Unit 1 - Anatomy and physiology for health and exercise - muscular system

Question 1

What is a smooth muscle?

Answer 1

It’s the most widely distributed and it predominates i8n the internal tissues of the body, including the digestive, circulatory, urinary and reproductive systems.
Control of this form is muscle is involuntary and is exerted via the autonomic system.

Question 2

What is a cardiac muscle (myocardium)?

Answer 2

→ It’s found in the heart
→ involuntary
→ possesses the capability of self-excitation
→ autonomic system exerts some control by both increasing or decreasing heart rate and the strength of contractions.

Question 3

What are the skeletal muscles?

Answer 3

→ attached from bone-to-bone across joints
→ predominantly under voluntary control
→ via the somatic nervous system

Question 4

Name some functions of skeletal muscles.

Answer 4

→ producing movement
→ stabilising body positions i.e. maintenance of posture
→ facilitating the circulation of blood and lymphatic fluid
→ generating heat

Question 5

Give an overview of the basic anatomy of a skeletal muscle.

Answer 5

Skeletal muscle is made up of a number of
→ rod-like structures called muscle fibres, and these fibres run parallel along its length.
→ each series of fibres are themselves constructed from smaller parallel fibres and so on.
→ collagen-based membranes protect and surround the muscle
→ the outermost membrane covers the whole muscle and is called the epimysium

Question 6

What is the outermost membrane surrounding a muscle called?

Answer 6

The Epimysium (epi - meaning upon).

Question 7

What are the groups of muscle fibres called within the epimysium?

Answer 7

Fascicles (groups muscle fibres formed into bundles).

Question 8

What is the outer sheath of a fascicle called?

Answer 8

Perimysiym (peri - meaning around).

Question 9

What is inside each fascicle?

Answer 9

Bundles of muscle fibres, each separated from the other by, another membrane called the endomysium (endo - meaning inside)

Question 10

What are tendons?

Answer 10

→ strong, inelastic, strap-like structures

→ attach muscle to the periosteum (tough fibrous layer that coats the bones) e. g. Achilles tendon.

Question 11

Define force generation in muscles.

Answer 11

→ below the endomysium are even smaller rows of fibres called myofibrils.
→ Within, two contractile proteins called myosin and actin (often referred to as thick and thin filaments), are arranged in a
→ series of compartments called sarcomeres that run the length of the myofibril.
→ During muscular contraction, the myosin heads attach themselves to the actin filament and rotate.
→ the thinner actin filaments are drawn inwards dragging the ends of the sarcomeres together, this is referred to as the sliding filament mechanism.

Question 12

What is the power that drives the myosin head?

Answer 12

→ ATP (adenosine triphosphate) → primes the myosin for activity by binding with the head.
→ energy from the ATP is almost immediately transferred to the head.

Question 13

What is the relation between actin and calcium?

Answer 13

→ The myosin heads can only bind with the actin with the presence of calcium.
→ In a relaxed state, the myosin-binding sites on the actin are blocked by a combination of other molecules (troponin and tropomyosin), that must be moved before myosin can be attached.

Question 14

What is sarcoplasmic reticulum?

Answer 14

A network of tubes surrounding the myofibrils that act as calcium reservoirs. When stimulated by an action potential they release their calcium into the fluid surrounding the myosin and actin.

Question 15

What stimulates the release of calcium from the sarcoplasmic reticulum?

Answer 15

→ the spread of electrical activity (action potential) along the length of the muscles.
→ the arrival of an action potential at the neuromuscular junction (where the nerve meets the muscle) causes the release of a neurotransmitter (acetylcholine).
→ sodium rushes through the muscle membrane
→ reversal of electrical activity (depolarization), will cascade along the muscle fibre as an action potential, triggering calcium release and beginning the sliding filament mechanism.

Question 16

Muscles are divided in to …. ?

Answer 16

motor units

Question 17

What does a single motor unit consist of?

Answer 17

→ 1 motor neuron (nerve)

→ muscle fibres it innervates

Question 18

Explain the all or nothing law.

Answer 18

→ The all-or-none law is a principle that states that the strength of a response of a nerve cell or muscle fibre is not dependent upon the strength of the stimulus.
→ If a stimulus is above a certain threshold, a nerve or muscle fibre will fire.
→ Essentially, there will either be a full response or there will be no response at all for an individual neuron or muscle fibre.

Question 19

How is the control of muscular force achieved?

Answer 19

→ through a combination of adjusting the number of motor units recruited (i.e. the greater the number, the greater the force)
→ increasing the frequency of their discharge

Question 20

What is coordinated motor unit activity fundamental to?

Answer 20

→ optimising force generation

→ improving exercise performance

Question 21

What are the two small neural sensors (proprioception) called that help provide feedback and respond to changes within the muscle itself?

