1. Topic 6.2 + Option H5 Transport System
IB Biology

2. Components of Transport System
Blood
Heart
Blood Vessels

3. Types of Circulation 1) Pulmonary 2) Systemic heart – lungs – heart
heart – body – heart

4. Types of Circulation 3) Coronary
blood vessels that supply heart muscle with oxygen and nutrients / remove waste products

5. Heart Structure 2 sides with different functions:
right: to receive + pump blood to the lungs
left: to receive + pump blood to the body
2 types of chambers: atrium + ventricle
4 chambers: 2 atria/2 ventricles
Cardiac muscle: involuntary
Ultimate control:
Autonomic Nervous System (ANS)

6. Heart Valves Allow blood to flow in only one direction Four valves
Atrioventricular valves – between atria and ventricles
Bicuspid valve (left)
Tricuspid valve (right)
Semilunar valves between ventricle and artery
Pulmonary semilunar valve
Aortic semilunar valve

7. Vessels of the heart Aorta Pulmonary arteries Vena cava
Leaves left ventricle
Pulmonary arteries
Leave right ventricle
Vena cava
Enters right atrium
Pulmonary veins (four)
Enter left atrium

8. Blood in the heart chambers does not nourish the myocardium
The heart has its own nourishing circulatory system
Coronary arteries
Cardiac veins
Blood empties into the right atrium via the coronary sinus

9. Heart contractions

10. The Heart: Cardiac Cycle
Atria contract simultaneously
Atria relax, then ventricles contract
Systole = contraction
Diastole = relaxation
Cardiac cycle – events of one complete heart beat
Mid-to-late diastole – blood flows into ventricles
Ventricular systole – blood pressure builds before ventricle contracts, pushing out blood
Early diastole – atria finish re-filling, ventricular pressure is low

11. Blood
Plasma – fluid
Red blood cells or erythrocytes – produced in the bone marrow of large bones / transport O2 and CO2
White blood cells (lymphocytes and phagocytes) – produced in the bone marrow / belong to immune system
Platelets - cell fragments that help blood clotting

12. (antibodies)
urea
+ HEAT

15. Blood Vessels Arteries Veins Capillaries
carry blood Away from heart; strong thick walls; smooth muscle (elastic); fibrous coat; small lumen = ↑ pressure
Veins
carry blood back to heart; large lumen; thin wall/muscle; ↓ elastic; valves
Capillaries
connect arteries and veins; no valves; pores; no muscle/not elastic extremely thin (1 cell thick) = fast exchange

16. Blood Pressure Blood applies pressure to the walls
If it is too low - cells might not get enough O2
If it is too high - vessels can rupture (heart attack, stroke)
Salt can increase blood pressure
Normal blood pressure: 120/80 mm Hg

17. Coronary Heart Disease
Slow build up of plaque (lipids, cholesterol) = ATHEROSCLEROSIS
Arteries become harder, less flexible
Less space for blood
Coronary arteries supply O2 to heart cells
Thrombosis = clot = heart attack = heart cells die
Factors affecting coronary heart disease (CHD):
Age, race, heredity, gender, cholesterol levels, blood pressure, obesity, diabetes, smoking, sedentary lifestyle, stress

19. Heartbeat Control Myogenic muscle contraction:
Sino-Atrial Node (SA) – specialized cells generate electrical impulse on their own with regular frequency (PACEMAKER)
Impulse spreads to both atria → atria contract together
Atrio-Ventricular node (AV) picks up the impulse in lower right atrium septum and conduces to the ventricles through fibers
Ventricles contract: AV valves close / semi-lunar valves open (SYSTOLE)
Contraction stops – ventricles relax (DIASTOLE)

20. Heartbeat Control
Autonomic Nervous System and hormones can modify myogenic rhythm:
Nerves from brain stem (medulla) have involuntary control over heart rate = affect SA node
Exercise = ↑CO2 / ↓O2 = medulla oblongata (brainstem) takes over
Chemoreceptors detect ↑CO2 = H+ causes decrease in pH
Adrenaline targets sino-atrial node (SAN): stimulant

22. Cardiac Cycle One whole heartbeat Sound = valves closing
Systole = contraction / Diastole = relaxation
Valves prevent backflow
Sound = valves closing
1st = atrio-ventricular valves (mitral, tricuspid)
2nd = semilunar valves (aortic, pulmonary)
Important = valves open and close depending on pressure inside chambers/blood vessels
Atria systole = pressure not too great (thin walls, most blood already moved to ventricles)
Ventricular systole = pressure great inside both ventricles