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 Branch vessels in each organ Tubular heart Pores Hemolymph in sinuses (a) An open circulatory system Heart (b) A closed circulatory system Heart Blood Dorsal vessel (main heart) Auxiliary hearts Ventral vessels Interstitial fluid

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 Lung and skin capillaries Body capillaries Vein Gill capillaries (a) Single circulation: fish Heart: (b) Double circulation: amphibian Key Systemic capillaries Pulmocutaneous circuit Artery Ventricle (V) Atrium (A) Oxygen-rich blood Oxygen-poor blood Right Left A A V Systemic circuit Lung capillaries (c) Double circulation: mammal Systemic capillaries Pulmonary circuit Right Left A A V Systemic circuit V

Figure 34.5 Capillaries of abdominal organs and hind limbs Aorta Capillaries of right lung Superior vena cava Pulmonary artery Pulmonary vein Right atrium Right ventricle Inferior vena cava Capillaries of left lung Pulmonary artery Pulmonary vein Left atrium Left ventricle Capillaries of head and forelimbs Aorta

Figure 34.6 Aorta Atrioventricular (AV) valve Semilunar valve Pulmonary artery Right atrium Right ventricle Pulmonary artery Left atrium Left ventricle Atrioventricular (AV) valve Semilunar valve

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 Signals (yellow) from SA node spread through atria. SA node (pacemaker) 1 Signals are delayed at AV node. Bundle branches pass signals to heart apex. Signals spread throughout ventricles. AV node Bundle branches Heart apex Purkinje fibers ECG 234

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 Connective tissue Smooth muscle Connective tissue Smooth muscle Endothelium Artery Vein Artery Vein Red blood cells Basal lamina Capillary Red blood cell Capillary Arteriole Venule Valve 100  m 15  m LM

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 Interstitial fluid Lymphatic vessel Lymphatic vessel Blood capillary Tissue cells Lymph node Masses of defensive cells Lymphatic vessels Lymph nodes Peyer’s patches (small intestine) Appendix (cecum) Thymus (immune system) Adenoid Tonsils Spleen

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 Separated blood elements Solvent for carrying other substances Plasma 55% Cellular elements 45% ConstituentMajor functions Osmotic balance, pH buffering, and regulation of membrane permeability Water Ions (blood electrolytes) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance, pH buffering Clotting Defense Fibrinogen Plasma proteins Albumin Immunoglobulins (antibodies) Substances transported by blood Nutrients (such as glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O 2 and CO 2 ) Hormones Functions Leukocytes (white blood cells) Transport of O 2 and some CO 2 Cell type Number per  L (mm 3 ) of blood Basophils Lymphocytes Eosinophils Neutrophils Monocytes Platelets Erythrocytes (red blood cells) 250,000–400,000 5,000,000– 6,000,000 Blood clotting 5,000–10,000 Defense and immunity

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