Answer 21

→ muscle spindle: deep within the muscle fibres. It’s a small sensory unit wrapped tightly around the individual muscle fibres like a coiled spring. When the muscle length changes, the coils are either pulled apart or pushed together. This stimulates neural firing to the central nervous system at the spinal level. The result is a stimulus to contract the same muscle. The greater the range of motion and the faster the muscle lengthens, the greater the resulting contraction will be. This is called the stretch reflex.
→ Golgi Tendon Organ (GTO): in the tendon. When a muscle contracts, it pulls on the tendon, creating tension within that tendon.
When activated, the GTO sends a signal to the spine which brings about an inhibitory effect of the same muscle. This relaxation response is called the inverse stretch reflex.

Question 22

When the spindles bring about muscuar contraction that assists with the movements being performed, what is the GTO’s response?

Answer 22

The GTO responds just after the muscular contraction has engaged by inhibiting the muscular contraction to allow the opposite action to be performed.
→ Muscle spindles and GTO’s serve like the on and off switches for muscle activity during exercise and movement.

Question 23

Explain reciprocal inhibition (RI).

Answer 23

When a muscle is causing its primary actions to occur, the opposing muscles need to be switched off to allow that movement to take place.

Question 24

What could be a negative “side-effect” of reciprocal inhibition be?

Answer 24

It can play a part in creating muscular imbalance. A very tight muscle group will send a continuous RI signal to the opposing muscle which can lead to that muscle becoming inhibited in its function.

Question 25

Name the three categories of muscle tissue.

Answer 25

→ Type 1 or slow-twitch
→ Type 2a and
→ Type 2b or fast-twitch

Question 26

Wich muscle fibres type have been found to be the most aerobic in nature with greater blood supply and more mitochondria?

Answer 26

Type 1 (slow-twitch) muscle fibres.

Question 27

Which muscle fibres type are very anaerobic in nature with a reduced blood supply and much fewer mitochondria?

Answer 27

Type 2b (fast-twitch)

Question 28

What are type 2a fibres?

Answer 28

They have all the characteristics that one would find in other fast-twitch fibre types, but with the added ability to adapt a little more and take on some more properties of the Type 1 fibre.

Question 29

What is muscle fatigue simply put?

Answer 29

A decline in the ability of the muscle to produce force.

Question 30

Give some reasons for muscle fatigue.

Answer 30

The cause of fatigue will very much be dependent on the mode of exercise being undertaken. It can arise from depletion of glycogen stores, which will limit the rate at which ATP can be synthesised. Or, insufficient oxygen, which will lead to changes in the internal chemistry which directly interrupts the sliding filament mechanism.

Question 31

What is DOMS?

Answer 31

Delayed onset muscle soreness, typically occurs 24-72 hours following a fairly heavy bout of exercise activity.
→ associated with intense eccentric muscular activity and
→ unfamiliarity with an exercise

Question 32

How can DOMS be minimised?

Answer 32

→ minimising eccentric muscle activity during the early stages of training
→ starting a progressive training programme at a very low intensity and introducing overload fairly gently
→ beginning training at a high intensity (initially high DOMS, subsequent exercise will produce less and less muscle soreness

Question 33

Muscular activity.

What does isotonic mean?

Answer 33

used to describe muscle actions involving movement, i.e. concentric and eccentric.

Question 34

Muscular activity.

What does concentric mean?

Answer 34

muscle generates force whilst shortening

Question 35

Muscular activity.

What does eccentric mean?

Answer 35

muscle generates force whilst lengthening

Question 36

Muscular activity.

What does isometric mean?

Answer 36

muscle generates force and remains the same length

Question 37

Muscular activity.

What does isokinetic mean?

Answer 37

muscular actions involving movement at a constant speed

Question 38

Into which categories can muscles be placed in, to distinguish between the diverse roles during movement?

Answer 38

→ agonist/primer mover: the muscle(s) that causes the desired action
→ antagonist: the opposing muscle(s) to the agonist
→ synergist: the muscle(s) that assist or modify the movement of the prime mover
→ fixators: the muscle(s) that stabilized the part of the body that remains fixes.

Question 39

Give an example for an agonist.

Answer 39

the bicep brachii during a bicep curl

the quadriceps during a leg extension

Question 40

Give an example for an antagonist.

Answer 40

the triceps during a bicep curl

the hamstrings during a leg extension

Question 41

Give an example for a synergist.

Answer 41

During hip extension, the hamstrings act as synergists for the gluteus maximus.

Question 42

Give an example for a fixator.

Answer 42

Shoulder girdle muscles stabilise the scapula to allow efficient movement at the shoulder joint.