Chapter 4
Circulatory system in human body
Circulatory system

RBC

WBC

Platelets

Plasma

Blood vessels – veins / arteries / capillaries

Double circulation
Components of blood

Solid particles and liquid components

Solid – RBC/WBC/platelets

Liquid – plasma
Human heart
Human heart
Functions of blood

Related to its components

Transport digested food , hormones, antibiotics, waste products(urea) –
plasma

Also CO2 to lungs

Maintain water balance

Maintain temperature of the body

Transport oxygen to all parts of body
Red blood cell RBC

No nucleus

Biconcave disc shaped

Red colour – due to haemoglobin

Pigment has a high affinity to O2

Short life span – 3 months

Produced in bone marrow and destroyed in liver/ spleen

Shape allows RBC to squeeze through capillaries
White blood cell
WBC

No fixed shape

At least 4 types , which have different functions

Defence system

Has a nucleus

Also produced and destroyed by the body

Fight bacteria and virus
Blood vessels
Arteries

Carry blood under high pressure

Carry oxygenated blood

Exception pulmonary artery

Under high pressure – you can feel a pulse

Thick walls/ small lumen/ muscular walls
Veins

Carry deoxygenated blood

Exception pulmonary vein

Low pressure

Large lumen/ thin walls

Has valves
Capillaries

Smallest blood vessel

Reaches the cells

Can carry oxygenated or deoxygenated blood , depending where they are
Capillary
In alveolus
Role of capillary
Double circulation
Diet and heart disease

Diet – cholesterol low and high

Saturated and unsaturated fats

High salt – affects blood pressure

Linked to heart problems

Exercise – can cause to become more efficient - whole body – muscles/
skeletal system/ nervous systems/ respiratory/ circulatory - to work better

Calories is linked to energy – intake

Obesity is linked to diseases
arteriosclerosis
arteriscleriosis
Label the heart