Major Muscles of the Body and Muscle Physiology

These flashcards cover major concepts, structures, and functions related to the muscular system, with a focus on muscle types, contraction mechanisms, and physiological responses.

What are the three major types of muscle tissue?

Skeletal, smooth, and cardiac muscle.

What type of control is skeletal muscle under?

Somatic (voluntary) control.

Which type of muscle is involuntary and can use myogenic mechanisms to contract?

Smooth muscle.

Which muscle type is responsible for pumping blood throughout the body?

Cardiac muscle.

What is the role of T-tubules in muscle contraction?

They help to depolarize the muscle cell during action potential propagation.

What structure serves as a point of anchorage for actin filaments in muscle cells?

Z line.

What is a sarcomere?

A repeating unit of muscle tissue specialized for contraction.

What do gap junctions in cardiac muscle allow?

They allow transmission of action potentials between adjacent cardiac cells.

What is the function of the sarcoplasmic reticulum?

To store and release calcium ions during muscle contraction.

What triggers the release of calcium ions from the sarcoplasmic reticulum?

An action potential reaching the SR.

What causes muscle contraction according to the sliding filament mechanism?

Myosin heads pull on thin actin filaments, causing sarcomeres to shorten.

What are the three types of skeletal muscle fibers?

Slow-twitch oxidative (Type I), fast-twitch oxidative-glycolytic (Type IIa), and fast-twitch glycolytic (Type IIb).

Which skeletal muscle fiber type has the highest resistance to fatigue?

Slow-twitch oxidative (Type I).

What do fast-twitch glycolytic fibers primarily use for energy?

Anaerobic metabolism.

What is oxygen debt?

The amount of oxygen required to restore metabolic conditions to resting levels after activity.

How does skeletal muscle support the circulation of blood?

Through the skeletal muscle pump mechanism.

What muscle contraction is responsible for peristalsis in the gastrointestinal tract?

Smooth muscle contraction.

What effect does sympathetic stimulation have on heart rate?

Increases heart rate.

What is the primary function of smooth muscle in blood vessels?

Regulating blood pressure through vasoconstriction and vasodilation.

What structure in the heart generates the action potential for cardiac muscle contraction?

Sinoatrial (SA) node.

What mechanism allows muscle fibers to contract without nervous stimulation in smooth muscle?

Myogenic activity.

What neurotransmitter is released at the neuromuscular junction?

Acetylcholine (ACh).

Which part of the nervous system controls voluntary muscle movements?

The somatic nervous system.

What initiates the depolarization of the muscle cell membrane?

Binding of acetylcholine to nicotinic receptors on the motor end plate.

In cardiac muscle tissue, what connection allows for coordinated contraction?

Intercalated discs with gap junctions.

What is the role of calcium ions in muscle contraction?

They enable the interaction of actin and myosin filaments.

What happens during lactic acid accumulation in muscles?

Muscle fatigue occurs.

What type of muscle is the diaphragm?

Skeletal muscle.

What happens to the blood pressure during vasodilation?

Blood pressure decreases.

What does the motor unit consist of?

A motor neuron and all the muscle fibers it innervates.

What type of muscle fiber is primarily utilized in high-intensity, short-duration activities?

Fast-twitch glycolytic (Type IIb).

What is the appearance of skeletal muscle fibers under a microscope?

Striated with alternating light and dark bands.

What is the main function of cardiac muscle?

To pump blood throughout the body.

What do sympathetic and parasympathetic divisions of the autonomic nervous system regulate?

Involuntary muscle contraction and gland activities.

What is the function of creatine phosphate in muscle metabolism?

Phosphorylate ADP to produce ATP rapidly during intense exercise.

What is functionally different between smooth muscle and striated muscle in terms of contraction?

Smooth muscle lacks organized sarcomeres.

What muscle type is primarily involved in involuntary reflexes?

Cardiac and smooth muscle.

Which type of muscle has a high concentration of mitochondria?

Slow-twitch oxidative (Type I) fibers.

What property do cardia muscle cells exhibit that skeletal muscle cells do not?

Autorhythmicity.

What are the two types of neurons in the autonomic nervous system?

Preganglionic and postganglionic neurons.

How is the skeletal muscle pump beneficial during exercise?

It increases venous blood flow to the heart.

What does the term 'triad' refer to in muscle structure?

The arrangement of T-tubules sandwiched between terminal cisternae.

What is the primary regulator of heart rate from the nervous system?

The autonomic nervous system.

How do cardiac muscle cells communicate with each other?

Through gap junctions in intercalated discs.

Which muscle type contracts rhythmically to propel substances?

Smooth muscle.

What role do mitochondria play in muscle fiber functionality?

They are the site of aerobic respiration for ATP production.

What contributes to the high aerobic capacity of slow-twitch fibers?

High myoglobin content and rich capillary supply.

What is the significance of the Z line in a sarcomere?

It acts as an anchor point for actin filaments.

What happens during the relaxation of a muscle fiber?

Calcium is pumped back into the sarcoplasmic reticulum.

What is the key difference between Type IIa and Type IIb muscle fibers?

Type IIa has moderate resistance to fatigue, while Type IIb has low resistance.

In response to sympathetic stimulation, what happens to blood vessels?

They constrict to divert blood to vital organs.

What is the fastest method for replenishing ATP during a brief, intense workout?

Anaerobic respiration via creatine phosphate.

How does the diaphragm assist in breathing?

By contracting to increase the volume of the thoracic cavity.

What physiological effect does extreme muscle fatigue have on performance?

It leads to a temporary decrease in muscle strength and endurance.

What is the effect of parasympathetic stimulation on digestion?

It promotes digestion.

What component of muscle fibers makes them striated?

The organized arrangement of thin and thick filaments.

What triggers the myogenic action in cardiac muscle?

Action potentials generated by pacemaker cells.

Describe the structure of smooth muscle cells.

They are spindle-shaped, non-striated, and uninucleate.

Explain the significance of the autonomic nervous system in muscle control.

It controls involuntary muscle movements and regulates heart and digestive functions.

What is the primary energy source for muscle contraction during resting conditions?

Aerobic respiration.

How do blood vessels respond to cold temperatures?

Vasoconstriction occurs to conserve heat.

What role does epinephrine play in muscle function?

It increases heart rate and enhances muscle performance during stress.

Which muscle type is primarily responsible for voluntary actions?

Skeletal muscle.

Name the two types of muscle contractions.

Isometric and isotonic contractions.

What happens to calcium levels during muscle contraction?

Calcium ion levels increase in the cytoplasm.

What is the primary function of myoglobin in muscle fibers?

To store oxygen for aerobic respiration.

What happens to the action potential when it reaches the neuromuscular junction?

It leads to the release of acetylcholine.

How does the muscular system assist with thermoregulation?

Muscle contractions generate heat to maintain body temperature.

What is the role of the vagus nerve in heart function?

It decreases the heart rate through parasympathetic stimulation.

How do muscle contractions affect the body's posture?

They help maintain an upright position by stabilizing bones and joints.

Which type of muscle fiber would a marathon runner primarily utilize?

Slow-twitch oxidative (Type I) fibers.

How does the structure of skeletal muscle fibers contribute to their function?

The striated structure enables efficient and strong contractions.

What physiological change occurs in muscles during high-intensity exercise?

Increased reliance on anaerobic respiration and lactic acid accumulation.