1. Topic 6.2 and Option H5 – The Transport System

2. The Transport System
In order to maintain homeostasis, various materials must be transported through the body
Mammals have a closed circulatory system – meaning materials are transported within vessels
The medium for transport through the body is blood

3. Blood
Form of connective tissue made of cells suspended in a liquid (plasma)
Average human body has 4-6 liters.
Functions:
Transporting materials through the body
Transfer heat to body surface
Defend body against disease
6.2.7

4. Blood and Transport
Blood is responsible for transporting many materials through the body:
Nutrients
Hormones
Antibodies
Urea (nitrogen waste)
Oxygen
Carbon dioxide
Oxygen and carbon dioxide are associated with red blood cells, all other materials dissolve in blood plasma
6.2.7

5. Blood Components Plasma – 55% Red blood cells – 45% White blood cells
less than 1%
Platelets
6.2.6

6. Blood Plasma Components of Blood Plasma:
Water – 90% - solvent for carrying materials
Plasma Proteins
Fibrinogen – clotting
Globulins – defense
Albumins – maintain osmotic balance, viscosity
Dissolved nutrients
Hormones
Waste materials
6.2.6

7. Blood Cells Erythrocytes (red blood cells) –
90% of blood cells
Transport oxygen and carbon dioxide
Leucocytes (white blood cells) –
Phagocytes – non-specific defense
Lymphocytes – produce antibodies – specific defense
Thrombocytes - platelets
6.2.6

8. Blood Components
6.2.6

9. Structure of the Heart
Cone-shaped organ about the size of a clenched fist
Located just beneath the sternum (breastbone)
Base
Point where large vessels attach (pulmonary artery, aorta)
Apex
Cone-shaped end, points down

10. Heart Chambers Chambers – collect and pump blood to lungs and body
Left and right atria – collection chambers for blood returning to heart from body and lungs
Left and right ventricles – pumping chambers to send blood out to lungs and body
Right ventricle pumps blood to lungs
Left ventricle pumps blood to body
6.2.1
6.2.3

11. Structure of the Heart
6.2.1

12. Heart Chambers
Heart Chambers

13. Heart Valves
Valves – control direction of blood flow through the heart
Atrio-ventricular (AV) valves – separate atria from ventricles
Right = tricuspid, Left = bicuspid (mitral valve)
Semilunar valves – located at two exits of heart (pulmonary artery and aorta)
Right = pulmonary, Left = aortic
6.2.1
6.2.3

14. Heart Valve Function
Heart valves are flaps of tissue controlled by the flow of blood
As blood flows through the heart the flaps are pushed open – allowing blood to flow from chamber to chamber
If blood tries to flow backward – the valves close shut – preventing backflow
6.2.3

15. Heart Valves
Heart Chambers

16. Great Vessels
Vena cava (superior and inferior) – carry blood into right atrium
Pulmonary arteries – carry blood from right ventricle to lungs (for O2)
Pulmonary veins – carry blood from lungs to left atrium
Aorta – carries blood from left ventricle to body
Coronary arteries – supply the heart muscle with O2 and nutrients
6.2.2

17. Structure of the Heart
6.2.1

18. Quick Review… Aorta Superior vena cava Right atrium Tricuspid valve
Right ventricle
Inferior vena cava
Pulmonary artery
Pulmonary veins
Left atrium
Mitral valve
Aortic semilunar valve
Left ventricle

19. Double Circulation Heart pumps blood through two circuits:
Pulmonary circuit – Right Atrium/Ventricle to lungs (for O2)
Systemic circuit – Left Atrium/Ventricle to body

20. Double Circulation Pulmonary Circuit: Systemic Circuit:
Body  vena cava  R. A.
R. A.  tricuspid AV valve  R. V.
R. V  Pulmonary semilunar Valve 
P. Artery  Lungs (for O2)
Lungs  P. Vein  L. A.
Systemic Circuit:
L. A.  bicuspid (mitral) AV valve  L. V.
L. V.  Aortic semilunar valve Aorta body

21. Blood Vessels Arteries – carry blood AWAY from heart
Thick-walled vessels to withstand high pressure
Outer layer of collagen and elastic fibers allow vessel to stretch and recoil
Middle layer of smooth muscle to help pump
Lumen – narrow interior maintains high pressure
6.2.5

22. Blood Vessels Veins – RETURN blood to the heart
Smaller and thinner-walled than arteries
Low pressure – little danger of bursting
Wide lumen to accommodate slow moving blood
Thin walls can be flattened to help move blood
Contain valves to prevent backflow
6.2.5

23. Arteries and Veins
Artery
Vein
6.2.5

24. Blood Vessels
Capillaries – exchange materials in blood with body tissue
Small microscopic vessels
Thin porous walls made of single layer of endothelium
Very narrow lumen
Moderate pressure
6.2.5

25. Blood Vessels
Heart Chambers
6.2.5

26. Control of the Heart
Myogenic – heart beats on its own – does not require nervous system control
Cardiac muscle contractions are stimulated by electrical impulses generated by the sinoatrial node (SA node) and atrioventricular node (AV node)
Located in wall of right atrium
6.2.4

