The Muscular System

Muscles Day 1

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Muscular System Webquest: http: www.kidshealth.org/kid/htbw/muscles.html

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Warm Up: Pretest at http://tinyurl.com/muscle-pretest own sheet of paper in Notes. Count up and write this in your coloring book on page 67.

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e/6esL5I-htx0?list=RDI5Zk2vUmjpkhttps://youtu.b

Function of Muscles

• Produce movement

• Maintain posture

• Stabilize joints

• Generate body heat

Partner

Work

• Get in new partner groups and select someone whos body you’ll trace
• Label Traced body Anterior

And Posterior

• Fill in any skeletal muscles

You know as a group

• Use FLEX SOME MUSCLES

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Fun Facts about Muscles

• There are 656 muscles in the human body.
• In all its forms makes up half the body’s mass!
• It takes 17 muscles to smile and 43 to frown.
• The tongue is the strongest muscle in the body.
• The gluteus maximus (the buttocks) is the largest muscle in the body.
• The sartorius muscle is the longest muscle in the body.

Functional Characteristics of Muscles

• Four properties of muscle:
• Excitability: ability to receive and respond to a stimulus
• Contractility: ability to shorten with force when stimulated
• Extensibility: ability to be stretched or extended
• Elasticity: ability of a muscle fiber to return to its original or resting length

Three types of muscle tissue :

Muscles from Kahn AcademyA

DRAW THESE THREE

Smooth Muscle Characteristics

• Has no striations

• Single nucleus

• Found mainly in the walls of hollow organs

Smooth Muscle

Cardiac Muscle Characteristics

• Has striations

• Usually has a single nucleus

• Joined to another muscle cell at an intercalated disc

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• Found only in the heart

Cardiac Muscle

Connective Tissue Wrappings of�Skeletal Muscle Page 42

• Epimysium – covers skeletal muscle fascicles

• Perimysium – covers fascicle (bundle) of fibers

• Endomysium – around single muscle fiber

Each muscle contains at least one artery and one or two veins

… why?

Anatomy of a Skeletal Muscle

• Most attach to bones by tendons (connective tissue extensions)� 1) insertion: bone that moves during contraction�

2) origin: bone that stays still during contraction

• Some muscles attach directly to bone by their connective

tissue coverings

Functional Characteristics of Muscles

• Four properties of muscle:
• Excitability: ability to receive and respond to a stimulus
• Contractility: ability to shorten with force when stimulated (Irritability)
• Extensibility: ability to be stretched or extended
• Elasticity: ability of a muscle fiber to return to its original or resting length

Muscular System and Muscle Action

Pages 43 and 67

• Agonist (Prime Mover)

-Provide the major force for producing a specific movement

• Antagonists

-Oppose or reverse a particular movement

3. Fixator (Fix or stabilize background)

4. Synergist (Secondary Movers) movement

Behavioral Properties of Muscles

EXIT DIRECTIONS

Label Anterior Muscles on sheet and pay attention to word origin.

• Skip head, neck, and facial
• Highlight or underline muscles you know, you familiar with, or you recognize word origin.
• Take time one table at a time to see 3 muscle types in microscope.

HOMEWORK

Page 42, 43, 67 - Must be checked off today

Page 54 and Page 55 - Thursday

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Use colored Pencils for this and read over left side of page. You may listen to music.

Muscles: Name, Action, and Innervation

• Name and description of the muscle – be alert to information given in the name
• Origin and insertion – there is always a joint between the origin and insertion
• Action – best learned by acting out a muscle’s movement on one’s own body
• Nerve supply – name of major nerve that innervates the muscle

Naming Skeletal Muscles

• Location - bone or body region associated with the muscle
• Shape -e.g. Deltoid = triangle
• Relative Size - e.g. maximus and minimus (smallest), longus (long)
• Direction of fibers or fascicles - e.g. rectus (abdominalis rectus- fibers run straight), transversus, and oblique (fiber run at angles to an imaginary defined axis)
• Number of origins - bicep, tricep
• Location of attachments—named according to point of origin or insertion Example: sternocleidomastoid (originates on the sternum and clavicle, inserts on the mastoid)
• Action—e.g., flexor or extensor, muscles that flex or extend Example: extensor digitorum (extends the fingers)

Posters: Arms, Chest, Shoulder and Back HOMEWORK pg: 54, 55

Muscles for 15 point quiz Monday (Upper Body “Movers”)

• Arms: Biceps Brachii, Triceps Brachii, Brachialis, Coracobrachialis, Pronator Teres, Brachioradialis, Anconeus, Supinator, Pronator Quadratus
• Shoulder & Chest: Deltoid, Pectoralis Major and Pectoralis Minor
• Back: Trapezius, Latissimus Dorsi, Teres Major,

