Week 4 - The Muscular System Flashcards
(68 cards)
What are the four key functions of muscular tissue?
- Producing body movements
- Stabilising body positions
- Storing and moving substances
- Generating heat
What are the four key properties of muscular tissue?
- Electrical excitability
- Contractility
- Extensibility
- Elasticity
What are the three types of muscle tissue?
Skeletal, Cardiac, and Smooth muscle.
Describe skeletal muscle tissue.
- Long, cylindrical, multinucleated cells
- Striated, voluntary
- Attaches to bones via tendons
- Controlled by somatic motor neurons
Describe cardiac muscle tissue.
- Branched, cylindrical, single central nucleus
- Striated, involuntary
- Found only in the heart
- Autorhythmic; connected by intercalated discs and gap junctions
Describe smooth muscle tissue.
- Small, flat (squamous), single nucleus
- Not striated, involuntary
- Found in walls of hollow organs
- Contracts in twisting motion
Which muscle tissue types can regenerate, and how?
- Skeletal: Limited regeneration; relies on enlargement (hypertrophy); mostly fibrosis
- Cardiac: Cannot regenerate; only fibrosis (e.g. post-MI)
- Smooth: Can regenerate via hypertrophy and hyperplasia (e.g. uterus)
What are the key organelles and structures in skeletal muscle fibres?
- Sarcolemma: Muscle cell membrane
- T-Tubules: Carry action potentials inside cell
- Sarcoplasm: Cytoplasm, stores glycogen & myoglobin
- Myofibrils: Contractile organelles
- Sarcoplasmic reticulum: Stores and releases Ca²⁺
- Sarcomere: Functional unit of contraction
What proteins are involved in contraction?
- Contractile proteins: Actin (thin) & Myosin (thick)
- Regulatory proteins: Tropomyosin, troponin
- Structural proteins: Provide alignment, elasticity (e.g., titin)
What is a sarcomere?
The basic functional unit of a myofibril, composed of actin and myosin filaments.
How does contraction occur in skeletal muscle?
Actin slides over myosin, shortening the sarcomere.
What are the connective tissue components in muscle structure?
- Fascia – surrounds muscles
- Epimysium – around entire muscle
- Perimysium – around fascicles
- Endomysium – around individual fibres
Why are skeletal muscles highly vascularised and innervated?
To deliver oxygen/nutrients, remove waste, and receive signals for contraction.
What are the seven features used in naming muscles?
- Direction of fascicles
- Size
- Shape
- Action
- Number of origins
- Location
- Origin and insertion
What movements can muscles produce across joints?
- Flexion / Extension / Hyperextension
- Lateral Flexion
- Abduction / Adduction
- Circumduction
- Rotation (Medial/Lateral)
- Elevation / Depression
- Protraction / Retraction
- Inversion / Eversion
- Plantarflexion / Dorsiflexion
- Supination / Pronation
What roles do muscles play in coordinated movement?
- Prime mover: Main muscle causing action
- Antagonist: Opposes the prime mover
- Synergist: Assists prime mover
- Fixator: Stabilises the origin
What are the three classes of levers in the body?
- First-class: Fulcrum between load and effort (e.g., neck)
- Second-class: Load between fulcrum and effort (e.g., standing on toes)
- Third-class: Effort between fulcrum and load (e.g., bicep curl)
How does fascicle arrangement affect muscle function?
Determines power and range of motion; arrangements include parallel, fusiform, circular, triangular, and pennate.
What is the primary function of skeletal muscles in relation to movement?
Producing voluntary body movements by pulling on bones.
How do muscles help maintain posture?
By stabilising joints and holding the body in position.
How do muscles assist in moving substances within the body?
Smooth muscle moves substances like food and blood through hollow organs.
What role do muscles play in thermoregulation?
Muscular contractions generate heat as a byproduct (e.g., shivering).
What is electrical excitability?
The ability of muscle tissue to respond to stimuli by producing action potentials.
Define contractility.
The ability of muscle tissue to shorten and generate force.
