Human Anatomy, Physiology, and Medicine. Anything human! 7 posts
• Page 1 of 1 1. I'm not sure contracitlity is a word, but if
you expand I can try and help. 2. CO binds irreversibly to
haemoglobin in red blood cells and so prevents them from
carrying oxygen around the body. Not sure how F+F would affect
this. 3. Is PNS peripheral nervous system here? If not you've
lost me - try to expand acronyms! 4. Enervated simply means that
nerves are attached, so in this case both parasympathetic and
sympathetic nervous fibres are linked to the sino-atrial node.
The nervous system uses action potentials to pass on signals,
and these pass on the signals to effectors (such as cardiac
muscle) via neuromuscular junctions so any chance in the
potential of the node will affect the action of the muscle.
Therefore Ach (acetylcholine) is a neurotransmitter that's
inhibitory in this situation and slows down heart rate by
slowing the rate of action potentials that are fired, thus
slowing the overall speed of contractions. Likewise