Muscular System

Question 1

What are the four types of tissues?

Answer 1

Connective, Epithelial, Muscle, Nervous

Question 2

What are the components of the muscular system?

Answer 2

Skeletal: Attaches to bone
Cardiac: Principal tissue of the heart
Smooth: Located in walls of hollow organs and blood vessels

Connective tissue components: Fascia, Epimysium, Perimysium, Endomysium

Question 3

What is skeletal muscle tissue?

Answer 3

Attached to bones via tendons, long cylindrical cell fibers, striated (tiger stripes), multinucleated, nuclei are located peripherally, voluntary nervous control, straddle over a joint and is involved in movement of what they are connected to

Question 4

What is smooth muscle tissue?

Answer 4

Within the hollow organs, airways, blood vessels and attaches to hair follicles, non-striated, each cell has one nucleus located centrally, involuntary control, lacks striations, seen in gut, contracts in multiple different directions

Question 5

What is cardiac muscle tissue?

Answer 5

Striated, has one nucleus located centrally, involuntary control (autorhythmic), takes on a different property of a branched appearance, forked tubules which means that is has a matrix connection so it can contract

Question 6

Functions of the muscular system?

Answer 6

Movement due to muscular contraction, movement of the whole body (walking, running), localized movements (grasping a pencil), stabilizes body position, postural muscles contract when your away (sustained contractions of neck muscles hold your head upright)

Question 7

Function: Storage and movement

Answer 7

Contraction of sphincters (muscular rings) to prevent outflow of contents from a hollow organ (pyloric, urethral). Temporary storage of food (stomach) and urine due to sphincters

Movement: Cardiac contractions pump blood through the blood vessels, contraction/ relaxation of smooth muscles in various bodily locations can move foods, gametes, urine through

Question 8

Function: Generate heat

Answer 8

Muscular tissue contracts and produces heat to maintain normal body temperature (shivering)

Question 9

What are the properties of muscle tissue?

Answer 9

Electrical excitability: The ability to respond to stimuli by producing action potentials

Contractility: The ability to contract forcefully when stimulated by an action potential

Extensibility: The ability to stretch within limits without being damaged

Elasticity: The ability to return to its original length and shape after contraction or extension

Question 10

Skeletal muscle structure:

Answer 10

Contains: cells/fibers that are long cylindrical multinucleated wrapped in a connective tissue layer (endomysium). Filled with contractile organelles called myofibrils, muscle cells are bundled into fascicles which are wrapped in a connective tissue layer (perimysium)

Muscle cell/fiber (wrapped in endomysium)

bundled together

Fascicle (wrapped in perimysium)

bundled together

Skeletal Muscle (wrapped in epimysium)

Question 11

Skeletal Muscle cell contraction:

Answer 11

Sarcoplasm (muscle cell cytoplasm) contains hundred of myofibrils (contractile organelles)
Each Myofibril contains bundles of protein filaments that interlock
Myofilaments: Actin (thin) and Myosin (thick)
Myosin binds to actin
Actin slide inwards covering myosin
This action causes the striated appearance
Thick and thin filaments slide over each other contracts the sarcomere

Question 12

Cardia muscle tissue and contraction:

Answer 12

Individual muscle cells/fibers branching. Fibers contain thick and thin filaments arranged, adjacent cells are joined end-to-end via intercalated discs. Allows for transmission of action potentials and muscle cells are able to act as a single functional unit

Question 13

Smooth muscle tissue and contraction:

Answer 13

Small and flat squamous shaped cells, contain thick, thin and intermediate filaments but not arranged in an orderly fashion

Single unit smooth muscles: cells contract in unison
Multi unit smooth muscles: contract independently

Question 14

How do we move?

Answer 14

Muscles attached to our skeleton contract and bring two ends of the muscle together and must cross a joint to make a movement

Muscle attachment sites are;

Origin: Muscle beginning: Does not move during contraction (usually the proximal end of a bone/joint)

Insertion: Muscle end, is pulled towards the origin during contraction, usually the distal end of a bone/joint

Question 15

What are some available movements?

Answer 15

Flexion, extension, hyperextension
Abduct our hands (out) Adduction (in)
Palmer and dorsal surface of hands
Lateral flexion
Pronation and supernation: Prone= face down lying position, supine= faced up on their back)
Opposition
Inversion e.g. rolled ankle

Question 16

What features do we use to name muscles?

Answer 16

Direction: Orientation of muscle fascicles relative to the body’s midline e.g. Rectus abdominus

Size: relative size of the muscle e.g. Gluteus maximus

Shape: Relative shape of the muscle e.g. Serratus anterior

Action: Principle action of the muscle e.g. Supinator

Number of origins: Number of tendons of origins e.g. Triceps brachii

Location: Structure near where muscle is found e.g. Temporalis

Origin and Insertion: Sites where muscle originates and inserts e.g. sternocleidomastoid

Question 17

How do muscles regenerate?

Answer 17

Skeletal Muscle:
- Muscle fibers cannot divide after 1st year, so future growth only via enlargement of existing cells
- Some muscle repair available via specialized cells however, it is often insufficient fibrosis occurs (scar tissue formation)

Cardiac muscle:
- Cannot divide or regenerate; repair via fibrosis only e.g in myocardial infarction

Smooth muscle:
- Cells can grow in size (hypertrophy) or number (hyperplasia) e.g. uterus during pregnancy
- Regeneration is possible