27. The Heart’s Electrical System
Sinoatrial node (SA node):
The “pacemaker” – sets the rhythm of the heart
Sends impulse directly into atria = atrial contraction
Atrioventricular node (AV node):
Receives message from SA node
Sends impulse through conducting fibers into ventricle = ventricular contraction
Can work as the pacemaker in the absence of SA node
6.2.4
H.5.3

28. The Heart’s Electrical System
6.2.4
H.5.3

29. Pathway of Cardiac Impulse
Impulse originates in SA node
Spread rapidly over right and left atria
Atria contract – blood flows into ventricles
Slight delay – ensures ample ventricular filling of blood
Impulse enters AV node
Moves along Bundle of His
Branches to right and left bundle fibers
Spreads rapidly along Purkinje fibers
Ventricles contract (beginning at apex and traveling up) – blood flows into arteries
5.2.3
H.5.3

30. Pathway of Cardiac Impulse…Quick Review

31. Electrocardiogram (ECG)
Measures electrical activity of the heart.
P- wave
Depolarization of the atria, just before contraction
QRS wave
Depolarization of ventricles.
T-wave
Repolarization of ventricles
Use to detect damage to the heart

32. Control of Heart Rate SA node can be influenced by nervous system
Vagus nerve connects nervous system to heart
Parasympathetic action will slow heart rate down
Sympathetic action will speed heart rate up
SA node also influenced by hormones and temperature.
Epinephrine from adrenal gland speeds heart rate up
Increased body temperature increases heart rate
6.2.4

33. The Cardiac Cycle
Each heart beat involves 4 phases of heart muscle contraction and relaxation – the cardiac cycle
Useful terms:
Diastole – relaxed state
Systole – contracted state

34. The Cardiac Cycle Diastole Atrial Systole
All four heart chambers relaxed
Atria fill with blood
Atrial pressure increases and opens AV valves
Slow flow of blood into ventricles
Passive ventricular filling
Atrial Systole
SA node fires and atria contract
Atrial pressure rises rapidly and remaining blood pushed into ventricles
Active ventricular filling
H.5.1

35. The Cardiac Cycle
H.5.1

36. Cardiac Cycle Ventricular systole Ventricles contract
Ventricular pressure increases sharply
AV valves forced closed
Semilunar forced open, sending blood into arteries.
At the same time the atria reenter diastole and begin filling with blood from veins
H.5.1

37. The Cardiac Cycle Ventricular diastole – Ventricles relax
Ventricular pressure decreases
Semilunar valves close
AV valves open, sending slow flow blood from atria to ventricles
Passive ventricular filling
H.5.1

38. The Cardiac Cycle
H.5.1

39. Heart Sounds The heart is generally thought to have a “lub-dub” sound
The “lub” comes from the closing of the AV valves – ventricular systole
The “dub” comes from the closing of the SA valves – ventricular diastole
H.5.1

40. Pressure, Volume, and the Cardiac Cycle
Atria:
Atria fill during ventricular systole and diastole
Volume and pressure of atria increase
When atrial pressure rises above ventricular pressure, AV valves open and blood flows into ventricles
Pressure rise/fall in atria small compared to rise/fall in ventricle
H.5.2

41. Pressure, Volume, and the Cardiac Cycle
Heart Chambers
H.5.2

42. Pressure, Volume, and the Cardiac Cycle
Ventricles:
Ventricles fill passively during atrial diastole and actively during atrial systole
Volume and pressure of ventricles increase
During ventricular systole volume decreases and pressure rises sharply and blood flows into arteries
Pressure much greater in left ventricle than right ventricle – why?
H.5.2

43. Pressure, Volume, and the Cardiac Cycle
Heart Chambers
H.5.2

44. Blood Pressure Hydrostatic pressure of blood against vessel walls
Much greater in arteries than in veins – why?
Read as systolic/diastolic – e.g. 120/80
Systolic
Pressure during heart contractions
Blood pressure at highest (120 mmHg)
Diastolic
Pressure during heart relaxation
Blood pressure drops (80 mmHg)

45. Blood Pressure and Velocity
Heart Chambers

46. Atherosclerosis Lipid deposits build up on inside of artery walls
Limits blood flow and may cause formation of blood clots
Walls of damaged arteries begin to thicken and harden
H.5.4

47. Artherosclerosis
H.5.4
H.5.4

48. Coronary Thrombosis Begins with artherosclerosis in coronary arteries
Coronary arteries supply heart walls with blood
If coronary arteries are totally blocked by clot, heart cells are unable to respire or contract
Myocardial infarction = heart attack
H.5.4

49. Coronary Heart Disease
Wide spectrum disease of the heart involving artherosclerosis, coronary thrombosis, and heart muscle damage over time
Risk factors include:
Genetics, gender (sorry guys), smoking, obesity, diet (high fat, low fiber), exercise (or lack thereof)
H.5.5