary control.
Surrounded by connective tissue.

Connective Tissue Wrappings of Skeletal Muscle

Endomysium: around single muscle fibers.
Perimysium: around bundles of muscle fibers (fascicles).
Epimysium: covering the entire muscle.
Fascia: outside the epimysium.

Skeletal Muscle Attachments

Epimysium blends with connective tissue attachments.
- Tendon: cord-like structure.
- Aponeuroses: sheet-like structure.
Attachment sites:
- Bones
- Cartilages
- Connective tissue coverings

Smooth Muscles

Non-striated.
Spindle-shaped cells.
Single nucleus.
Involuntary control.
Found in hollow organs.

Cardiac Muscles

Striated.
Usually single nucleus.
Joined to other muscle cells at intercalated discs.
Involuntary control.
Found only in the heart.

Functions of Muscles

Produce movement.
Maintain posture.
Stabilize joints.
Generate heat.

Microscopic Anatomy of Skeletal Muscles

Cells are multinucleated.
Nuclei are located just below the sarcolemma.
Sarcolemma: specialized plasma membrane.
Sarcoplasmic reticulum (SR): specialized smooth endoplasmic reticulum that stores calcium.
Myofibril: bundles of myofilaments; responsible for striated appearance.

Sarcomere

Contractile unit of a muscle fiber.
Thick filaments: myosin filaments; contain myosin protein and ATPase enzymes.
Thin filaments: actin filaments; composed of actin protein.

Properties of Skeletal Muscle Activity

Irritability: ability to respond to a stimulus.
Contractility: ability to shorten when stimulated.

Nerve Stimulus to Muscles

Skeletal muscles require nerve stimulation to contract.
Motor Unit: consists of one neuron and all muscle cells it stimulates.

Neuromuscular Junction

The site where nerve and muscle meet.
Synaptic cleft: gap between nerve and muscle; filled with interstitial fluid.

Transmission of Nerve Impulse to Muscle

Neurotransmitter: chemical released by the nerve when an impulse arrives.
- Acetylcholine is the neurotransmitter for skeletal muscle.
Neurotransmitter binds to receptors on the sarcolemma.
Sarcolemma becomes permeable to sodium (Na+).

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Description

Explore the three types of muscles: skeletal, cardiac, and smooth. Learn about their unique characteristics, structures, and the connective tissue that supports them. This quiz covers essential terms and features of skeletal muscles and their attachments.