Lecture 3 Flashcards
Boundary
Load bearing surfaces separated by lubricin molecules
Fluid Film
Load bearing surfaces separated by film of lubricate maintained under pressure
Thixotropic
Viscosity varies inversely with joint velocity & temperature
Electromechanical Delay
Usually 10-15 milliseconds. Time between when electrical activity begins and when there is a mechanical response.
Where are motor neuron cell bodies located?
In the ventral horn of the spinal cord.
Can muscles in the same motor unit have different types of muscle fiber?
No, they are all the same.
How do you increase muscle tension?
By increasing motor unit recruitment & the frequency of impulses.
In what order are the types of muscle fibers recruited?
1st - slow
2nd - intermediate
3rd - fast
What type of motor units do older people tend to lose & why?
Fast twitch motor units because they are not using them.
If people are losing fast twitch motor units, what kind of exercise do they need to do?
Resistance training with as much weight as they can handle for 6-8 reps.
Tetany
When the contraction is smooth & no longer jerky
Physiological Cross Sectional Area (PCSA)
Always perpendicular to the muscle fibers. Strength is directly proportional to the PCSA.
Anatomical Cross Sectional Area
Perpendicular to the overall muscle, but not necessarily the muscle fibers
Hypertrophy
The existing muscle cells get bigger, but do not increase in number.
Hyperplasia
The muscle cells do not grow in size, but they do multiply. This is incredibly unlikely to occur. It’s never been proven to truly happen, but it’s never been proven to be impossible. It’s simply a theory.
Golgi Tendon Organ
Sends info to inhibitor neuron, which prevents muscle from producing as much force as possible. Allows more force to be produced as you continue to work out (not in a single session). Also important for proprioception.
Does concentric exercise produce more or less force as speed is increased?
Less
Does eccentric exercise produce more or less force as speed is increased?
More
Synarthrosis
1) dense, irregular connective tissue
2) negligible motion
3) binds bones w/in a functional unit;disperses forces across the joined bones
Amphiarthrosis
1) hyaline cartilage or fibrocartilage
2) minimal to moderate movement
3) Provides a combination of relatively restrained movement and shock absorption
Diarthrosis (Synovial Joint)
1) true joint space filed w/ synovial fluid & surrounded by a capsule
2) extensive movement
3) provides the primary pivot points for movement of the musculoskeletal system
Types of Diathrodial Joints
1) hinge
2) plane
3) saddle
4) condyloid
5) pivot
6) ellipsoidal
7) ball and socket
Concave-Convex Rule
Concave segment of a joint rolls and slide in same direction
Think about which bone/body part is stationary
Convex - Concave Rule
Convex segment of a joint rolls and slides in opposite directions
(Think about which bone/body part is stationary)
