Muscle and Cardiac Physiology

What are the three types of muscle?

Skeletal, Cardiac, and Smooth.

Which muscles are striated?

Skeletal and Cardiac muscles are striated.

What is a fascicle?

A bundle of muscle fibers held together by connective tissue.

What is the structure of a skeletal muscle fiber?

A skeletal muscle fiber is a single multinucleated muscle cell.

What are myofibrils?

Rod-like elements that contain the contractile machinery of muscle cells.

How do muscles get bigger?

Muscles get bigger because more myofibrils are made.

What are T-tubules?

Extensions of the muscle cell membrane that extend deep into the muscle fiber.

What does the sarcoplasmic reticulum (SR) do?

Stores calcium and is similar to endoplasmic reticulum in other cells.

What is a neuromuscular junction?

The synapse between a motor neuron and a muscle cell.

What happens when acetylcholine binds to receptors at the motor end plate?

Opens ion channels that allow Na+ in and K+ out.

What is end plate potential (EPP)?

Depolarization of the muscle cell membrane that leads to muscle contraction.

What are Z lines?

Boundaries between adjacent sarcomeres.

What are the thick and thin filaments in a sarcomere?

Thick filaments are myosin, and thin filaments are actin.

What is the sliding filament theory?

Mechanism of muscle contraction where myosin and actin slide over each other.

What site on myosin binds to actin?

Actin-binding site.

What is the role of ATP during muscle contraction?

Provides energy for the myosin head to pull actin.

What happens to tropomyosin during muscle contraction?

It is moved out of the way by troponin when calcium binds.

What is crossbridge cycling?

The process where myosin heads attach and pull actin filaments.

What is the role of calcium in muscle contraction?

Calcium binds to troponin to initiate contraction.

What leads to muscle relaxation?

Calcium dissociates from troponin and tropomyosin covers binding sites.

What is a twitch?

The mechanical response of a muscle fiber to a single action potential.

Isometric twitch vs Isotonic twitch?

Isometric: muscle generates force but does not shorten. Isotonic: muscle shortens while lifting a load.

What are slow twitch fibers?

Muscle fibers that hydrolyze ATP slowly, used for endurance.

What are fast twitch fibers?

Muscle fibers that hydrolyze ATP quickly, used for quick bursts of energy.

What is glycolytic fiber?

Anaerobic fibers that generate ATP through glycolysis.

What is oxidative fiber?

Aerobic fibers that generate ATP through oxidative phosphorylation.

What is SERCA?

Sarcoplasmic or Endoplasmic Reticulum Calcium ATPase pump that transports calcium.

How is muscle contraction terminated?

By lowering cytosolic calcium levels and covering binding sites on actin.

What occurs during the atrial pressure peak?

The AV valves open to allow blood flow into the ventricles.

What characterizes cardiac muscle?

Contains sarcomeres and gap junctions for synchronized contractions.

What are pacemaker cells?

Cells that set the rhythm of heartbeat by producing action potentials.

What do conduction fibers do?

Transmit action potentials throughout the heart without producing them.

What is hypertrophy in muscle?

Increase in muscle size due to training and increased myofibrils.

What does hyperventilation cause?

Increased O2 levels and decreased CO2 levels; can lead to respiratory alkalosis.

What does hypoventilation lead to?

Decreased O2 levels and increased CO2 levels; can cause respiratory acidosis.

What is cardiac output?

The volume of blood the heart pumps per minute.

What are the components of the cardiovascular system?

Blood, blood vessels, and the heart.

What are erythrocytes?

Red blood cells that carry oxygen bound to hemoglobin.

What do leukocytes do?

White blood cells that mediate immune responses.

What is the function of platelets?

Aid in blood clotting.

What is the role of plasma?

The liquid component of blood that carries cells and nutrients.

What are arteries?

Blood vessels that carry blood away from the heart.

What are capillaries?

Smallest blood vessels where gas exchange occurs.

What are veins?

Blood vessels that carry blood back to the heart.

What prevents backflow of blood in the heart?

Heart valves.

What is the function of the aorta?

Carries oxygenated blood from the left ventricle to the body.

What happens during diastole?

Heart chambers fill with blood.

What happens during systole?

Heart chambers contract to pump blood out.

What is cardiac muscle's unique feature?

It is myogenic and contracts rhythmically without external input.

What are funny channels?

Channels in pacemaker cells that allow spontaneous depolarization.

What does hypoxia refer to?

Low oxygen levels in tissues.

