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Warm-Up
1.
What is the pacemaker? Where is it located?
2.
List the parts of the intrinsic conduction system of the
heart.
3.
Draw and label the 3 waves of a typical EKG tracing.
What is happening at each wave?
4.
What causes the heart sounds (lub-dub)?
Warm-Up
1.
Compare arteries, capillaries, & veins.
2.
Imagine you are a red blood cell. List the pathway you
would travel through the body in a complete circuit
starting at a pinky toe.
3.
Explain how blood pressure is measured.
Warm-Up
1.
What is hypertension? What are possible causes?
2.
What is atherosclerosis?
3.
What can you do to prevent atherosclerosis?
4.
What treatment options are available for patients with
coronary atherosclerosis?
Warm-Up


Draw the human heart and the main blood vessels
in/out of the heart.
Label the following on your diagram:

4 chambers

4 valves

All blood vessels going into/out of heart

Using a blue pencil, indicate oxygen-poor blood flow

Using a red pencil, indicate oxygen-rich blood flow
Chapter 13 Cardiovascular
System
Major Functions

Transport O2 and nutrients to tissues

Remove wastes from tissues
Anatomy and Location of Heart

Size of fist

Weight < 1 lb.

Within mediastinum of thoracic cavity

Apex points toward left hip

Flanked by lungs

Surrounded by pericardium (double-walled
sac)
Pericardium – encloses the heart

3 layers
 Fibrous

pericardium - outer layer; attached to diaphragm
 Visceral
pericardium - inner layer; covers heart
 Parietal
pericardium - inner lining of the fibrous pericardium
Pericardial Cavity
 Space
between parietal and visceral pericardium filled with
serous fluid to reduce friction during heart contractions
 Pericarditis
– inflammation of pericardium
Pericarditis
Layers of the Heart Wall
1. Epicardium –
outer layer
(pericardium)
Heart chamber
2. Myocardium –
cardiac muscle
3. Endocardium –
endothelium lines
chambers
Heart Chambers
Right Side

Atrium (R & L): receive blood
(entryway)

Ventricle (R & L): pump blood
out

Septum: wall between atria &
ventricles

Valves: prevent backflow of
blood
Left Side
Atria
Upper chambers
 Thin walls
 Left atrium
 Receives blood returning from the lungs via pulmonary veins
 Right atrium
 Receives blood from superior and inferior vena cava and the
coronary sinus
 Auricles on top of atria
 Help atria receive more blood

Ventricles

Lower chambers

Thick-muscled to pump blood to body
Contains:

Papillary muscles
 Contract
when the ventricle
contracts; attached to Chordae
tendinae

Chordae tendinae
 Attach
to valves to keep them
from swinging back into the atria
Right Ventricle

Pulmonary circuit = low
pressure
Left Ventricle

Systemic circuit = high
resistance to blood
flow

More powerful pump

3x as thick as right
ventricle
Heart Valves

Prevent back flow of blood

Atrioventricular (A-V) valves:

Tricuspid valve
 Between

Bicuspid (mitral) valve
 Between

left atria and left ventricle
Pulmonary semilunar valve


right atria and right ventricle
Between right ventricle and pulmonary artery
Aortic semilunar valve

Between the left ventricle and aorta
Mitral Valve Prolapse
Affects up to 6% of the
population
 Bicuspid valves stretch and
bulge into the left atrium
 Susceptible to endocarditis

Bacterial infection
 Prevent with antibiotics


Symptoms

Chest pain, palpitations,
fatigue, anxiety
Endocarditis
Double Circulation Loop

Pulmonary circuit: blood
to/from lungs

Systemic circuit: blood
to/from all body tissues
Pathway of Blood Through Heart
Pathway of Blood
Vena cava/coronary sinus  Right atrium 
Tricuspid  Right ventricle  Pulmonary
semilunar valve  Pulmonary arteries
(deoxygenated blood)  Lungs  Pulmonary
veins (oxygenated blood)  Left atrium 
Bicuspid  Left ventricle  Aortic semilunar
valve  Aorta  Body organs, tissues, and cells
Coronary Vessels
First 2 branches of the aorta
 Supply heart tissue with blood
 Myocardium

 Contains
MANY capillaries
 Drained by coronary veins

Veins empty into coronary sinus
 Returns
the blood to the right atria
Cardiac Cycle
Series of events that constitute a
heartbeat
 Pressure within the heart
chambers rises and falls with the
contraction and relaxation of
atria and ventricles
 70% - flows naturally
 30% - needs to be pumped
 0.8 seconds for one cycle to be
completed

