The circulatory system consists of the heart, blood vessels, and blood. The heart is a muscular pump made of cardiac muscle tissue composed of four chambers. It pumps blood through two circuits - the pulmonary circuit to the lungs and systemic circuit to the body. Blood vessels include arteries, veins, and capillaries. Blood contains plasma, red blood cells, white blood cells, and platelets. The cardiovascular system is regulated through intrinsic factors like Starling's law of the heart and extrinsic neural and hormonal control.

1. The Circulatory System
The Heart, Blood Vessels, Blood Types

2. The Closed Circulatory System
•Humans have a closed circulatory system,
typical of all vertebrates, in which blood is
confined to vessels and is distinct from
the interstitial fluid.
–The heart pumps blood into large vessels
that branch into smaller ones leading into the
organs.
–Materials are exchanged by diffusion
between the blood and the interstitial fluid
bathing the cells.

3. The Cardiovascular System
•Three Major Elements –
Heart, Blood Vessels, &
Blood
–1. The Heart- cardiac
muscle tissue
–highly interconnected
cells
–four chambers
•Right atrium
•Right ventricle
•Left atrium
•Left ventricle

5. Pathway of the blood•Superior Vena Cava
•Right Atrium
•Tricuspid Valve
•Right Ventricle
•Pulmonary Semilunar Valve
•Lungs
•Pulmonary Vein
•Bicuspid Valve
•Left Ventricle
•Aortic Semilunar Valve
•Aorta
•To the bodies organs &
cells

6. Circuits
•Pulmonary circuit
–The blood pathway
between the right side
of the heart, to the
lungs, and back to the
left side of the heart.
•Systemic circuit
–The pathway between
the left and right sides
of the heart.

7. The Cardiovascular System
2. Blood Vessels -A network of tubes
–Arteriesarterioles move away from the heart
•Elastic Fibers
•Circular Smooth Muscle
–Capillaries – where gas exchange takes place.
•One cell thick
•Serves the Respiratory System
–VeinsVenules moves towards the heart
•Skeletal Muscles contract to force blood back
from legs
•One way values

9. The Cardiovascular System
3. The Blood
A. Plasma
Liquid portion of the
blood. Contains clotting
factors, hormones,
antibodies, dissolved
gases, nutrients and
waste

10. The Cardiovascular System
•The Blood
B. Erythrocytes - Red
Blood Cells
–Carry hemoglobin and
oxygen. Do not have a
nucleus and live only
about 120 days.
–Can not repair
themselves.

11. The Cardiovascular System
•The Blood
C. Leukocytes – White
Blood cells
–Fight infection and are
formed in the bone marrow
–Five types – neutrophils,
lymphocytes, eosinophils,
basophils, and monocytes.

12. The Cardiovascular System
The Blood
•D. Thrombocytes –
Platelets.
–These are cell fragment
that are formed in the
bone marrow from
magakaryocytes.
–Clot Blood by sticking
together – via protein
fibers called fibrin.

13. Disorders of the Circulatory System
• Anemia - lack of iron in the blood, low RBC count
• Leukemia - white blood cells proliferate wildly,
causing anemia
• Hemophilia - bleeder’s disease, due to lack of
fibrinogen in thrombocytes
• Heart Murmur - abnormal heart beat, caused by
valve problems
• Heart attack - blood vessels around the heart
become blocked with plaque, also called myocardial
infarction

14. Unit 9 – The Heart
Cardiovascular System
The HeartThe Heart

15. Functions of the Heart
• Generating blood pressure
• Routing blood
– Heart separates pulmonary and systemic
circulations
• Ensuring one-way blood flow
– Heart valves ensure one-way flow
• Regulating blood supply
– Changes in contraction rate and force
match blood delivery to changing
metabolic needs

16. Size, Shape, Location
of the Heart
•Size of a closed
fist
•Shape
–Apex: Blunt
rounded point of
cone
–Base: Flat part at
opposite of end of
cone
•Located in thoracic
cavity in
mediastinum

17. Heart Cross Section

18. Pericardium

19. Heart Wall
• Three layers of tissue
– Epicardium: This serous membrane
of smooth outer surface of heart
– Myocardium: Middle layer composed
of cardiac muscle cell and
responsibility for heart contracting
– Endocardium: Smooth inner surface
of heart chambers

20. Heart Wall

21. External Anatomy
•Four chambers
–2 atria
–2 ventricles
•Auricles
•Major veins
–Superior vena
cava
–Pulmonary veins
•Major arteries
–Aorta
–Pulmonary trunk

22. External Anatomy

23. Coronary Circulation

24. Heart Valves
•Atrioventricular
–Tricuspid
–Bicuspid or mitral
•Semilunar
–Aortic
–Pulmonary
•Prevent blood
from flowing back

