Week 4 // Muscular Tissue

Question 1

What are the 3 types of muscular tissue?

Answer 1

Skeletal muscle
Cardiac muscle
Smooth muscle

Question 2

What is the function and location of skeletal muscles?

Answer 2

Skeletal, function is to move bones.

Question 3

What is the function and location of cardiac muscles?

Answer 3

In heart, function is to pump blood.

Question 4

What is the function and location of visceral (smooth) muscles?

Answer 4

various organs, various functions (ex. paristalsis)

Question 5

What is the appearance of skeletal, cardiac and smooth muscle tissue?

Answer 5

skeletal: multi-nucleated and striated
cardiac: one nucleus, striated, intercalated disks

Question 6

What are the functions of muscular tissue?

Answer 6

• Generating heat
• Producing body movements
• Stabilizing body positions
• Storing and mobilizing substances within the body
  (In a less known but critically important role, muscle influences energy andprotein metabolismthroughout the body. Muscle is a primary site forglucose uptakeand storage, and it is also a reservoir of amino acids stored as protein.)

Question 7

Properties of muscular tissue?

Answer 7

• Electrical excitability
• Contractility
• Extensibility
• Elasticity

Question 8

How are muscles formed?

Answer 8

Myoblasts

Question 9

How do skeletal muscles produce movements?

Answer 9

Skeletal muscles produce movements by exerting force on tendons
Tendons attach to and pull on bones, and movement occurs

Question 10

What are Muscular Hypertrophy and Atrophy

Answer 10

Muscular Hypertrophy
Enlargement of existing muscle fibers
Due to increased production of myofibrils, mitochondria, sarcoplasmic reticulum and other organelles

Muscular Atrophy
Decrease in size of muscle fibers due to loss of myofibrils
Occurs as a result of aging or disuse

Question 11

3 categories of muscle proteins

Answer 11

Contractile, Regulatory, Structural

Question 12

Muscle Protein: Contractile

Answer 12

(ex: Myosin Actin)

Proteins that generate force during muscle contractions

Question 13

Muscle Protein: Regulatory

Answer 13

(ex. Troponin and Tropomyosin)

Proteins that help switch muscle contraction process on and off.

Question 14

Muscle Protein: Structural

Answer 14

(ex. Titin, Nebulin, Alpha-actin, Myomesin)
Proteins that keep thick and thin filaments of myofibrils in proper alignment, give myofibrils elasticity and extensibility, and link myofibrils to sarcolemma and extracellular matrix.

Question 15

The Sliding Filament Mechanism

Answer 15

is a theory describing how muscles contract.

• Myosin pulls on actin, causing the thin filament to slide inward
• Consequently, Z discs move toward each other and the sarcomere shortens
• Thanks to the structural proteins, there is a transmission of force throughout the entire muscle, resulting in whole muscle contraction

Question 16

Excitation-contraction coupling

Answer 16

Excitation-contraction coupling refers to the sequence of events by which an AP (an electrical event) in the sarcolemma of the muscle cell initiates the sliding of the myofilaments, resulting in contraction (a mechanical event).

Question 17

Even at rest, the skeletal muscle exhibits a small amount of tension called _____

Answer 17

tone

Question 18

Isometric and isotonic contractions

Answer 18

Isometric: A muscular contraction in which the length of the muscle does not change.

Isotonic: A muscular contraction in which the length of the muscle changes.

Question 19

Types of skeletal muscle fibres

Answer 19

Slow Oxidative (SO) Fibers (Slow twitch)
Fast Oxidative–Glycolytic (FOG) Fibers (Fast twitch) 
Fast Glycolytic (FG) Fibers

Question 20

Slow oxidative

Answer 20

slow twitch / slow contraction (break ATP down slowly)
aerobic
red
high fatigue resistance (running a marathon)
high mitochondria, myoglobin, capillaries

Primary functions of fibers:
Maintaining posture and aerobic endurance activities.

Question 21

Fast-Oxidative-Glcolytic

Answer 21

fast-twitch / fast contraction (break ATP down quickly)
aerobic
pink
intermediate fatigue resistance

Primary functions of fibers:
Walking, sprinting.

Question 22

Fast Glycolytic (FG) Fibers

Answer 22

Low ATP, energy by anaerobic glycolysis
high glycogen stores
white
anaerobic
fast contraction

Primary function of fibres:
Rapid, intense movements of short duration.

Question 23

Skeletal vs cardiac vs. smooth location (not in ppt)

Answer 23

Cardiac muscle cells are located in the walls of the heart, appear striated, and are under involuntary control. Smooth muscle fibers are located in walls of hollow visceral organs, except the heart, appear spindle-shaped, and are also under involuntary control.

Question 24

Cardiac muscles have the same arrangement as skeletal muscles but they also have _____ _______

Answer 24

intercalated discs

Question 25

Intercalated discs contain _____ and ________ that allow muscle action potentials to spread from one muscle fibre to another

Answer 25

desmosomes and gap junctions

Question 26

Cardiac cells contain more

Answer 26

mitochondria

Question 27

Cardiac cells’ contractions last ____ longer than skeletal muscle contraction

Answer 27

10 to 15 times longer

Question 28

Smooth muscle cells look different from cardiac cells i this way

Answer 28

Smooth muscle looks quite different than cardiac and skeletal muscle. It is thick in the middle, tapered on the ends, and is not striated. It can be arranged as either single-unit or multi-unit fibers.

Question 29

Location of skeletal muscle

Answer 29

Most commonly attached by tendons to bones.

Question 30

Location of cardiac muscle

Answer 30

Heart

Question 31

Location of smooth muscle

Answer 31

Walls of hollow viscera, airways, blood vessels, iris and ciliary body of eye, arrector muscles of the hair.

Question 32

Aging and Muscle Tissue

Answer 32

Between 30–50 years of age, about 10% of our muscle tissue is replaced by fibrous connective tissue and adipose tissue. Between 50–80 years of age another 40% of our muscle tissue is replaced. Consequences are:
Muscle strength and flexibility decreases
Reflexes slow
Slow oxidative fiber numbers increase