cardiovascular system anatomy and physiology heart blood pressure

1. Anatomy ∙ Physiology
II
Chapter 15, Section 1
The Cardiovascular
System

2. FUNCTIONS OF THE
HEART
It pumps 7000L (1800 gallons) of blood through our body every day.
The heart contracts 2.5 billion times in a lifetime.

3. The heart is composed of two pumps
The systemic circuit carries
blood to the body
The pulmonary circuit carries
blood to the lungs

4. The heart is located within the mediastinum
It is about the size of a fist (14cm x 9cm)
2/3 of the heart is left of the midline
1/3
2/3

5. The heart is posterior to the sternum
Base
attachment of major vessels
2nd intercostal space
Apex
Pointed inferior margin
5th intercostal space

6. The heart is surrounded by a pericardial membrane.
The fibrous pericardium forms a thick outer
layer of connective tissue.
The parietal pericardium is a serous
membrane attached directly to the fibrous
layer.
A visceral pericardium is a serous
membrane that forms the outer layer of the
heart wall.
The pericardial cavity contains serous fluid.

7. The wall of the heart contains 3 layers
The epicardium is also called the visceral
pericardium
The myocardium contains a thick layer of cardiac
muscle, with blood vessels and nerves
The endocardium is a smooth layer of squamous
epithelium that lines the heart chambers and valves

8. The heart contains 4 chambers
The right atrium receives
blood from the body
The left atrium receives
blood from the lungs
The right ventricle pumps
blood towards the lungs
The left ventricle pumps
blood towards the body
Interventricular septum

9. A pocket, called the auricle
increases the capacity of the atria.

10. blood enters the heart through the great veins
The superior vena cava
returns blood from the
upper body to the heart
Four pulmonary veins
return blood from the
lungs to the heart
The coronary sinus
returns blood from the
myocardium to the heart
The inferior vena cava
returns blood from the
lower body to the heart

11. Great arteries carry blood away from the heart
The aorta delivers oxygenated
blood to the systemic circulation
The pulmonary trunk* delivers
deoxygenated blood to the lungs
* The pulmonary trunk immediately
divides into a left and right pulmonary

12. AV valves prevent backflow into the atria.
*AV = atrioventricular
The tricuspid valve
guards the right AV
orifice
The bicuspid (mitral)
valve guards the left
AV orifice

13. AV valves are anchored to the ventricles by chordae tendineae
Chordae tendineae anchored to the
cusps papillary muscles
Papillary muscles contract to pull the
valves tightly shut
Mitral Valve Prolapse – cusp of the mitral valve protrudes into atrium.
Symptoms include: chest pain, heart palpitations, and fatigue.

14. Semilunar valves prevent backflow of blood into the ventricles
A pulmonary valve is located at
the base of the pulmonary trunk
An aortic valve (not shown) is
located at the base of the aorta

15. Each cusp of a semilunar valve is
shaped like a crescent moon

16. path of blood through the right heart
1. Blood enters right atrium
through the SVC, IVC, and
coronary sinus
1
2. It passes through the tricuspid
valve into the right ventricle
4
4
3. Blood is pumped from the right
ventricle, through the pulmonary
valve, and into the pulmonary
trunk.
2
4. Blood passes into the
pulmonary arteries towards the
lungs
3
1

17. path of blood through the left heart
5. Oxygenated blood is returned to
the heart through 4 pulmonary
veins.
6. Blood enters the left atrium.
9
7. Blood passes through the
bicuspid valve into the left
ventricle.
8. The left ventricle pumps blood
through the aortic valve into the
aorta.
9. Blood enters systemic
circulation to the tissues
throughout the body.
9
9
8
5
5
6
7

18. Section 2, Chapter 15
Cardiac Cycle & Cardiac Conduction

19. The cardiac cycle
The left and right sides of the heart contract
together in a coordinated fashion
Systole – contraction
Diastole – relaxation
Ventricular Systole
• Ventricles contract to expel blood
• Atria are in diastole during ventricular systole, filling with blood
• Semilunar valves are opened, while AV valves are closed
Ventricular Diastole
• Ventricles are relaxed, filling with blood
• Ventricles are 70% full before atria contract
• Atrial systole pushes the remaining 30% of blood into ventricles
• AV valves are opened while semilunar valves are closed

20. Heart Sounds
The heart valves produce a distinct sound as they close, which
can be heard through a stethoscope.
Lubb-Dupp
Lubb (S1) = sound of AV valves closing
occurs during ventricular systole
Dupp (S2) = sound of semilunar valve closing
occurs during ventricular diastole
murmur = abnormal sound from the cusps not closing completely

21. Heart Sounds - Ausculation
aortic valve (A)
heard at 2nd intercostal space,
right of the sternum
1
pulmonary valve (P)
heard at 2nd intercostal space,
left of the sternum
2
3
4
5
tricuspid valve (T)
heard at 5th intercostal space,
either right or left of the sternum
6
7
8
9
mitral valve (M)
heard at 5th intercostal space,
below left nipple
10
Image from Grant’s Atlas of Anatomy. Each heart valve is indicated by a colored oval and the area of
auscultation of the valve is indicated as a circle of the same color containing the first letter of the valve
name.

