The Circulatory System
By: D. Reis
The Circulatory System
• The circulatory system has 4 principal
functions:
• Transportation of oxygen and carbon
dioxide
• Distribution of nutrients and transport of
wastes
• Maintenance of body temperature
• Circulation of hormones
Pulmonary Circuit
• The right side of
the heart pumps
deoxygenated
blood to the lungs,
where the blood
picks up oxygen
and returns to the
left side of the
heart.
•
The Systemic Circuit
• The left side of the
heart then pumps the
oxygenated blood out
to all parts of the
body, to deliver
oxygen.
•
The Circulatory System
• If you are confused as to which way the
blood flows through the heart, try this
saying "When it leaves the right, it comes
right back, but when it leaves the left, it's
left."
Heart Structure
• Septum – wall of
muscle separating the
ventricles
• Atrium – a thinwalled chamber of the
heart that receives
blood from veins
• Ventricle – a
muscular, thick-walled
chamber that delivers
blood to the arteries.
•
Heart Structure
• Atrioventricular valvesvalves separating the
atria and ventricles. The
AV valves ensure onedirectional flow.
• The right AV- valve is
also known as the
tricuspid valve
• The left AV-valve is also
known as the mitral or
bicuspid valve
Atrioventricular Valves
Semilunar Valves
• Semilunar valves
– valves
separating the
ventricles and
arteries that
prevent the
backflow of
blood from the
arteries to the
ventricles
•
The Difference between Arteries
and Veins
• Arteries usually carry oxygenated blood
away from the heart to tissues.
• Veins usually carry de-oxygenated blood
from the tissues back to the heart.
• THERE ARE SOME IMPORTANT
EXCEPTIONS!!!!
Exceptions in the Circulatory
System
• Pulmonary Veins –
carry oxygenated
blood from the lungs
to the left atrium
• Pulmonary Artery –
carries deoxygenated
blood from the heart to
the lungs
The Right Side of the Heart
• The right atrium receives deoxygenated
blood from the superior vena cava and the
inferior vena cava (2 large veins). The right
atrium pumps blood into the right ventricle .
The right ventricle pumps blood into the
lungs via the pulmonary artery. In the lungs
the deoxygenated blood receives oxygen.
The Left Side of the Heart
• The left atrium receives oxygenated blood
from the pulmonary veins. The left atrium
pumps blood into the left ventricle. The left
ventricle pumps oxygenated blood to all
parts of the body via the AORTA ( the
largest artery in the body)
• Both ventricles pump blood out of the heart
at the same time.
Contraction of the Heart
• Sinoatrial node (SA) node – •
sets the heart’s beat rate at
about 70 beats per minute
• Atrioventricular node (AV)
- passes the nerve impulses
to the ventricles allowing
them to contract
• Purkinje fibers – nerve
fibers in the septum that
branch carrying nerve
impulses
Heart Sounds
• Lubb – Dubb heart sounds
are caused by the closing
of the heart valves.
• Lubb sound occurs when
the AV valves shuts
during systole
• Dubb sound occurs when
semilunar valve shuts
preventing blood from
reentering the ventricles
Heart Murmur
• Occurs when the valves do not close
completely
• A gurgling sound is produced from the
blood rushing from the ventricles back to
the atria and can be detected with the use of
a stethoscope.
• The heart compensates for decreased
oxygen delivery by beating faster.