Download The Cardiovascular System - Bishop Allen Academy Health and

The Cardiovascular
System
Objectives
 The
Structure and Function of the
Cardiovascular System
 How blood flows through the heart
 The electrical activity within the heart
 The role of Vascular system and it’s
various components
 Cardiovascular disease
 Exercise response of the CV system
Functions
Functions of the CV system
 Delivery
and transport - Oxygen ,nutrients
and hormones from endocrine glands to
tissues
 Removal – Carbon dioxide and waste
products from tissues
 Maintenance – Temperature, and fluid
levels
 Prevention – fights infections and foreign
antigens
Parts of the Cardiovascular system
The Cardiovascular system
Components
– The heart, a double pump.
Pumps oxygenated blood to tissues and
deoxygenated blood to the lungs.
 Channels – the blood vessels where the
blood travels through. Arteries, arterioles,
capillaries, venules, veins
 Fluid Medium – blood carries nutrients to
and from the tissues.
 Pump
Blood

Plasma – 55%




90% water
7% plasma proteins
3% acids and salts
Formed elements 45%


99% RBC’s (Erythrocytes)
1% WBC’s (Leukocytes)
Anatomy of the Heart
The Heart

Specialized muscle
tissue called
myocardium
 Suspended in the
chest by the aorta,
vena cava, and
pulmonary arteries
and veins
 Made of four
chambers
Heart

The heart is
contained in a sac like
structure
(pericardium)
Heart Layers

Pericardium - Shell
 Epicardium – Outer
layer
 Myocardium – Heart
muscle
 Endocardium – Inner
layer
Inside of the heart
 See

Homework assignment
Draw the Heart and all it’s components
Cont…
Valves Cont…

These valves are important for allowing the
blood to travel consistently in the correct path.
Thus they make sure that blood does not travel
backwards
 They open and close according to the pressure
differences that occur within the heart during the
cardiac cycle.
 The opening and closing of these valves result
in the Lub-Dub sound of the heart beat!
Lub Dub



Initial sound (Lub) is caused by the closing of the
Tricuspid and mitral (bicuspid) valves
As the ventricles contract pushing blood into the aorta
and pulmonary arteries, the pressure in the ventricles is
higher then the pressure in the atria, this causes the
valves to close
The second sound (dub) is caused by the increased
pressure in the aorta and pulmonary arteries (which are
filled with blood) and cause the aortic and pulmonary
semilunar valves to close. The ventricles are almost
empty at this point and so have a reduced pressure
when compared to the aorta and pulmonary arteries
which are filled with blood at this point.
Cardiac Cycle
 One
cardiac cycle is one complete heart
beat. (0.8 sec.)
 On average the heart beats about 70-72
times/min.
 There is two parts to the cardiac cycle:
-Systole: the active phase of the cycle
when blood is ejected from the heart
- Diastole – Passive phase in which
heart relaxes and fills with blood
Steps to the Cardiac Cycle

Atrial Systole


Ventricular Systole




Ventricles contract
Pressure increases and closes the tricuspid valve and mitral
vlave
Semi lunar valves open and blood spurts into aorta and
pulmonary artery
Ventricular Diastole


Atria contract and blood is pushed into the ventricles
Semi lunar valves close and ventricles relax and fill
Atrial Diastole

Blood flows into the atria due to differences in pressure
Cardiac Cycle and Blood Pressure
 Blood
pressure is described using two
numbers (systolic over diastolic)
 Systolic- pressure in the arteries during
systole
 Diastolic – pressure in the arteries during
Diastole
 Blood pressure is measured in mmHg
 Normal blood pressure is approximately
120/80 mmHg
Factors affecting Blood pressure





Amount of blood (e.g. loss of blood volume due
to injury could decrease pressure)
A decrease in blood pressure may not allow
blood to flow properly since blood flow occurs
because of differences in pressure.
Heart Rate the faster the heart rate the higher
the pressure
Size of arteries (dilated vs. constricted)
Viscosity of blood (blood thinners, dehydration)
How the Chambers know when to
contract
 Cardiac
muscle cells allow electrical
signals to pass through from cell to cell
 This allows the heart to contract as a
single unit. The contracting of the heart
leads to the pumping of the blood
 When all of the cardiac muscle cells
contract at the same time = syncytium
 All or None!
Excitation of the Heart

Cardiac muscle cells are excitable like other
muscle cells. However, the constant signal to
contract comes from within. The heart can be
stimulated by the autonomic nervous system
(increase and decrease heart rate during
exercise, stress etc)
 The SA node sets the pace of the heart to keep
it contracting regularly
 The electrical signal from the SA node then
spreads through the atria and then ventricles to
contract.
Excitation of the Heart
Excitation of the heart
When Things go wrong with the
heart
 Heart Attack


Cholesterol
Hypertension
 Arrhythmia
 Valve
disorders
WHAT IS A HEART ATTACK?
 A myocardial
infarction or heart attack is
caused when the heart muscle tissue does
not get enough oxygen in order to
maintain muscle contraction (i.e. beating).
 This is most often caused by a blood clot
which forms when blood flow through one
or more of the coronary arteries is
restricted.
 Build up of Cholesterol is often the cause
HEART ATTACK
HEART ATTACK VS. CARDIAC ARREST

Heart Attack is simply
lack of blood f low to
the myocardial tissue
 The Heart is still
beating but not for
long.
 Symptoms of a heart
attack begin

Cardiac Arrest is when
the heart stops its
regular beating pattern
and begins to fibrilate.
 Shake like a bowl full of
jelly. Each contraction is
no longer strong
enough to pump blood
through the system
 Heart requires
defibrillation!
Treatment 1 - Medication
 Angiotensin
converting enzyme (ACE)
inhibitors are heart medications that widen
or dilate your blood vessels to improve the
amount of blood your heart pumps and
lower blood pressure. ACE inhibitors also
increase blood flow, which helps to
decrease the amount of work your heart
has to do
Treatment 2 - Angioplasty
Treatment 3 - Bypass
Arrhythmia
– Irregular heart beat
 Arrhythmia may cause your heart to beat
too slowly (bradycardia, less than 60 beats
per minute) or too quickly (tachycardia,
more than 100 beats per minute), or cause
uncoordinated contractions (fibrillation).
 Arrhythmia
Arrhythmia

Stress, smoking, heavy alcohol use, heavy
exercise, use of certain drugs (such as cocaine
or amphetamines), and too much caffeine or
nicotine can lead to arrhythmia in some people.
 A heart attack or an underlying condition that
damages the heart's electrical system also can
cause an arrhythmia. These conditions include
high blood pressure (hypertension), coronary
artery disease, heart failure.
 Some cases are simply genetic conditions in
which the electrical components of the heart are
faulty.
Valve problems
 Leaking
valves can produce other sounds
when the heart is examined. “Murmurs”
can result from leaky valves or from other
defects of the heart.
 If the Murmur is severe then medications
and or surgery is required
Hypertension

Normally the kidney control the level of salt in
our blood by excreting it in urine
 If intake levels get too high the kidneys can not
keep pace and reduce the sodium levels quickly
enough. Thus sodium levels remain high in the
blood.
 The extra sodium ends up attracting more water
into the bloodstream. This increases blood
volume and thus pressure in the blood vessels.
Homework Question sheet