1. 6.2 The blood system Understanding:
Arteries convey blood at high pressure from the ventricles to the tissues of the body
Arteries have muscle and elastic fibres in their walls
The muscle and elastic fibres assist in maintaining blood pressure between pump cycles
Blood flows through tissues in capillaries with permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary
Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart
Valves in veins and the heart ensure circulation of blood be preventing backflow
There is a separate circulation for the lungs
The heartbeat is initiated by a group of specialised muscle cells in the right atrium called the sinoatrial node.
The SA node acts as a pace maker
The SA node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria and then the walls of the ventricles
The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain
Epinephrine increases the heart rate to prepare for vigorous physical activity.
Applications:
William Harvey’s discovery of the circulation of the blood with the heart acting as the pump
Causes and consequences of occlusion of the coronary arteries
Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle
Skills:
Identification of blood vessels as arteries, capillaries or veins from the structure of their walls
Recognition of the chambers and valves of the heart and the blood vessels connected to it in dissected hearts of in diagrams of heart structure
Nature of science:
Theories are regarded as uncertain: William Harvey overturned theories developed by Galen on movement of blood in the body

2. Label the heart
Aorta Vena cava Pulmonary artery Pulmonary vein Right atrium Left atrium Right ventricle Left ventricle Atrio-ventricular valve Semi lunar valve
RIGHT
LEFT
Skills:
Recognition of the chambers and valves of the heart and the blood vessels connected to it in dissected hearts of in diagrams of heart structure

4. Valves
Semi lunar valves (Arteries) Atrioventricular valves (Atria/Ventricles) Prevent backflow of blood
Understanding:
Valves in veins and the heart ensure circulation of blood be preventing backflow

5. Skills:
- Recognition of the chambers and valves of the heart and the blood vessels connected to it in dissected hearts of in diagrams of heart structure

6. Key Terms
Arteries carry blood AWAY from the heart (high pressure) Pulmonary means it is to do with the lungs Systemic means it is to do with the body
Understanding:
There is a separate circulation for the lungs

7. Why is one side thicker? Understanding:
There is a separate circulation for the lungs

8. Put into order and label onto your heart

9. Blood is then pumped out of the heart round the body in the aorta Blood enters the heart through the pulmonary vein Blood enters the into the heart through the vena cava It enters the left atrium Blood becomes deoxygenated as it passes around the body Blood collects oxygen from the lungs It enters the right atrium It is pumped through a valve into the right ventricle It becomes oxygenated at the lungs The cycle starts again Blood leaves the heart via the pulmonary artery It is pumped through a valve into the left ventricle

10. Blood collects oxygen from the lungs
Blood enters the heart through the pulmonary vein
It enters the left atrium
It is pumped through the atrio-ventricular valve into the left ventricle
Blood is then pumped out of the heart through the semi-lunar valve round the body in the aorta
Blood becomes deoxygenated as it passes around the body
Blood enters the into the heart through the vena cava
It enters the right atrium
It is pumped through the atrio-ventricular valve into the right ventricle
Blood leaves the heart through the semi-lunar valve via the pulmonary artery
It becomes oxygenated at the lungs
The cycle starts again

11. Structure of blood vessels
Arteries Veins Capillaries
Understanding:
Arteries convey blood at high pressure from the ventricles to the tissues of the body
Arteries have muscle and elastic fibres in their walls
The muscle and elastic fibres assist in maintaining blood pressure between pump cycles

12. William Harvey
Demonstrated the presence of valves in veins Predicted the heart pumped blood out through arteries around the body and back into the heart through the veins. Previously believed the body ‘consumed’ blood Predicted finer vessels linking arteries to veins
Applications:
William Harvey’s discovery of the circulation of the blood with the heart acting as the pump
Nature of science:
Theories are regarded as uncertain: William Harvey overturned theories developed by Galen on movement of blood in the body

13. Arteries
Move blood from the heart to lungs or body High pressure Artery walls facilitate and control blood flow: Elastic tissue: Allow arteries to stretch, recoil helps propel blood down artery Smooth muscle contraction: controls amount of blood allowed down artery
Understanding:
Arteries convey blood at high pressure from the ventricles to the tissues of the body
Arteries have muscle and elastic fibres in their walls
The muscle and elastic fibres assist in maintaining blood pressure between pump cycles

