Download Pulmonary artery

The Circulatory System
Chapter 12
The Heart
and
Vascular System
The Human Circulatory System
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4 chambered heart
Arteries
Capillaries
Veins
Arteries
• Thick muscular vessels carrying blood
away from heart
• carry oxygenated blood
– Exception- pulmonary artery (to lungs)
Capillaries
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thin walled (one cell layer) vessels
arise from arterioles (tiny arteries)
form capillary beds
all exchange between blood & cells occurs here
Capillary Structure
Figure 8.4
Veins
• Venules receive blood from the capillaries
• Veins carry low O2 blood to heart
– Exception- pulmonary vein carries oxygenated blood
• Thin walled & flattened
• Nearer to body surface than arteries
Movement through veins assisted by:
1)
one way flap-like valves allow blood to move in one
direction (toward heart)
1)
some smooth muscle around larger veins that
contracts and moves blood
1)
limb and breathing movements literally massages
veins and squeezes blood along
Arterioles and Capillaries
Figure 8.2
Circulation Through Human Heart
Body blood enters RIGHT SIDE of HEART
Right atrium ----> right ventricle ----> Pulmonary artery
----> alveoli in lungs----> oxygenated blood --> Pulmonary
Veins ---->
Left Atrium. ----> Left Ventricle ----> blood leaves through
Aorta (first artery) ---> flows to body
The Heart
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Structure
Layers; epicardium, myocardium, endocardium
Chambers: two atrias, two ventricles
Valves
– Two atrioventricular valves: tricuspid and
bicuspid (mitral)
– Two semilunar valves: pulmonary and aortic
The Heart
Figure 8.8
Pulmonary Circuit: Oxygenation of
Blood
– Deoxygenated blood through the vena cava to the
right atrium
– through the right atrioventricular or Tricuspid valve
to the right ventricle
– through the pulmonary semilunar valve to the
pulmonary trunk and the lungs
– Oxygenated blood through the pulmonary veins to the
left atrium
– Oxygenated blood through the left atrioventricular or
mitral valve to the left ventricle
Systemic Circuit: Delivery of
Oxygenated Blood to Tissues and Return
of Blood to the Heart
– Oxygenated blood through the aortic semilunar valve
to the aorta
– Oxygenated blood through branching arteries and
arterioles to the tissues
– Oxygenated blood through the arterioles to capillaries
– Deoxygenated blood from capillaries into venules and
veins
– Ultimately to the superior and inferior vena cava and
into the right atrium
Cardiac Cycle
Figure 8.12
Heart Sounds and Heart Valves
• Lub-dub- due to pressure changes that occur
when the chambers contract and the valves close
• “Lub”- Ventricles contract the the tricuspid and
mitral valves close
• “Dub”- when the semilunar (aortic and
pulmonary) valves close and the ventricles relax
• Heart murmurs- slush sound after the lub due to
ineffective valves that allow blood to pass back
in the atria after the valves close
• Video
Cardiac Conduction System
Coordinates Contraction
• SA node: cardiac
pacemaker
• AV node: relay
impulse
• AV bundle and
Purkinje fibers:
carry impulse to
ventricles
Figure 8.14
Electrocardiograms (EKG/ECG)
• Three formations
– P wave: impulse across atria
– QRS complex: spread of impulse down septum,
around ventricles in Purkinje fibers
– T wave: end of electrical activity in ventricles
• Arrhythmia, abnormal rhythm
• Ventricular fibrillation- rapid and uncoordinated
contractions common during heart attacks
• Bradycardia: fewer than 60 beats per minute
• Tachycardia: more than 100 beats per minute
Electrocardiograms
(EKG/ECG)
P- depolarization of the
atrium. Atria contract due to
the impulse sent from the SA
node ( the pace maker)
QRS complex- depolarization
of the ventricles. They
contracts as the Purkenje
fibers carry the electrical
impulse.
T- represent the repolarization
of the ventricles.
ECG show the length of a
heartbeat
Figure 8.15B, C
Blood Pressure
• Definitions: “normal”
– Systolic pressure- contraction
– Diastolic pressure- relaxed
• Measurement: sphygmomanometer
Cardiovascular Disorders
• Atherosclerosis: accumulation of fatty materials
aka: plaque
• Angina pectoris: chest pain radiating in the left
arm
• Myocardial infarction/heart attack: permanent
cardiac damage
• Congestive heart failure: decrease in pumping
efficiency
• Embolism: blood clot
• Stroke: impaired blood flow to the brain
Cardiac Anatomy Quiz
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Test Yourself, page 172
Reducing the Risk of Cardiovascular
Disease
• Smoking: Don’t
• Blood lipids: monitor cholesterol levels
• Exercise: regular and moderate
• Blood pressure: treat hypertension
• 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