the cardiovascular system ch. 18,19. introduction cardiovascular system –heart –blood vessels...
TRANSCRIPT
The Cardiovascular System
The Cardiovascular System
Ch. 18,19Ch. 18,19
IntroductionIntroduction
• Cardiovascular system– Heart– Blood vessels
• Arteries• Capillaries• Veins
• Cardiovascular system– Heart– Blood vessels
• Arteries• Capillaries• Veins
Heart anatomyHeart anatomy
Structure of the heartStructure of the heart• Description-
hollow, cone-shaped, muscular pump
• 12 cm by 9 cm• Located behind
sternum, within mediastinum (space)
• Description-hollow, cone-shaped, muscular pump
• 12 cm by 9 cm• Located behind
sternum, within mediastinum (space)
Coverings of the heartCoverings of the heart• Pericardium – encloses heart –
tough connective tissue.• Fibrous pericardium surrounds
visceral serous pericardium.– Visceral pericardium- surrounds heart– Parietal pericardium-lines the cavity
• Paricardial cavity- space containing serous fluid between parietal and visceral pericardium – contains serous fluid
• Pericardium – encloses heart – tough connective tissue.
• Fibrous pericardium surrounds visceral serous pericardium.
– Visceral pericardium- surrounds heart– Parietal pericardium-lines the cavity
• Paricardial cavity- space containing serous fluid between parietal and visceral pericardium – contains serous fluid
Wall of the heartWall of the heart• 3 layers
– Epicardium-outermost layer• Connective tissue
and epithelium – contains blood vessels and lymph vessels
– Myocardium – cardiac muscle, middle layer
– Endocardium – innermost layer, contains nervous tissue for control of the heart.
• 3 layers– Epicardium-
outermost layer• Connective tissue
and epithelium – contains blood vessels and lymph vessels
– Myocardium – cardiac muscle, middle layer
– Endocardium – innermost layer, contains nervous tissue for control of the heart.
Skeleton of the heartSkeleton of the heart
• Rings of dense connective tissue• Surround pulmonary trunk and
aorta
• Rings of dense connective tissue• Surround pulmonary trunk and
aorta
Heart chambers and valves
Heart chambers and valves• Chambers
– Atria– Ventricles
• Septum • Atrioventricular (AV)
valve– Tricuspid– Bicuspid or mitral
• Cordae tendinae• Pulmonary valves• Aortic valve
• Chambers– Atria– Ventricles
• Septum • Atrioventricular (AV)
valve– Tricuspid– Bicuspid or mitral
• Cordae tendinae• Pulmonary valves• Aortic valve
Path of blood through heart
Path of blood through heart
• Inferior or superior vena cava
• Right atrium• Right AV valve• Right ventricle• Pulmonary artery• Pulmonary valve• Lungs
• Inferior or superior vena cava
• Right atrium• Right AV valve• Right ventricle• Pulmonary artery• Pulmonary valve• Lungs
• Pulmonary vein• Left atrium• Left AV valve• Left ventricle• Aorta• Aortic valve• Body
• Pulmonary vein• Left atrium• Left AV valve• Left ventricle• Aorta• Aortic valve• Body
Blood supply to the heartBlood supply to the heart• Branches of aorta, carry
oxygenated blood – right and left coronary arteries – feed heart
• Branches from coronary arteries feed capillaries of myocardium
• Smaller branches of arteries – anastomoses – alternate pathways for blood– Blocked artery – angina
pectoris – myocardial infarction – heart attack
• Cardiac veins- drain blood from heart
• Branches of aorta, carry oxygenated blood – right and left coronary arteries – feed heart
• Branches from coronary arteries feed capillaries of myocardium
• Smaller branches of arteries – anastomoses – alternate pathways for blood– Blocked artery – angina
pectoris – myocardial infarction – heart attack
• Cardiac veins- drain blood from heart
Heart beatingHeart beating
Heart actionsHeart
actions• Cardiac cycle – pressure in
chambers rises/falls with contraction/relaxation of atria and ventricles
• Atria fill, open av valves• Ventricles fill• Valves close• Ventricles contract, blood
goes through pulmonary artery and aorta
• Ventricles relax, valves close in vessels
• Cardiac cycle – pressure in chambers rises/falls with contraction/relaxation of atria and ventricles
• Atria fill, open av valves• Ventricles fill• Valves close• Ventricles contract, blood
goes through pulmonary artery and aorta
• Ventricles relax, valves close in vessels
Heart soundsHeart sounds
• Heart sounds caused by valve closure– First sound (lubb) – ventricles
contract and AV valves close– Second sound (dupp) ventricles relax
and aortic and pulmonary valves close.