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Deep Trunk and Arm Muscles

Microscopic Anatomy of a Skeletal Muscle pg. 42

• Muscle fiber: muscle cell with many nuclei
• Sarcolemma: plasma membrane of a muscle cell
• Sarcoplasm: cytoplasm of muscle cell, contains large amounts of glycogen and oxygen-binding protein
• Myofibrils: contractile portion of the muscle cell, made up of units called sarcomeres
• Each muscle fiber contains large numbers of myofibrils in the sarcoplasm, with mitochondria packed around them
• Sarcomeres contain two types of filaments:
• thick: contain the protein myosin
• thin: contain the protein actin

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Skeletal Muscle Organization page 42

Myofibril- rodlike

unit in fiber

Muscle fascicle (bundle)

Muscle fiber (cell)

Sarcomers

http://www.dnatube.com/video/1951/Molecular-basis-of-muscle-contration

Skeletal Muscle

Contraction of a Skeletal Muscle

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• Within a skeletal muscle, not all fibers may be stimulated at the same time (might be 100 or 1000s)

• Different combinations of muscle fiber contractions may give differing responses

• Graded responses – different degrees of skeletal muscle contraction activate different fiber #s.
• Example: finger muscles help you pick up a penny or a textbook
• Once the contraction starts, it cannot be stopped - ALL OR NOTHING PRINCIPLE

Nerve Stimulus to Muscle “Neuromuscular System”

Motor Unit: Nerve highway to connect to muscles at “Axon Terminals”. May connect to 100 or 1000s

Axon Terminals: there is a gap from the end of Motor Neuron (muscle Stimulator) and the Sarcolemma. This gap is called the Synaptic Cleft

Neuromuscular Junction (NMJ): link between Axon terminal and muscle fiber

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Neuromuscular Junction Up close

Neurotransmitters

are chemicals that bridges the nerve impulses to attach to receptors in the muscle fiber (the sarcolemma)

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In this case Acetylcholine (ACh) makes sarcolemma permeable and allows Na+ to invade and K+ ions to rush out.

Ca 2+ reverses electrical charge and depolarizes gap - Creates ACTION POTENTIAL (electrical energy)

https://www.youtube.com/watch?v=0mhAN4-8uWo

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For more on Neuromuscular Junction and the Beginning Process of Muscle Contraction, READ Chapter 10.2 from Rice University A &P

http://www.dnatube.com/video/1951/Molecular-basis-of-muscle-contration

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“THE PLAYERS”

Action Potential Uses Energy

Glucose- stored in muscle as glygocen and is energy for the Action Potential

Phosphocreatine- allows energy to transfer to protein filaments actin and myosin, which are the contractile proteins in sarcomere

Calcium Ions (Ca++) bond with troponin and trigger sliding of actin over myosin contracting the sarcomere.

ATP serving as the energy prepares myosin to move to high energy state and “fires” to actin.

ADP is recharge through cellular respiration to store energy (glucose) in cell

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ATP: Adenosine Triphosphate

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ADP: Adenosine Diphosphate

Simplest ATP Graphic

ATP gives energy for cellular work (muscle power) and releases a high energy Phosphate. H2O with ATP leads to hydrolysis which is high energy and leads to breakdown of ATP to ADP and P

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ADP uses energy from our food (glucose, creatine phosphate, various proteins and amino acids) to rebond with ATP.

How does ATP Power the Muscle?

https://www.youtube.com/watch?v=0kFmbrRJq4w

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Muscle Contraction: Sliding Filament Theory

• At rest, there is a bare zone that lacks actin filaments (no filament overlap)

• To start contraction, calcium (Ca+2) unlocks active sites on actin’s troponin

• Myosin heads bind to actin active sites – connections are called cross-bridges
• Myosin pulls the actin microfilaments toward the bare zone - muscle shortens
• Myosin detaches, and reattaches to another active site, shortening the muscle further https://www.youtube.com/watch?v=BVcgO4p88AA
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https://www.youtube.com/watch?v=m5dGQOn_Py0

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Sliding Filament Animation

Sliding Filament Animation

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For more on Sliding Filament and the Process of Muscle Contraction, READ Chapter 10.3 from Rice University A &P

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Quadriceps

Consisting of four heads

• Rectus Femoris
• Vastus Medialis
• Vastus Intermedius
• Vastus Lateralis

Angonist and Anterior of the thigh

Behind RF

Hamstrings

Hamstrings- three separate muscles: biceps femoris, semitendinosus, and semimembranosus.

