CIRCULATORY SYSTEM

1.- What is Blood Made Of?

Blood Cells

White Blood Cells or Leukocytes

White Blood Cells or Leukocytes

or Thrombocytes or Red Blood Cells

Functions of blood

1) Transport:

Blood transports the following substances:

- Gases, namely oxygen (O2) and carbon dioxide (CO2), between the

lungs and rest of the body.

- Nutrients from the digestive tract to the rest of the body.

- Waste products from the cells to the liver and kidneys.

- Hormones from the glands in which they are produced to their target cells

- Heat to the skin so as to help regulate body temperature

2) Defense:

- Leukocytes belong to the Immune System and defend us against

infections.

- Platelets help blood clotting and help minimise blood loss.

3) Regulation:

- Heat, pH, water...

Blood facts

- Approximately 8% of an adult's body weight is made up of blood.

- Females have around 4-5 l, while males have around 5-6 l.

- Its mean temperature is 38ºC.

- Whole blood is about 4.5-5.5 times as viscous as water

(therefore, it is more resistant to flow than water). This is important

because if blood flows too easily or with too much resistance, it

can strain the heart and lead to severe cardiovascular problems.

- Blood in the arteries is a brighter red than blood in the veins

because of the higher levels of oxygen found in the arteries.

- An artificial substitute for human blood has not been found.

Blood Types and Transfusions

2.- Blood Vessels

ARTERIES:- carry blood away

from the heart (exit the

heart by the ventricles )

- elastic and thick

muscular walls

- high blood pressure,

that decreases as they

go away from the heart.

- narrow lumen

- as they go away from

the heart, their size

decreases (arterioles)

VEINS:- carry blood into the

heart (they enter the heart

in the atria)

- less elastic thinner walls

- low blood pressure.

That increases as they

approach the heart. They

have valves that prevent

blood backflow.

- wide lumen.

- the smallest ones are

called venules (near the

tissues)

CAPILLARIES:- connect arteries and

veins in the tissues

- very thin wall (just

one-cell thick!) called

endothelium: they let

substances go in and

out (substance

exchange)

- low blood pressure

Substance exchange between tissues and capillaries:

CELLS

EXTRACELLULARMATRIX

CAPPILARIES

3.- Heart

A DOUBLE CIRCULATION:

SYSTEMIC CIRCULATION:

Heart Organs

PULMONARY CIRCULATION:

Heart Lungs

Heart Cycle

What can go wrong?

HIGH BLOOD PRESSURE

HEART ATTACK

STROKE What can go wrong?

HAEMOPHILIA

LEUKAEMIA

ANAEMIAWhat can go wrong?