muscles Flashcards
how do we influence external world?
muscle contraction
what are the functions of muscles ? (5)
- produce movement
- maintain posture
- protection
- heat production = thermogenesis
- driving circulatory system = vascular pump
what are the three types of muscles?
cardiac, smooth and skeletal
what is cardiac muscle?
muscles constituting heart specialised for involuntary cyclic contractions
what are smooth muscles?
involuntary for blood vessels and hollow organs e.g. stomach, intestine
what are skeletal muscles?
muscles specialised for producing forces required for body movement
what is the theory for contraction? explain
balloonist theory states the muscle swells like a balloon during contraction
how does the signal travel from head to muscles?
animal spirit flows from head to muscle
what is the Swammerdam experiment?
frog muscle in glass tube filled with water and tested if the water level underneath increased when he stimulated the muscle via a nerve
what was the outcome of the experiment?
it disproved the theory as the volume does not increase; it decreased
what are bundles of individual muscle fibres?
muscle fasicle
what happens when fibres individually contract?
each contractile fibre generates tension to apply force to both ends
what is a tendon?
attaches bone to muscle
how else is a bone attached to muscle?
directly without tendon e.g. eye
what is the junction called where tendon attaches to bone?
teno- osseous
what is the junction called where tendon attaches to muscle?
Musculo- tendinous
what is the site where two groups of fibres converge together? explain
- aponeurosis
- tandem like thin sheets
what is the arrangement of parallel muscles? give an example
- all fibres are parallel to axis of muscle e.g. biceps brachii
what is the arrangement of fusiform?
diagonal organisation to maximise force’s potential
what is the formation of pennate?
fibre directions are different from main axis of muscle
what is the formation of penniform muscle? what are the three types
angle between axis of muscle and fibre direction; unipennate= one row of diagonal fibres; bipennate= two rows; multipennate= multiple
how do you work out the strength of muscles? (2 ways)
- count number of fibres packed in
- draw perpendicular line and count number of fibres at intersect
what is the area of cross section perpendicular to its fibres called?
physiological cross sectional area
how do parallel bones converge ?
through tendons
how do pennate muscles generate forces?
- aponeurosis ; and then transmitted to tendon
which muscle is stronger pennate or parallel?
- pennate
what muscle is faster - pennate or parallel?
parallel as pennate has to shorten longer to cover the same distance
what do muscle fibres trade off between?
strength and speed
what is an isometric contraction?
external force is equal to muscle force so muscle length stays constant
what is a concentric contraction?
muscle force is greater than external force so muscle can be shortened
what is a eccentric contraction?
external force is greater than muscle force so muscle can be lengthened
what are muscle fibres bundles of? what do they look like
bundles of myofibrils
- striped patterns of dark and light regions
what is the functional unit of contraction?
- sarcomere, which has a mechanism to generate tension
what is actin?
thin protein fibre
what is myosin?
thick protein fibre
