Why the rate of heart beat reduces as the size of the animal increases?
396031
As the heart increase in size, the surface area increase by the square, while the internal volume increases by the cube.\nExample: internal volume = Length * Width * height\n\nAs the internal volume increases the amount of blood pumped per heart beat (stroke volume) increases.\n\nThe actual “strength” of the heart is unchanged. Cardiac myosites are essentially unchanged between different mammal species. \n\nWell trained athletes tend to have a health heart hypertrophy (enlarged heart) and have heart beats in the 40’s-50’s BPM while the average adults range in the 60’s-80’s.\n\nAs an end product of all of this, large animals tend to have slower metabolic rates because while it may be possible for a 6 oz bird to eat its weight in insects a day a large animal like a dog can not be expected to do so.
915230
The heart itself has an internal clock of when it contracts.  However, it is influnced by the autonomic nervous system, in that the sympathetic nervous system increases heart rate, and the parasympathetic system DECREASES heart rate.  Under normal conditions, the parasympathetic system is in more control of heart rate.  When you eat, parasympathetic control is EVEN GREATER.\n\nSo eating slows down your HR.
804419
My best knowledge would be excitment, which gives a boost of adrenaline, causing the heart to have to pump harder due to the adrenaline rush, causing it to sometimes skip a beat.
40640
Anything that can effect emotion will effect the heart rate.  Music can cause emotional reactions, so that if you enjoy a certain song and are happy to hear it, when it comes on your heartrate will increase.  The same is true for a song which you find dull or sad, which will cause your heartrate to slow.  It is the same effect as seeing a loved one, or hearing their voice- everyone knows that when they see someone they're attracted to, they can feel their heart racing.  The body responds mechanically to emotional directives.
38647
Your heart beat rises when you start having to work harder to get oxygen to your blood.  The better shape you're in, the faster we can begin to get oxygen after we stop exercising.  As the oxygen returns, your heart can slow down.
213361
Yes, respiration does have an affect on heart rhythm. Breathing in is an active process - muscles are contracting and your chest is expanding. Most of the time when you exhale (not exercising or being active), your muscles relax so your heart rate slows.  \n\nIf it bothers you, you might want to get it checked out.
877955
About a billion heartbeats a lifetime for animals, but three billion for humans.
666371
cause their vital capacity has been reduced
737267
beating the meat does not cause reduction in the size of the penis.  other factors can cause this trick of nature, but not soloing.  reduction in testosterone levels, diabetes, high blood pressure, etc, can all impact the size of one's endowment. \nif it is bothersome to you, see a urologist or an endocronologist to explore the possible causes.
451829
The Valsalva Manoeuvre will slow your heart rate down, or it should. It's a manoeuvre that is like having a bowel movement. Someone will ask you to "bear down, like you're having a bowel movement", then put electrodes on you to monitor your heart rate. They will ask you to "bear down" and then relax, "bear down" and relax a few times to get a good understanding on your ECG. You can try it yourself - "bear down" like I said, continually monitoring your pulse or HB with your fingers over top of your carotid artery, or your wrist. Anywhere you know there is a pulse to be felt. Your heart rate should slow down and then resume it's normal pattern after you stop the "bearing down". Hope I helped...GOOD LUCK!
19027
I think the scientific explanation is that this is a behavior trait that is hard-wired into their brains through the wonders of natural selection.  When animals are born (including people), their brains (and actually their entire physical bodies) are pre-programmed to do certain things.  They eat when they're hungry.  They "feel" hunger when they haven't eaten in a while.  They run when they're scared.  They feel scared when they see, smell, hear, or feel certain types of things.  Their hearts beat.  Their eyes blink.  They sleep when they're tired.  Having these characteristics gave them the ability to survive as a species and be around today to be observed by us.  Animals who had hearts that didn't "know" to beat automatically didn't last long.\n\nSo flying south for the winter is an instinct that allowed birds to survive.  The many birds who lacked that instinct had more difficulty surviving.
772768
It cushions the heart and regulates temperature. It also protects the heart from damage.
1163412
It is theoropy related to breating and heart beating.
1154701
The ventricles are larger. Why this makes a difference is unknown.
395427
Your heartrate will slow down as you keep holding your breath. Once you start breathing again, it will increase to above normal for a while and then settle back to normal.\n\n(Assuming you are not exerting additional force, such as swimming underwater)
366362
In the domestic cat, Felis sylvestris, the cardiovascular system, compared to humans, is much, much smaller.
277110
Largest blue whale, about the size of a small car.The smallest mammalian heart would belong to the estruscan shrew I would guess