Download Muscle Contraction and Movement

Muscle Contraction and
Movement
Biology 2121
Origins and Insertions
(1). Origin: attachment to less
or non-moveable bone
(2). Insertion: muscle inserts
on the moveable or more
moveable bone.
(3). Example
– Deltoid:
– O= scapula (spine); clavicle
I = deltoid tuberosity of
humerus
Levers
• (1). Muscular movement resemble a ‘leverfulcrum’ system
• (2). Effort: muscle contraction; Load: bone
• (3). Most skeletal muscles = 3rd class lever
system
Levers
Muscle Contractions
• (1). Muscle Tension moves a load
• (2). Isometric vs. isotonic (next slide)
• (3). Motor Units
– Muscles do not always contract with same force
– Nerves branch out to serve different motor units
Types of Contractions
• (1). Isometric
– muscle tension < load
– Load not moved
• (2). Isotonic
– Shortening; muscle
tension > load
– Load is moved
Muscles Work Together and in
Opposition
• (1). Oppositional muscles
– Agonists vs. Antagonist
– Agonist: Biceps; Antagonist: Triceps
• (2). Aiding Prime Movers
– Synergists
– Arm Abduction: supraspinatus and deltoid
• (3). Immobilizing parts of a muscle
– Fixators
– Quads stabilize the knee when flexed to flex up on the toes
Motor Unit
• (1). Individual Muscles
– Have one or more motor units
that branches
• (2). One motor unit
– Neuron + all fibers ------ NM
junction
• (3). Firing of the motor nerve
– All fibers that branch off will fire
at same time
Twitches and Responses
• Measuring Muscle
Contractions:
– (1). Twitch (Latent,
Contraction and
Relaxation)
– (2). Graded Responses
• Change Stimulus
Frequency
• Change Stimulus Strength
Effect of Frequency and
Increasing/Decreasing Stimulus Strength
• (1). Stimulus Frequency
– Wave summation;
tetanus
• (2). Strength
– Threshold and
recruitment; Threshold
stimulus
Fiber Types
• Type I – Slow Oxidative (Red – Slow Twitch)
– Myoglobin; mitochondria; Slow contraction
velocity; resistant to fatigue; long distance running
• Type II(a) – Fast Oxidative (Red- Fast Twitch)
– Opposite to type I; fatigue fast; sprinters
• Type II(b) – Fast Glycolytic (White)
– Low myoglobin; glycogen; mitochondria; fatigue
fast; sprinting
Fiber Types – Effects on Contractions
Type 1 Fibers: Dark
Type 2 Fibers: Lighter
Other
• (1). Muscle Tone
– Muscles are slightly contracted due to spinal
reflexes
• (2). Muscle Fatigue
– Why do muscles fatigue? What does it mean?
– What are contractures?
– What is meant when someone goes into oxygen
debt?
Development
• (1). Embryonic stem cell
– Myoblasts
• (2). Week 7
– Skeletal muscles are contracting
• (3). Fusion of skeletal muscle cells
What to Do About Chapter 10?
1. Any muscle you have covered in the lab you are responsible
for in lecture
–
–
–
–
Area or region of the body it is located
Part of larger grouping of muscles (quads, etc.)
Given a simple description identify the muscle (or vise-versa)
Given a general function identify the muscle (vise-versa)
2. Know these origins and insertions for the lecture test
–
Masseter; Rectus Abdominus; Deltoid; Biceps Brachii; Sartorius;
Gastrocnemius
Additional Information
Concerning Chapter 9
1. Be sure to compare skeletal muscle to
smooth muscle using table 9.3. Compare
based on the following criteria:
– Location; shape and appearance; regulation of
contractions; speed of contraction; rhythmic
contraction