Section 6 vocabulary

1. Septum: cavities or masses of soft tissue

2. Process: marked prominance protruding from the bone

3. Plexus: network of nerves or vessels

4. Meatus: tube like opening within bone

5. Lumen: opening within tubular organ or bone

6. Insertion: site of muscle/tendon attachment

7. Fossa: pit or depressions

8. Foramen: natural opening in bone

9. Flexion: movement at joint that brings bones together

10. Fascia: Connective tissue beneath skin

11. Efferent: Carrying fluid or impulses away

12. Afferent: Carrying fluid or impulses towards an area

13. Articulation: union between bones

14. Ampula: sac like

15. Adduction: movement towards the midline

16. Abduction: movement away from the midline

Introduction to Muscles and Muscular System

Mid-point agenda meeting

Muscle Coloring Assignment• 30 point quiz grade

If you still do not have a coloring book, photocopy the pages from someone else’s book and give them a buck.

• Pages 58-95

• Only color the following: Pages 59, 61, 65, 69, 71, 73, 75, 83-95

• Do not color: Pages 63, 67, 77, 79, or 81

• Due the day of the test at the beginning of class

• I will no longer be accepting late coloring assignments.

Muscles and Muscle Tissue

1. Explain the structure of muscle tissue2. Describe how an action potential is

initiated in a muscle cell

3. Describe the events of a muscle cell contraction

4. Describe three ways in which ATP is regenerated during muscle activity

Aims:

Overview of Muscle Types

The muscular system is composed of three types of muscle tissue: skeletal, smooth, and cardiac muscles.

Each type of tissue has a separate Each type of tissue has a separate function, though all have the similar function, though all have the similar characteristic of contracting when characteristic of contracting when stimulatedstimulated..

Muscle Types1. Cardiac – heart

2. Smooth – internal organs

3. Skeletal – "voluntary"» Attach to bone» Move appendages» Support body» Antagonistic pairs» Flexors» Extensors

I. Functions of Skeletal Muscle

A. Movement

B. Heat Production

C. Posture

D. Stabilizing Joints

II. Characteristics

A. Excitability/ irritability - can be stimulated

B. Contractility- can shorten

C. Extensibility- can stretch

D. Elasticity- can recoil after stretching

A. Gross Muscle Anatomy

1. Epimysium- outermost dense irregular connective tissue; covers whole muscle

2. Perimysium- middle fibrous connective tissue; covers fascicles (groups of muscle fibers)

3. Endomysium- innermost reticular connective tissue; covers muscle fiber (skeletal muscle cells)

B. Microscopic Skeletal Muscle Anatomy

1. Muscle fiber cell is covered by sarcolemma (cell membrane) and contains sarcoplasm (cytoplasm).

2. Muscle fibers have myofibrils that make the muscle look striated. Myofibrils are the contractile elements of skeletal muscle cells.

Microscopic Anatomy

• Cigar shaped multinucleated cells

• Voluntary via nervous system controls and reflexes

• Slow to fast speed of contraction

• No rhythmic contraction

C. Parts of a Myofibril 1. Sarcomere- segment of myofibril between Z lines; functional unit

of skeletal muscle

2. A band- wide, dark stripe; thick (myosin) myofilaments

3. I band- narrow, light stripe; thin (actin) myofilaments

4. H zone- lighter band within the A band

5. M line/ band- dark line bisecting the H zone

D. Myofilaments

1. Thin filaments- protein actin. Also contains troponin & tropomyosin to

wrap around actin at muscle rest to block it from interaction with myosin

D. Myofilaments

2. Thick filaments- myosin with “head” attracted to actin

IV. Muscle Physiology

• Neuromuscular Junction

• Muscle Contraction

A. Neuromuscular Junction1. Each skeletal muscle fiber connects to a fiber

from a motor neuron. The connection is a neuromuscular junction or synapse.

2. Here the muscle fiber is specialized into a motor end plate or motor unit.

3. At the end of the neuron are many vesicles which store chemicals called neurotransmitters (ex: Acetylcholine or ACh)

4. When a nerve impulse from the brain or spinal cord reaches the end of a motor neuron fiber, a bit of ACh is released into the gap (synaptic cleft) between the neuron & the motor end plate of the muscle fiber. This stimulates muscle contraction.

Sliding Filament Theory of Muscle Contraction

• States that a myosin cross-bridge can attach to an actin binding site and bend slightly, pulling the actin filament with it.

• This causes a contraction.

• Contractions require ATP and ACH.

1. When the muscle receives a nerve impulse, ACH is released into the neuromuscular junction.

2. Calcium diffuses into the sarcoplasm of the muscle fiber, where it binds to troponin.

3. When the concentration of calcium ions increases, tropomyosin shifts exposing the binding sites on the actin filaments This leads to linkages between actin and myosin. .

4. When a myosin cross-bridge binds to actin, it pulls actin in toward the H zone at the center of the sarcomere.

5. As the thin filaments slide past the thick filaments, the entire muscle shortens.

6. ACHase causes the contraction to cease by breaking down ACH. The Ca ions are actively transported into the sarcoplasmic reticulum. Troponin and tropomyosin return to their original position.

7. The linkages between the actin and myosin break and the muscle fiber relaxes.