Muscle Physiology I Flashcards
What are the functions of muscular tissue?
- movement
- stabilize body positions
- storing and mobilizing substances (storage of glycogen)
- generate heat (used to maintain body temp)
- support soft tissues
- guards entrances and exits (sphincters)
What are the main properties of muscular tissue?
- electrical excitability
- contractility
- extensibility
- elasticity
What type of signals does skeletal muscle respond to?
Electrical stimulation from the nervous system
What type of signals does cardiac and smooth muscle respond to?
Both neural and hormonal inputs
In short, how do muscles contract?
When muscle cells are stimulated, shorterning occurs as myosin (thick) pulls actin (thin) filaments towards the centre of the sarcomere which exerts force on the tendons
Definition:
Spasticity
Lack of extensibility (muscles cannot extend, can only shorten)
Deifnition:
Ability to recoil or bound back to the original length after being stretched
Elasticity
What are the characteristics of cardiac muscle?
- short branching cells with a single nucleus and ligth striations
- intercalated discs join muscle cells
- gap junctions allow ions to move easily between cells
What are the characteristics of smooth muscle?
- long (fusiform shape) cells with a single nucleus
- no striations
- involuntary control
What are the characteristics of skeletal muscle?
- cells are long and multinucleated, cylindrical hape and heavily striated (comes from arrangment of contractile filaments)
- voluntary control
Definition:
Slow twitch (Type I) fibres
- appear darker due to higher [myoglobin]
- mainly generate ATP through aerobic respiration
- high [mitochondria] and [capillaries]
- slow twitch velocity
- very fatigue resistance
Definition
Fibres that:
- appear lighter due to low [myoglobin]
- generate ATP mainly through glycolysis
- low [mitochondria] and [capillaries]
- faster twitch velocity
- fatigue rapidly, but provide power rapidly
fast twitch (Type IIb/x - glycolytic)
Definition:
fast twitch (Type IIa- oxidative-glycolytic)
- red-pink due to moderate [myoglobin]
- generate ATP through aerobic and anaerobic glycolysis
- high [mitochondria] and [capillaries]
- moderate velocity and power twitch contractions
- fairly fatigue resistant and are good for running sustained speed events (400-800m)
T/F: motor units can innervate multiple types of muscle fibre
false! will only innervate 1 type
What does the force developped by the whole muscle depend on?
Recruitment pattern and proportion of fibre types present in the muscle
