Muscular System Flashcards
What does the muscular system consist of?
Muscular System consists of the named skeletal muscles, as well as smooth muscle and cardiac muscle.
What are two functions of the muscular system include?
- Facilitate movement and posture (with the skeletal system)
- Generates heat – this helps maintain a constant body temperature which then contributes greatly to homeostasis.
What are the three types of muscle tissue?
Skeletal, Cardiac and Smooth
What does skeletal muscle look like?
Skeletal muscle is striated, it has long thin multinucleated fibres.
What does smooth muscle look like?
Smooth muscle has no stripes or striations when looking at it under a microscope.
It consists of narrow spindle shaped cells with single nuclei.
What does cardiac muscle look like?
The cardiac muscle contains sarcomeres – similar to skeletal muscle.
What is the function of skeletal muscle?
Skeletal muscle enables the body to produce movement.
It is also involved in resisting movement or posture
What is the functional unit of skeletal muscle?
The sarcomere
At each end of the sarcomere where it connects to the next sarcomere there are lines called what?
Z-disks/Z-lines
The sarcomere is composed of thin filament containing what?
The thin filament contains actin and the troponin-tropomyosin complex
The sarcomere contain thick filament made of what?
Myosin
What happens when sarcomere contracts?
The muscle contracts
During a muscle action potential what gates open during the depolarisation phase?
Na+ (Sodium)
During a muscle action potential what gates open during the repolarisation phase?
K+ (Potassium)
What does filament interaction lead to?
Muscle contraction
When does the sliding occur as described by the sliding filament model?
The sliding can only occur when the myosin binding sites on the actin are exposed.
What do we need for muscle contraction?
ATP (energy)
When is ATP not present?
Rigor mortis
What is the force generated by contraction of skeletal muscle involving the shortening of sarcomeres called?
Tension
What are the two main types of skeletal muscle contraction called?
- Isotonic
2. Isometric
Describe Isotonic Contractions
o When the tension in the muscle stays constant and a load is moved as the length of the muscle changes
What are the two types of isotonic contraction?
Concentric (muscle shortening) and eccentric (muscle lengthening).
Describe isometric contractions
Muscle produces tension without changing the angle of the joint, or when the load does not move.
What is the motor unit?
The motor unit is the motor neuron and all the muscle fibres that it innervates.
Describe fast twitch muscle fibres.
Rapid energy generation for quick powerful actions.
Less fatigue resistant – fatigue quickly but produce energy quickly for powerful actions.
Describe slow twitch muscle fibres.
Large numerous mitochondria for greater reliance on oxidative metabolism.
Highly fatigue resistant – don’t produce energy as quickly but don’t tire so quickly.
Where is cardiac muscle found?
The heart
How are cardiac muscle fibres connected?
The cardiac muscle fibres are extensively branched, and they’re connected by and intercalated discs.
What are gap junctions?
Cardiac
Gap junctions are the channels between the fibres that allows the current to flow from one cell to another. This allows the heart to function as a muscle pump.
What are desmosomes?
Cardiac
Desmosomes are sealed structures that anchor the ends of the fibres to one another so that when contraction occurs, the cells don’t pull away from one another
What are varicosities?
Smooth
A series of neurotransmitter filled bulges
Where does the varicosity release a neurotransmitter to?
Smooth
The synaptic cleft.
What causes smooth muscle fibre to contract?
The dense bodies and intermediate filaments that are networked through the sarcoplasm
Where does muscle tissue arise from?
Embryonic mesoderm
What are satellite cells?
• Satellite cells are muscle stem cells that help to repair skeletal muscle cells. They are also involved with muscle growth
What are satellite cells required for?
The regeneration of skeletal muscle.
Where are satellite cells located?
o They are located underneath the basal lamina of the myofibre.
When are satellite cells activated?
Muscle damage/muscle growth
What are the three stages of regeneration for skeletal muscle?
- Inflammatory phase.
- Satellite cell activation/differentiation phase.
- Maturation phase (remodelling of newly formed myofibers).
What does the term ‘Insertion’ mean?
Insertion refers to the moveable end of the muscle that attaches to the bone
What does the term ‘origin’ mean?
Origin refers to the end of the muscle attached to a fixed (stabilised) bone.
What does the term ‘prime mover (agonist)’ mean?
Prime mover refers to the principal muscle involved in the action.
What does the term Antagonist mean?
Antagonist refers to muscle with the opposite action of the prime mover (agonist)
