Answer:
virus
Explanation:
viruses are the smallest type of pathogen
Norepinephrine is released from sympathetic nerves, causing the heart rate to increase to higher values.
<h3>What is Norepinephrine?</h3>
Norepinephrine is a neurotransmitter (i.e., a chemical messenger) which is well known for sending information to the brain in order to increase alertness during some particular situation and also serve to constrict blood vessels.
In conclusion, norepinephrine is released from sympathetic nerves, causing the heart rate to increase to higher values.
Learn more about Norepinephrine here:
brainly.com/question/13753173
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