Lecture Outline - Chapter 6

6.1 Blood Vessels (p. 124, Fig. 6.2)
	1.	Arteries and Arterioles: Away from the Heart (p. 124)
		a.	Arteries are thick-walled and are designed to carry high-pressure blood away from the heart.
		b.	Artery walls have an inner endothelium, a middle muscular layer, and an outer layer of fibrous connective tissue.
		c.	Arterioles have less elastic tissue but have smooth muscle.
		d.	When arterioles constrict, blood pressure increases.
	2.	Capillaries: Exchange Takes Place (p. 125, Fig. 6.3)
		a.	Arterioles branch into capillaries, which have one-cell thick walls.
		b.	At the arteriole end of a capillary, fluids and nutrients are forced out into tissues. At the venule end, fluids with wastes reenter the bloodstream. Lymphatic capillaries drain excess tissue fluid. 
		c.	Shunting of blood is possible via thoroughfare channels that bypass capillary beds.
	3.	Veins and Venules: To the Heart (p. 125)
		a.	Veins and venules return blood to the heart. These vessels have the same layers as arteries but have less muscle.
		b.	Larger veins have valves to stop the backflow of blood.
6.2 The Heart (p. 126, Fig. 6.4)
	1.	The heart is a four-chambered, cone-shaped muscular organ located between the lungs. It has a septum, atrioventicular valves, chordae tendineae, and semilunar valves.
	2.	Taking Blood Through the Heart (p. 127, Fig. 6.5)
		The vena cavae carry deoxygenated blood from the body to the right atrium --> right atrioventricular valve (tricuspid) to the right ventricle --> to the lungs (pulmonary semilunar valve and the pulmonary arteries) pulmonary veins--> left atrium --> left atrioventricular valve (bicuspid) --> left ventricle --> aortic semilunar valve to the aorta, which begins the distribution of blood throughout the body.
	3.	When the Heart Beats (p. 128, Fig. 6.6)
		a.	Each heartbeat is called a cardiac cycle. The two atria contract (systole), then both ventricles contract, and the entire heart relaxes (diastole).
		b.	Heart sounds can be heard as the respective valves close.
		c.	A pulse can be detected with ventricular systole.
	4.	Conduction System Controls Heartbeat (p. 128, Fig. 6.7)
		a.	Two areas of nodal tissue are located within the heart: the sinoatrial (SA) node or pacemaker, and the atrioventricular (AV) node. Purkinje fibers distribute the impulse for ventricular contraction.
		b.	Ionic changes within the heart can be measured at the body surface with an electrocardiogram. The P wave represents excitation of the atria. The QRS wave occurs just prior to ventricular contraction. The T wave occurs just before ventricular relaxation.
		c.	Examination of an electrocardiogram can determine abnormalities, such as fibrillation, characterized by uncoordinated contraction.
		d.	Nervous System and Hormones Modify Heartbeat (p. 129)
			i.	The parasympathetic branch of the autonomic nervous system slows the actions of the heart; the sympathetic branch speeds them.
			ii.	Epinephrine from the adrenal medulla is a cardiostimulator.
			iii.	Thyroxin from the thyroid gland causes a sustained increase in heart rate, leading to damage from hyperthyroidism.
	5.	Blood Pressure Affects Swiftness of Flow (p. 130, Figs. 6.8, 6.9, 6.10)
		a.	Blood pressure is the pressure of blood against the walls of blood vessels, measured with a sphygmomanometer.
		b.	The highest arterial pressure (systolic pressure) occurs as blood is ejected from the heart. Lowest pressure (diastolic pressure) occurs when the ventricles are relaxing. 
		c.	Blood pressure drops with increasing distance from the left ventricle.
		d.	The velocity of blood flow is driven by the blood pressure in the arteries. 
		e.	The movement of blood in veins and venules is due to contraction of skeletal muscles. Valves prevent blood backflow.
