msq : muscle construction

Three general types of muscle tissues are

Skeletal, Cardiac, and Smooth muscle

Skeletal muscle is responsible for

Movement and posture

Is Skeletal muscle voluntary or involuntary?

Voluntary

Skeletal muscle is innervated by which nerves?

Somatic nerves

Do somatic nerves initiate or modify skeletal contraction?

Initiate contraction

Cardiac muscle is responsible for

Pumping blood

Is Cardiac muscle voluntary or involuntary?

Involuntary

Cardiac muscle receives which type of nervous supply?

Autonomic nervous supply

Do autonomic nerves initiate or modify cardiac contraction?

Modify contraction

Smooth muscle is responsible for

Sustained contractions in blood vessels and GI tract

Is Smooth muscle voluntary or involuntary?

Involuntary

Smooth muscle receives which type of nervous supply?

Autonomic nervous supply

Skeletal muscle forms about of body mass

40 to 50%

Skeletal muscle fibers are attached to bone by a tough cord called

Tendon

How are skeletal muscle fibers arranged?

In parallel bundles

Which muscle types are described as "Striated"?

Skeletal and Cardiac muscles

Which muscle type is Non-striated?

Smooth muscle

Main functions of skeletal muscle include

Producing movement, maintaining posture, stabilizing joints, heat production

Individual muscle cells are also called

Myocytes or Muscle Fibers

Why are muscle cells called fibers?

Because they are long and slender

The cell membrane of a muscle fiber is called

Sarcolemma

The cytoplasm of a muscle fiber is called

Sarcoplasm

Invaginations of the sarcolemma that carry signals deep into the cell are

T-tubules (Transverse tubules)

The specialized endoplasmic reticulum in muscle is called

Sarcoplasmic Reticulum (SR)

The main function of the Sarcoplasmic Reticulum is

Storage and release of Calcium (Ca++)

Myofibrils are made up of protein filaments called

Myofilaments

The two main types of myofilaments are

Actin (Thin) and Myosin (Thick)

The functional unit of muscle contraction is called

Sarcomere

The Sarcomere is the distance between two successive

Z lines

The dark band in the sarcomere is called

A band

The A band contains which filaments?

Myosin (thick) and overlapping Actin (thin)

The light band in the sarcomere is called

I band

The I band contains which filaments?

Only Actin (thin)

The Z line is located in the middle of the

I band

The lighter area in the center of the A band is called

H zone

The H zone contains which filaments?

Only Myosin (thick)

The line in the center of the H zone is called

M line

The contractile proteins in muscle are

Actin and Myosin

The regulatory proteins in muscle are

Troponin and Tropomyosin

Which protein forms the thick filaments?

Myosin

Which protein forms the thin filaments?

Actin, Troponin, and Tropomyosin

The Myosin head has binding sites for

Actin and ATP

The protein that covers the active sites on Actin at rest is

Tropomyosin

The protein that binds Calcium during contraction is

Troponin

A motor unit consists of

A single motor neuron and all muscle fibers it innervates

The neuron that stimulates a muscle fiber is called

Motor Neuron

The connection between a motor neuron and a muscle fiber is

Neuromuscular Junction (NMJ)

The space between the neuron and the muscle membrane is

Synaptic cleft

The neurotransmitter released at the Neuromuscular Junction is

Acetylcholine (ACh)

What ion is essential for releasing ACh from the nerve ending?

Calcium (Ca++)

Where are ACh receptors located?

On the Sarcolemma (Motor end plate)

The enzyme that breaks down Acetylcholine is called

Acetylcholinesterase

The theory explaining muscle contraction is called

Sliding Filament Theory

What triggers the release of Calcium from the SR?

Action potential traveling down T-tubules

Calcium binds to which specific protein to initiate contraction?

Troponin

When Calcium binds to Troponin, what happens to Tropomyosin?

It moves away, exposing binding sites on Actin

During contraction, the myosin heads form

Cross-bridges with Actin

The movement of the myosin head pulling the actin is called

Power Stroke

What is required for the Power Stroke to occur?

Energy from ATP hydrolysis

What molecule is required for the myosin head to DETACH from actin?

A new ATP molecule

During muscle contraction, which band shortens?

I band

During muscle contraction, which zone disappears or narrows?

H zone

During muscle contraction, which band remains the same length?

A band

Immediate source of energy for muscle contraction is

ATP

After ATP is depleted, the muscle uses which energy reserve?

Creatine Phosphate

When oxygen is limited, muscles produce energy via

Anaerobic respiration (Glycolysis)

The byproduct of anaerobic respiration in muscles is

Lactic acid

Accumulation of lactic acid causes

Muscle fatigue and lower pH (acidity)

Oxygen debt is the amount of oxygen needed to

Restore ATP/Creatine Phosphate and remove Lactic acid

In the liver, lactic acid is converted back into

Glucose or Glycogen

The small scale contraction that maintains posture is called

Muscle Tone (Tonus)

Muscle tone is maintained by signals from parts of the CNS like the

Cerebellum

Absence of muscle tone (flaccidity) is called

Hypotonia

Myasthenia Gravis is what type of disorder?

Autoimmune disorder

Myasthenia Gravis is caused by antibodies attacking

ACh receptors at the NMJ

Botulinum toxin is produced by which bacteria?

Clostridium botulinum

Botulinum toxin causes paralysis by

Inhibiting ACh release

The type of paralysis caused by Botulinum toxin is

Flaccid paralysis

Tetanus toxin (Tetanospasmin) is released by which bacteria?

Clostridium tetani

Tetanus toxin causes paralysis by

Blocking inhibitory neurotransmitters

The type of paralysis caused by Tetanus toxin is

Spastic paralysis