Functional Anatomy Flashcards
What is the Epimysium
Connective tissue surrounding each muscle
What is the permimysium
Connective tissue that surrounds the fasicle
What is a fasicle
Bundle of skeletal muscle fibres
what is a myofibril
Comprised of actin and myosin
Actin
Thin myofilament
Myosin
Thick myofilament
Motor end plates
attaches axon terminals to muscle fibers
Whats a sarcomere
contractile component of muscle fiber, comprised of actin and myosin
Z-line
Dark thin protein band, to which actin filaments are attached in muscle fiber, making boundaries in adjacent sarcomeres’
A-band
Center of sarcomere containing both actin and myosin filaments
H-zone
Center of A-band, free from myosin cross bridges
I-band
The area of myofibril containing ONLY actin
M-line
Found in H-zone, middle of sarcomere
What is a motor unit
A single motor neuron and all of the corresponding muscle fibers
All or nothing principle
When eletrical impulses reach a certain THRESHOLD all of the muscle fibres in the motor unit will contract at the same time, as forcefully as possible
Explain fibre recruitment
- increase number of motor units recruited: increases strength of nerve impulses sent from the brain(stronger impulse) more activated muscle fibres
- increased frequency of motor unit discharge: Greater frequency of arrival of nerve impulses = greater force production
Whats is preferential recruitment
Recruitment of the type of muscle fibre is determined by the intensity of the task
- endurance=slow twitch
- speed endurance= fast twitch a
- speed/power= fast twitch b
Role of the brain in the nervous control of muscular contraction
interprets information and makes a decision on sensory input to then send messages to muscles to contract and movement occurs
Role of the spinal cord in the nervous control of muscular contraction
Part of the central nervous system (CNS) that connects with the peripheral nervous system (PNS)
Pathway for motor information relaying information between the brain –> body and body –> brain.
Sensory Neuron
Conveys nerve impulses to spinal cord bases on the information picked up from stimulus/ sensory receptors
Motor Neuron
Moves impulses away from the CNS and effectively activates movements
Characteristic of slow twitch muscle fibre (type 1)
-slow contraction speed
-low force of contraction
-high capacity for ATP production
-fatigue resistant
-contracts repeatedly for continuous activity
-posses high amounts of aerobic characteristics:
increased myoglobin, mitochondria, capillary density
-smaller fibres
-stimulated by smaller motor neurons
Characteristics of fast twitch muscle fibre (type2b)
- rapid contraction speed
- high force of contraction
- large muscle fibres
- large motor unit stimulates muscle fibres
- posses anaerobic characteristics: increased glycotic enzymes, increased PC stores, increases glycogen
- simulated by large motor neurons
- fatigues quickly
Characteristics of a fast twitch muscle fibre (type 2a)
- fast contraction speed
- moderate force of contraction
- relatively large muscle fibres
- stimulated by relatively large motor neurons
- possesses some aerobic characteristics: moderate levels of mitochondria, myoglibin and capilaries
- fatigue resistant (less than slow twitch)
