Download The Heart

THE HEART IS A HOLLOW,
MUSCULAR ORGAN THAT
CONTRACTS AT REGULAR
INTERVALS, FORCING BLOOD
THROUGH THE CIRCULATORY
SYSTEM.

The Heart is cone-shaped,
about the size of a fist, and is
located between the lungs
directly behind the sternum.
(breastbone). The heart is
tilted so that the apex (the
pointed end) is oriented to the
left.

The heart is enclosed in a
protective membrane sac
called the pericardium. The
pericardium surrounds the
heart and secretes a fluid that
reduces friction as the heart
beats.

Vertically dividing the right
and left sides of the heart is a
wall called the septum. The
septum prevents the mixing
of oxygen-poor and oxygenrich blood.


The Human Heart
RIGHT SIDE OF THE HEART
 Deoxygenated blood from
the body enters the right side
of the heart through 2 large
blood vessels called:
 superior vena cava
carries deoxygenated blood
from the head and upper body
to the right atrium.
 Inferior vena cava carries
deoxygenated blood from all
veins below the diaphragm to
the right atrium.
LEFT SIDE OF THE HEART
 Receives oxygenated blood
from the lungs and pumps it
to the cells of the body.
1. Pulmonary Circulatory System blood carried to
and from lungs.
2. Cardiac Circulatory System blood travels through
the heart tissue.
3. Systematic Circulatory System blood travels to
and from the body cells.
Circulatory System
2 thin walled atria
(atrium) chambers of
the heart that receive
blood from veins.

2 thick walled
ventricles chambers of
the heart that deliver
blood to the arteries.


Cardiac Conduction
When the heart relaxes (between beats), pressure
in the circulatory system causes the atrium to fill with
blood.

When the heart contracts, blood is squeezed from
the right atrium to the right ventricle through flaps of
tissue called a atrioventricular (AV) valves

 AV valves separate the atria from the ventricles,
and maintain one-way flow.
When the heart contracts a second time, blood in
the right ventricle is sent through the semilunar valves
and to the pulmonary arteries to the lungs.

 Pulmonary Arteries are the only arteries to carry
oxygen-poor blood.
 Semilunar valve prevents blood from traveling
back into the right ventricle.
Oxygen-rich blood leaves the
lungs and returns to the heart by
way of blood vessels called the
pulmonary veins
 Pulmonary veins are the only
veins to carry oxygen-rich blood.
 Returning blood enters the left
atrium, it passes through the AV
valve to the left ventricle.
 From the left ventricle, blood is
pumped through the SL valve to
the aorta artery that carries blood
to every part of the body BUT the
lungs.
 At the base of the aorta is a
valve that prevents blood from
flowing back into the left
ventricle.

The aorta is the largest artery in the body, and
carries oxygenated blood to the body.

coronary arteries a branch of the aorta, that
carries blood (oxygen and nutrients) to the cardiac
muscles.

Pumping Animation
Fat deposits and plaques
accumulate here.
 Operation involves removing
the a vein from another patients
body and grafting it into the
position in the heart.
 However, to graft the vein, the
heart needs to be stopped.
 Heart is cooled and a heartlung machine maintains oxygen
supply and blood flow to tissues.
 Coronary Bypass Surgery
 YouTube - Off Pump Coronary
Artery Bypass - A Beating Heart
Procedure

A procedure where a small,
thin, hallow tub, called a
catheter, is passed into an artery
in the groin.
 The catheter is pushed up
through the aorta and into the
heart.
 A dye that is visible in X-rays is
then injected into the catheter.
 An area of restricted blood
flow pinpoints the blockage.
 Angioplasty balloon on the
end of the catheter opens the
blocked blood vessel.
 Blood sample tell info about
oxygen present in different
chambers


Appear striated (striped)

Display a branching pattern
Can contract without being stimulated by external
nerves, myogenic muscle.

 Explains why the heart will continue to beat when
removed form the body.

YouTube - beating Human heart

The heart contracts and relaxes in a rhythmic cycle.

Contracts pumps blood

Relaxes chambers fill with blood
One complete cycle of pumping and filling is the
cardiac cycle.

sinoatrial (SA) node
a small mass of tissue in the right atrium that sets the hearts beat rate at 70
beats per minute. The SA node acts as a pacemaker
Contraction now travel to a second node:
atrioventricular (AV) node (right atrioventriculal region)
This node is the conductor, passes impulses through the Purkinje Fibers,
and on to the ventricles.
 Purkinje fibers run along the septum that separates the right and left
ventricles, to the bottom tip of the heart. From here, branch fibers
carry impulses along the outer walls of the ventricles and back
towards the atria.
 Heart Beat
Sympathetic and parasympathetic nervous systems
conduct impulses from the brain to the SA node.

In stressful situations, the sympathetic stimulates an
increase in heart rate (increased blood flow).

During times of relaxation, parasympathetic nerves
are stimulated to slow the heart rate.

Familiar heart sounds are caused by the closing of heart valves.
When atria relax (diastole), it fills with blood and as blood increase the
atria contracts; thereby, forcing AV valves to open. Blood flows from the
atria to the ventricles.


As ventricles fill with blood and then they contract (systole), which closes
the AV valve. This creates the lub sound as blood in pushed into the arteries.
To prevent blood in the arteries from re-entering the semilunar valves
close. The closing of this valve creates the dup sound.

Occurs when valves
do not close
completely.
Murmur created when
blood leaks past the
valve.
Results in a faster
beat rate
(compensate for
decreased oxygen
delivery) and enlarged
heart (atria receive
additional blood from
the ventricle).
Used to map electrical fields within the heart to
make tracings to diagnosis certain heart problems.
 Changes in electrical current reveal normal or
abnormal events.
 Examples of ECGs

P wave the electrical impulse that causes atrial
contraction.

QRS wave the electrical impulse that causes the
ventricles to contract.


T wave signals that the ventricles are relaxed.
Irregular heart beats
caused by a blocked
coronary artery.
Beta blockers  helpful in
patients with irregular
heartbeats or who display high
blood pressure.

Receptor sites receive
hormones that affect the way
the cells behave.
 Epinephrine, a stress hormone,
increases heart rate and
narrowing blood vessels. Beta
blockers attach and block this
receptor.
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