• Antagonist to the Quadriceps Femoris
• Posterior side of the thighs

Lower Leg Anterior

Lower Leg- Posterior

Fibularis Longus

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Tibialis Anterior

Sartorius

Gastrocnemius

Soleus

Energy for Muscle Contraction

• ATP is the only energy source used for muscle contraction

• Only 4-6 seconds worth of ATP is stored by muscles
• After this initial time, other pathways must be utilized to produce ATP
• Anaerobic glycolysis/lactic acid fermentation
• Aerobic respiration

Energy for Muscle Contraction

• Aerobic Respiration (OXYGEN IS AVAILABLE)

• Series of chemical reactions that makes ATP from glucose in the presence of oxygen

• This is a slow reaction, but makes huge amounts of ATP
• Breaks down glycogen (chains of glucose) stored in muscles and liver
• Carbon dioxide and water are waste products of the reactions (breathing out and sweating)
• Provides 15-20 minutes of energy – long distance running, endurance exercises

Energy for Muscle Contraction

• Anaerobic Glycolysis/Lactic Acid Fermentation (NO OXYGEN AVAILABLE)

• Series of chemical reactions that makes ATP from glucose without oxygen
• This reaction FAST, but inefficient

• Huge amounts of glucose are needed to make ATP

• Lactic acid is a waste product of the reactions, causes muscle fatigue and soreness
• Provides 90 seconds of energy – weightlifting, sprints

Usain Bolt

Force of Muscle Contraction

Depends on four things:

• # of muscle fibers contracting – greater the number of motor units contracting, the greater the force
• Size of the muscle – bigger the muscle, the greater the force
• Elastic elements (tendons, tissue coverings) – greater the tension on the elastic elements, the greater the force
• Degree of muscle stretch – slight stretch increases the force of contraction

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Effects of Exercise on Muscle

Results of increased muscle use:

• Increase in muscle size (size of fiber, not number of fibers increases)
• Increase in muscle strength
• Increase in muscle efficiency (more capillaries, more mitochondria)
• Muscle becomes more fatigue resistant (more glycogen is stored, more mitochondria)

Muscles and Body Movements

• Movement is attained due to a muscle moving an attached bone

• Insertion – muscle attachment to bone that MOVES during contraction

Review:

• Origin – muscle attachment on bone that DOES NOT MOVE during contraction

Trunk and Posterior

Gluteus Maximus Gluteus Minimus

Gluteus Medius Piriformis

Internal Intercostal External Intercostal

Rectus Abdominus Illiopsoas

Serratus Anterior Transversus Abdominus

External Oblique

Internal Oblique

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Superficial Trunk- Thorax and Abdomen

Axial Musculature - Thoracic Cavity

Types of Body Movements

Review:

• Flexion
• Extension
• Rotation
• Abduction
• Circumduction

Types of Body Movements

Muscle Tone

• Slightly contracted state while muscle is at rest
• Keeps muscles ready to respond to stimulation
• Helps maintain posture
• Stabilizes your joints

• Atrophy – decrease in muscle tone; fibers become small and weak without stimulation

Types of Muscle Contractions

1) Isotonic contractions

• Tension remains constant

• The muscle changes length so movement can occur
• Concentric – muscle shortens as it contracts
• Eccentric – muscle lengthens as it contracts

2) Isometric contractions

• Tension in the muscles increases

• The muscle does not change length so positions can be held

**Most body movements are a combination of both types.**

Contraction: Muscle Responses to Stimuli

• Twitch – single, jerky contraction from a single stimulus
• Not a normal contraction
• Tetanus – smooth, sustained contraction from multiple stimuli building upon each other
• Cannot go on indefinitely or results in fatigue
• Treppe effect – increasingly forceful contractions due to increased efficiency of muscle, even with same stimulus
• As muscle warms up, more calcium is available, and enzymes are more effective

Muscle Contraction: Rigor Mortis

• After death, there is an influx of calcium
• Calcium causes myosin to bind with actin (forming cross bridges)
• Breathing stops, no energy is available to detach cross bridges, so they stay attached
• Muscles stiffen after 3 to 4 hours, peaks at 12 hours, and decreases between 48 and 60 hours

Major Skeletal Muscles: Anterior View

• The 40 superficial muscles here are divided into 10 regional areas of the body

Figure 10.4b

Major Skeletal Muscles: Posterior View

• The 27 superficial muscles here are divided into seven regional areas of the body

Figure 10.5b

Muscles of the Anterior Pelvis, Hip, and Thigh

Muscles of the Posterior Pelvis, Hip, and Thigh

Muscular System Disorders

Chronic Fatigue Syndrome

Fibromyalgia

Duchenne’s Muscular Dystrophy

Rotator Cuff Syndrome

Anterior Compartment Syndrome

Rhabdomyolysis

Cardiomyopathy

Myasthenia Gravis

Rhabdomyosarcoma

Inguinal Hernia

Polio

Carpal Tunnel Syndrome