25. Heart Valves

26. Function of the Heart Valves

27. Blood Flow Through Heart

28. Systemic and Pulmonary
Circulation

29. Heart Skeleton
•Consists of plate of
fibrous connective
tissue between atria
and ventricles
•Fibrous rings around
valves to support
•Serves as electrical
insulation between
atria and ventricles
•Provides site for
muscle attachment

30. Cardiac Muscle
• Elongated, branching cells containing 1-2 centrally located
nuclei
• Contains actin and myosin myofilaments
• Intercalated disks: Specialized cell-cell contacts
• Desmosomes hold cells together and gap junctions allow action
potentials
• Electrically, cardiac muscle behaves as single unit

31. Conducting System of Heart

32. Electrical Properties
• Resting membrane potential (RMP)
present
• Action potentials
– Rapid depolarization followed by rapid,
partial early repolarization. Prolonged
period of slow repolarization which is
plateau phase and a rapid final
repolarization phase
– Voltage-gated channels

33. Action Potentials in
Skeletal and Cardiac Muscle

34. SA Node Action Potential

35. Refractory Period
• Absolute: Cardiac muscle cell
completely insensitive to further
stimulation
• Relative: Cell exhibits reduced
sensitivity to additional stimulation
• Long refractory period prevents tetanic
contractions

36. Electrocardiogram
• Action potentials
through myocardium
during cardiac cycle
produces electric
currents than can be
measured
• Pattern
– P wave
• Atria depolarization
– QRS complex
• Ventricle
depolarization
• Atria repolarization
– T wave:
• Ventricle
repolarization

37. Cardiac Arrhythmias
• Tachycardia: Heart rate in excess of
100bpm
• Bradycardia: Heart rate less than 60
bpm
• Sinus arrhythmia: Heart rate varies 5%
during respiratory cycle and up to 30%
during deep respiration
• Premature atrial contractions:
Occasional shortened intervals
between one contraction and
succeeding, frequently occurs in
healthy people

38. Alterations in Electrocardiogram

39. Cardiac Cycle
• Heart is two pumps that work together,
right and left half
• Repetitive contraction (systole) and
relaxation (diastole) of heart chambers
• Blood moves through circulatory
system from areas of higher to lower
pressure.
– Contraction of heart produces the
pressure

40. Cardiac Cycle

41. Events during Cardiac Cycle

42. Heart Sounds
• First heart sound or “lubb”
– Atrioventricular valves and surrounding fluid
vibrations as valves close at beginning of
ventricular systole
• Second heart sound or “dupp”
– Results from closure of aortic and pulmonary
semilunar valves at beginning of ventricular
diastole, lasts longer
• Third heart sound (occasional)
– Caused by turbulent blood flow into ventricles and
detected near end of first one-third of diastole

43. Location of Heart Valves

44. Mean Arterial Pressure (MAP)
• Average blood pressure in aorta
• MAP=CO x PR
– CO is amount of blood pumped by
heart per minute
• CO=SV x HR
– SV: Stroke volume of blood pumped during each
heart beat
– HR: Heart rate or number of times heart beats
per minute
• Cardiac reserve: Difference between CO at rest
and maximum CO
– PR is total resistance against which
blood must be pumped

45. Factors Affecting MAP

46. Regulation of the Heart
• Intrinsic regulation: Results from normal
functional characteristics, not on neural or
hormonal regulation
– Starling’s law of the heart
• Extrinsic regulation: Involves neural and
hormonal control
– Parasympathetic stimulation
• Supplied by vagus nerve, decreases heart rate,
acetylcholine secreted
– Sympathetic stimulation
• Supplied by cardiac nerves, increases heart rate and force
of contraction, epinephrine and norepinephrine released

47. Heart Homeostasis
• Effect of blood pressure
– Baroreceptors monitor blood pressure
• Effect of pH, carbon dioxide, oxygen
– Chemoreceptors monitor
• Effect of extracellular ion concentration
– Increase or decrease in extracellular K+
decreases
heart rate
• Effect of body temperature
– Heart rate increases when body temperature
increases, heart rate decreases when body
temperature decreases

48. Baroreceptor and Chemoreceptor
Reflexes

49. Baroreceptor Reflex

50. Chemoreceptor Reflex-pH

51. Effects of Aging on the Heart
• Gradual changes in heart function,
minor under resting condition, more
significant during exercise
• Hypertrophy of left ventricle
• Maximum heart rate decreases
• Increased tendency for valves to
function abnormally and arrhythmias to
occur
• Increased oxygen consumption
required to pump same amount of
blood