Chapter 12
Lecture Slides
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Learning Outcomes
• Anatomy of the Heart
1. Identify the protective coverings of the heart.
2. Identify the parts of the heart and describe their
functions.
• Cardiac Cycle
3. Describe the events of the cardiac cycle.
4. Trace the flow of blood through the heart.
• Heart Conduction System
5. Identify parts of the heart conduction system and
describe their functions.
Learning Outcomes
• Regulation of Heart Function
6. Explain how the heart rate is regulated.
• Types of Blood Vessels
7. Describe the structure and function of arteries,
arterioles, capillaries, venules, and veins.
8. Describe how materials are exchanged between
capillary blood and interstitial fluid.
• Blood Flow
9. Describe the mechanism of blood circulation.
Learning Outcomes
• Blood Pressure
10. Compare systolic and diastolic blood pressure.
11. Describe how blood pressure is regulated.
• Circulation Pathways
12. Compare the systemic and pulmonary circuits.
• Systemic Arteries
13. Identify the major systemic arteries and the organs or
body regions that they supply.
Learning Outcomes
• Systemic Veins
14. Identify the major systemic veins and the organs or
body regions that they drain.
• Disorders of the Heart and Blood Vessels
15. Describe the common disorders of the heart and blood
vessels.
• Heart and blood
vessels are part of the
cardiovascular system
• Heart pumps blood
• Arteries carry blood
away from the heart to
capillaries
• Veins carry blood from
capillaries to heart
12.1 Anatomy of the Heart
• Four chambered muscular pump
• Lies between the lungs, superior to the
diaphragm
• Pointed apex extends to left side at
level of 5th rib
• Protective Coverings
– Pericardium surrounds the heart and
associated blood vessels
– Parietal and visceral pericardia are
serous membranes
• Secrete serous fluid into pericardial
cavity
• Functions to reduce friction during
contraction
– Parietal and visceral pericardia are
serous membranes
• Secrete serous fluid into pericardial
cavity
• Functions to reduce friction during
contraction
• The Heart Wall
– Myocardium
• Layer of cardiac muscle
• Provides force for contraction
– Epicardium (visceral pericardium)
• Outer most layer
• Contains blood vessels that nourish the heart
– Endocardium
• Inner layer
• Heart Chambers
– 2 atria
• Receive blood
from veins
– 2 ventricles
• Pump blood to
arteries
– Interventricular
septum
– Heart is a double pump
• Left atria and ventricle: left pump
• Right atria and ventricle: right pump
– Differences in wall thickness depend upon
work performed by the chamber
• Ventricles have more muscle then atria: atria
pump to ventricle, ventricles pump out to
body areas
• Left ventricle is most muscular: pumps blood
to body
• Right ventricle has less muscle: pumps blood
to lungs only
• Heart Valves
– Blood flows in one direction through the heart
due to valves
– Atrioventricular valves
• Prevents backflow
• Tricuspid valve: between R atrium and R
ventricle
• Bicuspid valve (or mitral valve): between L
atrium and L ventricle
– Semilunar valves
• Pulmonary semilunar valve: between R
ventricle and pulmonary trunk
• Aortic semilunar valve: between L ventricle
and aorta
12.2 Cardiac Cycle
• Includes:
– Systole: contraction phase
– Diastole: relaxation phase
• Flow of Blood Through the Heart
– Two basic circuits of blood flow
• Pulmonary circuit
– Deoxygenated blood flows from R ventricle
to lungs
– Oxygenated blood flows from lungs to L
atrium
• Systemic Circuit
– Oxygenated blood flows L ventricle to body
– Deoxygenated blood flows from body to R
atrium
• Steps of heart circulation
– Superior and inferior vena cava return
blood from body to R atrium
– Pulmonary veins return blood from lungs to
R atrium
– Atria push blood into ventricles
– R ventricle pumps blood into pulmonary
trunk
• Blood moves into R and L pulmonary arteries,
which head to lungs
– L ventricle pumps blood into the aorta,
which carries blood out to body
12.3 Heart Conduction System
• Conduction system consists of
specialized muscle tissue that acts as
neural tissue
– Spontaneously form impulses
– Impulses cause myocardium to contract
• Components include
– Sinoatrial (SA) node
– Atrioventricular (AV) node
– AV bundle
– Purkinje fibers
• Sinoatrial node
