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Circulatory System. Overall components are blood, blood vessels, and heart Overall function is to transport nutrients, gases, hormones, waste, immunity, and temperature regulation. Circulatory System. Ontogeny & Phylogeny First system to be functional in development
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Circulatory System • Overall components are blood, blood vessels, and heart • Overall function is to transport nutrients, gases, hormones, waste, immunity, and temperature regulation
Circulatory System • Ontogeny & Phylogeny • First system to be functional in development • Similar embryology in all vertebrates • Individual variation within species
Blood • Plasma (serum is plasma minus clotting factors) • Formed Elements = Cells • Erythrocytes • Red Blood Cells • Have hemoglobin pigment to carry oxygen • Need iron for hemoglobin synthesis
Blood • Leukocytes • Function in immunity, antibody production • Phagocytosis
Blood • Platelets • Clotting of blood
Blood • Hemopoiesis = Formation of blood cells • Sites in adult include liver, kidney, spleen and red bone marrow depending on class • Blood islands – located in wall of yolk sac is earliest site of hemopoiesis in vertebrates • Hemocytoblast = stem cell
Heart • Develops early from splanchnic hypomere • Functional by 30 hours in chick (21 d incubation) • Functional by 4 weeks in humans (280 d gestation)
Heart Wall • Endocardium – inner, smooth lining • Myocardium – striated cardiac m., intercalated discs • Epicardium – outermost layer
Heart • Parietal pericardium – part of pericardial sac that encloses the heart • Visceral pericardium = epicardium • Pericardial cavity – between parietal & visceral pericardium
Gill Breathing Fish Heart • Single circuit pump with 4 chambers • Sinus venosus – pacemaker (through reptiles) • Atrium • Ventricle • Conus arteriosus (trunk)
Gill breathing fish heart • AV valve – one way valve between atrium & ventricle to prevent backflow • Semilunar valve – one way valve between ventricle & conus arteriosus to prevent backflow
Lungfish & Amphibians • Two circuit heart • Divisions to divide heart into oxygenated and deoxygenated sides • Interatrial septum (partial or complete) • Interventricular septum/Ventricular trabeculae – partial • Spiral valve – tries to divide conus arteriosus
Amniote heart • More complete divisions of heart, 2 circuit heart • Two atria, two ventricles
Amniote Heart • Sinus venosus is the pacemaker through reptiles • Sinus venosus becomes the sinoatrial node in birds & mammals which is the pacemaker & is located in the wall of the RA • Pacemaker sets the pace for all heartbeats
Amniote heart • Interatrial septum is complete • Foramen ovale is an embyronic hole in interatrial septum • Auricle is an expansion of atria in mammals only • Interventricular septum is complete in most
Key Points • What do you suppose the function of the auricle is?
Key Points • Why would the foramen ovale be a necessary structure in the mammalian fetus?
Key Points • Summarize the difference between a single circuit and a double circuit pump. • What anatomical features support the heart being a double circuit pump?
Amniote heart • AV valves are bicuspid & tricuspid in mammals • Semilunar valves between ventricles and trunks
Amniote heart • Fate of conus arteriosus • Three trunks in reptiles • Two trunks in birds and mammals
Key Points • The conus arteriosus becomes trunks. Are trunks arteries or veins? • Name the two trunks in birds and mammals.
Circulation between lungs and heart • Pre/Postcava • RA • RV • Pulmonary trunk – arteries • Lungs • LA • LV • Aorta • Systemic circulation
Key Points • Without looking, trace the blood flow from pre/post cavas through heart, to lungs, back to heart to aorta.