Muscle

Question 1

What does myalgia mean?

Answer 1

Muscle pain

Question 2

What does myasthenia mean?

Answer 2

Weakness of muscles

Question 3

Define myocardium

Answer 3

Muscular component of the heart

Question 4

Define myopathy

Answer 4

Any disease of the muscles

Question 5

Define myoclonus

Answer 5

A sudden spasm of the muscles

Question 6

Define sarcolemma

Answer 6

Outer membrane of muscle cell

Question 7

Define sarcoplasm

Answer 7

Cytoplasm of muscle cell

Question 8

What are the two main classifications of muscle tissue?

Answer 8

Striated and non-striated

Question 9

What are the two types of striated muscle?

Answer 9

Skeletal and cardiac

Question 10

What is a type of non-striated muscle?

Answer 10

Smooth muscle

Question 11

Where can red skeletal muscle typically be found?

Answer 11

Limb muscles
Postural muscles in back
Breast muscle of migrating birds

Question 12

Where can white skeletal muscle be found?

Answer 12

Extraocular muscles
Muscles controlling fingers
Breast muscle of domestic hen

Question 13

True or false: myoglobin is present in skeletal, cardiac and smooth muscle

Answer 13

FALSE - not present in smooth muscle

Question 14

Which type of mammals have high amounts of myoglobin in their muscles and why?

Answer 14

Diving mammals to allow them to remain submerged for longer than air-breathing mammals

Question 15

What is a perimysium?

Answer 15

Connective tissue carrying nerves and blood vessels

Question 16

When does muscle atrophy occur?

Answer 16

Destruction > replacement

Question 17

When does muscle hypertrophy occur?

Answer 17

Replacement > destruction

Question 18

What are the symptoms of disuse atrophy?

Answer 18

Limb immobilisation
Sedentary behaviour
Bed rest

Question 19

What causes disuse atrophy?

Answer 19

Loss of protein -> reduced fibre diameter -> loss of power

Question 20

How can muscle loss be resisted?

Answer 20

Exercise

Question 21

How is muscle length increased?

Answer 21

Frequent stretching

Question 22

Complete the sentence:

Skeletal muscles are composed of _________, composed of muscle fibres, composed of ___________, composed of myofilaments (______ and ______).

Answer 22

Fascicles
Myofibrils
Actin and myosin

Question 23

Which three molecules make up the thin filaments of skeletal and cardiac muscle?

Answer 23

Actin
Tropomyosin
Troponin

Question 24

What are troponin assays used as a marker for?

Answer 24

Cardiac ischaemia

Question 25

What is an important enzyme in metabolically active tissues like muscle?

Answer 25

Creatine kinase (CK)

Question 26

CK used to be measured to diagnose what?

Answer 26

Myocardial infarction

Question 27

CK is an enzyme released into the blood by damaged skeletal muscle and the brain. What can a rise in plasma CK result from? (6)

Answer 27

``` Intramuscular injection Vigorous physical exercise A fall (elderly) Rhabdomyolysis (severe muscle breakdown) Muscular dystrophy Acute kidney injury ```

Question 28

Describe the structure of a thin skeletal muscle filament

Answer 28

Actin filament forms a helix Tropomyosin molecules coil around the actin helix, reinforcing it. Troponin complex is attached to each tropomyosin molecule

Question 29

Which troponin subunit does ionic calcium bind to in order to result in muscle contraction?

Answer 29

TnC

Question 30

What is rigor configuration?

Answer 30

Myosin head tightly bound to actin molecule

Question 31

Complete the sentences: Hydrolysis of ___ causes the uncoupled myosin head to bend and advance a short distance (___). The myosin head bends weakly to the _____ filament, causing release of _________ _________ which strengthens the binding and causes myosin head to return to its former position. ___ binds to myosin head and causes detachment from actin.

Answer 31

``` ATP 5nm Actin Inorganic phosphate ATP ```

Question 32

What are the two ways in which muscle tissues can increase in size?

