Partido State
University
Goa, Camarines Sur
COLLEGE OF EDUCATION
NAME: Abigail B. Candelaria E-MAIL: abi_candelaria2012@yahoo.com
How to prepare Handouts?
Title: The Human Heart
“The human heart feels things the eyes cannot see, and knows what the mind cannot understand”
The heart is the organ that supplies blood and oxygen to all parts of
the body. It is about the size of a clenched fist, weighs about 10.5
ounces and is shaped like a cone. The heart is located in the chest
cavity just posterior to the breastbone, between the lungs and superior
to the diaphragm. The heart is surrounded by a fluid filled sac called
the pericardium. Blood is pumped away from the heart through arteries and returns to the heart through veins. The major artery of the body is the aorta and the major veins of the body are the vena cavae
.The heart is one of the most important organs in the
entire human body. It is really nothing more than a pump, composed of muscle
which pumps blood throughout the body, beating approximately 72 times per
minute of our lives. The heart pumps the blood, which carries all the vital
materials which help our bodies function and removes the waste products that we
do not need. For example, the brain requires oxygen and glucose, which, if not
received continuously, will cause it to loose consciousness. Muscles need
oxygen, glucose and amino acids, as well as the proper ratio of sodium, calcium
and potassium salts in order to contract normally. The glands need sufficient
supplies of raw materials from which to manufacture the specific secretions. If
the heart ever ceases to pump blood the body begins to shut down and after a
very short period of time will die.
The heart is essentially a muscle(a little larger than the fist). Like any other muscle in the human body, it contracts and expands. Unlike skeletal muscles, however, the heart works on the "All -or-Nothing Law". That is, each time the heart contracts it does so with all its force. In skeletal muscles, the principle of "gradation" is present. The pumping of the heart is called the Cardiac Cycle, which occurs about 72 times per minute. This means that each cycle lasts about eight-tenths of a second. During this cycle the entire heart actually rests for about four-tenths of a second.
“The human heart feels things the eyes cannot see, and knows what the mind cannot understand”
.The heart is one of the most important organs in the
entire human body. It is really nothing more than a pump, composed of muscle
which pumps blood throughout the body, beating approximately 72 times per
minute of our lives. The heart pumps the blood, which carries all the vital
materials which help our bodies function and removes the waste products that we
do not need. For example, the brain requires oxygen and glucose, which, if not
received continuously, will cause it to loose consciousness. Muscles need
oxygen, glucose and amino acids, as well as the proper ratio of sodium, calcium
and potassium salts in order to contract normally. The glands need sufficient
supplies of raw materials from which to manufacture the specific secretions. If
the heart ever ceases to pump blood the body begins to shut down and after a
very short period of time will die.
The heart is essentially a muscle(a little larger than the fist). Like any other muscle in the human body, it contracts and expands. Unlike skeletal muscles, however, the heart works on the "All -or-Nothing Law". That is, each time the heart contracts it does so with all its force. In skeletal muscles, the principle of "gradation" is present. The pumping of the heart is called the Cardiac Cycle, which occurs about 72 times per minute. This means that each cycle lasts about eight-tenths of a second. During this cycle the entire heart actually rests for about four-tenths of a second.
Make-up of the Heart.
The walls of the heart are made up of three layers,
while the cavity is divided into four parts. There are two upper chambers,
called the right and left atria, and two lower chambers, called the
right and left ventricles. The Right Atrium, as it is called, receives
blood from the upper and lower body through the superior vena cava and
the inferior vena cava, respectively, and from the heart muscle itself
through the coronary sinus. The right atrium is the larger of the two
atria, having very thin walls. The right atrium opens into the right ventricle
through the right atrioventicular valve(tricuspid), which only allows
the blood to flow from the atria into the ventricle, but not in the reverse
direction. The right ventricle pumps the blood to the lungs to be reoxygenated.
The left atrium receives blood from the lungs via the four pulmonary
veins. It is smaller than the right atrium, but has thicker walls. The
valve between the left atrium and the left ventricle, the left
atrioventicular valve(bicuspid), is smaller than the tricuspid. It opens
into the left ventricle and again is a one way valve. The left ventricle pumps
the blood throughout the body. It is the Aorta, the largest artery in
the body, which originates from the left ventricle.
Chambers of the Heart
The heart is divided by a partition or septum into two halves. The halves are in turn divided into chambers. The upper two chambers of the heart are called atria and the lower two chambers are called ventricles. The atria receive blood returning to the heart from the body and the ventricles pump blood from the heart to the body. Valves allow blood to flow in one direction between the chambers of the heart.The Heart Wall
The heart is composed of cardiac muscle which enable the heart to contract and allow the synchronization of the heart beat. The heart wall is divided into three layers: the epicardium, myocardium, and endocardium.- Epicardium - outer protective layer of the heart.
- Myocardium - muscular middle layer wall of the heart.
- Endocardium - inner layer of the heart that is continuous with the inner lining of blood vessels.
Cardiac Conduction
Cardiac conduction is the rate at which the heart conducts electrical impulses. Cardiac muscle cells contract spontaneously and are coordinated by nodal tissue, specifically the sinoatrial node. There are other factors that influence heart rate as well. These include endocrine hormones, body temperature and exercise.Cardiac Cycle
Reference:
http://www.worldinvisible.com/apologet/humbody/heart.htm
http://www.educatingtheheart.org/
http://www.mplsheartfoundation.org/kids/lets_learn.html
http://www.startwithyourheart.com/
http://www.heartfoundation.org.au/Pages/default.aspx
http://www.worldinvisible.com/apologet/humbody/heart.htm
http://www.educatingtheheart.org/
http://www.mplsheartfoundation.org/kids/lets_learn.html
http://www.startwithyourheart.com/
http://www.heartfoundation.org.au/Pages/default.aspx
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