2. The Heart Video
VR SCI 040

3. Heart Glossary
• Your assignment is to create a
HEART GLOSSARY.
– The glossary should contain
all of the structures of the
heart.
– Your Glossary Should also
include a labeled diagram of
the heart.

5. How The Heart Works

6. The Heart
• Structure of the heart
– 4 chambers
• 2 upper atria
• 2 lower ventricles
• Each pair of chambers is separated
by a septum
– Heart wall
• Major portion is the myocardium-
cardiac muscle
• Inner surfaces lined with
endocardium
• Outer surfaces lined with
pericardium

7. External Heart Anatomy

8. The heart cont’d.
• Heart valves
– Atrioventricular valves
• Lie between the atrium and
ventricle on each side
• Mitral (bicuspid) valve-
between the left atrium and
left ventricle
• Tricuspid valve- between the
right atrium and right
ventricle

9. The heart cont’d.
• Heart valves
– Semilunar valves
• Between the ventricle and great
vessel on each side
• Aortic valve-between the left
ventricle and aorta
• Pulmonary valve-between the
right ventricle and the
pulmonary artery
– Valves control the flow of blood
through the heart

10. Internal view of the heart

11. The heart cont’d.
• Passage of blood through the heart
– Superior and inferior vena cavae bring O2-poor blood
to the right atrium
– Blood flows through tricuspid valve to right ventricle
– From right ventricle blood passes through the
pulmonary valve to the pulmonary artery
– Blood picks up oxygen in the lungs and returns to
the heart through the pulmonary veins
– Pulmonary veins empty oxygenated blood into the
left atrium
– Blood flows through the mitral valve to the left
ventricle
– From the left ventricle blood flows through the aortic
valve to the aorta
– Aorta carries blood out to the body

12. The heart cont’d.
• Blood flow through the heart cont’d.
– The heart is actually 2 pumps
• Right side is the pulmonary pump
– Pumps deoxygenated blood to
pulmonary circuit and lungs
• Left side is the systemic pump
– Pumps oxygenated blood out to
systemic circulation
– Note that deoxygenated and oxygenated
blood never mix
– Left ventricle pumps blood under higher
pressure
• Left ventricular wall is more muscular

13. The heart cont’d.

14. Cardiac Cycle

15. Cardiac Cycle
• The heartbeat
– The events of each heartbeat are called the cardiac
cycle
• Highly coordinated so that both atria contract
together and then both ventricles contract
together
• Systole- ventricular contraction of heart muscle
• Diastole-ventricular relaxation of heart muscle
– Normal heart rate at rest is about 60-80
beats/minute
– “Lub dup” heart sounds are produced by turbulence
and tissue vibration as valves close
• “lub” sound occurs as atrioventricular valves
(AV) close
• “dup” sound occurs as semilunar valves close
– Other abnormal sounds are referred to as heart
murmurs

16. Systole & Diastole

17. Stages
in the
cardiac
cycle

18. semilunar
valves
aorta
pulmonary
vein
left
atrium
left
ventricle
a.
right
ventricle

19. semilunar
valves
aorta
pulmonary
vein
left
atrium
left
ventricle
a.
right
ventricle pulmonary
arteries aorta
atrioventricular
valves
b.

20. semilunar superior
valves vena cava
aorta
pulmonary
vein right
left atrium
atrium
left
ventricle c.
inferior
a. vena cava
right
ventricle pulmonary
arteries aorta
atrioventricular
valves
b.

21. Conduction system of the heart
• Intrinsic control of heartbeat
– Heart has its own intrinsic
conduction system
– Nodal tissue-2 areas in the
heart
• Has both muscular and
nervous characteristics
• Can generate action
potentials to cause
contraction
• SA node and AV node

22. Conduction system of the heart

23. Conduction system of the heart

24. Control of Heartbeat

25. Control of Heartbeat

26. Control of Heartbeat

27. Control of Heartbeat
• When the SA node "fires", the nerve impulse spreads
quickly over both atria, causing the atrial muscles to
contract. The impulse then reaches a second node of
tissue, the atrioventricular node (AV node), located in
the septum between the ventricles but in contact with
the lower portion of the right atrium. The stimulation of
the AV node causes nerve impulses to be sent down
the bundle of nerve fibers, known as the Bundle of His.
The Bundle of His branches into a pair of nerve fibers
through the septum and circling around the base of
each ventricle. The impulse started in the SA node and
picked up by the AV node reaches the muscles of the
ventricles and causes them to contract.
• The heart has special muscle fibers called Purkinje
fibers that conduct impulses five times more rapidly
than surrounding cells. The Purkinje fibers form a
pathway for conduction of the impulse that ensures that
the heart muscle cells contract in the most efficient
pattern.

