1. The Cardiovascular System

2. The Cardiovascular System
A closed system of the heart and blood vessels
The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products
Extensive some 60,000 miles worth.
Due to diffusion!

3. The Heart Location About the size of your fist
Thorax between the lungs
Pointed apex directed toward left hip
lies upon diaphragm
About the size of your fist
Average Size of Heart
14 cm long
9 cm wide

4. The Heart

5. Pericardium Superficial fibrous pericardium
Protects, anchors, and prevents overfilling
Deep two-layered serous pericardium
Parietal layer lines the internal surface of the fibrous pericardium
Visceral layer (epicardium) on external surface of the heart
Separated by fluid-filled pericardial cavity (decreases friction)

6. The Heart: Heart Wall
Three layers
Epicardium
Myocardium
Endocardium

7. The Heart: Chambers Right and left side act as separate pumps
Four chambers
Atria- Receiving chambers
Separated internally by the interatrial septum
Coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles
Ventricles- Discharging chambers
Separated by the interventricular septum

8. Brachiocephalic trunk Left subclavian artery Superior vena cava
Left common carotid
artery
Brachiocephalic trunk
Left subclavian artery
Superior vena cava
Aortic arch
Ligamentum arteriosum
Right pulmonary
artery
Left pulmonary artery
Ascending aorta
Left pulmonary veins
Pulmonary trunk
Right pulmonary
veins
Auricle of
left atrium
Circumflex artery
Right atrium
Left coronary artery
(in coronary sulcus)
Right coronary artery
(in coronary sulcus)
Anterior cardiac vein
Left ventricle
Right ventricle
Great cardiac vein
Right marginal artery
Anterior interventricular
artery (in anterior
interventricular sulcus)
Small cardiac vein
Inferior vena cava
Apex
(b) Anterior view
Figure 18.4b

9. Aorta Left pulmonary artery Superior vena cava Right pulmonary artery
Left atrium
Left pulmonary
veins
Pulmonary trunk
Right atrium
Mitral (bicuspid)
valve
Right pulmonary
veins
Fossa ovalis
Aortic valve
Pectinate muscles
Pulmonary valve
Tricuspid valve
Left ventricle
Right ventricle
Papillary muscle
Chordae tendineae
Interventricular
septum
Trabeculae carneae
Epicardium
Inferior vena cava
Myocardium
Endocardium
(e) Frontal section
Figure 18.4e

10. Blood Flow The heart is two side-by-side pumps
Right side is the pump for the pulmonary circuit
Vessels that carry blood to and from the lungs
Very thin myocardium?
Left side is the pump for the systemic circuit
Vessels that carry the blood to and from all body tissues
Very thick myocardium

11. Capillary beds of lungs where gas exchange occurs Pulmonary Circuit
Pulmonary veins
Pulmonary arteries
Aorta and branches
Venae cavae
Left atrium
Left ventricle
Right atrium
Heart
Right ventricle
Systemic
Circuit
Oxygen-rich,
CO2-poor blood
Capillary beds of all
body tissues where
gas exchange occurs
Oxygen-poor,
CO2-rich blood
Figure 18.5

12. Left
ventricle
Right
ventricle
Interventricular
septum
Figure 18.6

13. Blood Circulation

14. Path of Blood Flow

15. Coronary Circulation Arteries Veins
Right and left coronary (in atrioventricular groove), marginal, circumflex, and anterior interventricular arteries
Veins
Small cardiac, anterior cardiac, and great cardiac veins

16. (a) The major coronary arteries
Aorta
Pulmonary
trunk
Superior
vena cava
Left atrium
Anastomosis
(junction of
vessels)
Left
coronary
artery
Right
atrium
Circumflex
artery
Right
coronary
artery
Left
ventricle
Right
ventricle
Anterior
interventricular
artery
Right
marginal
artery
Posterior
interventricular
artery
(a) The major coronary arteries
Figure 18.7a

