Chambers and the valves of the heart
A
normal heart has two upper and two lower chambers. The upper chambers, the
right and left atria, receive incoming blood. The lower chambers, the more
muscular right and left ventricles, pump blood out of your heart. The heart
valves, which keep blood flowing in the right direction, are gates at the
chamber openings
Heart and circulatory system — How they work
Your heart is a pump. It's a muscular organ about the size
of your fist and located slightly left of center in your chest.
Your heart is divided into the right and the left side. The
division protects oxygen-rich blood from mixing with oxygen-poor blood.
Together, your heart and blood vessels comprise your
cardiovascular system, which circulates blood and oxygen around your body.
In fact:
- Your heart pumps about 5 quarts of blood every minute.
- It beats about 100,000 times in one day — that's about 35 million times in a year.
Oxygen-poor blood, "blue blood," returns to the
heart after circulating through your body.
The right side of the heart, composed of the right atrium
and ventricle, collects and pumps blood to the lungs through the pulmonary
arteries. The lungs refresh the blood with a new supply of oxygen, making it
turn red.
Oxygen-rich blood, "red blood," then enters the
left side of the heart, composed of the left atrium and ventricle, and is
pumped through the aorta to the body to supply tissues with oxygen.
Four valves within your heart keep your blood moving the
right way.
The tricuspid, mitral, pulmonary and aortic valves work like
gates on a fence. They open only one way and only when pushed on. Each valve
opens and closes once per heartbeat — or about once every second.
A beating heart contracts and relaxes. Contraction is called
systole, and relaxing is called diastole.
During systole, your ventricles contract, forcing blood into
the vessels going to your lungs and body — much like ketchup being forced out
of a squeeze bottle. The right ventricle contracts a little bit before the left
ventricle does.
Your ventricles then relax during diastole and are filled
with blood coming from the upper chambers, the left and right atria. Then the
cycle starts over again.
Your heart is nourished by blood, too. Blood vessels called
coronary arteries extend over the surface of your heart and branch into smaller
capillaries. Here you can see just the network of blood vessels that feed your
heart with oxygen-rich blood.
Your heart also has electrical wiring, which keeps it
beating. Electrical impulses begin high in the right atrium and travel through
specialized pathways to the ventricles, delivering the signal to pump.
The conduction system keeps your heart beating in a
coordinated and normal rhythm, which in turn keeps blood circulating. The
continuous exchange of oxygen-rich blood with oxygen-poor blood is what keeps
you alive.
When it contracts, or beats, it sends a surge of blood through the vessels, increasing blood pressure. This is called systolic pressure. When your heart relaxes between beats, your blood pressure decreases. This is called diastolic pressure.
For example, if your systolic pressure is 120 and your diastolic is 70, your blood pressure is recorded as 120 over 70.
Monitoring your blood pressure at home is easy to do. It's done with a blood pressure monitor. There are two main types: manual, also called aneroid, and automatic.
Automatic equipment contains electronics that sense the pulse wave under an inflated arm cuff. Automatic equipment minimizes human error and is recommended if you have hearing or vision loss.
Using the proper cuff will help ensure an accurate reading. Look for a D-ring cuff style for easier use. Children and adults with smaller or larger than average sized arms may need special-sized cuffs.
How to measure blood pressure using a manual monitor
This equipment requires coordination. It's difficult to use if you're hearing or visually impaired or if you're unable to perform the hand movements needed to squeeze the bulb and inflate the cuff.
When you're ready to take your blood pressure, sit quietly for three to five minutes beforehand.
To begin, place the cuff on your bare upper arm one inch above the bend of your elbow. Pull the end of the cuff so that it's evenly tight around your arm. You should place it tight enough so that you can only slip two fingertips under the top edge of the cuff. Make sure your skin doesn't pinch when the cuff inflates.
Once the cuff is on, place the disk of the stethoscope facedown under the cuff, just to the inner side of your upper arm.
Next, place the stethoscope earpieces in your ears, with the earpieces facing forward, pointing toward the tip of your nose. Rest the gauge in the open palm of the hand of your cuffed arm so that you can clearly see it.
Then, squeeze the pump rapidly with your opposite hand until the gauge reads 30 points above your usual systolic pressure. (Be sure to inflate the cuff rapidly). Stop squeezing. Turn the knob on the pump toward you (counterclockwise) to let the air out slowly.
Let the pressure fall 2 millimeters, or lines on the dial, per second while listening for your heart sounds. Note the reading when you first hear a heartbeat. This is your systolic pressure.
Note when you no longer hear the beating sounds. This is your diastolic pressure.
Rest quietly and wait about one to two minutes before taking another measurement. Record your numbers either by writing the information down or by entering the information into an electronic personal health record.
How to measure blood pressure using an automatic monitor
When you're ready to take your blood pressure, sit quietly for three to five minutes beforehand.
Place your feet flat on the floor and rest your arm on a tabletop even with your heart. Lean against the back of the chair. Stretch out your arm, palm upward.
Place the cuff on your bare upper arm one inch above the bend of your elbow. Make sure the tubing falls over the front center of your arm so that the sensor is correctly placed. Pull the end of the cuff so that it's evenly tight around your arm. You should place it tight enough so that you can only slip two fingertips under the top edge of the cuff. Make sure your skin doesn't pinch when the cuff inflates.
To get started, wait a moment, then press start. Remain still and quiet as the machine begins measuring. The cuff will inflate, then slowly deflate so that the machine can take your measurement. When the reading is complete, the monitor displays your blood pressure and pulse on the digital panel. If the monitor doesn't record a reading, reposition the cuff and try again.
Rest quietly and wait about one to two minutes before taking another measurement.
Record your numbers, either by writing the information down or by entering the information into an electronic personal health record. Some monitors can upload your blood pressure readings automatically into a computer or mobile device.