– Pacemaker of the heart
– Rhythmically forms impulses to initiate
each heartbeat
– Impulses cause simultaneous contraction
of atria
• Atrioventricular node
– Receives impulse from SA node
– Delay in passing through node allows time
for ventricular filling and the completion or
atrial contraction
– Passes impulse to the AV bundle
• AV bundle
– Divides into L and R branches
– Carries impulse down ventricular septum
and up lateral ventricle walls
– Forms Purkinje fibers
• Purkinje fibers
– Carry impulse to myocardium of ventricles
– Contraction occurs from the apex upward
• Electrocardiogram (ECG or EKG)
– Recording of the electrical current
generated during heart contraction
– Performed by an electrocardiograph
– Electrocardiogram has three distinct waves
• P wave: atrial depolarization
• QRS wave: ventricular depolarization
• T wave: ventricular repolarization
• Other factors affecting heart rate
– Age: resting rate declines with age
– Sex: females slightly faster than
males
– Physical condition: good condition
means lower heart rate
– Temperature: increase in temperature
increases rate
– Epinephrine: increases strengthens heart
rate
– Thyroxine: produces a lesser but longer
lasting increase in heart rate
– Blood calcium levels
• Low levels slow heart rate
• Increased levels increase heart rate and
prolong contraction
– Blood potassium levels
• Increased layers decrease both heart rate and
force of contraction
• Low levels can cause abnormal heart rhythms
• Arteries
– Carry blood away from the heart
– Branch into smaller arteries, eventually
forming arterioles
• Play an important role in controlling blood flow
and blood pressure
12.7 Blood Pressure
• Arterial blood pressure in the systemic
circuit
– Systolic blood pressure
• Highest pressure during ventricular systole
– Diastolic blood pressure
• Lowest pressure during ventricular diastole
• Factors Affecting Blood Pressure
– Cardiac output
• Volume of blood pumped by heart in one
minute
– Determined by heart rate and blood volume pumped
in contraction
• Increase cardiac output, increase blood
pressure
• Decrease cardiac output, decrease blood
pressure
– Blood volume
• Decrease in blood volume, decrease in blood
pressure
• Increase in blood volume, increase in blood
pressure
– Peripheral resistance
• Friction of blood against blood vessel walls
• Constriction of arterioles increase both
resistance and blood pressure
• Dilation of arterioles decreases both resistance
and blood pressure
12.11 Disorders of the Heart
and Blood Vessels
• Grouped into
– Heart disorders
– Blood vessel disorders
Heart Disorders
• Arrhythmia
– Abnormal heart beat
– Caused by factors such as damage to
conduction system and drugs
– Includes:
• Bradycardia
– Heart rate less then 60 beats/min
• Tachycardia
– Heart rate over 100 beats/min
• Heart flutter
– Heart rate over 200-300 beats/min
• Fibrillation
– Very rapid heart rate with uncoordinated contraction
– Blood is not pumped from ventricles
• Congestive heart failure (CHF)
– Acute or chronic inability of hear to pump
out returned to it
– Symptoms include fatigue, edema,
accumulation of blood in organs
– Possible cause is atherosclerosis
• Heart murmurs
– Unusual heart sounds associated with
defective heart valves
• Myocardial infarction
– Death of myocardium due to coronary
artery blockage
– Heart attack
• Pericarditis
– Inflammation of pericardium due to viral or
bacterial infection
Blood Vessel Disorders
• Aneurysm
– Weakened vessel wall bulges, forming
balloon-like sac filled with blood
– Rupture can be fatal
• Arteriosclerosis
– Hardening of the arteries
– Due to calcium deposits accumulating in
tunica media
• Atherosclerosis
– Formation of fatty deposits in the tunica
interna of arteries
– Plagues reduce lumen size and increase
probability of blood clot formation
• Hypertension
– Chronic high blood pressure
– Pressure exceeds 140/90
– Pre-hypertension
• A systolic pressure between 120-139 and
diastolic pressure between 80-89
– Causes include stress and smoking
• Phlebitis
– Inflammation of a vein
– Most common in the legs
– Thrombophlebitis involves the formation
of blood clots at the inflammation site
• Varicose veins
– Dilated, swollen veins due to
malfunctioning valves
– Causes include heredity, pregnancy, and
lack of physical activity
– Hemorrhoids