6.3 Vascular Pathways (p. 132, Figs. 6.11, 6.12)
	1.	Pulmonary Circuit: Through the Lungs (p. 132)
		The pulmonary arteries leave the heart and carry deoxygenated blood to the lungs. The pulmonary veins return oxygenated blood to the heart.
	2.	Systemic Circuit: Serving the Body (p. 132)
		a.	The systemic circuit includes blood vessels that leave the left ventricle, distribute blood throughout the body, and return blood to the right atrium.
		b.	The largest artery is the aorta; the largest veins in the body are the superior and inferior venae cavae.
		c.	Coronary arteries feed the heart with oxygenated blood.
		d.	The hepatic portal system begins with a set of capillaries leaving the small intestine with nutrient-rich blood from digestion, continues with the hepatic portal vein leading to the liver, and ends with the capillaries of the liver. 
			HEALTH FOCUS: Prevention of Cardiovascular Disease (p. 134, Fig. 6A)
			i.	Smoking, drug abuse, and obesity all lead to cardiovascular disease.
			ii.	A healthy diet and exercise can prevent cardiovascular disease.
6.4 Circulatory Disorders (p. 134)
	1.	Hypertension Is Deadly (p. 134)
		a.	Approximately 20% of all Americans are hypertensive. A blood pressure of 120/80 (brachial artery) is considered normal. A reading of 160/95 or above is hypertensive for women; for men under age 45, 130/90 is too high, and for men over age 45, 140/95 is considered hypertensive. Diastolic pressure is the guideline for medical treatment.
		b.	Hypertension can lead to stroke or heart attack, and in some has a genetic basis.
	2.	Atherosclerosis and Fatty Arteries (p. 134)
		a.	Atherosclerosis is characterized by plaque accumulation in arteries that begins in early adulthood.
		b.	A diet low in saturated fat and cholesterol and rich in fruits and vegetables minimizes plaque buildup.
		c.	Plaque can eventually clog arteries, leading to a thrombus (stationary clot) or an embolus (a clot on the move).
		d.	Certain families have a genetic predisposition to hypercholesterolemia.
	3.	Stroke, Heart Attack, and Aneurysm (p. 135)
		a.	A cardiovascular accident (CVA), or stroke, blocks oxygen delivery to a portion of the brain.
		b.	Myocardial infarction (MI), or heart attack, occurs when a portion of heart muscle dies due to lack of oxygen.
		c.	Angina pectoris, or pain in the chest and left arm, indicates a partial blockage of one of the coronary arteries.
		d.	An aneurysm is a ballooning of a blood vessel, usually in the abdominal cavity. If a major vessel bursts, death is likely.
	4.	Dissolving Blood Clots (p. 136)
		a.	Tissue plasminogen activator (tPA), a genetically engineered treatment that dissolves blood clots, is used for heart attack victims.
		b.	Blood thinners, such as aspirin, are used when the patient has symptoms of angina or stroke.
	5.	Clearing Clogged Arteries (p. 136, Fig. 6.13)
		a.	Balloon angioplasty involves the catheterization of the clogged artery and insertion of a balloon to force the vessel open.
		b.	Coronary bypass involves the removal of a segment of a blood vessel from the leg or other area that is inserted into the heart to bypass an obstructed coronary artery.
		c.	Other treatments include laser surgery to allow the ventricles to be nourished from the blood they carry, and gene therapy for vegF, a growth factor that encourages new blood vessels to grow past clogged arteries.
	6.	Heart Transplants and Other Treatments (p. 138)
		a.	People with congestive heart failure may require a heart transplant. 
		b.	Experimental cardiac cell transplants will one day be tested to see whether the heart can be induced to repair itself.
		c.	Mechanical heart pumps can be placed inside the body and are under development.
	7.	When Veins Are Dilated and Inflamed (p. 138)
		a.	Varicose veins develop when valves are defective or weakened. In the rectal area, they are called hemorrhoids.
		b.	Phlebitis is an inflammation of a vein.
6.5 Working Together (p. 138)
	The Working Together box (p. 137) illustrates how the cardiovascular system works with other systems of the body to maintain homeostasis.