Principles of Animal PhysiologyCirculatory Systems
▪Components of circulatory systems▸Fluid - contains transport molecules and
cells (blood or hemolymph)▸Pump - to move the fluid around▸Conduits (vessels) - to carry the fluid
between pump and body tissues
Introduction
Principles of Animal PhysiologyCirculatory Systems
▪Types of circulatory systemsIntroduction
Principles of Animal PhysiologyCirculatory Systems
▪Open and Closed systems▸Open circulation
♦Contains Hemolymph♦Hemolymph moves from vessels to extracellular
spaces among tissues♦Hemocoel - extracellular spaces containing
hemolymph♦Hemolymph may be moved by body movements,
cilia or flagella, or by hearts
Introduction
Principles of Animal PhysiologyCirculatory Systems
▪Circulation in an open systemIntroduction
Principles of Animal PhysiologyCirculatory Systems
▪Open and Closed systems▸Colsed circulation
♦Contains Blood♦Blood moves through vessels but not among
tissues♦Capillaries - exchange of materials occur♦Blood moved about the body by the heart or by
body movements
Introduction
Principles of Animal PhysiologyCirculatory Systems
▪Ciruclation in a closed systemIntroduction
Principles of Animal PhysiologyCirculatory Systems
▪Two components to circulatory fluids▸Plasma
♦Watery, containing dissolved and dispersed molecules
▸Cellular elements♦In hemolymph
–Hemocytes - various cell types–Responsible for immune functions, clotting, oxygen transport
–Blood–Erythrocytes - red blood cells for transporting oxygen–Leukocytes - white blood cells for immune response–Thrombocytes for platelets - for clotting
Circulatory Fluids
Principles of Animal PhysiologyCirculatory Systems
▪The Hematocrit▸Percent of packed cell volume in whole
blood♦Human - 45% in males; 42% in females♦White whale - 53% in females; 52% in males♦Pekin duck - 45% at seal level; 56% at high
altitude♦Sriped bass - 39% at 5°C; 53% at 25°C
Circulatory Fluids
Principles of Animal PhysiologyCirculatory Systems
▪Plasma and Hematocrit volumesIntroduction
Principles of Animal PhysiologyCirculatory Systems
▪Plasma in Circulatory Fluids▸Contains 90% or more water▸A medium for carrying organic and inorganic
substances▸Plasma proteins - 6-8% of plasma weight -
osmotic pressure and buffering
▸Most abundant electrolytes - Na+, Cl-, HCO3-, K+,
and Ca++
▸Nutrients - glucose, amino acids, lipids, and vitamins
▸Waste - creatinine, bilirubin, urea▸Dissolved gases▸Hormones
Circulatory Fluids
Principles of Animal PhysiologyCirculatory Systems
▪Erythrocytes▸Transport oxygen▸Transport carbon dioxide▸Oblong oval or biconcaved flattened discs▸Flexible▸Contain no nucleus, orgennelles, or
ribosomes▸Contain plasma and hemoglobin▸Does not use the oxygen that they carry▸Lifespan - 100 to 120 days
Circulatory Fluids
Principles of Animal PhysiologyCirculatory Systems
▪ErythrocytesCirculatory Fluids
Principles of Animal PhysiologyCirculatory Systems
▪Blood Cell Production (Hemopoiesis)Circulatory Fluids
Principles of Animal PhysiologyCirculatory Systems
▪Pumps▸Flagella
♦Fluid moved by beating epithelial cells
▸Extrinsic muscle or skeletal pumps♦Fluid moved by motion of skeletal muscles♦May occur during locomotion
▸Peristaltic muscle pumps♦Occurs during contraction of vessel muscle walls
▸Chamber muscle pumps♦Hearts♦Most have at least two chambers
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Types of pumps in animalsCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Two chambered heartCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Dual Pumps in Avian and Mammalian Hearts▸4 chambers - 2 atria and 2 ventricles▸Atria receive and store blood▸Ventricles pump blood away from the heart▸Veins return blood to the heart▸Arteries take blood away from the heart▸Septum is muscular tissue that separates
the two sides of the heart
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Dual PumpsCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Atria - holding chambers▪Ventricles - produce pressure to drive blood through system▪Arteries - low-resistance, little pressure loss, pressure
resevoirs▪Arterioles - high resistance, regulate blood pressure,
distribute blood to various organs▪Capillaries - site for nutrient and waste product exchange▪Venules - nutrient and waste product exchange, regulates