17. (b) The major cardiac veins
Superior
vena cava
Great
cardiac
vein
Anterior
cardiac
veins
Coronary
sinus
Small cardiac vein
Middle cardiac vein
(b) The major cardiac veins
Figure 18.7b

18. The Heart: Valves Allow blood to flow in only one direction
Four valves
Atrioventricular valves –
Bicuspid valve (left)- mitral valve
Tricuspid valve (right)
Chordae tendineae
Semilunar valves between ventricle and artery
Pulmonary semilunar valve- right ventricle
Aortic semilunar valve- left ventricle

19. attached to tricuspid valve flap Papillary muscle
Pulmonary
valve
Aortic
valve
Area of
cutaway
Mitral
valve
Tricuspid
valve
Chordae tendineae
attached to tricuspid valve flap
Papillary
muscle
(c)
Figure 18.8c

20. Operation of Heart Valves

21. The Heart: Associated Great Vessels
Aorta
Pulmonary arteries
Vena cava
Pulmonary veins (four)

22. The Heart: Conduction System
Intrinsic conduction system (nodal system)
1% of cardiac cells are self excitable
Heart muscle cells contract, without nerve impulses, in a regular, continuous way
However, these cells are synchronized by the sinoatrial (SA) node, or pacemaker,
located in the wall of the right atrium.

23. The Heart: Conduction System
Sinoatrial node- Pacemaker
75 bpm
Atrioventricular node
50 bpm
Atrioventricular bundle
Bundle branches
Purkinje fibers
30 BPM

24. (a) Anatomy of the intrinsic conduction system showing the
Superior vena cava
Right atrium
The sinoatrial (SA)
node (pacemaker)
generates impulses. 1
Internodal pathway
The impulses
pause (0.1 s) at the
atrioventricular
(AV) node. 2
Left atrium
The atrioventricular
(AV) bundle
connects the atria
to the ventricles. 3
Purkinje
fibers
The bundle branches
conduct the impulses
through the
interventricular septum. 4
Inter-
ventricular
septum
The Purkinje fibers
depolarize the contractile
cells of both ventricles. 5
(a) Anatomy of the intrinsic conduction system showing the
sequence of electrical excitation
Figure 18.14a

25. Control
While the SA node sets the tempo for the entire heart, it is influenced by a variety of physiological cues.
Two sets of nerves affect heart rate with one set speeding up the pacemaker and the other set slowing it down.
The pacemaker is also influenced by hormones.
For example, epinephrine from the adrenal glands increases heart rate.
The rate of impulse increases in response to increases in body temperature and with exercise.

26. Dorsal motor nucleus of vagus The vagus nerve (parasympathetic)
decreases heart rate.
Cardioinhibitory center
Medulla oblongata
Cardio-
acceleratory
center
Sympathetic trunk ganglion
Thoracic spinal cord
Sympathetic trunk
Sympathetic cardiac
nerves increase heart rate
and force of contraction.
AV node
SA node
Parasympathetic fibers
Sympathetic fibers
Interneurons
Figure 18.15

27. The Heart: Cardiac Cycle
Atria contract simultaneously
Atria relax, then ventricles contract
Systole = contraction
Diastole = relaxation

29. The Heart: Cardiac Output
Cardiac output (CO)
CO = (heart rate [HR]) x (stroke volume [SV])
5.25 L/min up to 35 L/min
Stroke volume
The average stroke volume for a human is about 75 mL
Heart Rate
Varies but at rest is 70 bpm

30. Cardiac Output Regulation

31. The Heart: Regulation of Heart Rate
Starling’s law of the heart – more stretch = stronger contraction
Changing heart rate is the most common way to change cardiac output

32. The Heart: Regulation of Heart Rate
Increased heart rate
Sympathetic nervous system
Crisis
Low blood pressure
Hormones
Epinephrine
Thyroxine
Exercise
Decreased blood volume

33. The Heart: Regulation of Heart Rate
Decreased heart rate
Parasympathetic nervous system
High blood pressure or blood volume
Dereased venous return

