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surround entire muscle


surrounds bundle


surrounds single fiber

Connective Tissue

stabilizes and supports components of skeletal muscle
Surrounds muscle at each organization level.

How many muscles does the human body contain?

600 (40-50% body weight)


Basic skeletal muscle unit. Capable of force production and shortening. Arrangement of protein filaments and gives straight appearance.

tropomin 1

Holds Actin

tropomin T

hold Tropomyosin

tropomin C

can bind calcium


ATP production through aerobic metabolism

As Sarco Shortens

actin filaments slide over myosin.
Z-lines approach end of myosin filaments

As Sarco relaxes

It returns to original length
Less overlap between actin and myosin

The sliding filament theory

• Formation of cross bridges between actin and myosin filaments.
• Reduction in distance between z-lines or sarcomere "power stroke"
• ATP is required for muscle contraction
o Myosin ATPase breaks down ATP as fiber

Biochemical Proporties

o oxidative capacity
o type of ATPase

Contractile Properties

o maximal for production
o Speed of contraction
o muscle fiber efficiency

Fast Fibers (Type IIx)

• Fast-Twitch Fibers
• Fast- Glycolytic
• Anaerobic

Type IIa Fibers

• Intermediate Fibers
• Fast-oxidative
• Glycolic fibers
• Anaerobic and Aerobic


• Type I fibers
• Slow-Twitch
• Slow-Oxidative fibers
• Always Start first
• Aerobic


• 10% muscle mass lost is between 25-50 years of age
• additional 40% lost between 50-80 years of age
• Also a loss of fibers and gain in slow fibers
• Also due to reduced physical activity

Proprioception & Kinetic sense

• How the body sense where it is in space
• Receptors: Located in the muscles and tendons
• Info from proprioceptors is sent to the brain

Learning Effect

• Ability to repeat a specific motor unit recruitment pattern
• Results in success performance of a skill
• Requires practice

Muscle Spindles

• Located within the skeletal muscle
• 2 functions: monitor stretch and length of muscle
• initiate a contraction when muscle is stretched

Stretch Reflex

• Quickly stretched muscle
• Initiate immediate contraction
• Due to being stretched

Golgi Tendon Organ

• Located in the tendon
• 2 functions: monitor and respond to tension in tendon
• inhibits actin of muscle to prevent injury


o Muscle exerts force without changing length
o Pulling against immovable actions
o Postural muscles


o Dynamic constant external resistance


o Muscle shortens during force production


o Muscle produces force but length increases

The two Principal contractile proteins found in the skeletal muscle are:

Actin and Myosin

The layer of connective tissue that surrounds the outside of the skeletal muscle is called the:


Calcium is stored in the:

Sarcoplasmic Reticulum

The formation of cross bridges in the contractile process in skeletal muscle is initiated by:

Calcium binding to tropomyosin

The motor neuron and all the muscle fibers it innervates are called a motor:


The site where the motor neuron and muscle cell meet is called the:

neuromuscular junction

The breakdown of ATP in muscle is accomplishment via enzyme:


A successful endurance athlete would likely have ________ compared to a sedentary person.

a higher percentage of type I fibers

Type IIx Fibers

are fast glycolytic

Which of the following events in muscle contraction is the FIRST to occur chronologically ?

the innervating alpha-motor neuron has an action potential

Three Parts to the structure of a Neuron:

Cell Body, Dendrites, Axon


Conduct Impulses toward the cell body


long nerve fiber that conducts away from the cell body of the neuron


the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

Central Nervous System

consists of the brain and spinal cord


the sensory and motor neurons that connect the central nervous system to the rest of the body


This nervous system provides involuntary control over smooth muscle, cardiac muscle, and glands.

Sympathetic Nervous System

a branch of the autonomic nervous system and prepares the body for quick action in emergencies; "fight or flight"

Parasympathetic Nervous System

the division of the autonomic nervous system that calms the body, conserving its energy (Rest and Digest)

Sensory- Somatic Nervous system

Carries information from skin, sensory organs, skeletal muscles, joints, and internal organs to CNS; directs voluntary movements

Motor Division

Initiates contraction of muscles and limb movements


the electrical discharge that travels along a nerve fiber


channels for Na+ open and enters cell


Channels for K+ open and it leaves cell

Cardiovascular system

Transport O2 to tissues and removal of waste (CO2)
Transport nutrients to tissues
Regulation of body temperature

Sinoatrial node

the heart's pacemaker, located in the wall of the right atrium

Atrioventricular node

delays impulse by 1/10 of second, allowing atria to contract before ventricles

Purkinje fibers

rapidly spreads impulse to contract throughout ventricles

Cardiac Output

Q = HR (bmp) × SV (mL) (5-Men) (4.5-Women)

Adaptations due to endurance training

Increased cardiac output during endurance activity
Increased oxygen delivery to skeletal muscle
Increased endurance performance

Adaptations due to weight training

Increased ability to maintain cardiac output against increased BP during weight training

force velocity curve

ability of muscles to produce force w/ increasing velocity. muscle force increases, velocity of contraction decreases

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