What is pulmonary circulation?

The flow of blood from the heart to the lungs and back.

What is systemic circulation?

The flow of blood from the heart to the rest of the body and back.

How do gases move across membranes?

Gases move from areas of high partial pressure to low partial pressure.

What is the respiratory zone?

The part of the respiratory system where gas exchange occurs.

What is the conducting zone?

The part of the respiratory system that humidifies and transports air.

What muscles are involved in inhalation?

Diaphragm and intercostal muscles.

What is the pressure change during inhalation?

Increased volume leads to decreased pressure, causing air to flow in.

What is Boyle's Law?

Pressure and volume are inversely related.

What is the effect of the diaphragm during exhalation?

It relaxes and moves upward, decreasing chest cavity volume.

What is the role of the epiglottis?

Covers the trachea during swallowing to prevent food from entering the airway.

What is the definition of hypernea?

Increased ventilation in response to elevated tissue demand.

What is the purpose of alveoli?

To provide a large surface area for gas exchange.

What is an example of a physiological adaptation to altitude?

Increased production of red blood cells to improve oxygen transport.

What does the term 'resistance' refer to in the respiratory system?

The opposition to airflow, affected by airway diameter.

What is the main goal of the respiratory system?

To facilitate gas exchange and maintain proper gas levels in the blood.

What occurs in the muscles during an isotonic contraction?

The muscle fibers shorten, causing movement.

What occurs in the muscles during an isometric contraction?

Muscles generate force without changing length.

Which muscle type is responsible for voluntary movement?

Skeletal muscle.

What is the primary function of myoglobin in muscle fibers?

To store oxygen for use during muscle contraction.

What is the role of calcium in smooth muscle contraction?

Calcium binds to calmodulin, activating MLCK to phosphorylate myosin.

What are the three types of muscle?

Skeletal, Cardiac, and Smooth.

Which muscles are striated?

Skeletal and Cardiac muscles are striated.

What is a fascicle?

A bundle of muscle fibers held together by connective tissue.

What is the structure of a skeletal muscle fiber?

A skeletal muscle fiber is a single multinucleated muscle cell.

What are myofibrils?

Rod-like elements that contain the contractile machinery of muscle cells.

How do muscles get bigger?

Muscles get bigger because more myofibrils are made.

What are T-tubules?

Extensions of the muscle cell membrane that extend deep into the muscle fiber.

What does the sarcoplasmic reticulum (SR) do?

Stores calcium and is similar to endoplasmic reticulum in other cells.

What is a neuromuscular junction?

The synapse between a motor neuron and a muscle cell.

What happens when acetylcholine binds to receptors at the motor end plate?

Opens ion channels that allow Na+ in and K+ out.

What is end plate potential (EPP)?

Depolarization of the muscle cell membrane that leads to muscle contraction.

What are Z lines?

Boundaries between adjacent sarcomeres.

What are the thick and thin filaments in a sarcomere?

Thick filaments are myosin, and thin filaments are actin.

What is the sliding filament theory?

Mechanism of muscle contraction where myosin and actin slide over each other.

What site on myosin binds to actin?

Actin-binding site.

What is the role of ATP during muscle contraction?

Provides energy for the myosin head to pull actin.

What happens to tropomyosin during muscle contraction?

It is moved out of the way by troponin when calcium binds.

What is crossbridge cycling?

The process where myosin heads attach and pull actin filaments.

What is the role of calcium in muscle contraction?

Calcium binds to troponin to initiate contraction.

What leads to muscle relaxation?

Calcium dissociates from troponin and tropomyosin covers binding sites.

What is a twitch?

The mechanical response of a muscle fiber to a single action potential.

Isometric twitch vs Isotonic twitch?

Isometric: muscle generates force but does not shorten. Isotonic: muscle shortens while lifting a load.

What are slow twitch fibers?

Muscle fibers that hydrolyze ATP slowly, used for endurance.

What are fast twitch fibers?

Muscle fibers that hydrolyze ATP quickly, used for quick bursts of energy.

What is glycolytic fiber?

Anaerobic fibers that generate ATP through glycolysis.

What is oxidative fiber?

Aerobic fibers that generate ATP through oxidative phosphorylation.

What is SERCA?

Sarcoplasmic or Endoplasmic Reticulum Calcium ATPase pump that transports calcium.

How is muscle contraction terminated?

By lowering cytosolic calcium levels and covering binding sites on actin.

What occurs during the atrial pressure peak?

The AV valves open to allow blood flow into the ventricles.