Muscles Flashcards
What are the three types of muscle in the body?
Skeletal muscle
Cardiac muscle
Smooth muscle (aka involuntary muscle)
Describe the fiber appearance of; 1) skeletal, 2) cardiac, 3) smooth muscle.
1) striated
2) specialised striated
3) non-striated
Is the muscle voluntary/involuntary?
1) skeletal
2) cardiac
3) smooth
1) voluntary
2) involuntary
3) involuntary
Describe the arrangement of;
1) skeletal
2) cardiac
3) smooth
1) Regularly arranged so contraction is in one direction
2) cells branch and interconnect resulting in simultaneous contraction
3) no regular arrangement- cells contract in different directions
What is the contraction speed like in;
1) skeletal
2) cardiac
3) smooth
1) rapid contraction
2) intermediate contraction
3) slow contraction
What is the length of contraction like in;
1) skeletal
2) cardiac
3) smooth
1) short
2) intermediate
3) relatively long time
Describe the structure of skeletal muscle.
Fibres are tubular and multinucleated
Describe the structure of cardiac muscle.
Fibres are branched and uninucleated. Fainter striations than in skeletal muscle.
Describe the structure of smooth muscle.
Striped muscle. Fibres are spindle shaped and uninucleated.
What is the plasma membrane called that encloses the skeletal muscle?
Sarcolemma
What is the sarcoplasm?
The shared cytoplasm within a muscle fibre.
What are T tubules?
Parts of the sarcolemma that are folded inwards to help spread electrical impulses through the sarcoplasm.
Why are T tubules important?
They ensure the whole fibre receives the impulse to contract at the same time.
What organelle is highly abundant in muscle fibres?
Mitochondria
What is the modified version of endoplasmic reticulum in the muscle fibres?
Sarcoplasmic reticulum
What are myofibrils and where are they found?
They are long cylindrical organelles made of protein. Found in the muscle fibres.
What two types of protein filaments that make up myofibrils?
Actin and Myosin
Describe the structure of actin.
Thinner filament. It consists of two strands twisted around each other.
Describe the structure of myosin.
Thicker filament. It consists of long rod-shaped fibres with bulbous heads that project to one side.
What are the light bands of myofibrils?
What are they also known as?
Region where the actin and myosin filaments do not overlap. AKA isotopic bands/I-bands.
What are the dark bands of myofibrils?
What are they also known as?
Region where thick myosin filaments are present.
AKA anisotropic bands/A-bands.
What is the Z-line of myofibrils?
Line found at the centre of each light band.
What is the H-zone?
Lighter coloured region found in the centre of each dark band.
What is a sarcomere?
The distance between adjacent Z-lines.