Heart Sounds

“Lub”: closing of AV
valves

“Dub”: semilunar valves
close at end of systole

Murmur – abnormal
sounds that indicate
valve problem
Heart Rhythm


Cardiac muscle cells can contract spontaneously and
independently
Regulation of heart activity:
1. Autonomic nervous system
▪ Epinephrine, thyroxine:  heart rate
▪ Low Ca2+ levels:  heart rate
2. Intrinsic conduction system
▪
Built into heart tissue & sets basic rhythm
▪
Pacemaker = Sinoatrial (SA) Node
Intrinsic conduction system
Sequence of action:
1. Sinoatrial (SA) node – right atrium
 Generates impulses  Starts each heartbeat
2. Atrioventricular (AV) node – between atria & ventricles
 Atria contract
3. Bundle of His (or AV bundle)
4. Bundle branches – interventricular septum
5. Purkinje fibers – spread within ventricle walls
 Ventricles contract
Homeostatic Imbalances


Angina pectoris:

Heart muscle deprived of O2

Crushing chest pain
Myocardial infarction (Heart
Attack):

Prolonged angina

Heart cells may die
Homeostatic Imbalances
Ischemia: lack of adequate
blood supply to heart
 Fibrillation: uncoordinated
shuddering of heart muscle,
useless pump


Major cause of death from
heart attacks
Heartbeat Regulation

Amount of blood pumped at any one time must adjust to the
current needs of the body (more is needed during strenuous
exercise)

S-A node is innervated by branches of the sympathetic and
parasympathetic divisions

Medulla oblongata maintains a balance between the sympathetic
and parasympathetic divisions of the nervous system

Impulses from cerebrum or hypothalamus may also influence heart
rate

So do body temperature and the concentrations of certain ions

Norepinephrine - increases contractions

Acetylcholine - decreases contractions
Electrocardiogram (ECG/EKG)

Records the electrical activity of the heart

Electrocardiograph: graphic record of heart activity
How to read an ECG

P wave: atria contact

QRS complex: ventricles
contract

T wave: ventricles relax
Abnormal EKG

Tachycardia - >100 beats/min

Bradycardia - <60 beats/min

Flutter - rapid; 250-350 beats/min.

Fibrillation - rapid; uncoordinated
 Heart
becomes useless as a pump
Overview of EKG
Blood Vessels


Vascular System: blood circulates inside closed transport
systems
Types of Blood Vessels:
 Arteries (takes blood away from heart)
 Arterioles
 Capillary beds
 Venules
 Veins (return blood back to heart)
Arteries
Capillaries
Blood away from heart
• Walls 1-cell thick
Thicker walls
• Exchange gases
Withstand high pressure
between blood and
Aorta - largest
tissue cells
Vasoconstriction
• Form connections
• Contract
between arterioles and
• Diameter reduced
venules
• Vasodilation
•
•
•
•
•
• Relax
• Diameter increased
Veins
Blood back to heart
Thinner walls
Low pressure
Large lumen
Valves: prevent blood
backflow
• Skeletal muscles
enhance venous
return
•
•
•
•
•
Varicose Veins




People stand for long periods of
time  inactivity or pressure on
veins
Blood pools in feet and legs
Valves weaken  veins become
twisted & dilated
Treatment: compression stockings,
exercise, laser treatment, surgery
Homeostatic Imbalances

Atherosclerosis – artery walls thicken due to fatty
deposits (plaques)

Treatments
 By-pass
 Angioplasty
(stent)
Atherosclerosis
Angioplasty vs. Bypass Surgery
Bypass
Congestive Heart Failure



Progressive weakening of heart
Low heart efficiency  circulation inadequate to
meet tissue needs
Caused by:
 Coronary atherosclerosis
 Persistent high blood pressure
 Multiple heart attacks – scar tissue
New heart surgery technology
Untold stories of the ER
Vital Signs

Pulse: expansion & recoil of
an artery with each beat of
left ventricle

Pressure points (eg. carotid
artery, radial artery)

Normal resting: 70-76
beats/min
Vital Signs

Blood pressure: pressure of blood on inner walls of blood
vessels
 Directly
 What
related to volume of blood
happens to when blood is lost?

Stroke volume  ~ 70ml discharged

Blood volume = sum of blood cells + plasma

Hypertension – persistent elevated blood pressure (>140/90)
Measuring Blood Pressure

Systolic pressure: peak of ventricular
contraction (top #)

Diastolic pressure: ventricles relaxed
(bottom #)

Written: Systolic/Diastolic

Normal: (120 mm Hg)/(70 mm Hg) or
120/70
Using a Sphygmomanometer




Wrap cuff around upper arm
Place stethoscope on brachial artery
Inflate cuff to 180 mm Hg
Slowly release air  listen for whooshing sounds in
brachial artery (Korotkoff sounds)
 Systolic: when sound begin to appear
 Diastolic: when sounds disappear