• Heart sounds caused by valve closure– First sound (lubb) – ventricles
contract and AV valves close– Second sound (dupp) ventricles relax
and aortic and pulmonary valves close.
Cardiac conduction systemCardiac conduction system• Functional synctium – atrial
and ventricular – mass of fibers that works as a unit
• Cardiac tissue conducts impulses through myocardium – cardiac conduction system.
• Sinoatrial node in right atrium – pacemaker – self exciting
• Impulses spread through atrial synctium then ventricular synctium.
• Purkinje fibers contract tiny muscles attached to chordae tendinae
• Functional synctium – atrial and ventricular – mass of fibers that works as a unit
• Cardiac tissue conducts impulses through myocardium – cardiac conduction system.
• Sinoatrial node in right atrium – pacemaker – self exciting
• Impulses spread through atrial synctium then ventricular synctium.
• Purkinje fibers contract tiny muscles attached to chordae tendinae
ElectrocardiogramElectrocardiogram• ECG – electrical
recording of changes that occur in cardiac cycle
• P wave – depolarization of atria
• QRS complex – depolarization of ventricles
• T wave – ventricular repolarization
• ECG – electrical recording of changes that occur in cardiac cycle
• P wave – depolarization of atria
• QRS complex – depolarization of ventricles
• T wave – ventricular repolarization
Regulation of the cardiac cycle
Regulation of the cardiac cycle
• Amount of blood pumped must adjust according to body needs
• SA node innervated by sympathetic and parasympathetic nervous system divisions so CNS controls heart rate.
• Cardiac control center in medulla oblongata – adjusts heart rate based on blood pressure measurements from baro receptors.
• Cerebrum/hypothalamus influence heart rate as well
• Amount of blood pumped must adjust according to body needs
• SA node innervated by sympathetic and parasympathetic nervous system divisions so CNS controls heart rate.
• Cardiac control center in medulla oblongata – adjusts heart rate based on blood pressure measurements from baro receptors.
• Cerebrum/hypothalamus influence heart rate as well
Blood vesselsBlood vessels• Blood vessels
– include:Arteries , arterioles, capillaries, venules, veins
• Create closed system – carries blood away from heart to cells in body then back to the heart.
• Blood vessels– include:Arteries ,
arterioles, capillaries, venules, veins
• Create closed system – carries blood away from heart to cells in body then back to the heart.
Arteries and veinsArteries and veins• Arteries –strong, elastic• Divide into arterioles• Wall of artery - smooth
muscles and connective tissue• Capable of
vasoconstriction/vasodilation – increases/decreases blood flow/pressure
• Clogged vessels – artherosclerosis – diets high in fat– Diets high in
fruits/vegetables=add phyto sterols to blood – scour out plaque deposits
• Arteries –strong, elastic• Divide into arterioles• Wall of artery - smooth
muscles and connective tissue• Capable of
vasoconstriction/vasodilation – increases/decreases blood flow/pressure
• Clogged vessels – artherosclerosis – diets high in fat– Diets high in
fruits/vegetables=add phyto sterols to blood – scour out plaque deposits
capillariescapillaries• Smallest vessels – layer of
endothelium– Allows substances to be
exchanged with cells– More permeability in
capillaries of liver, intestines, glands
– More metabolic activity – higher number of capillaries
– Precapillary sphincters – regulate amount of blood entering capillary bed
– Capillary beds can close down if more is needed elsewhere.
