Topic 6.2 + Option H5 Topic 6.2 + Option H5

Transport SystemTransport System

IB Biology

Components of Transport SystemComponents of Transport System

Blood

Heart

Blood Vessels

Types of CirculationTypes of Circulation

1) Pulmonary heart – lungs – heart

2) Systemic heart – body – heart

Types of CirculationTypes of Circulation

3) Coronary blood vessels that

supply heart muscle with oxygen and nutrients / remove waste products

Heart StructureHeart Structure2 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 + ventricle4 chambers: 2 atria/2 ventricles

Cardiac muscle: involuntary Ultimate control:

Autonomic Nervous System (ANS)

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Heart ValvesHeart Valves Allow blood to flow in only one direction Four valves Atrioventricular valves – between atria and

ventriclesBicuspid valve (left)Tricuspid valve (right)

Semilunar valves between ventricle and artery

Pulmonary semilunar valveAortic semilunar valve

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Vessels of the heartVessels of the heartAorta 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

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Heart contractionsHeart contractions

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The Heart: Cardiac CycleThe Heart: Cardiac Cycle

Atria contract simultaneously

Atria relax, then ventricles contract

Systole = contraction

Diastole = relaxation

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

Cardiac cycle – events of one complete heart beat

BloodBloodPlasma – 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

urea+ HEAT

(antibodies)

Blood VesselsBlood VesselsArteries

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

Blood PressureBlood 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

Coronary Heart DiseaseCoronary Heart DiseaseSlow build up of plaque (lipids, cholesterol) = ATHEROSCLEROSISArteries become harder, less flexibleLess space for bloodCoronary arteries supply O2 to heart cellsThrombosis = 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

Heartbeat ControlHeartbeat ControlMyogenic 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)

Heartbeat ControlHeartbeat ControlAutonomic Nervous System and hormones can modify myogenic rhythm:

oNerves from brain stem (medulla) have involuntary control over heart rate = affect SA node Exercise = ↑CO2 / ↓O2 = medulla oblongata (brainstem) takes overChemoreceptors detect ↑CO2 = H+ causes decrease in pH

oAdrenaline targets sino-atrial node (SAN): stimulant

Cardiac CycleCardiac CycleOne whole heartbeat

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 vesselsAtria systole = pressure not too great (thin walls, most blood already moved to ventricles)Ventricular systole = pressure great inside both ventricles