22. Cardiac Conduction of the Heart
The heart is autorhythmic:
Specialized cardiac tissue initiate and distribute
electrical impulses that generate heart contractions.
Syncytium – intercalated discs contain gap junctions that transmit action
potentials from cell-to-cell. Cardiac muscles contract as a functional unit
(syncytium)
Atrial Syncytium – left and right atria contract together
Ventricular Syncytium – left and right ventricles contract together

23. Cardiac Conduction of the Heart
sinoatrial (SA) node
Pacemaker of heart
Initiates atrial syncytium
Fires 80 impulses per minute
Parasympathetic inhibition keeps
heart rate at about 72 beats per
minute
junctional fibers
conduct impulses towards
towards AV node
Figure 15.18 Illustrates the cardiac conduction system.

24. Cardiac Conduction of the Heart
atrioventricular (AV) node
Located within inferior wall of
interatrial septum
Provides a junction between
atrial and ventricular syncytia
AV Bundle (Bundle of His)
Only known conduction pathway
between atria and ventricles
divides into left and right bundle
branches
Figure 15.18 Illustrates the
cardiac conduction system.

25. Cardiac Conduction of the Heart
bundle branches (left and right)
Conduction pathways along the
interventricular septum
Gives rise to Purkinje Fibers
purkinje fibers
Transmits action potentials to
ventricular myocardium and papillary
muscles
Initiates ventricular syncytium at apex
of heart

26. Figure 15.19 Summarizes the cardiac conduction system
Figure 15.20 Muscle fibers of the ventricles are
whorled shape, which increases the blood output
during ventricular systole.
End of Section 2, Chapter 15

27. section 3, chapter 15
Electrocardiogram
An electrocardiogram, or ECG (or EKG) is a recording of the
electrical changes in the myocardium during the cardiac cycle.

28. Electrocardiogram
P Wave
atrial depolarization that initiates atrial
contraction
conduction of electrical impulse across
atria from right to left and downward
QRS Complex
Ventricular depolarization that initiates
contraction of the ventricles
This massive wave hides the atria
repolarization

29. Electrocardiogram
T Wave
represents repolarization of ventricles
Normal ECG pattern

30. Heart Arrhythmias:
normal
ECG of a regular heart rhythm at 75 beats per minute
Atrial Flutter. Atria fire 250-350 times per minute. For every QRS complex there may
be 4 or more P waves.

31. Examples of Heart Arrhythmias. Arrows indicate p Wave.
Bradycardia – cardiac rhythm less than 60 beats per minute.
Tachycardia– cardiac rhythm greater than 100 beats per minute.

32. Examples of Heart Arrhythmias, fibrillation
Atrial fibrillation. Instead of contracting, the atria become quivering chambers. The
ventricles respond only to impulses that make it to the AV node.
Ventricular fibrillation = Life threatening arrhythmia. Ventricles quiver, and are unable to pump
blood properly. Requires immediate defibrillation.

33. regulation of cardiac cycle
The heart rate is controlled intrinsically by the SA node, but
sympathetic and parasympathetic fibers alter the rate at which
the pacemaker fires.

34. Cardiac Control Center
Located within Medulla Oblongata
Receives sensory impulses from throughout the cardiovascular system
and relays motor impulses to heart in response.
The cardiac control centers include a Cardioinhibitor & cardioaccelerator
reflex center

35. Cardioinhibitor reflex center
Parasympathetic fibers from vagus nerves innervate SA &
AV nodes.
Vagus nerves release Acetylcholine (ACh) that decreases
the firing rates of SA & AV nodes.
Heart rate decreases

36. Cardioaccelerator reflex center
Sympathetic fibers from accelerator nerves innervate SA & AV nodes.
Norepinephrine released from fibers increases the firing rates of SA &
AV nodes.
Heart rate and force of contraction increases

37. Cardioinhibitor & cardioaccelerator reflex centers alter the heart rate in
response to sensory impulses from receptors
Baroreceptors – monitor blood pressure
Located within aortic arch and carotid sinuses •
Rising blood pressure stimulates cardioinhibitor center •

