Laura Vega
HS_130 unit 2 option 2 seminar
September 6, 2011
The heart is the only specialized organ that is made of cardiac muscle. It has heart cells called cardiomyocytes that make up muscle fiber and conduct electrical impulse. The heart has four chambers. The upper which are called the atria and the lower called ventricles and are separated left and right by interventuicular and interatrial septum. These chambers are lined with a thin membrane called endocardium, which prevents the blood from clotting. The heart is protected by a membrane called pericardium, which is a fibrous sac that hold the heart in place.
Valves separate each atrium, each ventricle and exit point to the lungs to prevent back flow of blood. The tricuspid valve separates the right atrium and the bicuspid separates the left atrium and ventricle.
How the blood flows is during diastole blood is received by the right atrium and forces blood into the ventricle by systole. When the right ventricle contracts, it pushes the blood through the pulmonary semi lunar valve and into the pulmonary artery, this carries deoxygenated blood to the lungs for oxygenation. Now the blood flows into the left atrium through the pulmonary vein and to the left ventricle forcing blood through the aortic semi lunar valve and out of the body.
An example of homeostasis and negative feed back is the maintenance of blood pressure. Receptors in the heart and the internal carotid artery detect changes in the blood pressure. The nerves carry information to the brainstem. If the pressure is low the brainstem sends information to the heart to speed up and the blood vessels constrict, this increases blood pressure. If the pressure is too high the brainstem sends signals to the heart to slow down causing the vessels to dilate, lowering the blood pressure. Failure to maintain blood pressure could result in internal damage to...