Functions of Cardiovascular systemHeartSlide 3Slide 4CapillariesVenous SystemBloodBlood Cell CompositionBlood AnalysisSpleenFunction During ExerciseSlide 12Slide 13Functions of Cardiovascular systemsystem circulates blood throughout body•transports energy substrates (glucose, FA, ect.), electrolytes and hormones to tissues•removes waste productslactate, CO2 & H2OthermoregulationHeartheart rate mass:•average 1.0%•untrained horse 0.94%•trained 1.1%greyhound•heart size of a clenched fist •located in the chest•weighs about 1% of its BWHeartlocated in thoracic cavityapprox. 9-10 lbs (1% of BW)split into left and right halves•both contain an atria and a ventricle•left side circulates blood to systemic system•right side circulates blood to the pulmonary systemsystole - contractiondiastole - relaxationaorta has elastic wallspulse •expand during systole•recoil during diastolearteries/arterioles have muscular walls allowing for vasoconstriction and vasodilation•blood pressure increases when the walls of the arteries constrictCapillariesConstructed of permeable wallssight of gas, nutrient and waste product exchange•pulmonary capillaries discard CO2 and extract O2 from the alveoli of the lungscapillaries are very small in diameter•RBC flow through single file (blood is sluggish if the PCV is high)conditioning (training) can increase capillary density 50% •provides more efficient O2 deliveryVenous Systemvenules and veins have lower blood pressure than arterieshorse legs have valves to provide unidirectional blood flow in veinsvenous flow depends on muscle contractions•activity provides better venous blood movement•inactive - blood pools in extremities“stocking-up”•accumulation of fluid in legsBlood10% of horse BW of about 40 liters at rest•pulmonary circulation 20%•heart, arteries and arterioles 15%•venules and veins 60%blood is comprised of plasma and cells•plasma:55% of the total blood volume91% water and 9% solids (proteins)•albumin, globulin and fibrinogenBlood Cell Compositionred blood cells (RBC) - erythrocytes - contain hemoglobin•manufactured from bone marrow•life span of 100-120 dayswhite blood cells (WBC) - leukocytes - fight infection•manufactured in the spleen•renewed every 10 days•5 typesneutrophils (50-60%), eosinophils (2-5%), basophils (<1%), monocytes (5-6%), lymphocytes (30-40%)platelets - thrombocytes - clot blood•life span of 5-9 daysBlood Analysisblood scan: 5 minutes•for major changes from normal (PCV, total protein, hemoglobin and estimate white blood cell count)full blood count: 30 minutes•main count of WBC’s to detect infection, stress, allergies, ect.blood profile: 24 hours•detailed RBC count, individual WBC counts, enzymes, electrolytes, ect.Plasma - fluid spun from unclotted bloodserum - blood is allowed to clot and fluid is spun from the clot (contains no fibrinogen)SpleenAbout 1% of BWsplenic contraction•1/3 to 1/2 RBC stored in spleen at rest•hematocrit or packed cell volume (PCV)rest 35-45%maximum 60-65%•hemoglobin content of extra RBC in the blood acts as a pH buffer, enabling horses to tolerate extremely high blood lactate concentrationsFunction During ExerciseHeart rate - bpm•resting HR 25-45 bpm•maximal HR 240 bpmdesirable cardiovascular features•large, muscular heart•low resting HR•high maximal HRHR: 20-110 •not very predictableintensity of work•120 (low),160 (moderate), 200 (intense)steady state 2-3 minutes•regulated by sympathetic nervous activity and/or hormonessteady state constant during sub-maximal workcontinual increase in HR with intense exercise (warm-up)monitor HR - indication of any problemsFatigue•170 bpm 24 min•205 bpm 4 mincardiovascular