Muscular Pathology Flashcards
State the 4 main properties of muscle tissue
Elasticity - stretch and return
Extensibility - stretch no damage
Contract ability
Excitability - can be stimulated
name the 3 types of muscle tissue
Skeletal (striated)
Smooth
Cardiac
Describe the difference between type 1 and type 2 striated muscle
Type 1 - slow twitch: abundant mitochondria, aerobic metabolism
Type 2 - fast twitch: stores glycogen in muscle, anaerobic metabolism
Describe the structure of striated muscle tissue
Individual striated fibres of actin & myosin filaments in long cylindrical cells (sarcomeres). Multi-nucleated, cross-striations and connective tissue surrounds bundles into sarcomeres
What’s the functional unit of muscle tissue
Myofibril
Function of skeletal muscle
Voluntary movement, posture, respiration, communication
Examples of skeletal muscle pathologies
Muscular dystrophy, atrophy, neurogenic atrophy, tumours
Characteristics of Muscular Dystrophy (particularly Duchenne MD)
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
Characteristics of muscular atrophy
Decrease in muscle mass from lack of use, starvation, age related (sarcopenia) or neurogenic atrophy
Where can smooth muscle be found
Blood vessels, eyes, intestines
Describe the structure of smooth muscle
Single central nucleus, fusiform (spindle shape), not striated
Function of smooth muscle
Continuous rhythmical contractions, involuntary, low force, peristalsis, vascular tone, pupil dilation etc.
Describe motility mechanism
Use microtubules in a mesh work more that actin & myosin filaments sliding over each other
Name some pathologies of smooth muscle
- Hypotension (excessive vasodilation): decrease in systematic blood output.
- Hypertension: increase in RAA Activation)
- tumours: benign - leiomyoma, Malignant - leiomyosarcoma
Describe the structure of cardiac muscle
1 or 2 nuclei, extensive cytoplasm, cross-striations, branched, highly vascular (need continuous rich blood supply)
Separated by intercalated discs
Function of sarcoplasmic reticulum
Ca2+ store, signal releases Ca2+ into cytoplasm to allow contraction
What are desmosomes and what do they do
Intracellular junctions that provide strong adhesion between cells. Form adhesive bonds in a network that gives mechanical strength to tissues
Function of gap junction
allow passage of one signal from one muscle cell to another - signals must go in order, unbroken like Mexican wave
Term given to connective tissue surrounding muscle fibres
Sarcolema
Function of cardiac muscle
- 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
Name some pathologies of cardiac music
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
