Muscular System Chapter 6 The 3 Muscle Types

Muscular System Chapter 6

The 3 Muscle Types • The job of all muscles is to contract • They are all fibrous because cells are elongated • The 3 Muscle Types Are: – Skeletal Muscle – Cardiac Muscle – Smooth Muscle

Skeletal Muscle • • • Cigar Shaped Multinucleated Striated Voluntary Can Be Involuntary When Reflexes Are Involved • Very Strong and Fast But Need Rest • Most Attached to Bone Skeletal Muscle Overview Of Skeletal Muscle

Skeletal Muscle Cell

Cardiac Muscle

Smooth Muscle Long thin nuclei and no striations

How are Muscles Structured? • Muscle Cells have a plasma membrane called a Sarcolemma. • The muscle fiber is enclosed in Endomysieum. (Endo= , Mys= ) • Many Muscle fibers bound together make a Fascicle. • The Fascicle is wrapped in a membrane called the Perimysieum (Peri= ).

Muscle Structure Continued • Many fascicles are wrapped together by an Epimysium. (Epi= ) • Epimysia attach to tendons or Aponeuroses. (Pg. 86) • Tendons: Strong, Thin, and made up of collagen (dense connective tissue). Aponeuroses are sheet-like tendons.

Skeletal Muscle (pg. 174) Quiz Yourself

What is the major Organelle of the Muscle Cell? • Myofibril(s)=Working unit of the muscle cell. Made of Subunits called sarcomeres. – Give muscles the striped or striated appearance – The light band is the I-band Match the Terms – The dark band is the A-band – Between the I-bands is the Z-line – Between the A-bands is the H-zone

Mechanism of muscle contraction • The above micrographs show that the sarcomere gets shorter when the muscle contracts • The light (I) bands become shorter • The dark bands (A) bands stay the same length

Take a long deep breath, its not that bad. • And remember a bicycle cannot stand alone, because it is two tired. • Now lets go on. • But lets first watch this short video clip. Overview of the Job of the Bands

So how do these bands work? • The myofibrils are surrounded by the sarcoplasmic reticulum, a specialized form of smooth endoplasmic reticulum that releases calcium. • They are made of bands of – Actin (the thin filaments) that make up the Ibands – Myosin (the thick filaments) that make up the A-bands

So what is the Molecular Basis of Muscle Contraction? (pg. 176) • 1) Nerve sends out Acetylcholine or Ach • 2) Motor Unit= All muscles triggered by nerve. (1 nerve Triggers 100’s of cells) • 3) The Sarcolema becomes permeable to Na+ • 4) Na+ causes an action potential because it disturbs the electrical conditions of the sarcolema (pg. 178)

How does ACh stimulate the muscle? • ACh causes the sarcolema to release Calcium (Ca+) • Ca+ binds to the actin causing it to change shape. • Myosine finds actin’s new shape attractive and grabs hold.

What happens after the Myosin grabs hold? (pg. 179) • Myosin’s head snap towards the H-band of the sarcomere. • ATP releases and re-cocks the myosin • Only some myosin heads move at one time. • Over all: Pg. 181 Description of Muscle movement

How does the muscle relax? • When the action potential ends: – Sarcomere absorb Ca+ – ATP releases myosin heads – Actin takes on its former and less attractive shape. Best Movie on – Muscle Cells can relax Muscle Contraction Revisited

Write one paragraph explaining how a muscle works. Do this from memory. This will help you learn.

So, What is this Action Potential? • Action Potential – Electrical Current or Charge – In order to return the cell to its original condition, K+ is pumped into the cell by the sodium potassium pump. Fig 3. 10 Sodium/ Potassium Pump

How together? Howdo domuscles Muscles work Together? • Prime Mover: Major muscle doing the bulk of the work contracting. • Synergist: Group of muscles working together to contract. • Antagonist: Muscle that works against the prime mover and or synergists.

• http: //www. bbc. co. uk/science/humanbody/interactives/3 djigsaw_02/index. shtml ? muscles • http: //www. healthchecksystems. com/exerc ise 1. htm#hyper

Types of Muscle Movements

To exercise the: Quadriceps

To exercise the: Gastronemius

To exercise the: Hamstring Group Includes the bicepts femoris

Exercise the: Trapezius

Exercise for: Latissimus Dorsi

Exercise for: Deltoid

Exercise For: Gluteus Maximus

Exercises for: Oblique

Exercises for: Rectus Abdominus

Exercise for: Pectoralis Major Push up: Works Pecs on The Up-Motion

Exercises for: Bicep

Exercises for: Triceps

Now Quiz Yourself! See if you know your muscles… Another good Quiz site

Interesting Aspects: • Some of us may have a spare muscle: the Plantaris muscle 1 in 10 don’t. Plantaris In • Want to see it? Click the link. Action • Groin pull? Here is the problem: Groin Pull