The Muscular System

Question 1

What are the components of the muscular system (connective tissue components)

Answer 1

Muscle
- skeletal
- cardiac
- smooth

Connective tissue components
- fascial epimyslium
- perimysium
- endomysium

Question 2

What are the properties of musclular tissue

Answer 2

electrical excitability = responding to stimuly by producing action potetionals (electrical signals)

contractility = contract forcefully when stimulated by action potention

extensibility = stretching within limits without being damaged

elasticity = return to original length and shape after contraction or extension

Question 3

how many functions of the muscular system are there

Answer 3

there are 4 functions
1. produce body movement
2. stabalise body position
3. storage and movement of substances
4. generate heat

Question 4

function: produce body movement

Answer 4

• resulted from muscular contraction
• movements of the whole body (walking/ running)
• localised movements (grasping a pencil)

Question 5

Function: stabilise body position

Answer 5

• contractions of skeletal muscle stabalises joints to maintain posture
• postural muscles contract continuously when awake (hold head upright)

Question 6

Function: storage and movement of substances

Answer 6

Storage:
- contraction of sphincters to prevent outflow of contents from a hollow organ
- temporary storage of food and urine

Movemenet:
- cardiac muscle contractions = pump blood through blood vessels
- contraction/ relaxation of smooth muscles in various bodily locations = move food, gametes and urine

Question 7

Function: generate heat

Answer 7

• muscular tissue contract = heat production
  heat is used to maintain normal body temperature
• involantary skeletal muscle contraction (skivering) can increase heat production

Question 8

what are the 3 types of muscle?

Answer 8

skeletal muscle
cardiac muscle
smooth muscle

Question 9

what is the skeletal muscle features

Answer 9

• attached to bone via tendons
• striated
• each cell is multinucleated
• nuclei are located peripherally

Question 10

what is the cardiac muscle features

Answer 10

• muscles of the heart
• branched, cylindrical cells/ fibres
• involuntary control

Question 11

what are the smooth muscle features

Answer 11

• within the walls of hollow organs, airways, blood vessels and attached top hair follicles
• each cell has one nucleus
• involuntary control

Question 12

how does skeletal muscle regenerate

Answer 12

muscle fibres cannot divide after first year so future growth only via enlargment of existing cells

some muscles repair available via specialised cells, however it is often insufficient and fibrosis occurs

Question 13

how does cardiac muscle regenerate

Answer 13

cannot divide or regenerate

Question 14

how does smooth muscle regenerate

Answer 14

cells can grow in size or number (uterus during preganncy)
regeneration is possible

Question 15

skeletal muscle tissue

Answer 15

myofibril (individual bits)
bundled together in a
Fascicle (wrapped in perimysium)
bundled together in the
skeletal muscle (wrapped in epimysium)

Question 16

what are the muscle cell contraction key components

Answer 16

• sarcoplasm (muscle cell cytoplasm) contains hundreds of myofibrils
• each myofibril contains bundles of protein filaments that interlock
  myofilaments = Actin (thin) and Myosin (thick)
• myofilaments contain repeating contractile units called sarcomeres

Question 17

How does skeletal muscle cells contract

Answer 17

1. myosin (thick) binds to actin (thin)
2. actin slides inwards, covering the myosin
3. causing the striated muscle appearance

Question 18

How does cardiac muscle tissue contract

Answer 18

1. Individual muscle cells/ fibres exhibit branching
2. Adjacent cells are joined end-to-end via intercalated discs (specialised structures)
3. Gap junctions present with the intercalated discs

Question 19

How does smooth muscle tissue contract

Answer 19

small and flat squamous shaped cells contain thick, thin and intermediate filaments that twist upon contraction

• signle unit smooth muscle = cells contract in unison
• multiunit smooth muscle = cells contract independently

Question 20

what are the 7 features used in naming muscles

Answer 20

1. direction (orientation of muscle from midline)
2. size (relative size of muscle)
3. shape (shape of muscle)
4. action (principle action of the muscle)
5. number of origins (number of tendons of origin)
6. location (structure near where muscle is found)
7. origin and insertion (site where muscles originates and inserts)

DISSANOLOI

Question 21

How do we move?

Answer 21

muscles that are attached to our skeleton contract and bring two ends of the muscle closer together

Question 22

how do the muscles contract to move

Answer 22

• muscle must cross a joint to make a movement

muscle attachment sites are:
Origin = muscle beginning, does not move during contraction
Insertion = muscle end is pulled towards the origin during contraction