Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in...
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Transcript of Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in...
![Page 1: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/1.jpg)
Muscles
Syllabus 3.5.3
Toole pages 184 - 191
![Page 2: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/2.jpg)
Aims:
1. Identify and describe the 3 types of muscle in humans.
2. Label a diagram showing the gross and microscopic structure of skeletal muscle.
3. Describe how actin and myosin is arranged within a myofibril.
4. Identify and describe the 2 types of muscle fibre.
![Page 3: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/3.jpg)
Muscles as effectors.
• Muscles are effector organs.
• They respond to nervous stimulation by contracting, which brings about movement.
![Page 4: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/4.jpg)
Types of muscles
There are three types of muscle in the body.1. Smooth2. Cardiac3. Skeletal
![Page 5: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/5.jpg)
Smooth muscle
• Found in the wall of the gut, blood vessels and various cavities.• Unstriated (Does not have strips running across them). • Involuntary.• Contracts and fatigues slowly.
![Page 6: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/6.jpg)
Cardiac muscle
• Found exclusively in the heart.• Striated (Has strips running across them). • Involuntary.• Contracts myogenically, so is able to contract without
receiving impulses from nerves.• Contracts rhythmically without fatigue.
![Page 7: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/7.jpg)
Skeletal muscle
• Attached to the skeleton.• Striated (Has strips running across them). • Voluntary.• Contracts and fatigues rapidly.
![Page 8: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/8.jpg)
The gross and microscopic structure of skeletal muscle
• Individual muscles are made up of millions of tiny muscle fibres called myofibrils.
• The myofibrils are lined up parallel to each other in order to maximise their strength and give maximum force.
• Myofibrils are composed of two types of protein filament:1. Actin2. Myosin
![Page 9: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/9.jpg)
Actin
• This is a thinner filament.
• It consists of two globular protein strands twisted around one another.
• It contains two important proteins:1. Tropomyosin
• These are long thin fibrous strand that are wound around the actin filaments.
2. Troponin• Involved in muscle contraction.
![Page 10: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/10.jpg)
Myosin• This is a thicker
filament.
• It has a long rod shaped tail composed of several hundred fibrous proteins arranged into a filament.
• It has 2 bulbous heads that project to the side, which are composed of a globular protein.
![Page 11: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/11.jpg)
The fine structure of muscle
• Parallel myofibrils can be seen with characteristic pattern of alternating dark and light bands.
![Page 12: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/12.jpg)
• The diagrams to the left show a short length of a single myofibril.
• The region of myofibril from one Z line to the next is called a sarcomere.
• A sarcomere is the basic unit of a myofibril.
• When a muscle contracts the sarcomeres shorten and the pattern of light and dark bands change.
• The whole myofibril consists of a long chain of such units placed end to end.
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The bands explained• Myofibrils appear
stripped due to their alternating light coloured and dark coloured bands.
• The light bands are called isotropic bands (I bands).
• They appear light because actin and myosin filaments do not overlap in this region.
• The dark bands are called anisotropic bands (A bands).
• They appear darker because the actin and myosin filaments overlap in this region.
![Page 14: Muscles Syllabus 3.5.3 Toole pages 184 - 191. Aims: 1.Identify and describe the 3 types of muscle in humans. 2.Label a diagram showing the gross and microscopic.](https://reader036.fdocuments.us/reader036/viewer/2022062517/56649f185503460f94c2f3ac/html5/thumbnails/14.jpg)
The bands explained• At the centre of each anisotropic band is a lighter coloured region called the H-zone.
• Running across the middle of the H-zone is a dark M-line.
• At the centre of each isotropic band is a line called the Z-line.
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Types of muscle fibres
• There are two main types of muscle fibres in the human body.
1. Slow twitch fibres
2. Fast twitch fibres
• They are distinguished by how quickly they contract.
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Slow twitch fibres• These fibres are predominate in muscles that are involved with
sustained but relatively low levels of activity (maintenance of posture and long distance running).
• In these activities the oxygen supply keeps pace with the demand for ATP, so aerobic respiration can provide the necessary energy and anaerobic respiration is not necessary.
• There are large numbers of mitochondria, as this is the site of aerobic respiration.
• These fibres have a good blood supply and contains lots of myoglobin, which serves as an oxygen store.
• The high myoglobin and blood content gives slow twitch fibres a brownish red colour (‘red muscles’).
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Fast twitch fibres• These fibres are the exact opposite.
• They are adapted for sudden bursts of maximum activity, such as sprinting, throwing, jumping and lifting.
• These activities consume ATP at such a rate that the supply of oxygen for aerobic respiration can not keep up with demand.
• The energy need is therefore met by very high rates of anaerobic respiration.
• These fibres have few mitochondria, but a large quantity of the enzymes required for anaerobic respiration.
• The myoglobin content is low and the blood supply is unexceptional.
• Muscles with a higher proportion of fast twitch fibres are therefore ‘white muscles’.