3 types of blood vessels
* Arteries: carry blood away from the heart to the capillaries * Capillaries: permit exchange of material with the tissues * Veins: return blood from the capillaries to the heart.
Wall has 3 layers
* Endothelium: inner layer, made up of simple squamous epithelium, with a connective tissue basement membrane that has elastic fibers. * Middle layer: thickest later and consists of smooth muscle that can contract to regulate blood flow and blood presser. * Outer layer: fibrous connective tissue near the middle layer, but it becomes loose connective tissue at its periphery. Aorta: largest artery in the human body
* Carries 0 rich blood from the heart to other body parts. * Smaller arteries branch off from the aorta, forming a large number of arterioles. Arterioles: small arteries just visible to the naked eye.
* Inner layer: endothelium
* Middle layer: elastic tissue and fibers that encircle the arteriole. When the muscle fibers are contracted, the vessels diameter becomes smaller. When the muscle fibers are relaxed, the vessels diameter becomes larger.
* Join arterioles to venules
* Walls are composed of single layers of endothelium with a basement membrane. * Total surface area in the body is about 6,000 square meters. * Cornea of the eye, is capillary free
Homeostasis in capillaries
* Oxygen and nutrients, such as glucose diffuse out of a capillary into the tissue fluid that surrounds cells. * Wastes, such as carbon dioxide, diffuse into the capillaries. * Any excess is picked up by the lymphatic vessels.
* Take blood from the capillary beds to the heart
Venules: small veins
* Venules drain blood from the capillaries and then join to form a vein
Have the same 3 layers as arteries do
Valves: allow flood to flow only toward the heart and open and prevent blood from flowing backwards when closed. * Valves are found in veins that carry blood against the force of gravity Blood flow in veins is primarily due to the skeletal muscle contractions * Blood can become pooling in the veins as one ages, causing them to enlarge and be visible as varicose veins. * 70% of blood is in the veins
* Superior vena cava is the biggest vein in the body
Heart: cone shaped, muscular organ about the size of a fist
* Located between the lungs and the sternum
* Myocardium: major portion of the heart, consisting of cardiac muscle tissue * Muscle fibers are tightly attached to the myocardium
* Pericardium: where the heart lays, has a serous membrane that secretes a small quality of lubricating liquid * Inner surface of heart is lined with endocardium, a membrane composed of connective tissue and endothelial tissue * Septum: separated the heart into the left and right side
4 chambers of the heart: two upper, thin walled atria, which are located above the two lower thick walled ventricles. * Ventricles: pump the blood to the lungs and body
* Direct the flow of blood and prevents its backwards movement * Atrioventricular valves: two valves that lie between the atria and the ventricles. * Supported by strong fibrous strings called chordae tendineae * Chordae: attached to muscular projections of the ventricular walls and supports the valves and prevents them from inverting when the heart contracts. * Tricuspid: The atrioventricular valve on the body's right side; has three flaps, or cusps. * Bicuspid: The valve on the left side; has two flaps.
* Semilunar valves: two valves between the ventricles
* The pulmonary semilunar valve lies between the right ventricle and the pulmonary trunk. * The aortic semilunar valve lies between the left ventricle and the aorta. Path of Blood Through the Heart
* The superior vena cava and the inferior vena cava, which carry...