Transcript Heart
CIRCULATORY SYSTEM Protists, Sponges, Cnidarians: no circulatory system Small-bodied, submerged in water Use simple diffusion for gas exchange Open circulatory systems: Organs submersed in pool of blood: blood sinus Simple tubular heart E.g., gastropod mollusks, arthropods Closed circulatory systems: Organs imbedded in network of fine vessels Capillary bed Blood cells always contained within vessels E.g., earthworms, vertebrates Hearts Arteries: Carry blood Away from heart Veins: Carry blood toward heart Capillaries: Gas exchange Closed systems can have high blood pressure Enables faster delivery of O2 and nutrients Hence, enables more active life: Gastropod mollusks - snails – open system Cephalopod mollusks – octopuses - closed Mammal/bird circulatory system pulmonary atria ventricles Double circuit: septum Pulmonary (lung), & Systemic (body) 4-chambered heart systemic 2 atria & 2 ventricles Oxygen-rich & O-poor blood completely isolated Septum separates ventricles Oxygen-rich vs. O–poor blood Fish heart 2-chambered Amphibian heart 3-chambered Circulation Distinguish between: 1) Pulmonary/systemic 2) Venous/arterial 3) O-rich/O-poor Internal anatomy of the mammalian heart vena cava (from systemic) semilunar valve right atrium right ventricle aortic arch (to systemic) pulmonary artery pulmonary vein left atrium atrioventricular valves left ventricle septum Physiology of the mammalian heart Heart contraction: Nerve nodes within heart initiate muscle contraction Nerve pulse is electrical Brain hormones only influence Atria first Atrio-ventricular node Then ventricles Contracts from top to bottom Sino-atrial node Heartbeat cycle Systole: contraction phase systole 1) Atria contract Blood forced into ventricles 2) Ventricles contract AV valves forced shut “Lub” of lub-dub sound Blood forced into arteries Diastole: relaxation phase diastole 3) Ventricles relax Semilunar valves close from arterial pressure “dub” of “lub-dub” Blood enters ventricles from atria Diastolic pressure: the pressure in blood vessels when the heart is relaxed Blood pressure drops at capillaries EKG (ECG): Electrocardiogram Graph of electrical activity of heart 1) P-wave Contraction of atria 2) QRS-complex Relaxation of atria Contraction of ventricles 3) T-wave Relaxation of ventricles Seconds Healthy heart: Correct & consistent timing Correct & consistent amplitude Heart attack See lab manual for risk factors Coronary artery Supplies O2 & nutrients to heart Atherosclerosis: Accumulation of lipids in blood vessels Especially Low Density (LD) cholesterol Measuring blood pressure 1. 2. 3. 4. 5. Close valve gently Inflate cuff to 140 Have stethoscope in place Open valve SLIGHTLY, until needle starts to move Observe where needle begins to pulse Should also hear pulse at this time This is systolic pressure 6. Watch for the needle to quit pulsing Pulse sound should also go away This is diastolic pressure Blood pressure = systolic / diastolic Normal = ~120/80 Heart dissection sulcus (fat) lies over septum right ventricle (thin wall) left ventricle (thick wall) plane of dissection aortic semilunar valve right ventricle left atrium atrioventricular valve left ventricle