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The Cardiovascular System
The Cardiovascular System
• The functions of the cardiovascular system are:
– Supply oxygen to tissues from the lungs
– Supply nutrients to tissues from the digestive tract
– Remove wastes from tissues and take them to the lungs
or kidneys or liver.
• The study of the heart and diseases associated with
it is termed cardiology.
• The heart lies in the mediastinum between the
lungs with about 2/3 of it on the left of the body’s
midline.
• The heart is the size of a closed fist.
Coverings of the Heart
•
The pericardium surrounds and protects the
external heart and holds it in place.
–
3 parts to the pericardium from the outside to the
inside:
• Fibrous pericardium- Tough, inelastic connective
tissue that prevents overstretching.
• Parietal pericardium- Fused to the fibrous
pericardium.
• Visceral pericardium- Also called the epicardium
and adheres tightly to the heart.
 Between the parietal and visceral layers is the
pericardial space containing pericardial fluid which
reduces friction as the heart moves.
 Inflammation of the pericardium is called
pericarditis.
•
•
The inside of the hollow heart (where the blood
flows) is a smooth covering called the
endocardium.
The majority of the heart is the myocardium which
is the cardiac muscle that pumps the blood
throughout the body.
Heart Chambers
•
The heart has four internal chambers: two atria
(right/left) on top and two ventricles
(right/left) on bottom.
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–
–
–
Atria receive blood returning to the heart and have
thin walls. On the exterior surface of each is a
wrinkled pouch-like structure called an auricle.
The thick-muscled ventricles pump blood to out of
the heart. The left ventricle is considerably larger.
The right and left atria are divided by an interatrial
septum.
The right and left ventricles are separated by an
interventricular septum.
•
•
•
Heart Valves
Valves are one-way “doors” that open and close
in response to pressure changes. They allow
blood to flow in one direction in the heart.
Atrioventricular valves (AV) are between the
atria and ventricles. The right AV valve is the
tricuspid and the left AV valve is the bicuspid or
mitral.
Both of these valves have tendonlike cords called
chordae tendineae. Chordae tendineae are
attached to papillary muscles in the inner heart
wall that contract when ventricles contract to
prevent the backflow of blood through the AV
valves.
Heart Valves continued….
• In between the ventricles and the major
arteries taking blood away from the heart are
2 semilunar valves (SL).
• The right SL valve is the pulmonary valve and
the left SL valve is the aortic valve.
Major Heart Blood Vessels
• Superior Vena Cava- Returns blood to the right
atrium from above the heart.
• Inferior Vena Cava- Returns blood to the right
atrium from below the heart.
• Pulmonary Trunk- Carries blood from the right
ventricle and branches into the right and left
pulmonary arteries leading to the lungs.
• Pulmonary Veins- Return oxygenated blood to
the left atrium.
• Aorta- Carries oxygenated blood away from
the left ventricle and directs it to the body.
Label the Heart
How the Chordae Tendineae Work
Blood Vessel Types
• There are 5 types of blood vessels in the
cardiovascular system:
– Arteries- Carry blood away from the heart
– Arterioles- Smaller arteries
– Capillaries- Smaller arterioles that are 1 cell
thick
– Venules- Groups of capillaries
– Veins- Return blood to the heart
Blood Vessels
Flow of blood through heart and body
• There are 2 branches of the cardiovascular system:
pulmonary and systemic circulation.
• Pulmonary circulation- The right side of the heart
pumps blood to the lungs to pick up oxygen and
drop off carbon dioxide.
• Systemic circulation- The left side of the heart
pumps blood to the body to drop off the oxygen
and pick up carbon dioxide waste.
**Pulmonary and Systemic circulation happen
simultaneously
Pulmonary Circulation Blood Flow
Systemic Circulation Blood Flow
Differences in Right and Left Ventricles- Now
that you know the blood flow, why is the left
ventricle so large?
Blood Supply to the Heart
• The first branches off of the aorta, which carry
freshly oxygenated blood, are the right and left
coronary arteries that feed the heart muscle itself.
• Branches of the coronary arteries feed many
capillaries of the myocardium.
• When these arteries become clogged due to the
build up of fats and cholesterol, various techniques
can be used including angioplasty and stents. If they
are unsuccessful, new arteries must be attached to
“by pass” these clogged arteries.
• Cardiac veins drain blood from the heart muscle and
carry it to the coronary sinus (large vein on posterior
side of heart), which empties into the right atrium.
Coronary Sinus
Coronary Arteries
Bypass Graft Animation
SHEEP HEART DISSECTION:
External:
Internal:
Aorta
Superior Vena Cava
R/L Auricle
R/L Atrium
R/L Ventricle
Pericardium
Myocardium
Pulmonary Artery
Pulmonary Vein
Tricuspid Valve
Mitral/Bicuspid Valve
Pulmonary Valve
Aortic Valve
Chordae Tendineae
Papillary Muscle
Endocardium
Interventricular Septum
R/L Atrium
R/L Ventricle
Pulmonary Artery
Pulmonary Veins
Aorta
The Heart Beat
• The heart beat is due to electrical impulses flowing
throughout the heart.