Answer 32

1. Enlargement of their individual cells = hypertrophy | 2. Multiplication of cell = hyperplasia

Question 33

What does ANP stand for?

Answer 33

Atrial natriuretic peptide

Question 34

What are natriuretic peptides?

Answer 34

Peptide hormones that are synthesised by the heart, brain and other organs.

Question 35

What stimulates the release of natriuretic peptides by the heart?

Answer 35

Atrial and ventricular distension/swelling (in response to heart failure)

Question 36

What are the main physiological actions of natriuretic peptides?

Answer 36

Reduce arterial pressure by decreasing blood volume and systemic vascular resistance.

Question 37

When is ANP released?

Answer 37

When the heart is stretched

Question 38

Where is ANP synthesised, stored and released?

Answer 38

Atrial myocytes

Question 39

When are elevated levels of ANP found?

Answer 39

During hypervolemic states which occur in congestive heart failure

Question 40

What does BNP stand for?

Answer 40

Brain-type natriuretic peptide

Question 41

Where is BNP synthesised?

Answer 41

Ventricles (also brain)

Question 42

What does NT-pro-BNP stand for?

Answer 42

N-terminal pro-BNP

Question 43

BNP and NT-pro-BNP are sensitive diagnostic markers for which condition?

Answer 43

Heart failure

Question 44

What role do natriuretic peptides play in the kidneys?

Answer 44

Promote the release of Na

Question 45

Complete the sentence: Natriuretic peptides serve as a counter-regulatory system for the _____-___________-___________ system

Answer 45

Renin-angiotensin-aldosterone

Question 46

Purkinje fibres are large cells with what? (3)

Answer 46

1. Abundant myoglobin 2. Sparse myofilaments 3. Extensive gap junction sites

Question 47

What are smooth muscle cells shaped like?

Answer 47

Spindle-shaped (fusiform) with a central nucleus

Question 48

True or false: smooth muscle contraction relies of actin-myosin interactions

Answer 48

TRUE

Question 49

True or false: smooth muscle cells may remain contracted for hours or days

Answer 49

TRUE

Question 50

Complete the sentence: Smooth muscle often forms ___________ _____ of passageways or cavities

Answer 50

Contractile walls

Question 51

Where can smooth muscle be found?

Answer 51

Gut Respiratory tract Genitourinary system

Question 52

True or false: smooth muscle is voluntary

Answer 52

FALSE - involuntary

Question 53

Which disorders can smooth muscle be of clinical significance in?

Answer 53

``` High BP (primary hypertension) Dysmenorrhea Asthma Atherosclerosis Abnormal gut mobility (IBS) Detrusor muscle instability ```

Question 54

Which two types of cells can modified smooth muscle cells occur singly as?

Answer 54

Myoepithelial | Myofibroblast

Question 55

Where can myoepithelial cells be found?

Answer 55

Form a basket work around secretory units of some exocrine glands (sweat, salivary and mammary glands). Also in ocular iris and they contract to dilate the pupil

Question 56

Where can myofibroblasts be found?

Answer 56

Sites of wound healing and tooth eruption

Question 57

Complete the sentence: Most smooth muscle cells are innervated by __________ nervous system fibres that release their neurotransmitters from ____________ into a wide ___________ ______.

Answer 57

Autonomic Varicosities Synaptic cleft

Question 58

True or false: skeletal muscle cells can divide

Answer 58

FALSE - cannot divide but tissue can regenerate by mitotic activity of satellite cells so hyperplasia follows muscle injury

Question 59

What happens when cardiac muscle is damaged?

Answer 59

Cardiac muscle is incapable of regeneration and following damage, fibroblasts invade, divide and lay down scar tissue

Question 60

True or false: smooth muscle cells retain their mitotic activity and can form new smooth muscle cells

Answer 60

TRUE

Question 61

Where is the ability of smooth muscle cells being able to retain their mitotic activity evident?

Answer 61

In the pregnant uterus where the muscle wall becomes thicker by hypertrophy and by hyperplasia of individual cells