Topic 7- Muscles Flashcards
What are the two types of muscles in the body that are important in exercise?
- Skeletal
- Cardiac (heart)
True or false?
Skeletal muscle determines the shape of the body and is generate great force to produce and control movement.
True!
What are the three main properties of skeletal muscle? Briefly explain each.
- Contractility- muscle contracts in response to signals from the nerve cells. This can be voluntary or involuntary.
- Extensibility- if acted on by external force, muscle has the ability to lengthen while generating force or contracting
- Elasticity- muscle returns to its normal length when relaxed folloeing stretching
How do muscles produce movement of the body?
Muscles are under the control of the brain and spinal cord and have a rich supply of blood vessels. Signals are transmitted from the central nervous system via nerve cells to the muscle fibres causing them to contract. If large groups of muscle fibres are stimulated in this way, the whole muscle contracts. The resulting shortening of the muscle exerts a force on the joints of the body causing movement.
How do muscles maintain body posture?
Some muscles of the body contract in a continuous manner to maintain body posture
How do muscles generate body heat?
Heat is generated by muscle contraction. The harder and longer the contraction of the muscles, the greater the heat that is generated. When body temperature falls below the optimum, the muscles contract involuntary to cause shivering which generates heat and rises the body temperature.
How do muscles stabilise the joints of the body?
Most muscles exert a force around joints and tend to work in opposing groups across a joint. While one group of muscles contracts, the opposing group of muscles also contract to stabilise the joint, resulting in a smooth andcontrolled movement.
What is cardiac muscle?
This muscle is able to beat regularly without external stimulation from the nerve cells and without rest. This means that we do not need to think about the heart contracting while we are doing other activities. Although the cardiac muscle contracts by itself, the rate is too slow for the heart to maintain adequate circulation for the body. The rate can be speeded up or slowed down by the autonomic nervous system.
Explain the strcture of skeletal muscle.
Skeletal muscle is made up of small units called muscle fibres which are arranged in bundles. These bndles are grouped together and in turn form the complete muscle. At the ends of the muscle, the tissue that surrounds the bundles, the connective tissue, is attached to the underlying bone. These are tendons.
What are the two types of fibres in muscles?
Red fibres and white fibres.
What are red muscle fibres?
Otherwise known as slow twitch fibres. These fibres can contract slowly and repeatedly over a long period of time and so have a high endurance capacity.
In dance, these fibres would be used in arabesques, dévelopé kicks, lateral extensions, pliés, adage and anything with balance.
What are white muscle fibres?
Otherwise known as fast twitch fibres. These fibres contract quickly for short periods of time, although they fatigue easily.
In dance, white fibres would be used in fast footwork, isolations, leaps, turns, jumps and travelling steps.
What is muscle fatigue and when does it occur?
Fatigue occurs when a muscle is no longer able to sustain a contraction. This causes the contraction to become progressively weaker until it fails due to insufficient energy available to meet its needs.
In fast nd vigorous exercise, this is due to a build up of lactic acid in the muscles and the blood. In less intensive exercise, this is due to the depletionof glycogen stores.
What is immediate (acute) muscle soreness caused by?
Due to insufficient blood supply to the contracting muscles. The continued contractions press on the blood vessles reducing blood flow. This leads to a build up of lactic acid.
What is the effect of a warm up?
