Skeletal muscle characteristics
- attach by tendons to bones
- Multi nucleated
- striated
- voluntary
What are the three basic muscle type found in the body?
- skeletal
- cardiac
- smooth
Aponeuroses
attach muscles and directly to bone cartilage or connected tissue coverings
Ex: abdomen
Smooth muscle characteristics
- spindle shaped
- no striations
- 1 nucleus
- involuntary
- in walls of hollow organs
Cardiac muscle characteristics
- striations
- 1 nucleus
- branching cells
- involuntary
- walls of heart
Function of skeletal muscles
- movement
- posture
- stabilizes joints
- generates heat
Sarcolemma
Specialized plasma membrane of muscle
Myofibrils
One organelles inside muscle cell, contractional units
Sarcoplasmic reticulum (SR)
Specialize smooth endoplasmic reticulum
Myofibrils are aligned to form what 2 types of bands?
- I band = light (thin filaments)
- A band = dark (length of thick filament)
Sarcomere
Contractile unit of a muscle fiber
How are the myofilaments in the sarcomere arranged?
- thick filaments = myosin
- thin filaments = actin
What stores calcium and surrounds the myofibril?
Sarcoplasmic reticulum
Excitability, responsiveness, irritability
Ability to receive and respond to a stimulus
Contractibility
Ability to shorten when an adequate stimulus is received
Extensibility
Ability of muscle cells to be stretched
Elasticity
Ability to recoil and resume resting length after stretching
Action potential
A moving signal
What does a nerve fiber need to contract?
An electrical signal
What is the neuromuscular junction?
Associated site of axon terminal of the motor neuron and muscle
Define twitch
- single, brief contraction
- not a normal muscle function
Define tetanus
Causes muscle to constantly contract
How long does ATP stored by the muscle last?
4-6 seconds
Define synaptic cleft
- Gap between nerve and muscle
- nerve and muscle do not make contact
What is the neurotransmitter for skeletal muscle?
Acetylcholine (ACh)
Explain sliding filament theory
Activation of myosin heads (cross bridges) attach to thin filaments. Myosin heads bind to next thin filament, pulling them to the sarcomere. This causes the sliding of myosin along actin resulting in the shortening of the muscle.
What are graded responses?
Different degrees of skeletal muscle shortening
After APT is depleted and ADP is left, what regenerates the ATP?
CP -creatine phosphate
How long does the CP supply last?
Exhausted in less than 15 seconds
What is aerobic respiration?
Glucose is broken down to carbon dioxide and water, releasing energy (32 ATP)
-slow reaction that needs oxygen
What is anaerobic glycolysis and lactic acid formation
Glucose is broken down to pyruvic acid to produce about 2 ATP
- NEEDS OXYGEN
- Pyruvic acid converts to lactic acid
What are the drawbacks to anaerobic glycolysis?
- not as efficient
- huge amount of glucose are needed
- lactic acid produces muscle fatigue
What are the benefits of aerobic exercise on the muscle?
- endurance
- strength
- flexibility
- greater resistance to fatigue
5 golden rules to skeletal muscle activity
- Skeletal muscles cross at least 1 joint
- Bulk of muscle lies proximal across joint
- At least 2 attachments (origin, insertion)
- Skeletal muscles only pull
- Insertion moves towards origin during contraction
Insertion
Attachment to a movable bone
Origin
Attachment to an immovable bone
Rotation
Movement of a bone around its longitudinal axis
Abduction
Movement of a limb away from the midline
Adduction
Movement of a limb toward the midline
Circumduction
Combination of flexing, extension, abduction, and adduction
Dorsiflexion
lifting the foot so that the superior service approaches the shin
Plantar flexing
Depression the foot towards the sole
Inversion
Turn the sole of the foot medially
Eversion
Turn the sole of the foot laterally
Supination
Forearm rotates laterally so palms faces anteriorly
Pronation
Forearm rotates medially so palm faces posteriorly
Opposition
Move them to touch the tips of other fingers on the same hand
Prime mover
Muscle with the major responsibility for certain movement
Antagonist
Muscle that opposes a reverse or reverses a prime mover
Synergist
Muscle that aids a prime mover in movement and helps prevent rotation
What are the benefits of aerobic exercise on the muscle?
- endurance
- strength
- flexibility
- greater resistance to fatigue
5 golden rules to skeletal muscle activity
- Skeletal muscles cross at least 1 joint
- Bulk of muscle lies proximal across joint
- At least 2 attachments (origin, insertion)
- Skeletal muscles only pull
- Insertion moves towards origin during contraction
Insertion
Attachment to a movable bone
Origin
Attachment to an immovable bone
Rotation
Movement of a bone around its longitudinal axis
Abduction
Movement of a limb away from the midline
Adduction
Movement of a limb toward the midline
Circumduction
Combination of flexing, extension, abduction, and adduction
Dorsiflexion
lifting the foot so that the superior service approaches the shin
Plantar flexing
Depression the foot towards the sole
Inversion
Turn the sole of the foot medially
Eversion
Turn the sole of the foot laterally
Supination
Forearm rotates laterally so palms faces anteriorly
Pronation
Forearm rotates medially so palm faces posteriorly
Opposition
Move them to touch the tips of other fingers on the same hand
Prime mover
Muscle with the major responsibility for certain movement
Antagonist
Muscle that opposes a reverse or reverses a prime mover
Synergist
Muscle that aids a prime mover in movement and helps prevent rotation