38. `
Figure 15.24b Illustration of the baroreflex arc
End of Section 3, Chapter 15

39. Section 4, Chapter 15
Blood Vessels

40. Veins
Arteries
• Returns blood towards the
heart
• Convey blood away from the
heart
Venules
Arterioles
• Receives blood from capillaries
• Thinner vessels that convey
blood towards capillaries
Capillaries
• Site of exchange between blood and
body tissues

41. Walls of the blood vessels consists of 3 Layers
Tunica Interna (inner)
Endothelium
A layer of smooth simple squamous •
epithelium
Secretes biochemicals with a wide •
variety of functions.
Basement membrane
Bed of connective tissue with elastic & •
collagenous fibers

42. 3 Layers of the blood vessel wall
Tunica Media (middle)
Smooth Muscles
Vasoconstriction – muscles contract, •
decreasing diameter of vessel
Vasodilation – muscles relax, allowing vessel •
diameter to increase
Elastic Connective tissue
Recoil of elastic fibers helps propel •
blood through vessels

43. 3 Layers of the blood vessel wall
Tunica Externa (outer)
Fibrous Connective Tissue
Elastic and collagenous fibers
Attaches blood vessel to organs
Vasa Vasorum “vessels of the vessels”
Provide blood supply to walls of thicker arteries

44. Arterioles
Arterioles are smaller divisions of arteries.
metarterioles – small arterioles that join capillaries
Arteriovenous shunt – connects an arteriole directly to a venule
Shunt allows blood to bypass a capillary bed.
Figure 15.27
An arteriovenous shunt
provided by a metarteriole.

45. Capillaries
Capillaries
smallest diameter blood vessels that
consists of a single layer of endothelial cells
Site of gas, nutrient, and waste exchange
Slits
Spaces between endothelia
that facilitate diffusion across
vessel wall
Figure 15.28 Substances are exchanged through
openings (slits) separating endothelial cells.

46. Capillaries
Precapillary sphincters
Smooth muscles that regulate the flow
of blood through a capillary
Closes a capillary bed when oxygen
demand to an organ is low
Figure 15.26 A precapillary
sphincter at the base of a capillary.

47. Capillaries
Sinusoids
large cavities within discontinuous capillaries
Sinusoids allow a rapid exchange of nutrients,
debris, proteins, and even cells.
located throughout the liver and spleen.
Artificially colored electron micrograph
depicts sinusoids throughout the liver.

48. Venules
Continue from capillaries and merge to form veins
Veins
Convey blood from body back to the atria of heart
Veins follow a pathway roughly parallel to arteries
Vessel wall of veins has 3 layers (tunics) similar to arteries

49. Differences between veins and arteries
Veins have poorly developed tunica media
Thinner walls, and a larger lumen than arteries
Tunica Interna of veins contain valves
Valves prevent blood from flowing backwards towards capillaries.
Veins act as blood reservoirs
Most blood (60-70%) is in the veins and venules.
Figure 15.31. Venous valves (a) open as blood moves towards the heart,
but (b) close to prevent blood from moving backward away from the
heart.

50. Differences between
veins and arteries
Figure 15.25 Blood vessels (a) the wall of an
artery. (b) The wall of a vein. (c) cross section
of an arteriole (bottom) and a venule (top).

51. End of Section 4, Chapter 15

52. Blood Pressure
Section 5, Chapter 15

53. Blood Pressure
Blood pressure is the force the blood exerts against
the inner walls of the blood vessels
Usually refers to pressure in systemic arteries
Arterial blood pressure:
Rises with ventricular contractions and falls as
ventricles relax
Systolic pressure is the maximum pressure during
ventricular contraction
Diastolic pressure is the minimum pressure when
the ventricles relax

54. Factors that influence blood pressure
Cardiac Output- volume of blood ejected from one ventricle per minute .1
cardiac output = stroke volume (mL) X heart rate (beats/minute)
Stroke Volume
Volume of blood expelled from ventricle with each contraction
Average = 70 milliliters per beat (mL/beat) for adult male
Heart Rate
Average = 72 beats per minute
Stroke Volume
example:
70 mL/beat
Heart Rate
X
70 beats/minute
Cardiac Output
=
5040mL/minute

55. Factors that influence blood pressure
Cardiac output (and blood pressure) increases
with an increase in stroke volume or heart rate.
heart rate increases
or
blood pressure increases
stroke volume increases

