The structure, function and control of the cardiovascular system

1. Cardiovascular system
r.watson@hull.ac.uk
Twitter: @rwatson1955

2. Cardiovascular system
The cardiovascular system is comprised of the heart and the blood
vessels. It is the primary means of transport around the body and it
distributes blood to all regions of the body. Blood is the means of
transport of oxygen, nutrients, hormones and waste products. The
cardiovascular system is controlled, primarily, by the cardiac centre in
the medulla of the brain.

3. Bozeman biology You Tube link
The circulatory system

6. The heart
Gross anatomical structure:
•Fist sized muscular organ located in the thorax

10. Heart valves
Prevent backflow of blood into atria and ventricles:
•Atrioventricular valves (bicuspid and tricuspid)
•Pulmonary valve
•Aortic valve

12. Circulation through heart
•Vena cava
•Right atrium
•Right ventricle
•Pulmonary artery
•Pulmonary vein
•Left atrium
•Left ventricle
•Aorta

14. Pulses
Pulses are located where an artery runs close to the surface of the
body and over a bony prominence.

16. radial
carotid
femoral

17. Electrical activity in heart
Pacemaker:
•Generated at sinoatrial node
•Travels to atrioventricular node and spreads across atria
•Travels through septum along Purkinje fibres
•Spreads across ventricles

20. Electrocardiogram (ecg)
At rest this picks up the electrical activity in the heart.

25. Cardiac cycle
Systole:
•When heart contracts and pumps blood into the arteries
Diastole:
•When the heart relaxes and the ventricles fill with blood

28. Cardiac muscle
One of three types of muscle:
•Skeletal
•Smooth
•Cardiac

30. Skeletal muscle

34. Cardiac muscle
•Structure allows rapid conduction of electrical activity across heart
•Acts as a functional syncytium – ie as one cell

36. Coronary circulation
The heart has its own blood supply

39. Control of the heart
The heart responds to different situations, eg
•Walking
•Resting
•Running up stairs

40. Cardiac output (CO)
This needs to change in different situations, eg
•Need more CO when running than when walking

41. Cardiac output (CO)
Composed of:
•Stroke volume (approx 70ml/beat)
•Heart rate (approx 70 bpm at rest)
70 x 70ml = 4900ml
Therefore: CO = approx 5 litres per minute at rest

42. Cardiac output (CO)
Mainly controlled by changing heart rate
Heart rate is controlled by:
•Sympathetic stimulation
•Circulating levels of catecholamines (adrenaline and noradrenaline)
Hard to separate control of heart rate from control of blood pressure
• Many factors involved

44. Vascular system
System of vessels through which the heart pumps blood to all regions
of the body.
Comprised of:
•Arteries
•Veins
•Capillaries

46. Arteries
Carry blood away from the heart under pressure from the ventricles
Structure:
•Mainly composed of smooth muscle

49. Veins
Carry blood to the heart using skeletal and respiratory muscle pumps
Structure:
•Mainly composed of smooth muscle
•Similar to artery but less smooth muscle
•Contain valves

52. Capillaries
•No smooth muscle
•Composed of epithelial cells
•Single cell layer
•Transport blood to tissues
•Enable diffusion of substances across capillary wall
•Diameter is same as a red blood cell (7μm)

55. Blood circulation
Achieved by blood pressure:
•Generated by the heart
•Maintained by the arteries

56. Blood pressure (BP)
Composed of:
•Cardiac output (CO)
•Peripheral resistance (PR)
Therefore:
BP = CO x PR

57. Peripheral resistance
Provided by the resistance to blood flow in the arterial system
Therefore BP can be controlled by changing
• cardiac output
• peripheral resistance

58. Peripheral resistance
Altered by changing the diameter of the arteries through:
• sympathetic stimulation (↓ diameter)
• parasympathetic stimulation (↑diameter)
NB: ↓ diameter → ↑ resistance → ↑ Blood pressure

59. Blood pressure and circulation
Blood circulation is achieved by the gradient of pressure from:
•The left ventricle to
•The right atrium

61. ‘Normal’ blood pressure
Measured in mmHg:
•Systolic = 120 mmHg
•Diastolic = 80 mmHg

