Chapter 15- Muscle structure and physiology (1) Flashcards
What is a muscle?
a soft tissue composed of myocytes which contracts to produce force and motion.
Muscle is responsible for many tasks including:
1- Posture
2- Generating heat
3- Movement
4- Regulating sight and hearing
Is the skeletal muscle voluntary or involuntary?
Voluntary (somatic)
Is the cardiac muscle voluntary or involuntary?
Involuntary (autonomic)
Is the smooth muscle voluntary or involuntary?
Involuntary (autonomic)
What does the myocyte contain?
1- A myocyte has a membrane called the sarcolemma
2- Contains a cytoskeleton which is densely packed with myofilaments of actin, myosin and titin.
3- A cytoplasm called the sarcoplasm which is rich in mitochondria
4- Has mitochondria called a sarcosome
5- Has a smooth endoplasmic reticulum which is called the sarcoplasmic reticulum which is full of calcium.
Skeletal muscle is composed of what 4 tissues:
1- Muscle tissue
2- Connective tissue
3- Blood vessels
4- Nerve tissue
What is a fascicle?
Bundles composed of many densely packed myocytes in the skeletal muscle.
Why are myocytes known as fibres?
Because they are elongated in one direction.
What tissue includes tendons that attach muscle to bone?
Connective tissue
Another form of connective tissue are 3 types of sheaths which compartmentalise the muscle and transport blood:
1- Epimysium wraps the muscle as a whole
2- Perimysium wraps each fascicle
3- Endomysium extends between individual myocytes
Muscle metabolism requires what?
A plentiful supply of oxygen and glucose
Is muscle tissue highly vascularised?
Yes. There is lots of blood vessels to get the blood in and carry the waste back out.
Each skeletal muscle is innervated by what?
A single motor axon
What is a myocyte generally made up of?
Multiple myofibrils
What is a myofibril generally made up of?
Myofilaments
What are myofilaments?
Strands of proteins involved in muscle contraction
What are the three types of proteins in myofilaments?
1- Myosin- made up of large proteins that make up thick myofilaments
2- Actin- Smaller proteins that make up thin myofilaments
3- Titin- elastic proteins
What is the general structure of myosin?
Myosin is an elongated protein molecule composed of a heavy tail and 2 light heads.
The junction of the heads and tail acts as a hinge.
An actin filament is made up of 3 components:
1- A helix of two strands of globular actin
2- Thin rod like tropomyosin molecules in a helix
3- Troponin at regular intervals along tropomyosin and is attracted to calcium ions
Elastic filaments are composed of what?
Titin- a long, stripy protein
What do elastic filaments aid in?
It aids in preventing overstretching of the thick filament.