56. Factors that influence blood pressure
Blood Volume
Average blood volume in adults = 5 Liters (1.3 gallons)
As blood volume increases, blood pressure initially increases
Peripheral Resistance
Peripheral resistance = friction between blood and blood vessels
Vasoconstriction increases resistance and increases blood pressure
Vasodilation decreases blood pressure
Viscosity of blood
Viscosity = resistance of a fluid to flow (thickness of a fluid).
Blood cells and some plasma proteins increase the viscosity of blood.
Anemia (deficiency of red blood cells) reduces viscosity & lowers blood
pressure

57. Factors that influence blood pressure
blood volume increases
heart rate increases
stroke volume increases
peripheral resistance
increases
blood viscosity increases
blood pressure
increases
Some of the factors that influence arterial blood pressure

58. Increased blood pressure
heart rate decreases
stroke volume decreases
cardiac output decreases
peripheral resistance decreases
blood pressure is maintained
cardiac output increases
heart rate increases
peripheral resistance increases
stroke volume increases
decreased blood pressure

59. Control of Blood Pressure
Factors that affect stroke volume
End-diastolic volume (EDV)
Volume of blood in ventricles at the end of ventricular diastole
Ventricles are filled with blood
End-systolic volume (ESV)
Volume of blood in ventricles at the end of ventricular systole
Only 60% of blood is expelled from heart during a normal
contraction
Increasing the force of ventricular contractions decreases ESV
Stroke volume = EDV– ESV
Increase stroke volume by increasing EDV or decreasing ESV

60. stroke volume
Stroke Volume is directly related to the force of ventricular contraction.
Two events that occur in the ventricles coincide with stroke volume:
1. End-diastolic volume (EDV)
Volume of blood in ventricles at the end of ventricular diastole
As ventricles fill with blood, muscle fibers are mechanically
stretched - preload
2. End-systolic volume (ESV)
Volume of blood in ventricles at the end of ventricular systole
A normal health heart expels 60% of blood present in ventricle.

61. stroke volume
Stroke Volume is the difference between end diastolic
volume (EDV) and end systolic volume (ESV): Stroke Volume = EDV - ESV
Frank-Starling Principle:
The ability of a heart muscle to generate force depends
on the original stretch of a muscle prior to contraction
(similar to stretching a rubber band)
The degree of stretch (preload) of the myocardial fibers
before contraction determines the stroke volume
A greater end diastolic volume results in a greater force of
contraction, leading to a greater stroke volume.

62. Venous Return
Blood pressure rapidly decreases as the blood moves through the
arterial system and into the capillary network.
Little pressure remains in the veins, therefore heart actions contribute
very little to venous return.
Figure 15H
Blood pressure decreases as blood
moves away from the heart.

63. Venous Return
Venous return depends on:
Skeletal muscle contractions – massaging actions push blood towards heart
Respiratory movements – generates pressure in abdominal and thoracic cavities
Changes in pressure pushes blood along veins
Vasoconstriction – contraction of smooth muscles in tunica media
Sympathetic reflexes vasoconstrict the smooth muscles in veins, which can
propel additional blood from venous reservoir towards the heart.

64. Arterial System
Aorta
Main trunk of the systemic circulation
Divisions of the aorta
Aortic root = attachment to heart
Ascending Aorta
Aortic arch
Thoracic aorta
Abdominal aorta

65. Components of the aortic root
Aortic Valve
Aortic Sinus
Swelling at aortic root
Right and left coronary arteries
Supply blood to myocardium of the heart
Myocardial infarction = blocked coronary artery
Aortic Bodies
Chemoreceptors - monitor CO2 & O2 levels in blood

66. Branches of the aortic arch
Brachiocephalic Artery
Brachiocephalic artery divides into:
Right common carotid artery Supplies blood to right
side of face and head
Right subclavian artery - Supplies blood to right arm
Left common carotid artery
supplies blood to left side of face and head
Left subclavian artery
supplies blood to left arm

67. Figure 15.42 The major branches of the aortic arch are highlighted in yellow.
End of Section 5, Chapter 15

68. Section 6, Chapter 15

69. Arterial Divisions
Aorta - Main trunk of the systemic circulation.•
Divisions of the aorta•
Aortic root = attachment to heart•
Ascending Aorta•
Aortic arch•
Thoracic aorta •
Abdominal aorta•

70. Section 6, Chapter 15
Systemic arteries and veins

71. Arterial Divisions
Aorta - Main trunk of the systemic circulation.
Divisions of the aorta
Aortic root = attachment to heart
Ascending Aorta
Aortic arch
Thoracic aorta
Abdominal aorta

72. Structures at the aortic root
Aortic Valve
Aortic Sinus - Swelling at aortic root
Aortic Bodies
Chemoreceptors - monitor CO2 & O2 levels in blood
4. Right and left coronary arteries

