09 animal physiology - circulatory systems

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


▪Types of circulatory systemsIntroduction


▪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


▪Circulation in an open systemIntroduction


▪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


▪Ciruclation in a closed systemIntroduction


▪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


▪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


▪Plasma and Hematocrit volumesIntroduction


▪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


▪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


▪ErythrocytesCirculatory Fluids


▪Blood Cell Production (Hemopoiesis)Circulatory Fluids


▪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


▪Types of pumps in animalsCirculatory Pumps


▪Two chambered heartCirculatory Pumps


▪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


▪Dual PumpsCirculatory Pumps


▪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


▪Heart Valves Ensure Unidirectional Blood FlowCirculatory Pumps


▪The Mammalian HeartCirculatory Pumps


▪Blood flow through mammalian heartCirculatory Pumps


▪The Mammalian Ventricles▸Myocardium▸Epicardium▸Epicardium

Circulatory Pumps


▪Mechanism of Valve ActionCirculatory Pumps


▪Organization of Mammalian Cardiac Muscle Fibers

▸Intercalated discs▸Desmosomes▸Gap junctions▸Functional syncytium▸Myoglobin

Circulatory Pumps


▪Conducting Pathway in Mammalian Heart▸SA node▸Internodal pathway▸AV node▸Bundle of His▸Left & Right bundle branches▸Purkinje fibers

Circulatory Pumps


▪Conducting Pathway in Mammalian HeartCirculatory Pumps


▪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


▪Pacemaker Activity of Cardiac Autorhythmic CellsCirculatory Pumps


▪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


▪Action Potential and Tension Development in Cardiac Contractile Muscle Cell

▸Refractory period▸Tetanus

Circulatory Pumps


▪Action Potential of Contractile Cardiac Muscle CellsCirculatory Pumps


▪Comparison of action potential in different regions of the heart

Circulatory Pumps


▪The ElectrocardiogramCirculatory Pumps


▪Mechanical Events of Mammalian Cardiac CycleCirculatory Pumps


▪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


▪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


▪Autonomic innervation of the heartCirculatory Pumps


▪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


▪Autonomic control of SA node activity and heart rate


▪Control of cardiac output


▪Summary of factors influencing cardiac output


▪Blood pressure in various blood vessels of the systemic circulation


▪Relation btw. Velocity of blood flow and Xsectional area of vascular tree

09 animal physiology - circulatory systems

Documents

cells blood

circulatory fluidsplasmawatery

circulatory fluidscontains

fluid aroundconduits

immune functions

immune responsethrombocytes

skeletal pumpsfluid

ribosomescontain plasma