Chapter 9: Muscles and Muscle Tissues

Question 1

Skeletal Muscle Cells…

Voluntary or involuntary?
Somatic or autonomic?
Striated or smooth?
Shape?
Function?
Uninucleated & central OR Multinucleated & peripheral?
CT Components?
Example location?

Answer 1

Voluntary
Somatic
Striated
Cylinder shaped
Helps to move the body.
Multinucleated and peripheral
Epimysium, Perimysium, and Endomysium
Attached to bone, i.e. biceps/quadriceps

Question 2

Cardiac Muscle Cells…

Voluntary or involuntary?
Somatic or autonomic?
Striated or smooth?
Shape?
Function?
Uninucleated & central OR Multinucleated & peripheral?
CT Components?
Example location?

Answer 2

Involuntary
Autonomic
Striated
Branched
To pump blood throughout the body
Uninucleated and central
Endomysium attached to fibrous skeleton of the heart
Only found in the wall of the heart

Question 3

Smooth Muscle Cells…

Voluntary or involuntary?
Somatic or autonomic?
Striated or smooth?
Shape?
Function?
Uninucleated & central OR Multinucleated & peripheral?
CT Components?
Example location?

Answer 3

Involuntary
Autonomic
Smooth
Spindle-shaped
To ensure the proper functioning of involuntary bodily processes
Uninucleated & central
Endomysium
Wall of bladder, wall of GI tract

Question 4

Skeletal, Cardiac, or Smooth?

Answer 4

Cardiac

Question 5

Skeletal, Cardiac, or Smooth?

Answer 5

Skeletal

Question 6

Skeletal, Cardiac, or Smooth?

Answer 6

Smooth

Question 7

What are 4 characteristics of muscle tissue? (ElConExEl)

Answer 7

1. Electrical Excitability: Muscle cells and neurons produce electrical signals (action potentials) in response to stimuli.
2. Contractility: Muscles produce tension; contractions can lengthen, shorten, or maintain muscle length.
3. Extensibility: Muscles can stretch without damage (e.g., cardiac muscle during heartbeats).
4. Elasticity: Muscles return to original length after being stretched or shortened.

Question 8

What are four functions of muscle tissue? (MPSH)

Answer 8

1. Body Movement Production: Muscle shortening and lengthening cause movement at joints by acting on bones.
2. Posture Maintainence & Body Positions: Tonic contractions of muscles keep the body in certain positions (e.g., upright stance, extended knees).
3. Substance Moving Within the Body: Smooth muscle forms sphincters to control movement in organs; cardiac muscle pumps blood; skeletal muscle aids lymph and venous return.
4. Heat & Maintain Body Temperature: Muscle contractions produce heat, helping to stabilize body temperature through exercise or shivering.

Question 9

What are the three layers of connective tissue that surround muscle and how are they arranged within the muscle?

Question 10

What is the difference between a tendon and an aponeurosis?

Question 11

How do skeletal muscle cells form and develop from single cells to multinucleated cells? If mature skeletal muscle cells are post-mitotic, how does new muscle form if the muscle is injured?

Question 12

Define and explain the role of…
a. muscle fiber
b. sarcolemma
c. sarcoplasm
d. myoglobin
e. T-tubule
f. sarcoplasmic reticulum (SR)
g. triad
h. terminal cistern

Question 13

What are the differences / relationships between muscle fibers, myofibrils, sarcomeres, and myofilaments?

Question 14

What is the relationship between thick / thin filaments and actin / myosin?

Question 15

Label the following:
- M line
- A band
- Z disc
- I band
- H band
- Myosin
- Actin

Answer 15

Question 16

Explain the roles of the following in a sacromere:
- M line
- A band
- Z disc
- I band
- H band

Question 17

Explain the roles of Actin and Myosin.

Answer 17

Actin: Thin filaments; provides binding sites for myosin during contraction.

Myosin: Thick filaments; interacts with actin to generate muscle contraction.

Question 18

What are the functions of Titin and Dystrophin?

Answer 18

Titin: Provides elasticity and stability to sarcomeres; helps muscles return to resting length. Z disc -> M line

Dystrophin: Anchors muscle fibers to the extracellular matrix; protects against damage during contraction.

Question 19

Explain the steps in the cycle of contraction.

Answer 19

1. ATP Hydrolysis: Myosin head binds ATP, hydrolyzing it to ADP and phosphate, energizing the myosin.
2. Myosin-Actin Binding: Myosin head attaches to actin, forming a cross-bridge and releasing phosphate.
3. Power Stroke: ADP is released, and the myosin head swivels, pulling actin toward the sarcomere center, shortening the muscle.
4. Detachment: ATP binds to myosin, breaking the actin-myosin bond. ATPase hydrolyzes ATP, re-cocking the myosin head for the next cycle.