Anatomy And Physiology

Anatomy Physiology



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The heart is a magnificent organ. In humans, this fist-sized muscle is generally located just off-center in the chest cavity, slightly to the left side. In some instances, it can be located off to the right side, but this is quite rare. In either case, the heart serves as a must-have item. Its purpose is to pump blood and oxygen throughout the entire body. This task is carried out by means of a continuous expanding and contracting of the muscle from a short time after a fetus is conceived until the onset of bodily death.

The speed at which this vital organ performs this ongoing process of expansion and contraction each minute is known as the heart rate. The method of measurement is really quite simple. The number of expansions and contractions are referred to as heartbeats. Thus, to determine one’s heart rate, the number of beats are merely counted over this span of time. This can be accomplished in many ways. The most common method involves placing the index and middle fingers firmly over the main arteries located on the underside of the wrist until the rhythmic pulse is felt. Typically, these beats, or pulses, are counted for a period of fifteen seconds and then multiplied by four to obtain results.

In fully grown adults, resting heart rates can range anywhere from 60 to 100 beats per minute. Where a particular individual’s “normal” heart rate falls is largely dependent on his or her lifestyle habits. Someone who is athletic and/or regularly exercises and maintains a healthy diet will tend to fall into the lower end of this range. Conversely, the couch potato who smokes and/or regularly eats fast food will likely fall into the upper end.

Regardless of one’s chosen lifestyle, it’s important to know that a person’s heart rate constantly changes with activity, and this is why that range listed above refers to a rested, relaxed state. In other words, counting someone’s heartbeats while he or she is briskly walking or rowing a boat won’t reflect their resting heart rate at all! In fact, there are many factors that will significantly raise that heart rate. The most common of these are listed below:

Exercise

Any activity of exercise, whether mild, moderate, or intense will raise the heart rate. The more strenuous the activity, the faster the heart will beat to supply the body with blood and oxygen. For example, a fast-paced game of basketball or tennis can double that “normal” rate.

Emotional Stress

When a person is excited, anxious, nervous, scared about something, depressed, or angry, this results in an adrenaline rush. When the brain senses this, it signals the heart to beat faster. When sleeping, the heart is typically beating at its slowest speed, but an exciting dream or nightmare can trigger such arousal as well. As an individual’s level of stress is reduced, the heart rate gradually decreases.

Illness/Fever

With the onset of bodily infection from viral or bacterial causes, the heart will work harder to assist the immune system in fighting it. Oftentimes, fever will also be present. When the body temperature is elevated, the affected person’s heart rate will be, too. For instance, it isn’t uncommon for someone with a flu bug to have a heart rate of 120-140 during the course of the illness. People with chronic conditions such as diabetes also tend to have faster heart rates.

Food, medications, unnatural substances

Following a meal, the body digests food. During this process, the heart rate will increase. The bigger the meal, the longer it will take for the heart to return to a normal rate. Certain medications will also raise the heart rate as the body’s immune system responds to them. Smoking constricts the arteries which makes the heart beat faster to push blood and oxygen through. Caffeine is a stimulant that makes the heart react similarly to those aforementioned adrenaline rushes. An excess of alcoholic beverages will speed the heart as will illicit substances designed to invoke feelings of euphoria.

Heat

Anytime a person is subjected to a hot environment, the heart rate will increase to prevent overheating in a similar fashion as when fever occurs. Sitting in a steamy sauna, taking hot showers, or simply working on that tan in the hot sun will result in an elevated heartbeat. Once these activities cease and the skin temperature begins to cool, the heart slows down again.

When a person’s heart rate is consistently above 100 beats per minute and none of the causes such as those listed above can explain the phenomenon, the condition is known as tachycardia. In such cases, a cardiologist may be recommended to evaluate the problem and treat it accordingly.

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