Chapter 10: Muscle Tissues and Organization

What are cells of skeletal muscle called?

muscle fibers

What are the functions of skeletal muscle?

1. Movement

2. Posture

3. Temperature regulation (shivering)

4. Storage/movement of materials

- sphincters (in some organ systems)

5. Support

What is a bundle of muscle fibers called?

fascicles

What connective tissue makes up muscle?

- deep fascia

- epimysium

- perimysium

- endomysium

Epimysium is around the ______

muscle

Perimysium is around the _______

fascicle

Endomysium is around the ______

single muscle fiber

What makes up a muscle fiber? (3)

sarcolemma, sarcoplasm, myofibrils

What is the location of myofibrils?

length of cells

_________ make up myofibrils

myofilaments

2 kinds of myofilaments

actin and myosin

Name of thick myofilament

myosin (11 nm)

Name of thin myofilament

actin (9 nm)

Two proteins present in thin myofilaments (actin)

tropomyosin and troponin

Function of tropomyosin and troponin

regulate contraction

Function of nebulin (@ center of actin filaments)

thin filament formation

Which band corresponds to thick filament (myosin) and what shade is it?

A-band (dark)

Which band corresponds to thin filament (actin) and what shade is it considered?

I-band (light)

The electron microscope reveals the H-zone which corresponds to which filament?

thick filaments only (myosin)

The electron microscope reveals the M-line which is the attachment site for which fibers?

thick fibers

The electron microscope reveals the Z-disc which is the attachment site for which fibers?

thin fibers

Attachment site for thin fibers

Z-disc

Attachment site for thick fibers

M-line

Name of the distance between two Z-discs

sarcomere

Name of the functional unit of skeletal muscle contraction

sarcomere

3 parts of the neuromuscular junction

synaptic knob, synaptic cleft, motor end plate

Which part of the neuromuscular junction has synaptic vesicles that contain acetylcholine (ACh)?

synaptic knob

Which part of the neuromuscular junction has acetylcholinesterase?

synaptic cleft

What is the function of acetylcholinesterase in the synaptic cleft of the neuromuscular junction?

breaks down acetylcholine (ACh) from synaptic knob

Where are the sarcolemma and ACh receptors located in the neuromuscular junction?

motor end plate

What principal defines muscle contraction?

sliding filament theory

Describe the sliding filament theory

1. Thick and thin fibers pass each other during muscle contraction

2. H-zone and I-band disappear at maximal contraction

3. Overall shortening

4. Tension

When do the H-zone and I-band disappear?

at maximal muscle contraction

Steps of muscle contraction

1. Nerve impulse arrives at the neuromuscular junction

2. Arch released into synaptic cleft

3. Arch binds to receptors in the motor end plate initiating an impulse along the sarcolemma

4. Impulse travels along sarcolemma and T-tubules

5. Calcium is released from the sarcoplasmic reticulum

6. Calcium ions bind to troponin

7. Troponin moves tropomyosin and exposes active sites on the actin

8. Myosin heads bind to active sites and pivot

9. ATP binds to myosin head

10. Myosin head detaches from the actin and resets

11. Nerve impulse stops

12. Calcium ions transported back to sarcoplasmic reticulum

13. Tropomyosin covers active sites. Mason cannot bind. Muscle relaxes.

What is a single motor neuron and all muscle fibers it controls called?

motor units

What is resting tension in skeletal muscle called?

muscle tone

T/F:

Some motor units are always active (regarding muscle tone).

True

In which type of muscle contraction does the length of the muscle not change?

isometric contraction

In which type of muscle contraction is muscle tension ≤ resistance?

isometric contraction

Which type of isotonic contraction actively shortens a muscle?

concentric contraction

Which type of isotonic contraction is the controlled lengthening of a muscle?

eccentric contraction

In which type of muscle contraction is muscle tension > resistance?

isotonic contraction

Which type of skeletal muscle fibers are relatively thinner?

slow oxidative fibers

Which type of skeletal muscle fibers do slower/less powerful contractions?

slow oxidative fibers

Which type of skeletal muscle fibers stay contracted longer and do aerobic respiration?

slow oxidative fibers

Which type of skeletal muscle fibers have many mitochondria?

slow oxidative fibers

Which type of skeletal muscle fibers are defined as intermediate fibers (in size)?

fast oxidative fibers

Which type of skeletal muscle fibers do fast/powerful contraction?

fast oxidative fibers and fast glycolytic fibers

Which type of skeletal muscle fibers are lighter red and do aerobic respiration?

fast oxidative fibers

Why are fast oxidative fibers lighter red?

they have less myoglobin

Which type of skeletal muscle fibers are not as vascularized?

fast oxidative fibers

Which type of skeletal muscle fibers have fewer mitochondria?

fast oxidative fibers

Which type of skeletal muscle fibers have medium endurance?

fast oxidative fibers

Which type of skeletal muscle fibers are large in diameter?

fast glycolytic fibers

Which type of skeletal muscle fibers are white due to limited myoglobin?

fast glycolytic fibers

Which types of skeletal muscle fibers do anaerobic respiration?

all 3

Which type of skeletal muscle fibers have few capillaries?

fast glycolytic fibers

Which type of skeletal muscle fibers have the fewest mitochondria?

fast glycolytic fibers

Which type of skeletal muscle fibers are for a short duration?

fast glycolytic fibers

What is atrophy?

wasting of muscle (tone, size, and power)

What is it called when there is an increase in myofibril number and myofilament (fast fibers)?

hypertrophy

T/F:

Hypertrophy includes more mitochondria and larger glycogen stores.

True

A tendon is aponeurosis if it's like _____

a thin sheet

Which attachment is considered to be less mobile?

Origin

Which attachment is located proximal in limbs?

Origin

Which attachment is more mobile?

insertion

Which attachment is distal in limbs?

insertion

What is considered to be the strongest and prime mover in muscle movement?

agonist

What assists the agonist in muscle movement?

antagonist

What helps in reversing a muscle movement?

synergist