Heart and Blood Vessels

Major Arteries and Veins

Subclavian arterySubclavian vein

Jugular veinCarotid arterySuperiorvena cava

Inferiorvena cava

Commoniliac veinCommoniliac artery

Femoral artery

Great saphenous vein

Renal arteryRenal vein

Aorta

Femoral vein

Blood Vessels—Arterial SystemStructure: endothelium, middle, outer layersFunctions

Arteries carry blood away from heartArterioles and precapillary sphincters control

pressureCapillaries exchange nutrients, waste, and

defensive cells between vessel and tissue

Arterioles and Capillaries

Capillary Structure

Blood Vessels—Venous SystemStructure: three layers, thin-walledFunctions: carry blood toward the heartMechanisms in blood return

Contraction of skeletal musclesOne-way valvesPressure changes associated with breathing

Blood Vessels—Venous System

Blood Vessels—Summary

Inner layer:Endothelium

Middle layer:Smooth musclewith elasticfibers

Outer layer:Connectivetissue

Connective tissue

Endothelium

Vein

Venule

Artery

Arteriole

Capillary

Direction ofblood flow

Tissuecells

Epithelial cells ofcapillary endothelium

Smooth muscle

Lymphatic SystemFunction

Maintains blood volumeAlso functions in immune system

StructureBlind-ended capillariesLymphatic vesselsLymph is the circulating fluid

The Heart

Figure 8.7

Superior vena cava

Pulmonarysemilunar valveRight atrium

Right AV valveRight ventricle

Inferior vena cava

Pulmonary trunk

Left pulmonary veins

Left atrium

Left AV valve

Aortic semilunar valve

Chordae tendineae

Papillary muscles

Left ventricle

Septum

Right pulmonary artery

Left pulmonary artery

Aorta

The HeartStructureLayers: epicardium, myocardium, and

endocardiumChambers: two atrias, two ventriclesValves

Two atrioventricular valves: tricuspid and bicuspid (mitral)

Two semilunar valves: pulmonary and aortic

Pulmonary Circuit—Oxygenation of Blood Pathway

Deoxygenated blood from the body into heart1. Through the vena cava to the right atrium2. Through the right atrioventricular valve to the

right ventricle3. Through the pulmonary semilunar valve to the

pulmonary trunk and the lungs

Pulmonary Circuit—Oxygenation of Blood Pathway

Oxygenated blood from lungs to heart1. Through the pulmonary veins to the left atrium2. Through the left atrioventricular valve to the

left ventricle

Systemic Circuit—Delivery of Oxygenated Blood to Tissues

Pathway Oxygenated blood from the heart to tissues

1. Through the aortic semilunar valve to the aorta2. Through branching arteries and arterioles to

tissues3. Through the arterioles to capillaries

Systemic Circuit: Return of Blood to the Heart

Pathway Deoxygenated blood returns to heart

1. From capillaries into venules and veins2. To the vena cava and into the right atrium

Pulmonary and Systemic Circuits

Subclavian arterySubclavian vein

Jugular veinCarotid arterySuperiorvena cava

Inferiorvena cava

Commoniliac veinCommoniliac artery

Femoral artery

Great saphenous vein

Renal arteryRenal vein

Aorta

Femoral vein

Cardiac Cycle

Heart Sounds and Heart ValvesLub-dub (typical heart beat)

Sounds are valves closingHeart murmurs

Cardiac Conduction System Coordinates Contraction

SA node: cardiac pacemaker

AV node: relays impulse

AV bundle and Purkinje fibers: carry impulse to ventricles

Electrocardiograms (EKG/ECG)Measure the electrical impulses of the heartThree formations

P wave: impulse across atriaQRS complex: spread of impulse down septum,

around ventricles in Purkinje fibersT wave: end of electrical activity in ventricles

Arrythmias, ventricular fibrillation can be detected

Electrocardiograms (EKG/ECG) (cont.)

Blood PressureDefinitions

Systolic pressureDiastolic pressure

MeasurementSphygmomanometerWhat’s a “normal” reading? What would be considered “high” or “low”

blood pressure?

How Blood Pressure is Measured

Figure 8.16

Blood Pressure (cont.)Hypertension: high blood pressure

The silent killerHypotension: blood pressure too low

Clinical signs: dizziness, faintingCauses: orthostatic, severe burns, blood loss

Regulation of the Cardiovascular System: Baroreceptors

Baroreceptors: pressure receptors in aorta and carotid arteries

Steps in mechanism1. Blood pressure rises, vessels stretched2. Signals sent to brain in the cardiovascular

center3. Heart signaled to lower heart rate and force of

contraction4. Arterioles vasodilate, increasing blood flow to

tissues5. Combined effect lowers blood pressure

Regulation: Nervous and Endocrine FactorsCentral Nervous System signals

Sympathetic nerves: constrict blood vessels, raising blood pressure

Parasympathetic nerves: dilate blood vessels, lowering blood pressure

Hormones: epinephrine (adrenaline)Local requirements dictate local blood flowExercise: increased blood flow and cardiac

output

Cardiovascular DisordersAngina pectoris: a warning, chest painMyocardial infarction/heart attack:

permanent cardiac damageCongestive heart failure: decrease in

pumping efficiencyEmbolism: blockage of blood vesselsStroke: impaired blood flow to the brain

Reducing the Risk of Cardiovascular DiseaseSmoking: don’t Blood lipids: monitor cholesterol levelsExercise: regular and moderateBlood pressure: treat hypertension

Reducing the Risk of Cardiovascular Disease (cont.)

Weight: being overweight increases risk of heart attack and stroke

Control of diabetes mellitus: early diagnosis and treatment delays onset of related problems

Stress: avoid chronic stress

Cardiac Anatomy Practice