IB Health & Science Flashcards
What are the fundemental movements that apply to all joints?
- Flexion
- Extension
- Abduction
- Medial Rotation
- Adduction
What is a synovial joint ?
Most common joint, where space between bones allows for substantial movement.
What is a lever?
simple machine used to provide a mechanical advantage (allows small force to move big weight)
A lever consists of:
rod
fulcrum
load
effort
Levers in our body:
rod = bone
fulcrum = joint
load = body weight
effort force = muscle force
Types of levers
first Class: effort & load on opposite sides of fulcrum
second class: effort & load on same side of fulcrum with load closer to fulcrum benefit: ↓ effort lift ↑ weight
third Class: effort and load on same side of fulcrum with effort closer to fulcrum benefit:↑ range motion & speed
Type of levers in body
First Class: rare in body
example: muscles of neck provide effort to lift head (load)
Second Class: very rare in body
only example: calf muscles provide effort to lift body (load) when standing on the toes
Third Class: common
example: biceps brachii
provides effort at
elbow joint to hold
weight at hand
Torque
force applied to object that causes it to rotate
Importance of Torque
torque from muscles causes bones to rotate around joints.
center of mass:
point around which mass of a body is evenly distributed.
Importance of center of mass:
t determines stability of static positions
-Balance is achieved when center of mass is
above & within base of support
Impulse:
force multiplied by the time it acts for (J = Ft)
angular momentum (L):
measure of amount of rotation
L = moment of inertia x angular velocity
moment of inertia:
difficulty in rotating object
-depends on object’s mass and
its distribution around axis of rotation