62. Mean arterial blood pressure (MAP)
MAP = diastolic + (1/3 systolic – diastolic)
MAP is the blood pressure which maintains blood flow in the
peripheral arteries and the coronary arteries

63. Capillary exchange
Enabled by the difference between:
•Capillary blood pressure
•Capillary osmotic pressure

65. Lymphatic system
Serves two purposes:
• Maintenance of fluid balance
• Immune system function

67. Control of blood pressure
Achieved by changing cardiac output and peripheral resistance
Mediated via the medulla:
•Alters heart rate and
•Peripheral resistance

69. Control of blood pressure
Achieved by changing cardiac output and peripheral resistance
Mediated via the medulla:
•Alters heart rate and
•Peripheral resistance
And the kidneys:
•Alter blood volume (aldosterone)
•peripheral resistance (renin angiotensin system)

71. Blood
Blood is a tissue composed of:
•Plasma
•Blood cells

74. The red blood cell (erythrocyte)
Highly specialised cell designed primarily to carry oxygen
•No nucleus
•No mitochondria
Oxygen is carried mainly bound to haemoglobin

77. ABO blood grouping
This is due to the existence of antigen like molecules on the surface
of red blood cells:
• Agglutinogens
These bind antibody type molecules in the plasma:
• Agglutinins

79. ABO blood grouping
This is due to the existence of antigen like molecules on the surface
of red blood cells:
• Agglutinogens
These bind antibody type molecules in the plasma:
• Agglutinins
If the wrong combination of the above meet – as can happen in blood
transfusion:
• Agglutination
This is VERY dangerous and can lead to DEATH

81. Blood transfusion
People with blood type Are know as
0 Universal donors
AB Universal recipients

82. Cardiovascular system
The cardiovascular system is comprised of the heart and the blood
vessels. It is the primary means of transport around the body and it
distributes blood to all regions of the body. Blood is the means of
transport of oxygen, nutrients, hormones and waste products. The
cardiovascular system is controlled, primarily, by the cardiac centres
in the medulla of the brain.

83. Questions
1. What is the cardiovascular system comprised of and what are the
three types of blood vessel?
2. Describe the heart.
3. In addition to oxygen name four things that the blood transports.
4. What are the four chambers of the heart?
5. What are the four blood vessels attached to the heart?
6. What are the four valves in the heart?

84. Questions
7. Which blood vessels attached to the heart carry oxygenated blood
and deoxygented blood, resepectively?
8. Describe the flow of blood through the heart.
9. In addition to the radial pulse, name 8 other sites on the body
where a pulse can be felt.
10. Describe the generation and spead of electrical activity in the
heart.
11. What is a trace of electrical activity in the heart called: what are
the three sets of patterns observed?

85. Questions
12. What is happening at the three wave patterns on the
electrocardiogram? What can happen to the T-wave in a
myocardial infarction?
13. What are the two stages of the cardiac cycle and what is
happening at each stage?
14. Describe the cardiac output; what are its components and how is
it calculated?
15. What effect do: sympathetic stimulation, parasympathetic
stimulation and increased end diastolic volume have, respectively,
on the cardiac output? What happens to resting heart rate in
athletes?

86. Questions
16. What type of muscle is found in arteries and veins? How does this
differ between arteries and veins? What do veins have that
arteries lack? What is the space in the middle of a blood vessel
called?
17. What are the two factors that determine blood pressure? What is
the equation for bood pressuer based on these factors?
18. What two factors determine capillary exchange? Which is larger at
the arterial end of the capillary bed; what is the fluid in the tissues
called?

87. Questions
19. How are the medulla and the kidneys, respectively, involved in
control of blood pressure?
20. What are the three formed elements in the blood? How is one of
these formed elements further subdivided into two main types?
21. Describe four unique things about the specialisation of the
erythrocyte.
22. What are the four main blood types?

88. r.watson@hull.ac.uk
Four things about…(a simple approach to
anatomy and physiology)
Special Senses
r.watson@hull.ac.uk
Four things about…(a simple approach to
anatomy and physiology)
The cardiovascular system