28. Control of Heartbeat
• Extrinsic control of the heartbeat
– Cardiac control center in the medulla has
inputs to heart through the ANS
– Parasympathetic stimulation causes a
decrease in heart rate
– Sympathetic stimulation causes an
increase in heart rate and contractility
– Hormones also can control heartbeat
• Epinephrine and norepinephrine
cause increased heart rate
• Occurs during exercise, “fight or flight”
response

29. The Electrocardiogram
– An electrocardiograph is an
instrument that is used to measure
electrical activity in the heart. It
measures changes in electrical
potential across the heart and can
detect the contraction pulses that
pass over the surface of the heart.
The resulting record is called an
electrocardiogram (ECG or EKG).
– The EKG shows three slow, negative
changes, known as P, R, and T.
Positive deflections are the Q and S
waves.

30. Electrocardiogram
•P wave- atrial depolarization (prior to atrial contraction)
•QRS complex- ventricular depolarization (just prior to
ventricular contraction
•T wave- ventricular repolarization (ventricles are
recovering from contraction)

31. Conduction system of the heart
•P wave- atrial depolarization (prior to atrial contraction)
•QRS complex- ventricular depolarization (just prior to
ventricular contraction
•T wave- ventricular repolarization (ventricles are
recovering from contraction)

33. The Vascular Pathways

34. The Vascular Pathways
• The pulmonary circuit
– Right ventricle pumps deoxygenated
blood to pulmonary artery
– Branches into left and right
pulmonary arteries that go to the
lungs
– Within the lungs blood is distributed
to alveolar capillaries
– Oxygen diffuses into the blood and
carbon dioxide diffuses out
– Oxygenated blood now travels
through pulmonary veins to the left
atrium

35. The Vascular Pathways cont’d.
• The systemic circuit
– Oxygenated blood is pumped from the left
ventricle to the aorta
– Aorta distributes blood through the
systemic arteries
– As blood travels through the systemic
capillaries it drops off oxygen and picks up
carbon dioxide
– The deoxygenated blood is returned by
venules and then veins to the vena cavae
– The inferior vena cava drains the body
below the chest
– The superior vena cava collects blood from
the head, chest, and arms
– Blood is returned to the right atrium

36. Cardiovascular
System Diagram

37. Blood Pressure

38. Blood Pressure
• Blood pressure is defined as the
force of blood against the walls of
arteries.
• The pressure in any artery varies
as a result of two major factors.
– 1. Cardiac Output
o Volume of blood.
o Heart rate
– 2. Arteriolar Resistance
o Size
o Elasticity

39. Blood Pressure
• Measuring Blood Pressure
Two different pressures are measured and
compared in a blood pressure reading.
o Systolic pressure
o Diastolic pressure
• Blood pressure is measured using a device
called a sphygmomanometer.
o Normal blood pressure is less than 130 mm
Hg systolic and less than 85 mm Hg diastolic.
o Optimal blood pressure is less than 120 mm
Hg systolic and less than 80 mm Hg diastolic.
o A typical reading for a healthy adult is
120/70

40. Blood Pressure

41. Blood Pressure in the Vessels
• Blood pressure in the Capillaries
– The pressure of arterial blood is
significantly reduced when the blood
enters the capillaries.
• Blood pressure in the veins
– When blood leaves the capillaries and
enters the venules and veins, little
pressure remains to force it along.
• Blood pressure in the Arteries
– Blood pressure is the greatest in these
vessels because the heart has just
pumped the blood.

42. Exchanges between Blood and Cells
• Our blood does not come into direct contact
with the cells it nourishes.
• When blood enters the arteriole end of a
capillary, some components filter through the
walls of the capillaries into the tissue space.
This fluid, called interstitial fluid, is blood
plasma minus most of the proteins.
• Substances in the fluid can enter the cells by
diffusion or active transport. Substances, like
carbon dioxide, can diffuse out of cells and
into the interstitial fluid.
• Near the venous end of a capillary, the blood
pressure is greatly reduced. Here the osmotic
pressure causes fluid to re-enters the
capillary at the venous end.

43. Hypertension
• High blood pressure or hypertension is defined
in an adult as a blood pressure greater than or
equal to 140 mm Hg systolic pressure or greater
than or equal to 90 mm Hg diastolic pressure.
• Risk Factors You Can Control
– Smoking - Physical Inactivity
– Obesity - Diet (Salt Intake)
– Diabetes - Stress
• Risk Factors You Can’t Control
– Age
– Ethnicity (South Asians, First
Nations/Aboriginal Peoples or Inuit and
Blacks are at increased risk)
– Family history

44. Regulation of Blood Pressure

45. Heart Dissection