Topic 6.2 + Option H5

Transport System

IB Biology

Components of Transport System

Blood

Heart

Blood Vessels

Types of Circulation

1) Pulmonary heart – lungs – heart

2) Systemic heart – body – heart

Types of Circulation

3) Coronary blood vessels that

supply heart muscle with oxygen and nutrients / remove waste products

BloodPlasma – 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)

Heart 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)

Heart Structure

Blood 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 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 Disease

Slow 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 ControlMyogenic muscle contraction: -Sino-Atrial Node (SAN) – specialized cells generate electrical impulse on their own with regular frequency (PACEMAKER)-Impulse spreads to both atria → atria contract together-Atrio-Ventricular node (AVN) 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 (SISTOLE)-Contraction stops – ventricles relax (DIASTOLE)

Heartbeat 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 CycleOne whole heartbeat

Sistole = 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