MCATExamkrackers
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Hi, I’m Austin, one of the MCAT instructors at Examkrackers. With Valentine’s Day having come and gone once more, some of our students have asked about what influences your heart rate when you see your someone special.
The resting heart rate (sometimes called the basal heart rate) is set by cells that are in the sinoatrial node of the heart, which is often called the pacemaker. However, there are a few other signals that influence heart rate, including nervous system signals and hormonal signals.
MCAT Think: Can you explain how the nervous system and hormonal signals impact heart rate?
The medulla oblongata in the brain stem helps control the pacemaker cells of the heart by way of the autonomic nervous system. Remember that the autonomic nervous system is under involuntary control. Nerves connected to the brainstem regulate the heart rate by speeding it up or slowing it down.
· Noradrenaline from sympathetic nerves speeds up the heart rate
· Acetylcholine from the vagus nerve (a parasympathetic nerve) slows down the heart rate
How about hormones? Remember that hormones often have a more sustained impact because they circulate through the blood over time, often during times of physical activity.
· The adrenal glands that sit about the kidneys can release epinephrine to speed up the heart rate.
Hopefully this helps remind you about a few of the ways your heart rate is regulated when you see those special to you next Valentine’s Day!
The resting heart rate (sometimes called the basal heart rate) is set by cells that are in the sinoatrial node of the heart, which is often called the pacemaker. However, there are a few other signals that influence heart rate, including nervous system signals and hormonal signals.
MCAT Think: Can you explain how the nervous system and hormonal signals impact heart rate?
The medulla oblongata in the brain stem helps control the pacemaker cells of the heart by way of the autonomic nervous system. Remember that the autonomic nervous system is under involuntary control. Nerves connected to the brainstem regulate the heart rate by speeding it up or slowing it down.
· Noradrenaline from sympathetic nerves speeds up the heart rate
· Acetylcholine from the vagus nerve (a parasympathetic nerve) slows down the heart rate
How about hormones? Remember that hormones often have a more sustained impact because they circulate through the blood over time, often during times of physical activity.
· The adrenal glands that sit about the kidneys can release epinephrine to speed up the heart rate.
Hopefully this helps remind you about a few of the ways your heart rate is regulated when you see those special to you next Valentine’s Day!