34. Electrocardiogram
recording of electrical changes that occur in the myocardium:
P wave – atrial depolarizatoin
QRS wave – ventricular depolarization
T wave – ventricular repolarization

35. QRS complex Ventricular depolarization Ventricular Atrial
Sinoatrial
node
Ventricular
depolarization
Ventricular
repolarization
Atrial
depolarization
Atrioventricular
node
S-T
Segment
P-Q
Interval
Q-T
Interval
Figure 18.16

36. Atrial depolarization, initiated by the SA node, causes the P wave. Q
Repolarization R R P T Q P T S 1
Atrial depolarization, initiated by the SA node, causes the P wave. Q S
Ventricular depolarization is complete. 4
AV node R R P T P T Q S
With atrial depolarization complete, the impulse is delayed at the AV node. 2 Q S
Ventricular repolarization begins at apex, causing the T wave. 5 R R P T P T Q S Q 3 S
Ventricular depolarization begins at apex, causing the QRS complex. Atrial repolarization occurs. 6
Ventricular repolarization is complete.
Figure 18.17

37. (a) Normal sinus rhythm. (b) Junctional rhythm. The SA
node is nonfunctional, P waves
are absent, and heart is paced by
the AV node at beats/min.
(c) Second-degree heart block.
Some P waves are not conducted
through the AV node; hence more
P than QRS waves are seen. In
this tracing, the ratio of P waves
to QRS waves is mostly 2:1.
(d) Ventricular fibrillation. These
chaotic, grossly irregular ECG
deflections are seen in acute
heart attack and electrical shock.
Figure 18.18

38. Blood Vessels: The Vascular System
Arteries
Arterioles
Capillaries
Venules
Veins

39. The Vascular System

40. Blood Vessels: Anatomy
Three layers (tunics)
Tunic interna
Endothelium
Tunic media
Smooth muscle
Tunic externa
Mostly fibrous connective tissue

41. Differences Between Blood Vessel Types
Walls of arteries are the thickest
Lumens of veins are larger
Skeletal muscle “milks” blood in veins toward the heart
Walls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue

42. Movement of Blood Through Vessels
Most arterial blood is pumped by the heart
Veins use the milking action of muscles to help move blood

43. Capillary Beds

44. Diffusion at Capillary Beds

45. Major Arteries of Systemic Circulation

46. Major Veins of Systemic Circulation

47. Pulse Pulse – pressure wave of blood
Monitored at “pressure points” where pulse is easily palpated

48. Blood Pressure
Systolic –ventricular contraction
Diastolic –ventricles relax
Pressure in blood vessels decreases as the distance away from the heart increases

49. Measuring Arterial Blood Pressure

50. Comparison of Blood Pressures in Different Vessels

51. Blood Pressure: Effects of Factors
Neural factors
Autonomic nervous system adjustments (sympathetic division)
Renal factors
Regulation by altering blood volume
Renin – hormonal control

52. Blood Pressure: Effects of Factors
Temperature
Heat has a vasodilation effect
Cold has a vasoconstricting effect
Chemicals
Various substances can cause increases or decreases
Diet

53. Factors Determining Blood Pressure

54. Variations in Blood Pressure
Human normal range is variable
Normal
140–110 mm Hg systolic
80–70 mm Hg diastolic
Hypotension
(below 110 mm HG)
Often associated with illness
Hypertension
(above 140 mm HG)
Can be dangerous if it is chronic

55. Capillary Exchange: Mechanisms
Direct diffusion across plasma membranes
Endocytosis or exocytosis
Some capillaries have gaps (intercellular clefts)
Fenestrations of some capillaries
Fenestrations = pores

56. OLD AGE STINKS deposition of cholesterol in blood vessels
heart enlarges
cardiac muscle cells die
fibrous connective tissue of heart increases
adipose tissue of heart increases
blood pressure increases
resting heart rate decreases