1. Organisational Complexity of the Human
3.2.1
Organisational Complexity of the Human
Circulation System

2. You need to know…… The way a closed circulation system is organised
Arteries, arterioles, veins, venules and capillaries
Pulmonary & systemic circulation and portal systems
Structure of the heart & path of blood path through it
Role of muscle and valves in heart and blood vessels
Coronary arteries & veins supplying the heart muscle
Lymphatic system
ABO blood groups
Pulse
Composition of blood
Rhesus Factor
Blood pressure

3. Two types of Circulation System
Open Circulation Systems
Heart pumps blood into vessels that are open ended ……eg in Insects
Closed Circulation Systems
Blood remains in a continuous system of blood vessels…..eg in Humans

4. Advantages of a Closed Circulation System
1. Blood can be pumped faster
Therefore nutrients can be delivered faster to cells allowing the organism to be more active
2. Blood flow rate to different organs can be changed
For example blood flow can be increased to the leg mucles when running

5. Main parts of Human Circulation System
1. Heart
Arteries
Arterioles
2 Blood Vessels
Veins
Venules
3. Blood
Capillaries

6. Main Blood Vessels Arteries Veins Carry blood away from the heart
Carry blood under high pressure
Thick elastic wall
Narrow lumen
Veins
Carry blood under low pressure
Carry blood towards the heart
Have valves to prevent backflow
Thin wall
Wide lumen

7. Smaller Blood vessels Arterioles Venules Capillaries
Arterioles connect arteries and capillaries
Venules
venules connect capillaries to the veins
Capillaries
Tiny blood vessels linking arterioles and venules
The thin wall allows easy exchange of materials with cells

8. Blood vessels under the microscope
Veins
Arteries
Thin Wall
Thick Wall
Wide lumen
Narrow lumen
Have valves to prevent backflow

9. Cross section of blood vessel
Collagen
Muscle and Elastic fibres
Endothelium
Lumen

10. Learning check 1 Give three differences between arteries and veins
2 What is the function of valves in veins
3 Name the blood vessels that connect capillaries and veins
4 Give one advantage of a closed circulation system

11. Role of muscle and elastic fibres
Muscle expand to allow increased blood flow through the vessel
Elastic fibres bring the blood vessel back to shape
Valves prevent backflow

12. The Heart
Location
Between the lungs, slightly to the left side of the thorax, above the diaphragm
Function
To pump blood around the body
A hollow structure made of cardiac muscle, surrounded by a double membrane
Structure

13. Role of Heart Muscle 1. The heart wall is made of Cardiac Muscle
2. Contraction of the cardiac muscle drives blood around the body
3. Cardiac Muscle does not fatigue

14. Human Two-Circuit Circulation
Systemic Circuit
Pulmonary Circuit
Pumps to the head, trunk and limbs and back to the heart
Pumps to the lungs and back to the heart

15. Advantages of a Double Circulation System
1. Separation of oxygen rich and oxygen poor blood
2. Blood pressure can be kept high

16. Pathway of blood Around Body

17. Portal systems Hepatic Portal System
A blood pathway that begins and ends in capillaries
Hepatic Portal System
Connects the stomach and intestines with the liver

18. Learning check
1 Name the blood vessel that connects the digestive system with the liver
2 Distinguish between the systemic the pulmonary blood circuits
3 Give one advantage of a double circulation system

19. Vena Cava Aorta Pulmonary Vein Left Atrium Bicuspid Valve Right Atrium
Pulmonary Artery
Pulmonary Vein
Left Atrium
Bicuspid Valve
Right Atrium
Left Ventricle
Tricuspid Valve
Cardiac muscle
Right ventricle
Semi Lunar Valves
Septum

20. Blood pathway through heart
Aorta
Pulmonary artery
Vena Cava
Pulmonary vein
Left atrium
Right Atrium
Bicuspid valve
Tricuspid valve
Left ventricle
Right ventricle

