BL Muscles

Question 1

Outline the types of muscles

Answer 1

non striated muscle - smooth muscle
striated muscle - skeletal + cardiac muscle

Question 2

What is myalagia?

Answer 2

Muscle pain

Question 3

What is myasthenia?

Answer 3

Muscle weakenss

Question 4

What is myoclonus?

Answer 4

Sudden spasm of muscles

Question 5

What muscle types are striated?
What are the main features?

Answer 5

Skeletal muscle
Cardiac muscle

Myoglobin present
Striped

Question 6

What is myoglobin?

Answer 6

Red protein containing haem
Carries and stores oxygen in striated muscle cells

Question 7

What is detected in the blood when skeletal muscle dies?

Answer 7

Myoglobin

Question 8

What can high levels of myoglobin in the blood cause?
What can be used to detect this?

Answer 8

Renal damage&raquo_space; tea coloured urine

Question 9

Define each of these words:

• sarcolemma
• sacroplasm
• sarcosome
• sacromere
• sacroplasmic reticulum

Answer 9

• sarcolemma - outer membrane of a muscle cell
• sacroplasm - cytoplasm of a muscle cell
• sarcosome - mitochondrion
• sacromere - contraction unit of striated muscle
• sacroplasmic reticulum - smooth ER of muscle cell

Question 10

Explain the relationship between haemoglobin and myoglobin

Answer 10

Haemoglobin gives up oxygen to myoglobin, especially when pH is lowered

Active muscles produced CO2 or lactic acid&raquo_space; results in acidic conditions

Question 11

What is a muscle fibre?

Answer 11

A striated muscle cell

Question 12

Describe the skeletal muscle structure

Answer 12

• Actin and myosin within sarcomeres
• Many sarcomeres makes up a myofibril
• Many myofibrils make up a muscle fibre
• Muscles fibres are packaged into fascicles
• Endomysium between individual muscle fibres
• Perimysium wraps around a fascicle
• Epimysium wraps around many fascicles

Question 13

What is created at the origin and insertion tendon point of skeletal muscle?

Answer 13

Tension at origin tendon point
Movement at insertion tendon point

Question 14

Describe a sarcomere under a microscope

Answer 14

A band - myosin + actin - dark
H zone - myosin only
I band - actin only - light

Z lines at either end of the sacromere
Dark M lines in middle of sarcomere

Dark Z line | light I band | dark A band | light I band | Dark Z line

Question 15

Causes of muscle atrophy

Answer 15

Muscle inactivity
Malnutrition
Cancer
Neurogenic

Question 16

What are the types of muscle contraction speeds?

Answer 16

Slow - red
Fast - white
Intermediate - white

Question 17

Compare slow and fast twitch fibres in relation to:

• capillary supply
• aerobic or anaerobic
• myoglobin levels
• mitochondria
• cytochromes
• colour
• fatigue
• function

Answer 17

Slow twitch:
- rich blood supply
- aerobic
- high myoglobin levels
- many mitochondria
- many cytochromes
- red
- fatigue resistance
- endurance type activities

Fast twitch:
- poor capillary supply
- anaerobic
- low myoglobin levels
- few mitochondria
- few cytochromes
- white/pale
- rapidly fatigues
- strength

Question 18

Describe the structure of actin filament

Answer 18

• Forms a helix
• Tropomyosin molecules coil around > reinforcement
• Troponin complex attached to tropomyosin molecule
• Made of actin fibres + actin globules

Question 19

What does continued muscle contraction depend upon?

Answer 19

Ca2+ ions
Amounts of ATP

Question 20

Describe the structure of cardiac muscle fibres

Answer 20

Striated
Centrally positioned nuclei
Intercalated discs
Branching

Question 21

Explain and describe the use of troponin in enzyme assay

Answer 21

Used a marker for cardiac ischaemia
Released from ischaemic cardiac muscles

Indicative of cardiac muscle damage

Question 22

What can be detected in the blood after cardiac muscle damage?

