Skeletal, Cardiac and Smooth Muscle

Question 1

State the functions of muscle

Answer 1

-movement
-posture and joint stability
-energy store
-regulate organ volume
-propel fluids/food
-heat generation

Question 2

what do muscles convert chemical energy into

Answer 2

mechanical enery

Question 3

list the properties of muscle

Answer 3

excitability-ability to receive and respond to stimuli

-close relationship with surrounding CT
-contractility
-extensibility -stretch without damage
-elasticity

Question 4

name the 3 types of muscle

Answer 4

-cardiac
-smooth
-skeletal

Question 5

discuss properties of cardiac muscle

Answer 5

-forms most of the heart wall
-contraction and relaxation INVOLUNTARY
-has built in pacemaker for autorhythmicity
-speed and strength of contraction can be controlled by hormones and neurotransmitters.

Question 6

discuss the properties of smooth muscle

Answer 6

-non striated
-contains actin and myosin
-action is involuntary
-some smooth muscle also has autorhythmicty (GI tract)
-regulated by ANS and endocrine system

Question 7

discuss the properties of skeletal mucsle

Answer 7

-muscle is surrounded by connective tissue (fascia)
-forms compartments, seperating individual muscles or muscle groups
-contains several layers of connective tissue

Question 8

describe the fibres within skeletal muscle

Answer 8

-individual muscle cells are called fibres
-fibres have many nuclei in the periphery of the cell below the sacrolemma
-develop by fusion of myoblasts
-abundant mitochondria
-sacroplasmic reticulum (SR)

Question 9

describe myofibrils

Answer 9

-sacroplasm is filed with myofibrils
-cylindrical structures that carry out contractions
-these are where the striations can be seen

Question 10

state the length of myofibrils

Answer 10

1-2 micrometeres

Question 11

what are myofibrils composed of

Answer 11

functional units called sacromeres

Question 12

state the name of the light and dark bands of myofibrils

Answer 12

light-thin filaments
dark-thick filaments

Question 13

List and describe diseases of muscle

Answer 13

MYOPATHY
-abnormal condition or disease of muscle tissue

DYSTROPHY
-muscle destroying disease (progressive degeneration of muscle)
-duchennes muscular dystrophy

NEUROMUSCULAR DISORDER
-a condition affecting any part of the motor unit (motor neuron, NMJ or muscle fibre)

Question 14

describe metabolic myopathies

Answer 14

-defects in any stage of muscle ATP metabolism can lead to a myopathy

-onset normally childhood/teenage years

symptoms
-fatigie/muscle weakness/cramp and pains

Question 15

describe glycogen storage disease

Answer 15

-excersise intolerance or chronic illness
-symptoms often releived with rest

Question 16

describe mitochondrial myopathies

Answer 16

-often result from defects in DNA
-often associated with other clinical findings (stroke like episodes, dmentia, hearing loss)

Question 17

describe inflammatory myopathies

Answer 17

-chronic muscle inflammation and weakness
-often idiopathic
-autoimmune
-progressive muscle weakness (proximal-distal)

Question 18

describe drug induced and toxic myopathies

Answer 18

Malignant hyperthermia

Response to anaesthetics

Uncontrolled release of Ca2+ from SR

Muscles stiffen

Rise in temperature

Necrosis

Question 19

describe cardiomyopathies

Answer 19

-deterioration in the functioning of heart muscles
-can lead to heart failure and death
-symptoms include-chest pain and arrhythmia
-casues often unknown but can be associated with other condition
-little to no regeneration