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Structure and Function of the Heart
Inquiry into Life – pg. 220-226
Today’s Objectives:
 Describe the inter-relationships of the structures of the heart, including:
 Identify and give functions (including direction of blood flow) for the major structures of the
heart
 Recognize heart structures using both internal and extrenal diagram views
 Analyse the relationship between heart rate and blood pressure, including:
 Describe the location and functions of the sinoatrial (SA) node, atrioventricular (AV) node, and
Purkinje fibres
 Describe how the autonomic nervous system increases and decreases heart rate and blood
pressure
 Differentiate between systolic and diastolic pressures
 Describe hypertension and hypotension and their causes
 Demonstrate the measurement of blood pressure
Parts of the Heart
 Left and Right ________ – Collecting Chambers
 Right: collects blood from ________ _______
 Left: Collects blood from ____________ ________
 Left and Right ______________ – Pumps
 Right: Sends blood to the lungs via the _____________ _________
 Left: Sends blood to the body via the ________
 _________________ Valves
 Valves between the atria and ventricles
 Prevent backflow of blood
 Right side valve called “____________ _________”
 Has three cusps, or flaps
 Also called right atrioventricular valve
 Left side valve called “____________ ________”
 Has two cusps, or flaps
 Also know as the mitral valve or left atrioventricular valve
 ____________ ____________
 Strong, fibrous __________ that support the ______ _________
 Keep the flaps from inverting with the force of blood flow
 ________-_______ Valves (no chordae tendonae)
 Between ventricles and the Aorta (Aortic Valve)
 Between the ventricles and the Pulmonary Trunk (Pulmonary Valve)
 ______________ _________
 Branches off to form the ______________ _______
 Receives blood from the ________ ___________
 __________ (Ventricular Septum)
 The wall of the Heart
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 _____________ the left and right sides of the Heart
Cardiac Cycle and Intrinsic Beat
 Contraction of the Heart is a two step process:
 __________ – Contraction of the Heart
 __________ – Relaxation of the Heart
 Each heart beat (Cardiac Cycle) consists of:
TIME
ATRIA
VENTRICLES
_____ Sec
_____ Sec
_____ Sec
_____ Sec
 Average time of ____________________
Cardiac Cycle
 ______ ____________ have a stronger and longer contraction because blood must be
___________ throughout the _______
 The “lub-dup” sound of the heart is due to the closing of the ________: first the
atrioventricular, then the semi-lunar
 The beat of the heart is said to be ___________, meaning it will beat without any __________
__________ stimulation
 It can be removed from the body and still continue beating!)
 The beat is controlled by a special type of tissue called _________ __________, which has
both muscular and nervous tissue characteristics
Nodal Tissue
 There are two locations of Nodal Tissue in the Heart:
 1) ___ ________ (Sinoatrial Node)
 Found in the upper wall of the right atrium
 2) ___ ________ (Atrioventricular Node)
 Found at the bottom of the right atrium near the
Septum
 The SA Node (also called the _____________) initiates the
heartbeat and sends out an excitation impulses every 0.85
seconds.
 The impulse causes both _________ to contract. The
impulses are sent to the AV Node Via the _______________.
 When the impulse reaches the AV Node, an impulse is sent from the AV Node, down the
___________________ causing both ____________ to contract.
Electrocardiograms (EKG)
 An __________________ registers the ___________ _________ across the surface of the
heart as it beats.
 The letters __________ are the standard labels used to identify the parts of the EKG
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 The _________ records the
simultaneous contraction of
the atria as they drive the
blood out into their
ventricles
 The ________ is the
contraction of the ventricles
as they drive the blood out
into their respective arteries
 The ___ marks the recovery
of the Ventricles (restoration
of the normal electrical
condition, preparing them
for the next contraction)
Autonomic Control of the Heart
 The rate of the heart can also be controlled by the __________ _________
 The heart rate center is located in the __________ _____________ of the brain.
 The SA Node is connected to the brain by the ________ ________ (cranial nerve #10)
 This nerve pathway is called the ____________ _________ ___________ (not under conscious
control)
 Has two systems that affect the Heart Rate:
 ________________ System – causes the heart beat to slow down
 ____________ System – causes the heart beat to increase during times of stress
Autonomic Nervous System
 Factors such as a need for ___________ or the ________ __________ level determine which
of those systems become active
 When the brain perceives that the blood is getting delivered to the tissues too slowly, or if
blood pressure is low, the brain will signal the SA Node to speed up its contraction.
Blood Pressure
 Ventricles pump a volume of blood (approx
_______) each time they contract
 Must have elastic, expandable walls
 The force of blood against the blood vessel walls
is known as ________ ____________
 Blood Pressure is not constant
 The term __________ ___________ (or Systole)
refers to the blood pressure when the ventricles
contract
 The term __________ ___________ (Diastole)
refers to the blood pressure when the heart is at
rest
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Pulse
 As blood is pumped through the arteries, the
arterial walls _______, then _______
 This swelling can be felt in any artery that runs
close to the surface
 Blood pressure is normally measured along the
__________ ________ of the arm
 A reading of ________ is quite normal
 120 - Systolic reading as ventricles contract
 80 – Diastolic reading as the heart relaxes
Blood Pressure Changes
 A number of things can affect the blood pressure:
_________________: High Blood Pressure
 Example: 140/90 or 125/90
 Diet and Lifestyle are often to blame for elevated blood pressure
 Reasons for Hypertension:
 _________
 __________ – formed by fatty acid deposits from digested foods; line the walls of the
arteries, making the radius smaller, thereby raising blood pressure, (Arteriosclerosis,
Stroke, Heart Attack)
 High ___ Intake – retains water – greater fluid volume leads to greater volume of blood
 ____________
 ____________
 Lack of ___________
 ______ – amount of food and type
 __________ too hard
 _________________
________________: Low Blood Pressure
 Low Blood Pressure
 Blood does not reach all organs
 Example: 110/70
 Reasons for Hypotension:
 _______ or amputated limbs
 _______
 ____________
Effects of Blood Pressure Change
 Proper ___________ function can only be maintained if there is a sufficient pressure for
_____________
 Luckily, the body can adjust blood pressure
 Monitored by the _______________ (part of the brain), the body can _______ (widen)
arterioles thus lower blood pressure in them, or ___________ (narrow) them to raise the
blood pressure