14. Parts of the artery TUNICA EXTERNA Hollow centre of the vessel
TUNICA MEDIA
Outer layer of connective tissue
TUNICA INTIMA
Middle layer containing smooth muscle and elastic fibres
LUMEN
Endothelium (single layer of cells)

15. Parts of the artery Lumen Tunica externa
(hollow centre of tube)
Tunica externa
Outer layer of connective tissue
Tunica media
Middle layer containing smooth muscle and elastic fibres
Tunica intima
Endothelium (single layer of cells)

16. Capillaries
Branch and re-join to form capillary network Active cells are near capillaries Semi-permeability of capillary walls (large proteins cannot pass through, oxygen can) Capillaries can also change to respond to the needs of the tissues they provide nutrients for. Larger molecules can reach certain tissues if needed.
Understanding:
Blood flows through tissues in capillaries with permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary

17. Veins
Transport blood from capillary networks back to the heart Much lower pressure than arteries Blood flow in veins is assisted by gravity and pressure from other tissues (muscle contractions) Important the waste-rich blood moves in the right direction and not move backwards
Understanding:
Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart
Valves in veins and the heart ensure circulation of blood be preventing backflow

18. Veins
Veins undergo ‘pumping’ by movement of the skeletal muscles (get squashed) Blood gets forced back to the heart However, when the muscles relax and the veins open again, the blood would rush backwards (called reflux) if it weren't for the valves stopping this from happening. Valves act like gates – allow blood to move one way Also allow blood to move against gravity – valves provide footholds
Understanding:
Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart
Valves in veins and the heart ensure circulation of blood be preventing backflow

19. Arteries Veins Capillaries Where do they transport blood
Oxygenated or deoxygenated?
Pressure
Blood flow
Diameter
Thickness of wall
Valves
Muscle and elastic fibres in wall

20. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Pressure?
Blood flow
Diameter
Thickness of wall
Valves
Muscle and elastic fibres in wall

21. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Oxygenated (apart from P.A)
Deoxygenated (apart from P.V)
Both
Pressure?
Blood flow
Diameter
Thickness of wall
Valves
Muscle and elastic fibres in wall

22. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Oxygenated (apart from P.A)
Deoxygenated (apart from P.V)
Both
Pressure?
High
Low
Reducing
Blood flow
Diameter
Thickness of wall
Valves
Muscle and elastic fibres in wall

23. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Oxygenated (apart from P.A)
Deoxygenated (apart from P.V)
Both
Pressure?
High
Low
Reducing
Blood flow
Rapid
Slow
Slowing
Diameter
Thickness of wall
Valves
Muscle and elastic fibres in wall

24. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Oxygenated (apart from P.A)
Deoxygenated (apart from P.V)
Both
Pressure?
High
Low
Reducing
Blood flow
Rapid
Slow
Slowing
Diameter
Larger than 10 um
Around 10 um
Smaller than 10 um
Thickness of wall
Valves
Muscle and elastic fibres in wall

25. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Oxygenated (apart from P.A)
Deoxygenated (apart from P.V)
Both
Pressure?
High
Low
Reducing
Blood flow
Rapid
Slow
Slowing
Diameter
Larger than 10 um
Around 10 um
Smaller than 10 um
Thickness of wall
Relatively thick with narrow lumen
Thin wall, wide lumen
Thin wall with wide lumen
Valves
Muscle and elastic fibres in wall

26. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Oxygenated (apart from P.A)
Deoxygenated (apart from P.V)
Both
Pressure?
High
Low
Reducing
Blood flow
Rapid
Slow
Slowing
Diameter
Larger than 10 um
Around 10 um
Smaller than 10 um
Thickness of wall
Relatively thick with narrow lumen
Thin wall, wide lumen
Thin wall with wide lumen
Valves
No (apart from in heart)
Yes No
Muscle and elastic fibres in wall

