1. Describe the 3 types of muscle tissue (cardiac, smooth, skeletal). Functions and locations. Also, which ones are voluntary and which ones are involuntary?

Skeletal- movement heat production and posture, voluntary, skeletal bones

Cardiac, pump blood (systemic pulmonary, coronary circulation) , found in heart wall, involuntary

Smooth-  peristalsis in GI tract contraction of smooth muscle to propel food down gi tract, lines internal organs ( gi tract uterus) eye, blood vessels , skin, airways, attached to hair follicles, involuntary

2. What are the 4 properties of muscle tissue?  Know definitions.

   1. Electrical excitability-

                                               i.     Muscles ability to respond to certain stimuli by producing electrical signals called action potentials (impulses)

                                              ii.     Electrical signals – arise in muscular tissue (heart’s pacemaker)

                                             iii.     Chemical stimuli – neurotransmitters released by neurons, hormones, local changes in pH

2. Contractility

                                               i.     Ability of muscular tissue to contract forcefully when stimulated by action potential

2. Extensibility-

                                               i.     Ability of muscular tissue to stretch without being damaged

                                              ii.     CT within muscle limits range of extensibility and keeps it within the contractile range of muscle cells

                                             iii.     Ex. Smooth muscle in stomach stretches when it is full

2. Elasticity

                                               i.     Ability of muscular tissue to return to its original length and shape after contraction or extension

3. What is fascia?  Superficial vs. deep?

   1. Fascia is a sheet or band of dense fibrous irregular CT

                                               i.     deep to the skin and surrounds muscles and other organs

3. Superficial fascia (subcutaneous or hypodermis)-

                                               i.     separates muscle from skin

                                              ii.     composed of areolar CT and adipose tissue

                                             iii.     Function: provide a pathway for nerves and blood vessels, stores fat, insulates, and protects muscles

3. Deep fascia-lines body wall and limbs and holds muscles with similar function together

                                               i.     Function:  allows free movement of muscles, carries nerves, Carries blood vessels, Carries lymph vessels and Fills space between muscles

4. Describe the 3 layers of connective tissue that extends from fasica (epimysium, perimysium, and endomysium). What does each surround? 

}  3 layers of connective tissue extend from fascia

1.     Epimysium-outermost layer of dense (surrounds belly of muscle)

◦       irregular connective tissue encircling entire muscle

2.     Perimysium-layer of dense, irregular connective tissue (surrounds fascicles)

◦       surrounding groups of 10-100 muscle fibers, separating them into fascicles

3.     Endomysium-penetrates interior of each fascicle (surrounds fibers)

◦       separates individual muscle fibers from one another

5. Connective tissue components (tendon and aponeurosis). 

   1. Tendon-cord of dense connective tissue that attaches a muscle to the periosteum of a bone (ex. Achilles tendon)

   2. Aponeurosis-tendon that extends as a broad, flat layer

6. How do skeletal muscle fibers arise during embryonic development? What are myoblasts?

   1. Skeletal muscle fiber arise during embryonic development from fusion of hundred or more myoblast

   2. Myoblast- muscle immature cell

7. Microscopic anatomy of skeletal muscle fibers. This includes sarcolemma, T tubules, sarcoplasm, myofibrils, sarcoplasmic reticulum, terminal cisterns, triad, myofilaments, sarcomeres, actin, myosin, fascicles.  Know the definitions provided on the slides.  There is a worksheet on blackboard to assist you.

8. What 3 structures make up a triad?

1 Transverse tubule and 2 terminal cisterns

9. What is the main contractile unit of a skeletal muscle fiber?  Where are they found?

10. Know the definition of a sarcomere.  Also know the anatomy of sarcomeres. (Z line, M line, A band, H band, I band, actin, myosin). Know the definition provided on slides.

11. What are the 3 types of myofibril proteins?  Which type are actin and myosin? Which type are tropomyosin and troponin?  What are the functions of tropomyosin and troponin?

    1. Thin filaments-composed of protein actin          I band

    2. Thick filaments-composed of protein myosin A band

                                               i.     Both involved in contractile process

12. Know the structural components of actin and myosin.

13. Describe the sliding filament mechanism.

14. Describe the muscle contraction cycle. (ATP hydrolysis, attachment of myosin to actin to form cross-bridges, power stroke, detachment of myosin from actin). Know the order and what happens in each step! Look at the figure.

1.     ATP Hydrolysis

a.     Myosin head includes ATP-binding site

b.     ATPase hydrolyzes ATP into ADP and phosphate group (giving energy for contraction!)