• A node is a group of muscles. The heart has 2 nodes
that control the heart beat.
• The Sinoatrial (SA) node is in the right atrium just below
the opening of the Superior Vena Cava.
• The SA node receives the electrical message from the
brain and signals for the muscle tissue in the right and
left atria to simultaneously contract- forcing blood into
the ventricles.
• The SA node is called the “pacemaker” because it
regulates the heart rate.
• The second node in the heart is the
Atrioventricular (AV) node.
• The AV node is also located in the right atrium
and receives the message from the SA node.
• The AV node forwards the message onto the
atrioventricular bundle, then onto the right
and left bundle branches and finally the
Purkinje fibers.
• When the message is received by the Purkinje
fibers, the ventricles contract.
Animation and Practice Quiz
Heart Sounds
• Heart sounds can be described as a "lubb-dupp"
sound.
• The first sound (lubb) occurs as the ventricles
contract and the AV valves close.
• The second sound (dupp) occurs as the
ventricles relax and the SL valves close.
• A heart murmur is an abnormal sound consisting
of a rushing or gurgling noise. Most often this is
due to a valve disorder.
What causes the valves to close?
• When the atria fill, the blood pressure eventually
forces the AV valves open. This causes
approximately 75% of the atrial blood into the
ventricles.
• As the atria contract (due to the signal from the SA
node), the remaining blood into the ventricles.
• When the ventricles contract (due to the Purkinje
fibers), the blood is forced against the SL valves.
They are pushed open and blood enters the aorta
and pulmonary trunk.
• As the ventricles contract, the blood is also forced
against the open AV valves, causing them to close
(lubb). The chordae tendineae prevent them from
opening into the atria.
• As the ventricles relax, the blood in the aorta
and pulmonary trunk fall back due to gravity.
• This puts pressure on the SL valves, causing
them to close (dupp).
Operation of the AV valves
When the atria fill
with blood, the AV
valves open and 75%
of the blood in the atria
passes down into the
ventricles
When the atria get
the message to
contract, the
remaining 25% of
the blood is forced
into the ventricles.
AV valves open
Ventricles
When the ventricles
contract,
blood is forced
against the AV
valves, forcing them
to close.
Chordae tendineae
tighten, preventing
valve flaps from
everting into the atria
AV valves closed
Aorta
Pulmonary
trunk
As ventricles
contract,
blood is pushed
up against
semilunar
valves, forcing
them open
Semilunar valve
open
As ventricles
relax,
blood flows
back from the
arteries, putting
pressure on the
semilunar
valves and
forcing them
to close
Semilunar valve
closed
The Heart: Cardiac Cycle
• The term systole means contraction and diastole
means relaxation.
• The cardiac cycle consists of 3 phases:
1. Relaxation period- Brief period of time when all 4
chambers are relaxed (AV valves open-SL valves
closed).
2. Atrial systole (ventricular diastole)- This is when
the atria contract (AV valves open-SL valves closed).
3. Ventricular systole (atrial diastole)- This is when
the ventricles contract (SL valves open-AV valves
closed).
Animation and Practice Quiz
Electrocardiogram
• Electric currents that run through the heart can be picked
up by electrodes that are placed on a person’s skin. A
recording of the electrical changes during a person’s heart
beat is called an electrocardiogram or ECG or EKG.
• There are 3 waves viewed during an EKG:
1. P wave- when the current passes from the SA node
throughout the atria- which causes them to contract
(atrial depolarization).
2. QRS complex- When the current spreads throughout
the ventricles- which causes them to contract (ventricle
depolarization and atrial repolarization).
EKG continued…
3. T wave- Current change of the ventricles as they start
to relax (ventricle repolarization).
A
B
C
Valves
open
Ventricular
Systole
Atrial
Systole
Relaxation
Period
Valves
closed
Active
node
and/or
nerves
Sound
made
EKG
wave
Common Heart Disorders
• Heart block- Disorder when the electrical system
of the heart is damaged.
• Angina pectoris- Chest pain due to reduced blood
flow to the myocardium.
• Arrhythmia- Irregular heart rhythm
• Tachycardia- Heart beat that is too rapid.
• Bradycardia- Heart beat that is too slow.
• Fibrillation- Rapid, irregular, and unsynchronized
contraction of muscle fibers.
• Cardiac arrest- Cessation of a regular heart beat.
For the following, write the word
that comes next in the blood flow
1.
2.
3.
4.
5.
6.
7.
8.
Mitral valve
Pulmonary venules
Pulmonary trunk
Right atrium
Left ventricle
Arteries
Pulmonary veins
Veins
9. Tricuspid valve
10. Left atrium