Unit 7 - Skeletal Muscle Tissue

Question 1

List the 3 types of muscle tissue

Answer 1

Skeletal
Cardiac
Smooth

Question 2

Describe the connective tissue coverings of a skeletal muscle

Answer 2

An individual skeletal muscle is made up of muscle fibers wrapped in a connective tissue covering. Each muscle is surrounded by the epimysium. Fascia surrounds and separates the muscles.

Question 3

What is deep fascia?

Answer 3

The portion of the network of the fasciae that surrounds and penetrates the muscles

Question 4

What is subcutaneous fascia?

Answer 4

The portion that lies just beneath the skin forming the subcutaneous layer

Question 5

What is subsereous fascia?

Answer 5

The portion that forms the connective tissue layer of the serous membranes covering organs in various body cavities and lining those cavities

Question 6

What is a tendon?

Answer 6

A projection of connective tissue beyond the ends of the muscle that attaches to bone

Question 7

What is an aponeurosis?

Answer 7

A broad fibrous sheet of connective tissue that connects muscles to adjacent muscles

Question 8

List the 6 major parts of a skeletal muscle fiber

Answer 8

Sarcolemma
Sarcoplasm
Myofibrils
Sarcomere
Sarcoplasmic reticulum
Transverse tubules

Question 9

What is sarcolemma?

Answer 9

A muscle fiber’s cell membrane

Question 10

What is sarcoplasm?

Answer 10

A muscle fiber’s cytoplasm

Question 11

What are myofibrils?

Answer 11

The numerous, threadlike proteins that lie parallel to one another and are contained in the sarcoplasm

Question 12

What is a sarcomere?

Answer 12

The segment of the myofibril between two successive Z lines; causes the muscle fiber to appear striated

Question 13

What is sarcoplasmic reticulum?

Answer 13

The network of membranous channels that surround each myofibril running parallel to them; the specific name for the endoplasmic reticulum

Question 14

What are transverse tubules?

Answer 14

The invaginations of the fiber’s sarcoplasm that extend inward and pass completely through the fiber

Question 15

Describe a neuromuscular junction

Answer 15

Each skeletal muscle fiber is controlled by a motor neuron attached at the NMJ

Question 16

What is a motor unit?

Answer 16

A motor neuron and the muscle fibers it controls

Question 17

How do the numbers of fibers within a motor unit affect muscular contractions?

Answer 17

The fewer the muscle fibers, the more precise the movements

Question 18

Explain the function of a neurotransmitter substance

Answer 18

Neurotransmitters are chemical messengers. The role of the neurotransmitter is to carry messages from one neuron to another - through ‘carrying messages’

Question 19

Describe the 4 major events that occur when a muscle fiber contract

Answer 19

1. Motor neuron releases neurotransmitter causing a release of calcium ions
2. Calcium binds to troponin causing it to move tropomyosin away from binding sites on actin filaments
3. Myosin cross bridges attach to actin filaments
4. Cross bridges pull actin inward by bending

Question 20

Define threshold stimulus

Answer 20

A muscle fiber remains unresponsive until a certain amount of stimulus is applied. This minimal strength required is called the threshold stimulus

Question 21

Explain all-or-none response

Answer 21

A muscle fiber either contracts completely or not at all

Question 22

Describe treppe or the staircase effect

Answer 22

Muscle tension increases in a graded manner. The muscle contractions become more efficient.