Muscle Tissue

Question 1

Functions of muscle tissue?

Answer 1

• producing body movement
• stabilizing body positions/ posture/ joints
• movement of substances within the body
• opening and closing of passageways
• producing heat

Question 2

What is muscle tone? What is the purpose?

Answer 2

-the involuntary contraction of a small number of muscle fibres

• keeps muscle firm even when relaxed
• maintains posture
• stabilizes and strengthens synovial joints
• maintains blood pressure (vessel walls)

Question 3

What are the properties of muscle tissue?

Answer 3

contractility- muscles can contract
excitability- nerve signals stimulate muscle contraction
extensibility- muscles can stretch
elasticity- muscles can return to original state

Question 4

How are the properties of muscle tissue characterized?

Answer 4

• presence or absence of striations

- control is voluntary or involuntary

Question 5

What is the purpose of intercalated discs in cardiac muscle?

Answer 5

-to prevent the cells/ tissue from pulling apart when under a lot of force/pressure

Question 6

What is the plasma membrane called? cytoplasm? endoplasmic reticulum?

Answer 6

• sarcolemma
• sarcoplasm
• sarcoplasmic reticulum

Question 7

Endomysium

Answer 7

inner most layer

• surrounds each muscle fibre
• areolar connective tissue

Question 8

Perimysium

Answer 8

middle layer

• surrounds fascicles (group of muscle fibres)
• DICT

Question 9

Epimysium

Answer 9

outer most layer

• surrounds whole muscle
• DICT

Question 10

What causes the striations of muscles?

Answer 10

the internal structure of myofibrils

Question 11

What is the purpose of the sarcoplasmic reticulum?

Answer 11

• to store Ca2+
• tubules surrounding myofibrils
• carries the impulse to deep muscle to trigger the release of Ca2+ for muscle contraction

Question 12

Explain sliding filament theory

Answer 12

• myosin heads attach to actin

- the heads pivot pulling actin towards the centre of the sarcomere shortening it

Question 13

Spasm

Answer 13

involuntary contraction of single muscle

Question 14

Cramp

Answer 14

painful spasm due to low electrolytes

Question 15

Tic

Answer 15

involuntary twitching of muscles normally under voluntary control

Question 16

Tremor

Answer 16

rhythmic, involuntary contraction of opposing muscle groups

Question 17

Fasciculation/ Twitch

Answer 17

uncontrollable contraction of a small portion of a muscle/ local, involuntary discharge of bundle of muscle fibres

Question 18

What is the role of Titin?

Answer 18

• resists overstretching
• holds myosin in place
• helps sarcomeres return to resting length
• accounts for elasticity and extensibility

Question 19

When does rigor mortis occur?

Answer 19

3-4 hours after death

Question 20

What is rigor mortis?

Answer 20

• Ca2+ leaks causing myosin and actin to bind

- can not detach because there is no ATP synthesis

Question 21

When does rigor mortis go away?

Answer 21

after 24 hours because lysosomes digest myosin and actin

Question 22

What are the three types of muscle fibres?

Answer 22

• slow oxidative
• fast oxidative
• fast glycolytic

Question 23

Which of the 3 muscle fibres are O2 dependent?

Answer 23

-slow oxidative and fast oxidative

Question 24

Slow oxidative fibres contract ________ and are _______ to _________ when O2 is present

Answer 24

• slowly
• resistant
• fatigue

Question 25

What are slow oxidative fibres adapted for?

Answer 25

- maintaining posture by providing prolonged contraction | - aerobic endurance such as running a marathon

Question 26

Slow oxidative fibres contain a ______ number of mitochondria

Answer 26

-large

Question 27

Are slow oxidative fibres supplied with capillaries?

Answer 27

yes, richly

Question 28

Fast oxidative fibres have _______ myoglobin content and a _______ supply of capillaries

Answer 28

- high | - rich

Question 29

What are fast oxidative fibres adapted for?

Answer 29

walking | -somewhat fatigue resistant

Question 30

Fast oxidative fibres contract at a ______ rate

Answer 30

fast

Question 31

Fast glycolytic fibres contain _______ myoglobin and ______ mitochondria

Answer 31

- little | - few

Question 32

Fast glycolytic fibres contract _______

Answer 32

- quickly | - large force in a short time

Question 33

What are fast glycolytic fibres adapted for?

Answer 33

intense, short duration movements such as weightlifting, sprinting

Question 34

Neck, back, and leg muscles have higher proportions of ___________ fibres

Answer 34

postural, slow oxidative

Question 35

Shoulder and arm muscles have a higher proportion of _________ fibre

Answer 35

fast glycolytic

Question 36

When does DOMS begin?

Answer 36

8-24hours after activity

Question 37

What causes DOMS?

Answer 37

-microscopic tears in muscle fibres

Question 38

What does DOMS result in?

Answer 38

- inflammatory response results in swelling in connective tissues around muscle fibres (endomysium) - swelling compresses sensory nerve endings in muscle causing soreness

Question 39

What is the one upside to DOMS?

Answer 39

-the tears stimulate increased production of myofibrils and myofilaments resulting in increased muscle strength and size