Circulatory System
Heart Structure and Function
Our Goal This Section...
• Describe the parts of the heart and
how they work together
Anatomy of the Heart
• 4 chambers: 2 atria and
2 ventricles
• right side feeds the
pulmonary circuit
• left side feeds the
systemic circuit
Atria
• Receiving chambers
• Right Atria accepts blood from the anterior
and posterior vena cavae (DEOXYGENATED
BLOOD)
• Left Atria accepts blood from the pulmonary
veins (OXYGENATED BLOOD)
Atrioventricular Valves
• Structure:
• Location:
• Function:
• How it works:
Atrioventricular Valves
• Structure: Flaps of tissue
• Location: Separate the atria from the
ventricles
• Function: Ensure no back flow of blood in
the heart
• How it works: when the blood pressure in
the atria is greater then the blood
pressure in the ventricles - valves open
(atrial contraction) allowing blood to
enter the ventricles
AV Valves
Chordae Tendoneae
• Tendons
• Attach AV valves to ventricles
• Prevent AV valves from inverting when the
ventricles contract
Ventricles
• Contract together to send blood out of the heart
• Fill with blood when the atria contract
• Right ventricle contracts causing the AV closed
and blood enters pulmonary valve - leads to the
pulmonary trunk and then pulmonary arteries
• Pulmonary arteries take blood to lungs for
oxygen
• In left ventricle the flow of blood is the same
except that the blood enters the aortic valve
which leads to the aorta
• Semi-lunar valves
Pulmonary
Valve (Semilunar valve
Aortic Valve
(Semi-lunar
valve)
Chordae
Tendineae
Septum
• Structure:
• Keeps _________________ and _________________
circuits separate
Septum
• Structure: Muscular wall separating the left and
right side of the heart
• Keeps pulmonary and systemic circuits
separate
Coronary Arteries
• 1st branches of the aorta
• Feed heart muscle
• Coronary veins take blood back to the vena
cava when it enters the right atrium
Control of the Heart
Sino-atrial (SA) node
Atrio-ventricular (AV) node
Right Atrium
Made of special muscles and nerve cells
that can contract without stimuli – will
continue beating even outside of the
body!
• SA nodes is along the wall of the atrial
chamber
• AV node is deeper, close to the AV valve
•
•
•
•
SA Node
AV Node
• Causes atrial
contraction
• Send nerve impulse to
the __________________
(causes it to respond)
• Nicknamed the
____________________ as
it initiates the heartbeat
• AV node uses
_______________________
to stimulate the
massive ventricles
• Purkinje fibers are
nerves that begin at
the AV node sending
impulses through both
_______________________
SA Node
AV Node
• Causes atrial
contraction
• Send nerve impulse to
the AV node (causes it
to respond)
• Nicknamed the
pacemaker as it
initiates the heartbeat
• AV node uses PURKINJE
FIBERS to stimulate the
massive ventricles
• Purkinje fibers are
nerves that begin at
the AV node sending
impulses through both
ventricles
Remember Our Goal...
• Describe the parts of the heart and
how they work together
Our Goal this Section...
• Analyse the relationship between
heart rate and blood pressure
Heart Beat
Double sound
caused by the
closing of the AV
valves followed by
the semi-lunar
valves.
Electrocardiogram
(EKG)
Nervous System
SA node is connected to the
brain by a nerve.
Brain will signal the SA node
through a nerve to accelerate
its contraction if more blood is
needed in the tissues or blood
pressure too low.
Part of brain = medulla
oblongata
Autonomic
Blood Pressure
•
•
•
•
•
Low blood pressure can be harmful
Kidneys function is dependent BP
Hypertension: ________________________
Hypotension:_________________________
Body can adjust BP – monitored in the
________________________ of the brain
– Arterioles constrict or dilate to raise or
lower BP
Blood Pressure
•
•
•
•
•
Low blood pressure can be harmful
Kidneys function is dependent BP
Hypertension: high BP
Hypotension: low BP
Body can adjust BP – monitored in the
medulla oblongata of the brain
– Arterioles constrict or dilate to raise or
lower BP
Blood Pressure
• Force of blood against the blood
vessel walls
• Greater when the ventricles are
contracting (forcing blood through
arteries) – SYSTOLIC PRESSURE
• Between contractions the blood
pressure is lower – DIASTOLIC PRESSURE
• Measured along the brachial artery of
the arm
Blood Pressure
• 120/80 mmHg is normal
• High blood pressure strains tissues being fed by
blood
• High blood pressure is normal during physical
activity
• Blood pressure is affected by lifestyle, diet and
stress
• Plaques can line the insides of arteries and
arterioles increasing BP
• If plaque block a blood vessel then tissue
damage or tissue death may occur
• If coronary arteries are blocked then part of heart
muscle may die – heart attack
Heart
Structure
Heart
Beat
Blood
Pressure