73. Coronary Arteries
Right Coronary Artery branches
Posterior interventricular artery:
supplies walls of both ventricles
Marginal artery:
supplies right atrium and right ventricle
Left Coronary Artery branches
Anterior interventricular artery:
supplies walls of both ventricles
Circumflex Artery:
supplies left atrium and left ventricle
Blocked coronary artery = myocardial infarction

74. Branches of Aortic Arch
Brachiocephalic artery
supplies
Right common carotid artery:
right neck and head
Right subclavian artery:
supplies right arm
2. Left common carotid artery
supplies left neck and head
3. Left subclavian artery
Supplies left arm

75. Branches of Thoracic Aorta
Grant’s Anatomy. Branches of the thoracic aorta
Bronchial Arteries – supplies bronchi
Pericardial artery – supplies pericardium
Esophageal arteries – supplies esophagus

76. Branches of Abdominal Aorta
Phrenic arteries
supply diaphragm
Celiac Trunk
Gastric a. - supply stomach
Splenic a. – supply spleen & pancreas
Hepatic a. – supplies liver with O2 blood
Suprarenal a.
Supplies adrenal glands
Superior Mesenteric a.
Supplies small intestine

77. Branches of Abdominal Aorta
Renal arteries
Supplies kidneys
Gonadal arteries.
Male = testicular arteries
Female = Ovarian arteries
Lumbar arteries
Supplies skin and muscles of lower back
Inferior mesenteric artery
Supplies most of large intestine

78. Arteries to the Brain, Head, and Neck
Divisions of Common Carotid Arteries
External Carotid Arteries
Supplies blood to face,
neck, and scalp
Internal Carotid Arteries
Supplies blood to brain
Provides 75% of blood to brain
Carotid Sinus - point of bifurcation
Carotid bodies – chemoreceptors
Carotid baroreceptors
Common site of stenosis (narrowing)

79. Arteries to the Brain, Head, and Neck
Branches of Internal Carotid Artery
1. Ophthalmic artery
supplies eyes
2. Anterior cerebral artery
supplies medial surface of brain
3. Middle cerebral artery
Supplies lateral surface of brain
Internal carotid arteries

80. Arteries to the Brain, Head, and Neck
Vertebral Arteries
Provides 25% of blood supply to
brain
Branch from subclavian arteries
Pass through transverse
foramen of cervical vertebrae
Enter skull through foramen
magnum

81. Arteries to the Brain, Head, and Neck
Basilar Artery
Both vertebral arteries merge to form a basilar
artery at the base of the brain.
Supplies blood to brainstem
Branch: Posterior cerebral artery
Supplies occipital and temporal lobes

82. Arteries to the Brain, Head, and Neck
Cerebral Arterial Circle (Circle of Willis)
Joins the internal carotid arteries with basilar artery at base of brain
Provides anastomoses (alternate routes) for blood flow

83. Arteries to the Shoulder
and Upper Limb
Axillary Artery
Arises from subclavian artery
Brachial Artery
Continuation of axillary artery
Used for measuring blood pressure
Ulnar Artery
Continues along medial arm to wrist
Radial Artery
Continues along lateral arm to
wrist
Convenient vessel for taking your
pulse

84. Veins that drain the head
and neck
External Jugular Veins
Drains blood from face, scalp, and neck
Internal Jugular Veins
Drains blood from brain and
deep face
Arise from dural sinuses
Dural Venous Sinuses
Located between 2 layers of dura mater
Major CSF draining pathway from brain

85. Veins that drain the arm
Ulnar & Radial Veins
drain forearm and hands
Merge for form brachial veins
Basilic Vein
Located on medial aspect of arm
Joins the brachial vein near the axilla
Axillary Vein
Formed from the merging of basilic and brachial
veins
Cephalic Vein
Courses upward on the lateral arm
Joins axillary vein to form subclavian vein
Median Cubital Vein
Joins basilic and cephalic veins at elbow
Often the site of venipuncture

86. Hepatic Portal System
Portal System – drains blood from
one capillary bed into a second
capillary bed.
Hepatic Portal Vein (HPV)
Carries nutrient rich blood
from abdominal viscera to
the liver for processing
•

87. Hepatic Portal System
Tributaries of Hepatic Portal Vein
Gastric vein – blood from stomach •
Splenic vein – blood from spleen &
pancreas
•
•
Superior mesenteric vein – blood from
small intestine
Inferior mesenteric vein – blood from
large intestine
•
Pathway of Hepatic Portal System
heart
aorta
abdominal viscera
HPV
liver
hepatic vein
IVC
heart
End of Chapter 15