Download Cardiovascular System

The Cardiovascular System
 A closed system of the heart and blood
vessels
 function - transportation
- oxygen, nutrients
- carbon dioxide, wastes
- heat, hormones
- defensive cells
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Blood Circulation
Figure 11.3
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Blood Vessels: The Vascular System
 Taking blood to the tissues and back
 Arteries
 Arterioles
 Capillaries
 Venules
 Veins
Figure 11.8a
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The Vascular System
Three layers: endothelium, middle, outer layer
Middle layer is smooth muscle
Figure 11.8b
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Capillary Exchange
 Fluid forced out by
blood pressure
 Plasma proteins,blood
cells retained in blood
 Osmotic pressure brings
fluid back into capillary
 Excess tissue fluid
collected into lymphatic
system, returned to
blood
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Capillary Exchange: Mechanisms
 Direct diffusion across plasma membranes
 Endocytosis or exocytosis
 intercellular slits = gaps
 Plasma membrane
not joined by
tight junctions
 Pores
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Blood Vessels
 Venous system
 three layers, thin-walled
 carry blood toward the heart
 Mechanisms in blood return
 Contraction of skeletal
muscles
 One-way valves
 Pressure changes associated
with breathing
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Arterioles and Capillaries
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Figure 8.2
The Heart
Fist-sized; placed between lungs
Figure 11.1
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The Heart: Heart Wall
 Three layers
 Epicardium
 visceral pericardium
 Connective tissue layer
 Myocardium
 Mostly cardiac muscle
 Endocardium
 Endothelium
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The Heart: Chambers
 Right and left side act as separate pumps
 Four chambers
 Atria
 Receiving chambers
 Right atrium
 Left atrium
 Ventricles
 Discharging chambers
 Right ventricle
 Left ventricle
Figure 11.2c
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The Heart: Associated Great Vessels
 Aorta
 Leaves left ventricle
 Pulmonary arteries
 Leave right ventricle
 Vena cava
 Enters right atrium
 Pulmonary veins (four)
 Enter left atrium
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The Heart: Valves
 Allow blood to flow in only one direction
 Four valves
 Atrioventricular valves – between atria and ventricles
 Semilunar valves between ventricle and artery
 Valves open as blood
is pumped through
 AV held in place by
chordae tendineae
(“heart strings”)
 prevent backflow
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Operation of Heart Valves
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Fig 11.4
The Heart
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Figure 8.8
External Heart Anatomy
Figure 11.2a
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The Heart: Conduction System
 Intrinsic conduction system
(nodal system)
 Heart muscle cells contract, without nerve
impulses, in a regular, continuous way
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The Heart: Conduction System
 Special tissue sets the
pace
 Sinoatrial node
 Pacemaker
 Atrioventricular node
 Atrioventricular
bundle
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Electrocardiograms (EKG/ECG)
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Figure 8.15b,c
Filling of Heart Chambers – the Cardiac
Cycle
Figure 11.6
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Pulse
 Pulse – pressure wave
of blood
 Monitored at
“pressure points”
where pulse is easily
palpated
Figure 11.16
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The Heart: Cardiac Output
 Cardiac output (CO)
 Amount of blood pumped by each side of the
heart in one minute
 CO = (heart rate [HR]) x (stroke volume [SV])
 Stroke volume
 Volume of blood pumped by each ventricle in
one contraction
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The Heart: Regulation of Heart Rate
 Decreased heart rate
 Parasympathetic nervous system
 High blood pressure or blood volume
 Decreased venous return
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Cardiac Output Regulation
Figure 11.7
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Regulation of the Cardiovascular System
 Baroreceptors: pressure receptors in aorta and
carotid arteries
 BP rises, vessels stretched, signals sent to brain
 Heart lowers heart rate and force of contraction
 Arterioles vasodilate, increasing blood flow to tissues
 Neural factors - medulla oblongata
 Sympathetic nerves: constrict blood vessels
 Parasympathetic nerves: dilate blood vessels
 Hormones: epinephrine (adrenaline)
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Measuring Arterial Blood Pressure
Systolic – pressure at the
peak of ventricular
contraction
Diastolic –
pressure when
ventricles relax
Figure 11.18
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Variations in Blood Pressure
Normal range is variable
 140–110 mm Hg systolic
 80–75 mm Hg diastolic
 Hypotension
 Low systolic (below 100 mm HG)
 Often associated with illness
 Hypertension
 High systolic (above 140 mm HG)
 Can be dangerous if it is chronic
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Regulation of Blood Pressure
Renal factors (kidneys) - alter blood volume
Renin – stimulates hormonal control
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Blood Pressure: Effects of Factors
 Temperature
 Heat - vasodilation effect
 Cold - vasoconstricting effect
 Chemicals
 Various substances can cause increases or
decreases
 Diet
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Atherosclerosis
 Buildup of plaques on inner wall of arteries
 Source - injury from chemicals, physical
blow or pressure.
injured cells attract lipid deposits, muscle
cells which block lumen of vessel
Arteriosclerosis - hardening, loss of elasticity in
wall as cells die, fibers degenerate, rigid scar
tissue replaces elastic cells.
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Cardiovascular Disorders
 Angina pectoris: a warning
 Myocardial infarction (heart attack):
permanent cardiac damage
 Congestive heart failure: decrease in pumping
efficiency
 Embolism: blockage of blood vessels
 Stroke: impaired blood flow to the brain
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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
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings