the muscular system

Question 1

types of muscles

Answer 1

1. cardiac muscles
2. skeletal muscles
3. smooth muscles

Question 2

characteristics of cardiac muscles

Answer 2

• does not fatigue
• involuntary
• myogenic
  eg walls of heart

Question 3

characteristics of skeletal muscles

Answer 3

• fatiguing
• voluntary
• contract by impulses sent by the brain
  eg triceps, biceps, deltoids, gluteals

Question 4

characteristics of smooth muscles

Answer 4

• involuntary
• controlled by the nervous system
• control body functions eg movement of food / blood
  eg arteries, veins, bladder, stomach, intestines

Question 5

antagonistic muscle pairs

Answer 5

• when a muscle contracts it exerts a pulling force on the bones it’s attached too, causing them to move.
• muscles must cross the joints that they move, if a muscle does not cross a joint, no movement will occur.
• when a muscle contracts, one end is normally stationary, while the other is drawn towards it.
• the stationary is know as the origin and the end that moves is called the insertion
• muscles do not work in isolation, they are assembled in groups to create movement.
• they only act by contracting and relaxing, they do not push

Question 6

agonist

Answer 6

the muscle that contracts (prime mover)

Question 7

antagonist

Answer 7

the muscle that relaxes

Question 8

synergist

Answer 8

a muscle or group of muscles that assists the agonist to work effectively eg the soleus for the gastrocnemius in dorsiflexion at the ankle

Question 9

fixator

Answer 9

a muscle or group of muscles that stabilise the joint
eg the trapezius during a bicep curl to stop the scapula from moving

Question 10

types of muscle contractions

Answer 10

1. isometric
2. concentric (isotonic)
3. eccentric (isotonic)

Question 11

isometric

Answer 11

• very little or no movement
• muscle contracts
• it does not change in length, stays the same
  eg a plank, wall-sit, scrum (stationary)

Question 12

concentric (isotonic)

Answer 12

• muscle contracts and shortens
• known as the upwards phase of a movement (positive phase)
  eg upwards phase of bicep curl / press-up / squat

Question 13

eccentric (isotonic)

Answer 13

• muscle lengthens
• known as the downwards phase in a movement (negative phase)
  eg downwards movement of a bicep curl / press-up / squat

Question 14

fibre types

Answer 14

1. type 1
2. type 2a
3. type 2x

Question 15

type 1

Answer 15

• slow twitch
• contracts slowly
• contracts with less force
• most resistant to fatigue
• suited to longer duration, aerobic activities
• rich blood supply
• many mitochondria
• high capacity for aerobic respiration
  eg endurance offence; marathon, triathlon

Question 16

type 2a

Answer 16

• fast twitch
• produce great force when contracting
• resistant to fatigue
• fatigue quicker than type 1
• use oxygen
• suited to speed, power and strength activities
  eg middle distance events; gymnastics, 400m, weight training

Question 17

type 2x

Answer 17

• fast twitch
• produce greatest force
• contract rapidly
• least resistant to fatigue
• anaerobic activities
• depend on anaerobic respiration
• recruited for high intensity / short duration activites
  eg shot put, javelin

Question 18

all or none law

Answer 18

• in order for a muscle to contract, it muscle receive a nerve impulse.
• this impulse must be sufficient to activate the motor unit.
• once activated, all the muscle fibres within the motor unit will contract.
• if the impulse is not sufficient enough to activate the motor unit, then none of the muscles will contract