21. Role of Valves Semi Lunar valves Tricuspid valve Bicuspid Valve
Prevent backflow into heart
Tricuspid valve
Bicuspid Valve
Prevents backflow into right atrium
Prevents backflow into left atrium

22. Blood supply to the heart wall
Coronary arteries
Cardiac muscle is supplied with blood by the coronary arteries. These branch from the aorta just above the semi lunar valves ot the aorta
Coronary veins
Drain blood from heart wall into the right atrium

23. Learning check
1 Where does blood go immediately after leaving the right ventricle ?
2 Name the blood vessel that enters the right atrium
3 What is the function of the coronary arteries ?
4 State the exact location of the opening into the coronary arteries
2 Name the valve between the left atrium and left ventricle

24. Heartbeat and its control
The heart beat consists of alternate contraction and relaxation of the cardiac muscle
The heart beat is controlled by the pacemaker in the right atrium. This sends an electrical signal to the cardiac muscle
The heart beat sound is caused by the closing of the heart valves
( Higher level material on heartbeat control in section )

25. 3.2.4
Higher Level:
Heartbeat Control

26. What you need to know 1. The location of the SA and AV nodes
2. Distinguish between Systole & Diastole
3. Be aware that cardiac muscle in the heart wall is specialised not to fatigue
4. Be able to describe the sequence of events in the cardiac cycle
5. Explain the role of the SA and AV nodes in systole and diastole

27. Role of Heart Muscle 1. The heart wall is made of Cardiac Muscle
2. Contraction of the cardiac muscle drives blood around the body
3. Cardiac Muscle does not fatigue

28. Factors affecting heart rate
Heart rate is increased by
Exercise
Stress
Heart rate is decreased by
Sleep
Alcohol

29. Heart Rate Control
Controlled by the Pacemaker ( SA Node) in the right atrium wall
The SA node emits an electrical signal
This causes the atria to contract
This signal is picked up by the AV node
The AV node sends a signal to the ventricles
Causing the ventricles to contract

30. Stages of the heartbeat
Contraction of heart muscle is called SYSTOLE Relaxation of heart muscle is called DIASTOLE
Blood enters the two atria. All valves are closed All chambers are relaxed. (diastole).
2. The atria contract (systole), tricuspid and bicuspid valves open, blood is forced down into ventricles
3. Atria relax ( diastole), ventricles contract (systole), Bicuspid and tricuspid valves close, semi lunar valves open and blood is forced into the pulmonary artery and aorta
4. Ventricles relax (diastole), semi lunar valves close. The cycle starts again

31. Learning check 1. State the location of the SA node
2. Distinguish between Systole & Diastole
3. Name the specialised muscle in the heart wall
4. Explain the role of the SA and AV nodes in systole and diastole
5. Describe the sequence of events in the cardiac cycle
End of Higher Level

32. Pulse
The alternate expansion and contraction of arteries is called a pulse
A wave of expansion passes down the walls of arteries following a contraction of the left ventricle. The elastic fibres in the artery walls then bring about a contraction of the artery wall.
Average pulse rate is 72 beats per minute

33. Blood Pressure
Pressure in the due the to contraction of the ventricles which forces blood into the arteries
As blood passes from arteries to veins pressure drops
Blood pressure is measured with an instrument that records the pressure it takes to stop the blood flow in an artery of the upper arm

34. Effect of smoking on the circulation system
1. Nicotine increases the heart rate and blood pressure
These puts a bigger workload on the heart
2. CO2 reduces the amount of O2 carried by the blood
This reduces energy levels
3. Other chemicals in tobacco
Increase the chance of clots

35. Effect of Diet on the circulation system
High intake of fat causes a build up of cholesterol
Cholesterol may block arterioles and lead to stroke or heart attack
High salt intake
Raises blood pressure which can cause heart attack

