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The Heart
Ch. 46: Circulatory System
What is the heart?
A
specialized muscle that
pumps blood through the
body, which transports
oxygen, carbon dioxide,
nutrients and waste.
Where is it?
The
heart is located in the
middle of the chest, between
the lungs.
Its bottom is tipped to the left.
It is about the size of two fists.
Anatomy of the heart
Left side- oxygenated
Right side- deoxygenated
What does it look like?
The
pericardium is a tough
saclike membrane that
surrounds the heart and
secretes a fluid to reduce
friction.
Heart Chambers
Heart is divided into
four chambers.
 The upper chamber
are the right and left
atria.
 The lower chambers
are the right and left

ventricles.
Heart valves
Valves
are flaps of tissue that
direct blood to flow only in one
direction.
They prevent blood from
entering that chamber that it
just left.
There are 4 heart valves
Atrioventricular valves (AV)
Separates
the atrium from the
ventricle.
Right: tricuspid valve
Left: bicuspid (mitral) valve
Semilunar valves (SL)
Separates
the ventricles from
vessels exiting the heart.
Right: pulmonary valve
Left: aortic valve
Diagram of the Heart
1.
2.
3.
4.
5.
6.
7.
Aorta- Largest artery
in Body
Superior Vena Cava
Right Pulmonary
Artery
Right Pulmonary
Vein
Right Atrium
Tricuspid Valve
Right Ventricle
8. Inferior Vena Cava
9. Left Pulmonary Artery
10. Left Pulmonary Vein
11. Left Atrium
12. Bicuspid/Mitral Vale
13. Aortic Valve
14. Left Ventricle
15. Aorta
16. Septum
Pulmonary circulation
1.
2.
3.
4.
Vena cava (superior and
inferior) from body
Right atrium
Right ventricle
Pulmonary artery to lungs
5.
6.
7.
8.
Pulmonary Veins
Left Atrium
Left Ventricle
Aorta (to body)
Heart Beat
The
heart contracts in waves,
starting at the atria, followed
by the ventricles.
The
heart independently
stimulates an electrical impulse
at the sinoatrial node in the
right atrium, which stimulates
the atrioventricular node in the
septum.
The heart pumps blood in two phases:
 In
the systole phase, the
ventricles contract and blood is
pumped out of the heart.
 In the diastole phase, the
ventricles relax and blood rushes
into the heart.
The
lub dup sound of a heart
beat is the close of the AV and
SL valves.

http://www.csulb.edu/colleges/coe/org/bme/respiratory_sounds/heart.au
Pulse
The pulse is caused by the
contractions of the left
ventricle.
 Blood surges through the
arteries and the pressure
causes the arteries to expand.

Blood
Blood
is composed of a liquid
medium (55%) and solids
(45%).
Plasma
The sticky, yellowish colored
liquid medium of blood.
 Contains: 90% water
–Metabolites
–Nutrients
–Salt
–Wastes
–And proteins of various function
Red blood cells
AKA
Erythrocytes: transports
oxygen to cells all over the
body
Contain large amounts of the
protein, hemoglobin.
Hemoglobin
Carries
oxygen to necessary
cells.
Carries carbon dioxide from
cells to be removed by lungs.
White Blood cells
AKA
Leukocytes, help defend
the body from disease.
Platelets
 Cell
fragments that release blood
clotting enzymes when a blood
vessel is damaged.
 A chemical chain reaction
stimulates platelets to stick
together at the tear site and
release proteins to clog the tear.
 Eventually a scab forms.
Blood vessels
Artery
– Carries blood away from the
heart
– Made of a thick muscle layer
–Because the arteries feel
the greatest amount of
blood pressure.

Veins
–Carries blood back to the heart
– Made of a thinner muscle
layer and contains valves.
–Because there is less blood
pressure in the veins and
valves prevent gravity from
making blood flow
backwards.

Capillary
–Thin vessels that allow the
exchange of gases, nutrients,
and waste between blood
cells and other cells by the
process of diffusion.
Gas Exchange
 Occurs
in the alveoli of the lungs
 Factors that facilitate exchange:
–Alveoli are thin: one cell layer thick
–Excellent capillary blood supply
–Very large surface area
–Moist lining helps in diffusion
Oxygen transfer
Atmospheric
oxygen: 21%
O2 readily diffuses from air in
alveoli into the blood stream,
where it is picked by the
hemoglobin in red blood cells.
Carbon dioxide transfer
 The
concentration of CO2 is much
higher in cells, so CO2 readily
diffuses out of cells into the blood.
 7% is dissolved in the plasma.
 23% is carried by hemoglobin
 70% reacts with water to become
carbonic acid (H2CO3), which helps
maintain blood pH.
Mechanism of Breathing
Diaphragm:
muscle layer
below the lungs and above the
abdomen.
Inspiration/ Inhale
 Process
of taking in air.
–Diaphragm contracts and pushes
down the abdomen.
–Rib cage expands.
–Lung volume increases and fills
with air because pressure outside
lungs is greater than inside
Expiration/ Exhale
Process
of releasing air:
Diaphragm and rib muscles
relax
Rib cage condenses.
Lung volume decreases and
lungs deflate
Human Respiratory System
Sequence:
Mouth
Nasal passages
Pharynx
Larynx
Trachea
Bronchi
Lungs (brochioles—
alveoli)

Cardiovascular Diseases
Atherosclerosis
hardening of
narrowing
_________ and _________
the arteries.
 Arteries feel higher blood
pressure and suffer more
damage.

What happens?
Inner
lining of artery is
damaged.
LDL
“Bad cholesterol”,_____, build
up in the artery.
White blood cells
_______________engulf
LDL
accumulate and forms a
but __________
plaque which clogs the artery.
______,
Complications
Cardiovascular
disease is the
one killer in America.
number ____
arteries
Blood clots in coronary ______
causes damage and death of
heart muscles.
Leads to myocardial infarction/
heart attacks.
clots or ________
ruptures in
_____
blood vessels in the brain can
strokes
lead to _______.
Blood
Causes
 Smoking
 High
cholesterol
 High blood pressure/ hypertension
 Stress
 Diabetes
 Abdominal obesity
 Not eating fruits and vegetables
 Excess alcohol intake
 Not exercising regularly