Answer 22

Troponin

Question 23

Outline the morphology, connections, control and power of skeletal muscles

Answer 23

• Morphology - long parallel cylinders
  - multiple peripheral nuclei
  - striations
• Connections - fascicle bundles
  - tendonds
• Control - somatic + voluntary
• Power - rapid + forceful

Question 24

Outline the morphology, connections, control and power of smooth muscles

Answer 24

• Morphology - spindle shaped tapering ends
  - single central nuclei
  - no striations
• Connections - gap junctions
  - connective tissue
• Control - involuntary
• Power - slow + sustained

Question 25

Outline the morphology, connections, control and power of cardiac muscles

Answer 25

- **Morphology** - short branched cylinders - single central nuclei - striations - **Connections** - junctions - **Control** - involuntary - **Power** - lifelong variable rhythm

Question 26

What is creatine kinase used for?

Answer 26

To measure and diagnose heart attacks

Question 27

What could a rise in creatine kinase by due to?

Answer 27

Heart attack IM injection Rhabdomyolysis A fall Vigorous physical exercise

Question 28

What are natriuretic peptides?

Answer 28

Peptide hormones that are synthesised by heart, brain and other organs **Atrial natriuretic peptides** - atria **Brain-type natriuretic peptides** - ventricles

Question 29

When are natriuretic peptides released? Where from?

Answer 29

- By heart during heart failure (atrial + ventricle distension) - LV hypertropy + mitral valve disease **BNP** - Congestive heart failure **ANP** - **Atrial natriuretic peptides** - atria - **Brain-type natriuretic peptides** - ventricles

Question 30

What do natriuretic peptides do?

Answer 30

**Reduce arterial pressure** - By decreasing blood volume + systemic vascular resistance - reduce renin release - vasodilation

Question 31

What are purkinje fibres?

Answer 31

Specialised myocardial cells which carry impulses to ventricular muscle from AVN to allow ventricles to contract in a synchronous manner

Question 32

Cellular features of purkinje fibres

Answer 32

Abundant glycogen Sparse myofribrils Extensive gap junction sites

Question 33

Location of smooth muscles

Answer 33

Forms contractile walls of passageways or cavities

Question 34

What are indicators are muscle injury?

Answer 34

**Creatine kinase** - all muscle **Myoglobin** - skeletal muscle **Troponin I** - cardiac muscle

Question 35

What is an indicatior of skeletal muscle damage?

Answer 35

Myoglobin

Question 36

What is an indicatior of cardiac muscle damage?

Answer 36

Troponin I

Question 37

Why is troponin I assay better to diagnose than creatine kinase?

Answer 37

More specific CK is all muscle Troponin I is cardiac muscle

Question 38

- Actin and myosin within ** - Many sarcomeres makes up a ** - Many myofibrils make up a ** - Muscles fibres are packaged into ** - ** between individual muscle fibres - ** wraps around a fascicle - ** wraps around many fascicles

Answer 38

- Actin and myosin within **sarcomeres** - Many sarcomeres makes up a **myofibril** - Many myofibrils make up a **muscle fibre** - Muscles fibres are packaged into **fascicles** - **Endomysium** between individual muscle fibres - **Perimysium** wraps around a fascicle - **Epimysium** wraps around many fascicles

Question 39

Describe the structure of the three types of muscle cells

Answer 39

**skeletal**: - striated - multi nucleated **cardiac**: - striated - single central nucleus - intercalated discs - branching **smooth**: - non striated - central nuclei - spindle shaped

Question 40

Outline skeletal muscle repair

Answer 40

- cannot divide - regenerate but mitotic activity of satellite cells - causing hypertrophy + hyperplasia

Question 41

Outline cardiac muscle repair

Answer 41

- incapable of regeneration - fibroblasts invade, divide + lay down scar tissue > fibrosis + loss of function

Question 42

Outline smooth muscle repair

Answer 42

- retain mitotic activity - stable cells