27. Arteries Veins Capillaries Where do they transport blood
Away from heart
Towards heart
Links arteries to veins
Oxygenated or deoxygenated?
Oxygenated (apart from P.A)
Deoxygenated (apart from P.V)
Both
Pressure?
High
Low
Reducing
Blood flow
Rapid
Slow
Slowing
Diameter
Larger than 10 um
Around 10 um
Smaller than 10 um
Thickness of wall
Relatively thick with narrow lumen
Thin wall, wide lumen
Thin wall with wide lumen
Valves
No (apart from in heart)
Yes No
Muscle and elastic fibres in wall
Abundant
No/very small amounts
No – very thin walls for diffusion

28. Takes many years to become a serious problem.
Atherosclerosis
Arteries become clogged up by materials collectively called plaque (lipids, cholesterol, cell debris…)
Takes many years to become a serious problem.
Describe atherosclerosis (Step by step)
What happens when the arteries build up with plaque?
What could be a cause atherosclerosis?
What is an occlusion?
Applications:
Causes and consequences of occlusion of the coronary arteries

29. Atherosclerosis Process of Atherosclerosis:
What happens when the arteries build up with plaque?
What could cause atherosclerosis?
What is an occlusion?

30. Plaque begins to grow into the vessel narrowing the lumen Artery wall becomes damaged Macrophages consume LDLs Becomes surrounded by a capsule (plaque) Foam cells create fatty streaks in artery walls Calcium may be deposited – making it hard and inflexible LDLs (cholesterol) invades artery wall Blood pressure increases Plaque can rupture causing a blood clot which can completely block the artery Creates foam cells

31. Artery wall becomes damaged LDLs (cholesterol) invades artery wall Macrophages consume LDLs Creates foam cells Foam cells create fatty streaks in artery walls Becomes surrounded by a capsule (plaque) Plaque begins to grow into the vessel narrowing the lumen Calcium may be deposited – making it hard and inflexible Blood pressure increases Plaque can rupture causing a blood clot which can completely block the artery

32. 1. Artery wall becomes damaged

33. 2. LDLs (cholesterol) invades artery wall

34. 3. Macrophages consume LDLs

35. 4. Creates foam cells

36. 5. Foam cells create fatty streaks in artery walls

37. 6. Becomes surrounded by a capsule (plaque)

38. 7. Plaque begins to grow in to the vessel narrowing the lumen

39. 8. Calcium may be deposited – making it hard an inflexible

40. 9. Blood pressure increases

41. 10. Plaque can rupture causing a blood clot blocking the artery

42. Myogenic Heart
Myogenic = contraction stimulated from within the heart Sinoatrial node initiates the heart beat Sets the pace for heart beat Can be replaced by an artificial pace maker if it becomes defective
Understanding:
The heartbeat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node.
The SA node acts as a pace maker
The SA node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria and then the walls of the ventricles

43. Sino Atrial Node
Responds to signals from outside the heart Nerve impulses sent from medulla of the brain E.g. Epinephrine/adrenalin hormone: increases the heart rate to prepare for vigorous physical activity
Understanding:
The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain
Epinephrine increases the heart rate to prepare for vigorous physical activity.

44. The cardiac cycle Sequence of events in a heart beat
There are 3 different phases:
Atrial systole
Ventricular systole
Diastole
Applications:
Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle

45. Atrial Systole
Heart is full of blood and ventricles relaxed S-L valves are closed Both atria contract Blood passes into ventricles A-V valves open due to pressure seconds
Applications:
Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle

46. Early ventricular systole
Atria relax (diastole) Ventricles contract Rapid pressure build up A-V valves close seconds
Applications:
Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle

47. Late ventricular systole
Ventricular pressure higher than artery pressure Forces blood into pulmonary artery and aorta S-L valves open Pulse generated Pressure in atria rises as they fill again seconds
Applications:
Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle

48. Diastole
Ventricles relax Pressure in ventricle < pressure in arteries High pressure blood in arteries cause S-L valves to shut All muscles relax Blood from vena cava and pulmonary vein enter atria seconds
Applications:
Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle

49. Diastole
Pressure in ventricles drops below atria A-V valves open Blood from veins drains into atria, and then into ventricles Pressure starts to build before contraction seconds
Applications:
Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle