Description of the structure and function of the heart

1. Charter College T.Miller – 7/2017

2. Table of Contents
 Structure of the Heart
 Heart Chambers and Valves
 Function of the Heart
 Circulation of Blood
 Contraction of Heart
 Conduction System of the Heart
 ECG and the P-QRS-T System
 Blood Pressure
 Combining Form, Prefix, and Suffix Tables

3. Structure of the Heart
 The heart is divided into the left and right side by partitions called
septa (singular septum).
 The interatrial septum separates the two upper chambers, called
atria (from atri/o, meaning “upper chambers”).
 The interventricular septum separates the two lower chambers,
called ventricles (from ventricul/o, meaning “lower chamber).
Interatrial Septum
Interventricular
Septum

4. The Heart Consists of Four Cell Layers:
 The endocardium (from endo- + cardi/o + -ium, meaning “inner
layer of the heart”) is formed by endothelial cells, and it lines the
interior of the heart chambers and valves.
 The myocardium (from my/o + cardi/o + -ium, meaning “heart
muscle”) is the muscular middle layer of the heart that consists of
heart muscle cells.
 The epicardium (from epi- + cardi/o + -ium, meaning “outer layer of
the heart”) is formed by epithelial cells, and forms the outer cell
layer of the heart.
 The pericardium (from peri- + cardi/o + -ium, meaning
“surrounding the heart”) is a membranous sac that surrounds the
heart. It consist of two layers called the visceral pericardium
(adheres to the epicardium) and parietal pericardium (the outer
coat). The space between these two layers is called pericardial
cavity and it contains pericardial fluid.
Angi/o
Vessel
Thorac/o
Chest Arteri/o
Artery
My/o
Muscle
Cardi/o
Heart
Peri-
Surrounds

5. Heart Chambers and Valves
The human heart has four chambers, which are
responsible for pumping blood and maintaining blood
circulation throughout the body. The four chambers are
named:
The right atrium
The left atrium
The right ventricle
The left ventricle
Blood is only pumped to one direction. Four heart valves
ensure that blood does not flow backward within the
heart.

6. The Four Heart Valves are Named:
 • The tricuspid valve (from tri- + cuspid, meaning “having three
points”) located between right atrium and ventricle.
 • The pulmonary valve (from pulmon/o, meaning “lungs”) located
between right ventricle and pulmonary artery. Also called semilunar
valve.
 • The mitral valve, also called bicuspid valve ( from bi- + cuspid,
meaning “having two points”) located between left atrium and
ventricle.
 • The aortic valve located between left ventricle and aorta.
The tricuspid and bicuspid valves are also called atrioventricular
valves (meaning “located between the atrium and ventricle”).

7. Function of the Heart
The heart functions to circulate blood around the body. The right and
left side of the heart pump blood into two different circulations.
The right side pumps deoxygenated (from de- + oxygenated, meaning
“without oxygen”) blood into the pulmonary circulation, while the
left side pumps oxygenated blood into the systemic circulation.
The right atrium receives deoxygenated blood from the body tissues
via the superior (from super- meaning “above”) and inferior
(meaning below) vena cava (from ven/o meaning “vein”).
The blood enters the right atrium, which pumps the blood into the
right ventricle. The tricuspid valve prevents blood from flowing
backward into the right atrium. The right ventricle pumps the blood
into the pulmonary artery via the pulmonary valve.

8. The pulmonary artery will deliver the deoxygenated blood to the
lungs, where gas exchange occurs.
Oxygen is taken from the air into the blood (now called oxygenated
blood), while carbon dioxide is expelled from the blood into the air.
The oxygenated blood returns to the left side of the heart via the
pulmonary veins.
The oxygenated blood enters the left atrium.
The left atrium pumps blood into the left ventricle. The mitral valve
prevents blood from flowing backward into the left atrium.
The left ventricle pumps the blood into the aorta and systemic
circulation. The oxygenated blood is delivered everywhere in the
body (besides the lungs).

9. Blood Circulation
Blood circulates around the body via two distinct pathways; the
pulmonary circulation and the systemic circulation.
Together they create a closed pathways that keep the deoxygenated
and oxygenated blood separated.

10. Pulmonary Circulation
Pulmonary circulation begins at the right ventricle, where the
deoxygenated blood from the body tissues is pumped into the
pulmonary arteries and to the lungs.
In the lungs, the blood exchanges carbon dioxide (waste product of
cellular respiration) to oxygen.
The oxygenated blood them travels back to the heart and the left
atrium, via the pulmonary vein.

11. Systemic Circuit
The systemic circulation begins at the left ventricle that pumps
oxygenated blood into the aorta.
Aorta branches out into smaller arteries, which carry the oxygenated
blood to the rest of the body (with the exception of lungs).
Oxygen is delivered to the body tissues and exchanged to carbon
dioxide. The now deoxygenated blood is carried back to the heart
and the right atrium via veins.

12. Arteries vs Veins
The blood vessels that carry blood AWAY from heart are called
arteries.
The blood vessels that carry blood TOWARD the heart are called
veins.
Only in systemic circulation arteries carry oxygenated blood, while in
the pulmonary circulation arteries carry deoxygenated blood.

13. Contraction of the Heart
The contraction of the muscular wall of the heart chambers, called
myocardium generates the force to pump blood.
The heart contraction is divided into two phases: systole (meaning
“contraction”) and diastole (meaning “relaxation”).
Blood is pumped from the chambers during a contraction phase.
The heart chambers are filled with blood during a relaxation phase.

14. One round of heart contractions can be divided into
the following phases:
Relaxation phase  blood flows from the atria into the ventricles
passively via open atrioventricular valves.
The atrial systole  contraction of atria. Pumps the rest of the blood
into the ventricles.
The ventricular systole  contraction of the ventricles. Forces blood
into the pulmonary and systemic circulation. (During the ventricular
systole, the atria relax and begin to fill with blood arriving from vena
cava or the pulmonary veins.
Ventricular diastole the ventricles and atria are relaxed.

16. Conduction System of the Heart
The conduction system of the heart controls the rate and pattern of
your heartbeat.

17. Sinoatrial (SA) Node
Myocardium contracts after it receives an electrical impulse generated by a
specialized tissue located within the right atrium.
This is called the sinoatrial node (SA node), also called the pacemaker of the
heart. The SA node is a bundle of neurons that triggers the contraction of
the atria during the cardiac cycle.
The electrical currents next reach the ventricles, which contract after the
atria.
The SA node initiates approximately 75 electrical impulses each minute, with
variation between individuals’ age and general health.

18. The Purkinje Fibers
The Purkinje fibers are cells in the inner ventricle walls, just beneath the
endocardium. These fibers run between the ventricles to the apex (bottom)
of the heart. The Purkinje fibers play a crucial role in the cardiac cycle.
When an electrical stimulus leaves the AV node, it travels via the bundle of
His and branches to the Purkinje fibers. These fibers then carry the impulse
through the inner wall of each ventricle. This causes the ventricles to
contract after the atria contract.
The ventricle contraction forces blood from the right ventricle to the lungs
(pulmonary circulation) and from the left ventricle to the body (systemic
circulation).
These three elements generate a healthy heart rhythm known as sinus
rhythm. The rhythm, or contraction of the heart pumps blood throughout
the body. In roughly a minute’s time, blood travels from the heart to the
body and back.

19. ECG and the P-QRS-T System
An electrocardiogram (from electr/o + cardi/o + -gram), also called an
EKG or ECG, is a diagnostic test used to record and trace the electrical
activity of the heart.

20. The Electrical Activity of the Heart
The electrical activity in the heart is displayed as a P wave, QRS
interval and T wave.
The P wave correlates to atrial depolarization (systole) and atrial
contractions. There is not a wave associated with atrial repolarization
as it occurs during ventricular depolarization (during the QRS
interval).
The QRS complex correlates to ventricular depolarization (systole) as
the ventricles contract. The Q wave is the beginning, the R wave the
middle of the contraction, and the S wave is the end of ventricular
depolarization, and beginning of ventricular repolarization (diastole).
The T wave correlates to ventricular repolarization (diastole).

21. ECG Waves and What They Mean

22. Blood Pressure
Blood pressure is the pressure exerted by circulating blood against the
walls of the arteries.
Blood pressure varies from the maximum (systolic) to the minimum
(diastolic), and is normally around 120/80 mmHg; however this varies
between individuals.
Blood pressure greater than 120/80 mmHg is considered to be high.
The medical term for high blood pressure is hypertension (from
hyper- + tension, meaning “above pressure”).
Blood pressure is less than 120/80 mmHg is considered to be low, or
hypotension (from hypo- + tension, meaning “below pressure”).

23. Health Conditions
 Hypertension:
Hypertension is an abnormal condition that is primarily caused by
high blood cholesterol. Excess cholesterol is deposited on the
arterial walls as plaques. These plaques make the lumen of the
artery narrower, which causes the blood to flow with higher pressure.
If an artery becomes completely blocked, the cells supported by that
artery will suffer from lack of oxygen and die.
If this happens in the coronary arteries, which provide blood to the
heart, the result can be myocardial infarction (heart attack).

24.  Stroke:
An artery leading to the brain can become blocked. This can cause a
cerebral vascular accident, known as a stroke.

25.  Hypotension:
Hypotension is also an abnormal condition, in which the blood flows
with low pressure.
Hypotension occurs when a large volume of water or blood is lost
from the body.
The body’s loss of water, dehydration, can occur during diarrhea or
vomiting.
The body’s loss of blood, hemorrhage, can occur due to blood
disorders or injury to the blood vessels (trauma).
Hypotension can result in shock.

26. Combining Forms, Prefixes and Suffix’s
Word Meaning Example Definition
Aort/o aorta aortal Pertaining to the aorta
arter/o tube, artery arterial
of or relating to an artery
(e.g. arterial pressure)
atri/o
upper
chamber
atrium upper heart chamber
Cav/a hollow Vena cava
hollow vein (e.g. largest vein
in the human body)
cardi/o heart cardiac
pertaining to the heart (e.g.
cardiac patient)
Coron/o Heart, crown coronary Pertaining to the heart
lun/a moon semilunar Half moon
my/o muscle myocardium heart muscle

27. Word Meaning Example Definition
pulmon/o lung pulmonary pertaining to the lungs
Rhythm/o rhythm rhythmic Pertaining to rhythm
ven/o tube, vein venous
pertaining to vein (e.g.
venous blood)
ventricul/
o
lower
chamber
atrioventicular
pertaining to atrium and
ventricle
prefix meaning Example Definition
Bi- two, double bicuspid
having two points (e.g. two-
segmented valve)
De- without deoxygenated Without oxygen
Endo- Inner, in endocardium Inner heart cell layer
Epi- Outer, above epicardium Outer heart cell layer
Peri- surrounding pericardium
Surrounding heart structure
(layer)

28. Word Meaning Example Definition
Semi- half semilunar
Half moon shaped (e.g.
semilunar valve)
Super- above superior Pertaining to above
Tri- three tricuspid
having three points (e.g.
three-segmented valve)
suffix meaning example Definition
-al
pertaining
to
sinoatrial
of or involving the
sinoatrial node (e.g.
sinoatrial block)
-ic
pertaining
to
systolic
relating to, or happening
during a systole (e.g.
systolic pressure)
-ac
pertaining
to
cardiac
relating to heart (e.g.
cardiac rhythm)
-itis
inflammati
on
pericarditis
inflammation of the
pericardium
-ary
pertaining
to
pulmonary pertaining to the lungs
-ium
tissue,
structure
cardium heart tissue
-ous
pertaining
to
venous pertaining to a vein