Respuesta :
Answer:
The heart is an amazing organ. It starts beating about 22 days after conception and continuously pumps oxygenated red blood cells and nutrient-rich blood and other compounds like platelets throughout your body to sustain the life of your organs.
Its pumping power also pushes blood through organs like the lungs to remove waste products like CO2.
This fist-sized powerhouse beats (expands and contracts) about 100,000 times per day, pumping five or six quarts of blood each minute, or about 2,000 gallons per day.
In general, if the heart stops beating, in about 4-6 minutes of no blood flow, brain cells begin to die and after 10 minutes of no blood flow, the brain cells will cease to function and effectively be dead. There are few exceptions to the above.
The heart works by a regulated series of events that cause this muscular organ to contract (squeeze to push blood) and then relax (refill with blood).
The normal heart has 4 chambers that undergo the squeeze and relax cycle at specific time intervals that are regulated by a normal sequence of electrical signals that arise from specialized tissue.
In addition, the normal sequence of electrical signals can be sped up or slowed down depending on the needs of the individual, for example, the heart will automatically speed up electrical signals to respond to a person running and will automatically slow down when a person takes a nap.
Heart diagram parts, location, and size
Location and size of the heart
The heart is located under the rib cage -- 2/3 of it is to the left of your breastbone (sternum) -- and between your lungs and above the diaphragm.
The heart is about the size of a closed fist, weighs about 10.5 ounces and is somewhat cone-shaped. It is covered by a sack termed the pericardium or pericardial sack.
The normal heart anatomy consists of a four-chambered, hollow organ.
It is divided into the left and right side by a muscular wall called the septum.
The right and left sides of the heart are further divided into two top chambers called the atria (also termed the right and left atrium), which receive blood and then pump it into the two bottom chambers called ventricles, which pump blood to the lungs and to the body.
The coronary arteries are on the heart surface (left main, right coronary).
The coronary arteries and veins comprise the heart’s own mini-circulatory system.
Two major coronary arteries branch off from the aorta near the point where the aorta and the left ventricle meet:
Right coronary artery supplies the right atrium and right ventricle with blood. It branches into the posterior descending artery, which supplies the bottom portion of the left ventricle and back of the septum with blood.
Left main coronary artery branches into the circumflex artery and the left anterior descending artery. The circumflex artery supplies blood to the left atrium, side and back of the left ventricle, and the left anterior descending artery supplies the front and bottom of the left ventricle and the front of the septum with blood.
These arteries and their branches supply all parts of the heart muscle with blood.
