Muscular Pathology

Question 1

State the 4 main properties of muscle tissue

Answer 1

Elasticity - stretch and return
Extensibility - stretch no damage
Contract ability
Excitability - can be stimulated

Question 2

name the 3 types of muscle tissue

Answer 2

Skeletal (striated)
Smooth
Cardiac

Question 3

Describe the difference between type 1 and type 2 striated muscle

Answer 3

Type 1 - slow twitch: abundant mitochondria, aerobic metabolism
Type 2 - fast twitch: stores glycogen in muscle, anaerobic metabolism

Question 4

Describe the structure of striated muscle tissue

Answer 4

Individual striated fibres of actin & myosin filaments in long cylindrical cells (sarcomeres). Multi-nucleated, cross-striations and connective tissue surrounds bundles into sarcomeres

Question 5

What’s the functional unit of muscle tissue

Answer 5

Myofibril

Question 6

Function of skeletal muscle

Answer 6

Voluntary movement, posture, respiration, communication

Question 7

Examples of skeletal muscle pathologies

Answer 7

Muscular dystrophy, atrophy, neurogenic atrophy, tumours

Question 8

Characteristics of Muscular Dystrophy (particularly Duchenne MD)

Answer 8

Generally inherited, muscle weakness —> defects in muscle protein & death of muscles, DMD-Absence of dystrophia, X-linked recessive, symptoms appear in infancy, life ex < 25

Question 9

Characteristics of muscular atrophy

Answer 9

Decrease in muscle mass from lack of use, starvation, age related (sarcopenia) or neurogenic atrophy

Question 10

Where can smooth muscle be found

Answer 10

Blood vessels, eyes, intestines

Question 11

Describe the structure of smooth muscle

Answer 11

Single central nucleus, fusiform (spindle shape), not striated

Question 12

Function of smooth muscle

Answer 12

Continuous rhythmical contractions, involuntary, low force, peristalsis, vascular tone, pupil dilation etc.

Question 13

Describe motility mechanism

Answer 13

Use microtubules in a mesh work more that actin & myosin filaments sliding over each other

Question 14

Name some pathologies of smooth muscle

Answer 14

• Hypotension (excessive vasodilation): decrease in systematic blood output.
• Hypertension: increase in RAA Activation)
• tumours: benign - leiomyoma, Malignant - leiomyosarcoma

Question 15

Describe the structure of cardiac muscle

Answer 15

1 or 2 nuclei, extensive cytoplasm, cross-striations, branched, highly vascular (need continuous rich blood supply)
Separated by intercalated discs

Question 16

Function of sarcoplasmic reticulum

Answer 16

Ca2+ store, signal releases Ca2+ into cytoplasm to allow contraction

Question 17

What are desmosomes and what do they do

Answer 17

Intracellular junctions that provide strong adhesion between cells. Form adhesive bonds in a network that gives mechanical strength to tissues

Question 18

Function of gap junction

Answer 18

allow passage of one signal from one muscle cell to another - signals must go in order, unbroken like Mexican wave

Question 19

Term given to connective tissue surrounding muscle fibres

Answer 19

Sarcolema

Question 20

Function of cardiac muscle

Answer 20

• autonomous (pace maker cells), nervous system can alter pace & power of contractions
• cell to cell contacts at intercalated discs stabilise position of cells and maintain 3D structure
• Gap junctions allow cells to work together as functional unit
• circulate blood & maintain BP

Question 21

Name some pathologies of cardiac music

Answer 21

Hypertrophy: increase in muscle size in response to pressure or volume stress or hypertension e.g. ^BP —> thickening of walls —> phenotype change —> ^^BP —> ^^thickening —> cycle.
Thicker walls are harder to contract