Transcript Structure and Function of the Heart

Cardiovascular System
The Heart
Heart Facts
• The cardiovascular system is composed of the heart and a
_________system of vessels through which blood is circulated.
• Hollow muscular organ
• Tipped slightly so that a part of it sticks out and taps against the
______side of the chest (apex), which is what makes it seem as
though it is located there.
• During an average lifetime, the human heart will beat more than 2.5
billion times.
• Beats over 100,000 times/day and 35 million times/year to pump
blood around the body's 60,000 miles of blood vessels.
• ____pints of blood pump throughout your entire body with one single
heartbeat.
External Structure of the Heart
• Layers
– Edocardium (inner layer)
– Epicardium (outer layer)
– Myocardium (middle layer)
• _________________ - the protective membrane surrounding the heart
• ____________arteries – supply blood to the outside of the heart
External Structure
Internal Structure
•
•
•
Atria and ventricles
atria contract while the ventricles relax
ventricles contract while the atria relax.
•
____________________ (AV) Valves
• Bicuspid (____________)
Valve – between left atria and
ventricle
• Tricuspid Valve – between
right atria and ventricle
__________________(SL) Valves
• Pulmonary SL Valve –
between right ventricle and
pulmonary artery
• Aortic SL Valve – between left
ventricle and aorta
•
•
Ventricular ____________ - right and
left ventricles are divided by a thick
muscular wall
– babies born with "hole in the
heart“
– Why problematic?
Septum
connect papillary muscles to AV valves
“heartstrings”
The Cardiac Cycle
• The events associated with one heartbeat.
• A single cardiac cycle lasts ______ seconds
• Described as the contraction and relaxation of the four heart
chambers.
– During relaxation, chambers fill with blood (_________________).
– During contraction, chambers expel blood (_________________).
Heart Sounds
• The first heart sound (______) occurs during ventricular contraction
when the tricuspid and bicuspid valves (___valves) close.
• The second heart sound (________) occurs during ventricular
relaxation when the pulmonary and aortic valves (___ valves) close.
•The walls of the left ventricle are ________ as it has to pump blood to all the
tissues, compared to the right ventricle which only pumps blood as far as the _____.
Septum
Blood Pressure
• Blood moves through circulatory system from areas of high pressure
to low pressure. (Contraction of the heart produces the pressure.)
• Blood Pressure is a measurement of the _______ that blood exerts
against the inner walls of ______________.
• 120/80 is normal = systole/diastole
– systolic pressure - The maximum pressure during ventricular
contraction; systolic pressure is the peak arterial pressure.
– diastolic pressure - The lowest pressure of blood in the arteries
during ventricular relaxation (diastole); the arterial pressure drops.
Blood Pressure vs. Distance From Left Ventricle
Conduction System
• Heart muscle cells contract
without stimulation from the
nervous system in a
continuous, rhythmic pattern.
• Contraction is initiated by the
sinoatrial (SA) node
(_______________________).
– SA node is located in the right
atrium
– Cells of the SA node can
reach threshold on their own
– SA node initiates one action
potential after another (~70-80
times/min)
• Pathway of electrical impulse
– Sinoatrial (SA) node
– Atrioventricular (AV) node
– Atrioventricular bundle (bundle
of His)
– Bundle branches
– Purkinje fibers
Electrocardiograms (ECG / EKG)
• A recording of the electrical
changes that occur within
the myocardium as the
heart contracts.
R atr cont
Electrocardiograms (ECG / EKG)
Atria repolarized
Ventricle depolarized
Heart relaxed
AV node and
walls depolarize
Atrial walls
completely
depolarized
Atria repolarizes
Ventricle
depolarizes
Ventricular walls
repolarize