Muscle Tissue

4 common properties of muscle tissue

4 common properties of muscle tissue

• Excitability (stimulus reponse)

• contractablility

• extensibility

• elasticity

6 functions of skeletal muscle

• produce movement

• maintaining body postion

• supporting soft tissue

• guarding body entrance

• maintaining body temp

• storing nutrients

levels of muscle organization highest to lowest

• skeletal muscle

• muscle fasicle

• muscle fiber

• myofibril

• sarcomere

1

Skeletal Muscle (organ)

2

epimysium

3

perimysium

4

nerve

5

blood vessels

6

muscle fascicle (bundle of fibers)

7

muscle fiber

8

endomysium

9

capillary

10

myofibril

11

mitochondria

12

myosatellite cell

13

sarcoplasm

14

nucleus

15

axon of neuron

16

sarcolemma

3 ways skeletal muscle cells differ from other cells

• size (large)

• multinucleated

• striated

Thin myofilament protein

actin

Thick myofilament protein

myosin

1

I band (thin filament only)

2

A band (thick filament including overlap)

3

H band (thick filament only)

4

Z line (interconnect thin filaments of adjacent sacromeres)

5

titin (keep thick and thin filaments in proper alignment, restore resting sarcomere length after contraction)

6

thick filament

7

thin filament

8

sarcomere (functional unit of skeletal muscle)

9

M line

10

zone of overlap

1

binding sites (attaches to head)

2

thin filament (2 twisted strands)

3

tropomyosin (cover up the binding sites for myosin on the actin monomer)

4

head (attached to the nearest thin filament exposed binding site (tropomyosin retracted))

5

hinge

6

tail (attach to other myosin)

4 main proteins of thin filaments

• F actin

• nebulin

• tropomyosin

• troponin (regulates muscle contraction by responding to calcium concentrations in the cell)

3 factors that determine how long contraction lasts

1. Availability of calcium ions.

2. Amount of ATP present.

3. Duration of action potential stimulation.

sliding filament theory

describes how skeletal muscles contract:

• H and I bands narrow

• zone of overlap widens

• Z line moves closer

• width of A band is constant

describe what happens when an action potential reaches neuromuscular junction

1. The action potential triggers the release of acetylcholine.

2. Acetylcholine binds to receptors on the muscle cell membrane.

3. This leads to depolarization.

4. Initiation of muscle contraction occurs.

excitation-contraction coupling

The process that connects muscle activation (excitation) to contraction, involving calcium release in muscle fibers.

contraction cycle

1. ATP binds to myosin, causing it to detach from actin.

2. Myosin ATPase hydrolyzes ATP to ADP and inorganic phosphate, which cocks the myosin head.

3. The myosin head binds to a new position on the actin filament, forming a cross-bridge.

4. Inorganic phosphate is released, which initiates the power stroke.

5. The power stroke (ADP + P released) pulls the actin filament toward the center of the sarcomere.

6. ADP is released, and the cycle repeats as long as calcium ions and ATP are present.

recruitment

The process of activating additional motor units to increase muscle force during contraction.

muscle tone

The continuous and passive partial contraction of skeletal muscles, contributing to posture and readiness for action.

4 things normal muscle function require

1. adequate blood supply

2. nerve stimulation

3. proper nutrition

4. Blood pH within normal limits

molecules that indicate serious muscle damage

Myoglobin

1st class lever

Force is inbetween Applied force and Load

raising neck up

2nd class lever

Load lies between applied force and fulcrum going on your tippy toes

3rd class lever

force is applied between lever and fulcrum

elbow flexion

Agonist

• prime mover

• main muscle responsible for a particular muscle movement

Antagonist

opposes movement of agonist

synergist

• smaller muscle

• assists agonist

fixator

• type of synergist

• helps agonist by preventing movement at another joint

slow fibers

• slow contraction speed

• less myoglobin

• small diameter

• more mitochondria and blood vessels

• aerobic

fast fibers

• fast contraction speed

• more myoglobin

• large diameter

• fewer mitochondria

• anaerobic

myoglobin

protein that store and release oxygen to muscle cells