What are FOUR ways by which the heart rate can be changed? hormones
chemicals
age
sleep
ions
rest
autonomic nervous system

if you are asking how much they can go over the 1500 limit it would be safetly within the 2310 and 2600.mg

for me i have felt invisible when i was clearly struggling,or,i made a great achievement ,and,nobody took to notice me either because they just didn't see it,or,people just turned their back on me.i can see a person being invisible by choice,or,without choice like i did.the people who are invisible by choice don't try to talk to people,don't try to make friends,and,keep to themselves.i haven't been one of those people so i couldn't give you a reason.

hope this and can i get bainliest my dude : d

need more in formation

the answer is true because it was true