8) The nervous system and muscle function Flashcards
Muscle functions
Movement (muscle pulls on bone) Maintain posture (maintain position of the skeletal system) Produce heat (movement produces heat)
Types of muscke
Smooth
Skeletal
Cardiac
Smooth muscle
Visceral muscles Involuntary Non-striated Very elastic Sustained, slow, powerful contractions Walls of arteries Intestines etc
Cardiac muscle
Muscle of the heart wall
Involuntary
Striated
Very elastic and fatigue resistant
Skeletal muscle
Voluntary Striated Activated by CNS Made to contract and relax by conscious control Less elastic and fatigues Attach to and move the skeleton
Muscle Composition
Muscle tendon Muscle belly Bundles of muscles Muscle fibres Myofibrils Myofilaments
Characteristics of muscle
Irritability
Contractability (is capable of shortening”
Extensibility
Elasticity (can return to its original shape after being shortened or lengthened)
How we control the body
Electrical control
(Nervous system, electrical impulses)
Chemical control (endocrine system, hormonal circulation)
The central nervous system
Responsible for all conscious functions. Send messages to muscles 2 parts: Brain (sends orders to the body) Spinal Cord (Is the major phone line to the worksites of the body)
The brain is involved in:
CNS
Control of muscular movements
Emotional aspects of behaviour and memory
Interpretation of sensory impulses
Coordination of skeletal muscles
The spinal cord
CNS
Extends from skull to Lumbar vertebrae
Nerve roots branch off the spinal cords and travel to all regions of the body to send and receive information regarding body functions
All information from the body to the brain passes through the spinal cord
Peripheral nervous system
Consists of sensory (afferent) and motor (efferent) nervous tissue(our nerves) which are nerves that send info from the various body parts to the CNS
Nervous system (2 divisions)
Central nervous system
Peripheral nervous system
Motor responses
Somatic : run, jump etc
Enteric: digestive structures to move food down
Autonomic: cardiac and smooth muscles (heart beating)
Autonomic motor responses
Cause excitation or inhibition of cardiac and smooth muscle and glands
Sympathetic: fight or flight
Parasympathetic: rest and digest
Motor unit consists of..
Motor nerve
Motor end plate
The muscle fibres it activates (how many)
Every fibre activates at 100% in the motor unit or not at all
The force of the contraction is dependent on:
Number of motor units Frequency of firing of motor units Synchronisation of activation of motor units Inhibition of the antagonist muscles Sensitivity of the sensory organs Muscle fibre type Muscle size
How sensitive are your sensory organs
Muscle spindle: lives in the muscle belly and senses the rate of lengthening of a muscle (neck reflex)
Golgi tendon organ: senses the amount of tension in muscles and shuts down if too much
Type 1 red slow twitch fibres
Small in size Small motor nerve and motor end plate Low frequency of firing Low contraction force Slow contraction speed High endurance Aerobic (Long distance runners)
Fast twitch fibres
Type 2
Large, anaerobic fibres that have a high force output and very low endurance
2A
Fast oxidative gylcolytic fibres (fog)
Intermediate fibres as can turn into either type 1 or 2 depending on training
Type 2B
Fast Gylcoytic fibres (FG) Large fibres that have large motor nerve and motor plate High frequency of firing Strong contractions Low endurance Anaerobic
Fibre types can differ in persons due to:
Genetics
Hormones
Exercise training
Rules for recruitment of fibres
Activated in order of smallest to largest (slow to fast twitch)
The higher the force/tension the greater the number of fibres activated
High speed activities can activate fast twitch straight away eg fly swat
