Nervous coordination and muscles Flashcards
What is meant by the term Myogenic
does not need nervous stimulation for contraction e.g. the heart
What is the difference between sympathetic and parasympathetic nerves in the context of heart rate
sympathetic nerves - neurotransmitter released increases the rate of heart contraction
parasympathetic nerves - neurotransmitter released relaxes muscle to slow down heart rate
Why do muscle cells contain a large quantity of mitochondria
mitochondria produce ATP which is required for muscle contraction
Explain how a muscle contraction affects each part of the sarcomere
I band – gets shorter
A –band – stays the same
H-zone – gets shorter
Z – line – gets closer together
How is the structure of actin and myosin adapted for their functions
actin- binding sites for myosin heads
myosin - globular heads/binding sites for actin and ATP
What is the role of tropomyosin in muscle contraction
- tropomyosin blocks the actin-myosin binding sites
- prevents muscle contraction during rest period
- displaced in presence of calcium ions
Explain the role of calcium ions in a muscle contraction
- the action potential depolarize’ the sarcolemma
- depolarisation spreads down the T-tubules to the sarcoplasmic reticulum
- calcium ions are released causing tropomyosin to move out of the actin-myosin binding site
- myosin head binds to actin filament to form an actin myosin cross bridge
- ATPase gets activated by calcium ions
- calcium ions trigger muscle contraction
Describe the role of ATP in muscle contraction
- ATP binds to myosin causing head to detach from actin
- ATP hydrolysed to ATP + Pi
- energy released is used to reposition the myosin head
- cross bridge cycle can then be repeated.
Explain why rigor mortis causes the muscles to stiffen
no ATP is produced therefore actin-myosin bridges can’t be broken down
