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The cardiovascular system. How blood gets around the body. Types of blood vessels. Arteries Carry blood away from the heart Get progressively smaller Arteries (large elastic, medium muscular); arterioles; capillaries Can constrict or dilate Veins Carry blood back to the heart
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The cardiovascular system How blood gets around the body
Types of blood vessels • Arteries • Carry blood away from the heart • Get progressively smaller • Arteries (large elastic, medium muscular); arterioles; capillaries • Can constrict or dilate • Veins • Carry blood back to the heart • Venules, veins
Functions of different types of arteries • Elastic arteries • Largest diameter • Move blood to muscular arteries • Aorta, brachiocephalic, common carotid, subclavian, vertebral, pulmonary and iliac • Muscular arteries • More susceptible to dilation and constriction • Arterioles • Deliver blood to capillaries • Resistance to blood flow • Capillaries- molecular exchange • Absent from surface epithelia, cornea nad lens and cartilage
Different types of capillaries • Continuous • Skeletal and smooth muscle, connective tissue and lungs • Fenestrated (holes) • Kidneys, villi of small intestine, endocrine glands • Sinusoid (big holes) • Red marrow, liver, spleen
Venules converge into veins • Designed to bring blood back to the heart • Can serve as a reservoir of blood (can hold up to 64% of blood at rest) • Valves are critical to keep blood moving in the right direction
Circulatory routes of blood; pulmonary and systemic most prominent
Studying the circulatory routes • Exhibits give an overview of the vessels themselves and how they are organized • Origins of names of the blood vessels • Note that there are superficial and deep vessels (arteries are mostly deep) • Regions supplied (arterial) or drained (venous) • Illustrations- you have seen some of the major vessels in cats already!
Three systemic veins return blood to the heart • Superior vena cava- head, neck, chest, upper limbs • Inferior vena cava-abdomen, pelvic, lower limbs • Coronary sinus-myocardium • Venous networks are more irregular • Tend to be more superficial (good for injections or blood draws)
The hepatic portal system • Portal carries blood from one network to another without going through the heart • Sends blood from GI tract and spleen to liver before going to the heart • Blood is “processed” in the liver
Fetal circulation • Gas exchange occurs with maternal blood (within placenta) • Fetal lungs, kidneys and GI organs don’t function until birth • Umbilical vein delivers oxygen to fetus • Umbilical artery returns blood to placenta
Disorders of the circulatory system • Hypertension • Atherosclerosis • Risk factors: • Excess weight • Sedentary lifestyle • Dietary • Smoking • Genetic • Aging