MUSCLE TISSUE - Lancaster High School



MUSCLE TISSUE

I. Myology – the scientific study of muscles

II. Characteristics of muscle Tissue

A. Excitability – the ability to respond to a stimulus

B. Contractility – the ability to shorten when stimulated

C. Extensibility – the ability to be stretched

D. Elasticity – the ability to return to the original size

III. Functions of Muscle Tissue

A. Motion – movement

B. Posture – standing and sitting without falling

C. Heat Production – muscular contraction produces 85% of the body’s heat

IV. Types of Muscle

A. Skeletal

1. Location – attached to bones

2. Appearance – striated

3. Nervous Control – voluntary

B. Cardiac

1. Location – the heart

2. Appearance – striated

3. Nervous Control – involuntary

C. Smooth

1. Location – internal organs and blood vessels

2. Appearance – non-striated

3. Nervous Control – involuntary

V. Skeletal Muscle

A. Connective Tissue Associated with Skeletal Muscle – Covers muscles and holds muscle fibers in bundles

1.Fascia – sheets or bundles of fibrous connective tissue

a. Superficial Fascia – just beneath the skin

b. Deep Fascia – Holds muscles together

i. Epimysium – covers entire muscle

ii. Perimysium – covers bundles of fibers

iii.Endomysium – covers individual muscle fibers

c. Tendon – cord-like extension of deep fascia that connects muscle to bone.

d. Aponeurosis – a sheet of connective tissue, similar to a tendon that attaches muscles

B. Nerve and Blood Supply – Skeletal muscles are highly innervated and highly vascular

C. Histology of Muscle Tissue

1. Myofibers – Muscle Fibers (muscle cell)

a. Sarcolemma – plasma membrane of a muscle cell

b. Sarcoplasm – the cytoplasm of a muscle cell

c. Sarcoplasmic Reticulum – The ER of a muscle cell

d. Transverse Tubules (T-Tubules) – tubes that extend across the myofiber and open to the outside

2. Myofibril – structures that make up fibers

3. Myofilaments – structures that make up the fibrils

4. Sarcomeres – The basic functional unit of skeletal muscle

a. Z-lines – ends of the sarcomere

b. A-band – dark area made of both thick and thin filaments

c. I-band – area made of only thin filaments

d. H-zone – area made of only thick filaments

5. Actin and Myosin – proteins that make the filaments

D. Contraction of Skeletal Muscle

1. Sliding Filament Theory – the thin filaments slide over the thick filaments causing the sarcomere to shorten. This process uses ATP

E. Neuromuscular Junction – where a muscle is innervated

1. Neuron – nerve cell

a. Motor Neuron – the nerve that stimulates a muscle

b. Motor end plate – axon of a motor neuron that attaches to the sarcolemma of the muscle fiber

c. Acetylcholine (Ach) – the neurotransmitter released into the Neuromuscular Junction

2. Motor Unit – the combination of the motor neuron and the muscle fibers it innervates

F. Physiology of Contraction – an action potential causes the release of Ca+2 ions stimulating the myosin to move the actin filament

G. Energy for a Contraction – can come from one of three systems:

1. Phosphagen System – ADP + P + Energy ( ATP

2. Anaerobic System – 1C6H12O6 ( 2 C3H6O3 + ATP

3. Aerobic System – 1C3H6O3 + O2 ( CO2 + H2O + ATP

H. All or None Principle – When a muscle fiber is stimulated it either completely contracts or does not contract – it cannot partially contract.

1. Threshold Stimulus – the weakest stimulus that can cause a muscle contraction

2. Sub-Threshold Stimulus – Stimulus that is too weak to cause a muscle contraction

I. Myogram – a record of the electrical activity of a muscle to determine they type of contraction

1. Twitch – a rapid jerky response to a single stimulus

a. Latent Period – time between the application of the stimulus and the muscle contraction

b. Contraction Period – time when filaments are sliding over each other, causing a contraction

c. Relaxation Period – Time during which filaments slide back into place

d. Refractory Period - Time following a contraction during which a muscle is unable to respond to a stimulus

2. Tetanus – a sustained contraction

3. Treppe – a muscle contracts more forcefully after contracting several times

4. Isotonic – the tension remains constant but the muscle shortens

5. Isometric – the tension increases but the muscle does not shorten

L. Muscular Atrophy – Wasting away of muscle

M. Muscular Hypertrophy – Increase in the size of muscle fibers

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download

To fulfill the demand for quickly locating and searching documents.

It is intelligent file search solution for home and business.

Literature Lottery

Related searches