• Smallest vessels – layer of endothelium– Allows substances to be
exchanged with cells– More permeability in
capillaries of liver, intestines, glands
– More metabolic activity – higher number of capillaries
– Precapillary sphincters – regulate amount of blood entering capillary bed
– Capillary beds can close down if more is needed elsewhere.
Exchanges in the capillaries
Exchanges in the capillaries• Blood in capillaries – high
oxygen/nutrients• Diffuse through wall to
tissue• Plasma proteins stay in
capillary• Hydrostatic pressure –
drives passage of fluids/small molecules.
• Osmosis causes tissue fluid to return to blood
• Lymphatic vessels collect extra fluid and return it to circulation
• Blood in capillaries – high oxygen/nutrients
• Diffuse through wall to tissue
• Plasma proteins stay in capillary
• Hydrostatic pressure – drives passage of fluids/small molecules.
• Osmosis causes tissue fluid to return to blood
• Lymphatic vessels collect extra fluid and return it to circulation
Venules and veinsVenules and veins• Venules – lead from
capillaries – merge to form veins – veins return blood to heart.
• 3 layers with valves to prevent backflow
• Thinner, less muscular than arteries
• No high pressure blood• Function as blood reservoirs
• Venules – lead from capillaries – merge to form veins – veins return blood to heart.
• 3 layers with valves to prevent backflow
• Thinner, less muscular than arteries
• No high pressure blood• Function as blood reservoirs
Blood circulationBlood circulation
Paths of circulationPaths of circulation
• Two divisions– Pulmonary circuit – right
ventricle through pulmonary artery to lungs, then pulmonary veins to left atrium.
– Systemic circuit – carries blood from left ventricle through aorta to body cells and back through veins into the left atrium
• Two divisions– Pulmonary circuit – right
ventricle through pulmonary artery to lungs, then pulmonary veins to left atrium.
– Systemic circuit – carries blood from left ventricle through aorta to body cells and back through veins into the left atrium
Arterial systemArterial system
Venous systemVenous system
Blood pressureBlood pressure
• Factors that affect blood pressure– Heart action– Blood volume– Peripheral resistance– Blood viscosity
• Factors that affect blood pressure– Heart action– Blood volume– Peripheral resistance– Blood viscosity
Control of blood pressureControl of blood pressure
• adjusting Cardiac output and Peripheral resistance
• If blood pressure increases, heart rate slows and blood vessels dilate
• If BP drops, heart rate increases and blood vessels constrict.
• Vasomotor center of medulla oblongata controls
• adjusting Cardiac output and Peripheral resistance
• If blood pressure increases, heart rate slows and blood vessels dilate
• If BP drops, heart rate increases and blood vessels constrict.
• Vasomotor center of medulla oblongata controls
Fetal circulationFetal circulation• Two umbilical arteries – carry blood to placenta• Placenta – structure attached to uterine wall – substances
exchanged between blood of mother and baby• Umbilical vein – returns blood from placenta to baby.• Ductus venosus – returns blood from placenta to inferior
vena cava, bypassing liver• Foramen ovale – opening in septum between right and left
atria that allows most of blood to bypass fetal lungs• Ductus arteriosus-small vessel connecting pulmonary
artery with descending aorta, allows more blood to bypass fetal lungs
• After birth: Ovale closes, Ductus arteriosus contracts
• Two umbilical arteries – carry blood to placenta• Placenta – structure attached to uterine wall – substances
exchanged between blood of mother and baby• Umbilical vein – returns blood from placenta to baby.• Ductus venosus – returns blood from placenta to inferior
vena cava, bypassing liver• Foramen ovale – opening in septum between right and left
atria that allows most of blood to bypass fetal lungs• Ductus arteriosus-small vessel connecting pulmonary
artery with descending aorta, allows more blood to bypass fetal lungs
• After birth: Ovale closes, Ductus arteriosus contracts
Changes after birthChanges after birth