2.     Attachment of myosin to actin to form cross-bridges

a.     Energized myosin head attaches to myosin-binding site on actin and releases phosphate group

b.     When myosin heads attach to actin during contraction – cross bridge

3.     Power stroke

a.     Site on cross-bridge where ADP is still bound opens

b.     Cross-bridge rotates and releases ADP

c.      Cross-bridge generates force as it rotates toward center of sarcomere

                                                        i.     sliding the thin filament past thick filament toward M line

4.     Detachment of myosin from actin

a.     As ATP binds to ATP-binding site on myosin head, myosin head detaches from actin

5.     What is needed to link muscle excitation to calcium release from sarcoplasmic reticulum?

6.     Explain what happens during excitation-contraction coupling?  Where does the action potential propagate through?  What is the function of the T-tubules?  Function of the sarcoplasmic reticulum?  Know the difference between a resting skeletal muscle and a contraction.  See figure

7.     What starts and stops a muscle contraction? (hint: specific ion)

8.     Length-tension relationship curve.  Know definition.  What happens if the sarcomeres are too short?  Too long?

When sarcomeres are completely shortened:

a.     Myosin are pressed against the Z-lines

b.     myosin heads cannot pivot or produce tension

c.      Tension goes down

If sarcomere lengths are greater than the optimal range:

d.     Overlap shortens

e.     fewer myosin heads can make contact with actin (thin filaments)

f.      Tension the fiber can produce decreases

9.     Anatomy of the neuromuscular junction.  This includes: somatic motor neuron, synapse, synaptic cleft, neurotransmitters, synaptic end bulbs, synaptic vesicles, motor end plate, acetylcholine receptors. Know definitions. What about calcium and sodium ions?

·      Synapse-region where communication occurs between somatic motor neuron and skeletal muscle fiber

·      Synaptic cleft--space that separates neuron and muscle

a.     Action potential cannot jump this space, so neurotransmitters are needed

·      Neurotransmitters (acetylcholine; ACh) are released into gap by a cell to communicate with opposing cell

10.  How do synaptic vesicles get signaled to release neurotransmitters into synaptic cleft?

11.  What does the sarcoplasmic reticulum release during an action potential?  What is it’s purpose in the contraction cycle?

12.  What are the 3 ways muscle fibers produce ATP?  Which provides ATP for the first 15 s?

Muscle fibers have 3 ways to produce ATP

a.     Creatine phosphate-(first 15 sec)  Relaxed muscle fibers produce more ATP than they need for resting metabolism. Most of excess ATP is used to synthesize creatine phosphate

b.     Anaerobic glycolysis-ATP producing reaction that does not require oxygen

c.      Cellular respiration (Krebs cycle and electron transport chain)

13.  What is a motor unit?

A motor unit consists of a somatic motor neuron and the muscle fibers it innervates

14.  4 parts of twitch contraction. (latent period, contraction period, relaxation period, refractory period).  Know definitions provided on slides.  What happens at each period?

a.     Latent-calcium ions are released from sarcoplasmic reticulum

b.     Contraction period-Ca²⁺ binds to troponin and cross-bridges form

c.      Relaxation period-Ca²⁺ actively transported back in SR and tension in fiber decreases

d.     Refractory period-lost excitability period

                                                        i.     Muscle cannot be excited and contract

15.  Isotonic vs isometric contractions. Know definition provided on slides.  What about concentric and eccentric?  What are these 2 types of?  Definition of each.

Isotonic contraction – tension (force of contraction) is constant while muscle length changes

a.     Concentric- those which cause the muscle to shorten as it contracts (flexion)

b.     Eccentric- occur when the muscle lengthens as it contracts (extension)

Isometric contractions– muscle contracts but does not change length

16.  3 types of skeletal muscle fibers (SO, FOG, FG). Color, contracts fast or slow, and function of each.   See table.

}  Skeletal muscle fibers are not all alike in composition and function

1.     Slow oxidative (hydrolysis of ATP is slow, thus contraction is slow)

2.     Fast oxidative glycolytic

3.     Fast glycolytic

17.  Know the flow chart of a full skeletal muscle (connective tissue, fibers, myofrils, belly of skeletal muscle, fascicles, sarcomeres).  There is a worksheet online to assist you.

18.  Describe multiunit smooth muscle tissue and single-unit smooth muscle tissue.

Multi-unit-smooth muscle -cells in organ all behave independently. each cell contracts and relaxes on its own

a.     Large arteries

b.     airways to lungs

c.      arrector pili muscles attached to hair follicles

Visceral single unit smooth muscle–

d.     fibers connect to one another by gap junctions forming a network

e.     through which muscle action potentials can spread

                                                        i.     Contracts in unison as a single unit