Muscles Sci
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Muscles Revision Summary Action of muscles Muscles undergo: - Contraction which shortens the length of the muscle, increases diameter - Relaxation which allows length of muscle to return to its original length, decreases diameter
Eye
Gut
Skeletal
Antagonistic muscles: Present in pairs and act in opposite ways, when one contracts, the other relaxes. Having muscles in pairs enable a reversal of the action (as muscles can only contract and relax and one set brings about 1 action). Action & Muscle Arm movement: Attached to the skeleton: Biceps and triceps (antagonistic) Knee jerk reflex: Upper thigh muscle Peristalsis: Circular muscle and longitudinal muscle in gut wall (antagonistic)
Action Contraction of biceps (Relaxation of triceps) Contraction of triceps (Relaxation of biceps) Contraction of upper thigh muscle
Effect Forearm pulled upwards
Contraction of circular muscle (Relaxation of longitudinal muscle) Contraction of longitudinal muscle (Relaxation of circular muscle)
Narrows lumen of gut, pushes food forward Shortens length of gut (widens lumen of gut), pulls food forward, allows food to move forward
Accomodation: Cilary muscles attached to lens via suspensory ligaments (ligaments are passive, they cannot contract/relax) Entry of light into eye: Iris: Circular muscles Radial muscles
Contraction of ciliary muscles (Slackens pull of ligaments on lens) Relaxation of ciliary muscles (Increases upll of ligaments on lens) Contraction of circular muscles (Relaxation of radial muscles) Contraction of radial muscles (Relaxation of circular muscles)
Elastic lens becomes thicker, more convex, refracts light rays from nearby object Elastic lens becomes thinner, less convex, refracts light rays from faraway object Pupil constricts (less light enters into eye) Pupil dilates (more light enters into eye)
Forearm pulled down Lower leg kicks upwards
Eye
Gut
Skeletal
Antagonistic muscles: Present in pairs and act in opposite ways, when one contracts, the other relaxes. Having muscles in pairs enable a reversal of the action (as muscles can only contract and relax and one set brings about 1 action). Action & Muscle Arm movement: Attached to the skeleton: Biceps and triceps (antagonistic) Knee jerk reflex: Upper thigh muscle Peristalsis: Circular muscle and longitudinal muscle in gut wall (antagonistic)
Action Contraction of biceps (Relaxation of triceps) Contraction of triceps (Relaxation of biceps) Contraction of upper thigh muscle
Effect Forearm pulled upwards
Contraction of circular muscle (Relaxation of longitudinal muscle) Contraction of longitudinal muscle (Relaxation of circular muscle)
Narrows lumen of gut, pushes food forward Shortens length of gut (widens lumen of gut), pulls food forward, allows food to move forward
Accomodation: Cilary muscles attached to lens via suspensory ligaments (ligaments are passive, they cannot contract/relax) Entry of light into eye: Iris: Circular muscles Radial muscles
Contraction of ciliary muscles (Slackens pull of ligaments on lens) Relaxation of ciliary muscles (Increases upll of ligaments on lens) Contraction of circular muscles (Relaxation of radial muscles) Contraction of radial muscles (Relaxation of circular muscles)
Elastic lens becomes thicker, more convex, refracts light rays from nearby object Elastic lens becomes thinner, less convex, refracts light rays from faraway object Pupil constricts (less light enters into eye) Pupil dilates (more light enters into eye)
Forearm pulled down Lower leg kicks upwards
