Muscular System Overview

These flashcards cover key concepts related to the muscular system, its functions, components, and muscle actions as outlined in lecture notes.

What are the main functions of the muscular system?

Movement, heat generation, and maintaining posture/shape.

What structures are considered part of the muscular system?

Skeletal muscles, the heart, blood vessels, and the muscularis layers of organs.

What is a muscle fiber?

A muscle cell.

What are some key components of a muscle fiber?

Sarcoplasmic reticulum, sarcolemma, sarcoplasm, T-tubules, glycogen granules, and myoglobin.

What are the connective tissue layers associated with skeletal muscle?

Epimysium, perimysium, and endomysium, along with tendons.

What are the main proteins involved in muscle contraction?

Actin, myosin, tropomyosin, and troponin.

What is a sarcomere?

A functional unit of a muscle fiber, consisting of Z-Disc, M-Line, I-Band, A-Band, and H-Zone.

What happens during muscle resting potential?

Calcium ions are stored in the sarcoplasmic reticulum, blocking actin/myosin interaction.

How is a muscle contraction initiated?

By a neurological impulse from a motor neuron reaching the neuromuscular junction.

What causes myosin/actin crossbridges to be exposed during muscle action potential?

Calcium ions move into the sarcoplasm, causing troponin to react with Ca++, leading to crossbridge exposure.

What is required for the formation and breaking of myosin-actin crossbridges?

Each requires 1 ATP for formation and 1 ATP for disconnection.

Describe muscle relaxation. What occurs?

Neurological impulses cease, calcium is moved back into the sarcoplasmic reticulum, and crossbridges are blocked.

What is the difference between isotonic and isometric contractions?

Isotonic involves shortening of muscle fiber, while isometric does not change muscle length.

How is ATP generated in different muscle contractions?

Aerobic generates ATP via metabolism; glycolytic does so via glycolysis, potentially resulting in lactic acid.

What factors influence muscle development?

Exercise, hormones, and diet.

How do muscles adapt to use and disuse?

Muscles grow with use and atrophy without, prioritizing maintenance and repair.

Name a muscle of the head and its action.

Frontalis - Raises eyebrows.

Name a muscle of the mouth and its action.

Orbicularis oris - Closes lips.

Name some muscles of the tongue and their actions.

Genioglossus - Protrudes tongue; Hyoglossus - Depresses tongue.

Name a muscle of the neck and its action.

Sternocleidomastoid - Rotates head.

Name some ventral torso muscles and their actions.

Pectoralis major - Circumducts arm; Rectus abdominis - Flexes torso.

Name some dorsal torso muscles and their actions.

Trapezius - Retracts shoulders; Latissimus dorsi - Adducts arm.

Name some muscles of the arm and their actions.

Deltoid - Abducts arm; Biceps brachii - Flexes arm.

Name some proximal leg muscles and their actions.

Gluteus maximus - Extends femur; Rectus femoris - Extends knee.

Name some distal leg muscles and their actions.

Tibialis anterior - Flexes foot; Gastrocnemius - Extends foot.