capillary blood pressure▪Veins - low resistance conduits, facilitates flow back to the
heart
Principles of Animal PhysiologyCirculatory Systems
▪Heart Valves Ensure Unidirectional Blood FlowCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪The Mammalian HeartCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Blood flow through mammalian heartCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪The Mammalian Ventricles▸Myocardium▸Epicardium▸Epicardium
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Mechanism of Valve ActionCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Organization of Mammalian Cardiac Muscle Fibers
▸Intercalated discs▸Desmosomes▸Gap junctions▸Functional syncytium▸Myoglobin
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Conducting Pathway in Mammalian Heart▸SA node▸Internodal pathway▸AV node▸Bundle of His▸Left & Right bundle branches▸Purkinje fibers
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Conducting Pathway in Mammalian HeartCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Pacemaker Activity in Cardiac Autorhythmic Cells▸Pacemaker cells
♦SA node♦AV node♦Bundle of His♦Purkinje fibers
▸Pacemaker potential♦Decrease in outward K+ current♦Constant inward Na+ current♦Increase in inward Ca++ current
▸Depolarization♦Continued inward Na+ current♦Influx of Ca++
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Pacemaker Activity of Cardiac Autorhythmic CellsCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Action Potential of Contractile Cardiac Muscle Cells▸RMP about -90 mV▸Rising phase - influx of Na+
▸Initial repolarization - ↓PNA+; ↑PCa2+; ↓PK+
▸Plateau - slow inward Ca2+ current; decreased K+ efflux
▸Repolarization - inactivation of Ca2+ channels; increase outward K+ current
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Action Potential and Tension Development in Cardiac Contractile Muscle Cell
▸Refractory period▸Tetanus
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Action Potential of Contractile Cardiac Muscle CellsCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Comparison of action potential in different regions of the heart
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪The ElectrocardiogramCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Mechanical Events of Mammalian Cardiac CycleCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Mechanical Events of Mammalian Cardiac Cycle▸Early Ventriclular Diastole▸Late Ventricular Diastole▸End of Ventricular Diastole - end-diastolic
volume▸Onset of Ventricular Systole▸Isovolumetirc Venticular Contraction▸Ventricular Ejection▸End of Ventricular Systole - end systolic volume▸Onset of Ventricular Diastole
♦Dicrotic notch
▸Isovolumetric Ventricular Relaxation▸Ventricular Filling
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪The Cardiac Output▸ Cardiac out (CO) = volume of blood pumped by
each ventricle per minute
CO = HR x SV, HR = heart rate, SV = stroke volume
Starling’s law of the heart▸ Increased filling pressure (volume) leads to
increased cardiac output
▸ If HR = 72 beats/min, SV= 0.07L/beat, then CO = 72 beats/min X 0.07L/min = 5.0 L/min
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Autonomic innervation of the heartCirculatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪ACh
▪↑APs interval of pacemaker cells →↓ HR–Negative chronotropic effect
▪↓Velocity of conduction, may lead to AV▸block → ectopic pacemaker
▪Nor(epinephrine)▸↑ heart rate via pacemaker cells
–Positive chronotropic effect
▸↑ strength of contraction (myocardial cells)–Positive inotropic effect
Circulatory Pumps
Principles of Animal PhysiologyCirculatory Systems
▪Autonomic control of SA node activity and heart rate
Principles of Animal PhysiologyCirculatory Systems
▪Control of cardiac output
Principles of Animal PhysiologyCirculatory Systems
▪Summary of factors influencing cardiac output
Principles of Animal PhysiologyCirculatory Systems
▪Blood pressure in various blood vessels of the systemic circulation
Principles of Animal PhysiologyCirculatory Systems
▪Relation btw. Velocity of blood flow and Xsectional area of vascular tree