36. Effect of Exercise on the circulation system
Exersise strengthens the heart
This improves circulation
Exercise increases our ability to transport oxygen
This gives increased energy levels

37. Learning check
1 What causes the blood to be under pressure in the arteries ?
2 Explain the term Pulse
3 What controls the rate of heartbeat
4 Give two harmful effects of cigarette smoke on the circulation system
5 Explain why salt can have a negative effect on the circulation system

38. Lymphatic System Structure 1. Lymph vessels 2. Lymph Nodes 3. Lymph
A secondary transport system consisting of one way system of vessels that collects and returns excess tissue fluid to blood system
Structure
1. Lymph vessels
2. Lymph Nodes
3. Lymph

39. Lymph vessels & blood vessels
Blood in arteries is under very high pressure
Tissue Fluid is forced out of arteries and some is collected in the Lymph Vessels
Tissue Fluid moves by Osmosis
Lymph Nodes filter bacteria carried in the blood

40. Lymphatic System Functions
1. Collect tissue fluid and return it to the blood system
2. Fight Infection by
(a) Filtering out microorganisms in the lymph nodes
(b) Destroying microorganisms by antibody production
(c) Mature and store lymphocytes
3. Transport digested fat away from intestine

41. Composition of Blood Plasma Liquid part of the blood Red Blood Cells
White Blood Cells
Platelets

42. Higher level material in sec 3.2.3
Role of of Blood Parts
Plasma
Composed of mainly water which acts as a transport medium for the cells and dissolved substances
Higher level material in sec 3.2.3
Carry Oxygen
Red Blood Cells
Fight Infection
White Blood Cells
Platelets
Clotting

43. Role of Plasma
Composed of mainly water which act as a transport medium for the cells and dissolved substances
Digestion products ….Glucose, amino acids, Fatty acids, glycerol, minerals and vitamins
Waste….Carbon dioxide, urea
Hormones….eg Insulin
Antibodies

44. Blood Cells Higher Level Only

45. Learning objectives 1. Details of red blood cell structure &function
Details of two types of white blood cells
(a) Lymphocytes
(b) Monocytes

46. Composition of Blood Plasma Liquid part of the blood Red Blood Cells
White Blood Cells
Platelets

47. Functions of blood parts
Plasma
Composed of mainly water which acts as a transport medium for the cells and dissolved substances
Carry Oxygen
Red Blood Cells
Fight Infection
White Blood Cells
Platelets
Clotting

48. Red Blood Cells Biconcave discs ……gives large surface area No Nucleus
No mitochondria
Contain Haemoglobin…(has a high affinity for oxygen)
Flexible Cell membranes
Made in bone marrow of ribs & sternum

49. White Blood Cells 1. Lymphocytes Produce antibodies 2. Monocytes
Have a Nucleus
No definite shape
Formed in bone marrow and mature in spleen
Protect against disease
Two types
1. Lymphocytes
Produce antibodies
2. Monocytes
Engulf microorganisms

50. PLATELETS Cell fragments No nucleus Made in bone marrow
Function in clotting

51. Learning check
1. List four ways, other than colour, in which red blood cells are different from ordinary body cells
2. Name the chemical in red blood cells that has a high affinity for oxygen
Name two types of white blood cells and give the function of each type
End of Higher Level

52. 4 Blood Groups
It is essential to know a persons blood group for safe blood transfusions
Group A B AB O

53. Rhesus Factor Another blood grouping system
Involvs antigen called factor D on the red cells
If you have factor D you are Rhesus positive or Rh+
If you haven’t you are Rhesus negative or Rh-
Rhesus factor is important in pregnancy as problems may arise in second and further preganncies if the mother is Rh - and the baby is Rh +

54. Learning check 1 Name the three main parts of the Lymphatic System
2 Name three substances dissolved in plasma
3 Name a blood grouping system other than the ABO System
4 What is the function of white blood cells
5 Give two functions of the Lymphatic System

55. END