Structure of skeletal muscle Flashcards
What are muscles?
Muscles are effector organs that respond to nervous stimulation by contacting and producing movement
What are the three types of muscle? Describe them and where they are found too
1) Cardiac muscle: found in the heart only
2) Smooth muscle: found in the walls of blood vessels and the gut
3) Skeletal muscles: make up bulk of body muscle in vertebrates
What are muscles made up of?
Muscles are made up of tiny muscle fibres called myofibrils
What are myofibrils made up of?
Myofibrils are made up of fused cells that share nuclei and cytoplasm (called sarcoplasm)
There is also a higher number of mitochondria because a high amount of ATO needs to be produced
What two protein filaments make up myofibrils? What do these two protein filaments form?
Myosin and actin are protein filaments that form a sarcomere.
Actin is a thinner protein which consists of two strands twisted around one another
Myosin is a thicker protein which consists of long rod - shaped tails with bulbous heads that project to the side
Why do myofibrils appear striped?
Myofibrils appear striped due to their alternating light and dark coloured bands
What are light bands called and why are they called this?
Light bands are called “I bands” because the thick and thin filaments do not overlap in this region
What are dark bands called and why are they called this?
Dark bands are called A bands because the thick and thin filaments overlap in this region
What is the distance between adjeacwnt Z lines called?
The distance between adjacent Z lines is called the sarcomere
What happens to the sarcomere when muscles contract?
The sarcomere shortens and the pattern of light bands (I bands) and dark bands (A bands) change
Label the structure of a sarcomere
Label the structure of a sarcomere
