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