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CIRCULATION Types of circulatory systems • Diffusion – oxygen and carbon dioxide, based on body shape and size • Gastrovascular cavities – distribution of substances throughout the body and in digestion. • Open circulatory system – arthropods, some molluscs • Hemolymph, interstitial fluid, clear fluid • Pumped through vessels into sinuses and back to heart • Closed circulatory system – • Blood confined in vessles FIGURE 34.3 (a) An open circulatory system (b) A closed circulatory system Blood Heart Heart Interstitial fluid Hemolymph in sinuses Branch vessels in each organ Pores Dorsal vessel (main heart) Tubular heart Auxiliary hearts Ventral vessels Cardiovascular system • Closed circulatory system of humans • Arteries – blood away from heart • Capillaries – gas exchange, simple squamous tissue • Veins – blood to the heart • Not all arteries carry oxygenated blood and not all veins carry deoxygenated blood • 2 main chambers of the heart • Atrium – receiving chamber • Ventricle – pumping chamber Figure 34.4 (a) Single circulation: fish Gill capillaries (b) Double circulation: amphibian Lung and skin capillaries A Right Vein Pulmonary circuit Pulmocutaneous circuit Artery Heart: Atrium (A) Ventricle (V) (c) Double circulation: mammal Lung capillaries A V A Left Right V A V Left Systemic capillaries Body capillaries Key Oxygen-rich blood Oxygen-poor blood Systemic circuit Systemic capillaries Systemic circuit Figure 34.5 Superior vena cava Capillaries of head and forelimbs 7 Pulmonary artery Pulmonary artery Capillaries of left lung Aorta 9 Capillaries of right lung 6 2 3 3 4 11 Pulmonary vein Right atrium 1 Pulmonary vein Left atrium 5 10 Left ventricle Right ventricle Inferior vena cava Aorta 8 Capillaries of abdominal organs and hind limbs Figure 34.6 Aorta Pulmonary artery Pulmonary artery Right atrium Left atrium Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Right ventricle Left ventricle The mammalian heart • Approximately the size of a fist • Made of mostly cardiac tissue • Cardiac cycle – one complete sequence of pumping and filling of the heart. • Systole – contraction phase of cardiac cycle • Diastole – relaxation phase of cardiac cycle • Cardiac output – volume of blood each ventricle pumps per minute Valves • Atrioventricular – separate the atrium from the ventricle • Bicuspid – mitral valve • tricuspid • Semilunar valves – found at exits of the heart • Pulmonary – leaving heart for lungs • Aortic – leaving the heart to the aorta • Lub Dup • Lub – blood against the closed AV valves • Dup – closing of semilunar valves • Murmurs – abnormal sounds Conduction system • sinoatrial node – pace maker – sets rate and timing of cardiac muscle contraction. • Atrioventricular node – conduct impulses through wall separating atrium and ventricle • ECG – electrocardiogram – graph depicting stages in the cardiac cycle Figure 34.8-4 1 Signals (yellow) from SA node spread through atria. SA node (pacemaker) ECG 2 Signals are delayed at AV node. AV node 3 Bundle branches pass signals to heart apex. Bundle branches Heart apex 4 Signals spread throughout ventricles. Purkinje fibers Blood vessels • 3 layers of tissue • Endothelium – think epithelial tissue • Smooth muscle • Durable connective tissue • Artery – arterioles – capillaries – venules - veins • Arteries and veins differ slightly in structure • Arteries have thicker walls due to higher pressure • Veins have valves to prevent backflow Figure 34.9 LM Artery Vein Red blood cells 100 m Valve Basal lamina Endothelium Smooth muscle Connective tissue Endothelium Smooth muscle Connective tissue Capillary Artery Vein Capillary 15 m Red blood cell Venule LM Arteriole Blood pressure • Arterial blood pressure is highest during systole (contraction) • Pulse – rhythmic bulging of the artery walls with each heart beat. • Diastole – relaxation phase, arteries go back to normal, lower pressure Homeostasis • To maintain blood pressure as best it can... • Arterioles will dilate or constrict • Endocrine and nervous system will produce Nitric oxide that will induce vasodilation, regulating blood pressure • Gravity – you will faint to get head level to heart, increasing blood flow to brain • Giraffes have higher systolic pressure, 250mmHg • Lymphatic system – gains liters of fluid (lymph) a day begin lost from capillaries. • Lymph nodes – contain cells that destroy bacteria and viruses. Figure 34.12 Blood capillary Interstitial fluid Adenoid Tonsils Lymphatic vessels Thymus (immune system) Tissue cells Lymphatic vessel Lymphatic vessel Spleen Lymph nodes Appendix (cecum) Peyer’s patches (small intestine) Lymph node Masses of defensive cells Blood • 55% plasma – liquid made of water, proteins, wastes, gas • 45% - formed elements • Erythrocytes – red blood cells • Red biconcave disks • No nucleus • Formed in red bone marrow • Leukocytes – white blood cells • Immune system • 5 types • Thrombocytes – platelets • Blood clotting Figure 34.13 Cellular elements 45% Plasma 55% Constituent Water Ions (blood electrolytes) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Major functions Solvent for carrying other substances Osmotic balance, pH buffering, and regulation of membrane permeability Leukocytes (white blood cells) per L (mm3) of blood Functions 5,000–10,000 Defense and immunity Separated blood elements Lymphocytes Basophils Eosinophils Plasma proteins Albumin Number Cell type Neutrophils Osmotic balance, pH buffering Fibrinogen Clotting Immunoglobulins (antibodies) Defense Substances transported by blood Nutrients (such as glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones Monocytes Platelets Erythrocytes (red blood cells) 250,000–400,000 5,000,000– 6,000,000 Blood clotting Transport of O2 and some CO2 Cardiovascular disease • Disorders of heart and blood vessels • Cholesterol • Atherosclerosis – hardening of the arteries by fatty deposits heart attack – myocardial infarction – damage or death of cardiac muscle tissue resulting from a blockage of one or more coronary arteries Stroke – death of nervous tissue in the brain due to lack of oxygen. Hypertension – high blood pressure – damages endothelium in arteries, promoting plaque build up