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Transport Systems in Plants

Flowering plants have separate transport systems:

Xylem tissue transports: water and mineral ions from: the roots to: the stem/leaves

Phloem tissue transports: dissolved sugars from: the leaves to: the rest of the plant (e.g. growing regions and storage organs)

The transpiration stream is the movement of water from the roots and out of the leaves, via the xylem.

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The Blood

Blood is a tissue. It consists of plasma, which is a fluid that contains red blood cells, white blood cells and platelets.

Plasma transports:

Carbon dioxide from: the organs to: the lungs

Soluble products of digestion from: the small intestine to: other organs

Urea from: the liver to: the kidneys

Red blood cells transport:

Oxygen from: the lungs to: the organs

Red blood cells have no nucleus, which allows them to contain a larger volume. They contain haemoglobin, which is a red pigment. Haemoglobin combines with oxygen in the lungs to form oxyhaemoglobin. In the other organs (to which it is transported in the bloodstream), the oxyhaemoglobin splits up again into haemoglobin and oxygen.

White blood cells do have a nucleus. Their function is to help to protect the body against micro-organisms that pose a threat e.g. infection (these are called pathogens). They do this by surrounding and ingesting them

Platelets do not have a nucleus. They are little fragments of cells and their function is to help the blood to clot. This is important because if the skin is broken, the blood needs to clot in order to prevent the body from losing too much blood.

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The Blood System

The heart, veins, arteries and capillaries make up the circulatory system. This is an organ system that transports substances around the body.

The heart is an organ that pumps blood around the body.

The wall of the heart is made from mainly muscle tissue.

Blood enters the atria of the heart (singular atrium).

The atria contract and force blood into the ventricles.

The heart contains valves, whose purpose is to ensure that blood flows in the correct direction.

Blood is transported from the heart to the organs by arteries. It is transported from the organs to the heart by veins.

Arteries have thick walls consisting of muscle and elastic fibres.

Veins have thinner walls. They often contain valves, which is how they prevent the blood from flowing the wrong way.

In the organs, blood flows through very narrow blood vessels called capillaries.

Capillaries have very thin walls -- only one cell thick. This allows substances to pass out of the blood and into the body tissues that need them. The thin walls and narrowness of the capillaries provides a short path for diffusion.

There are actually two separate circulation systems: one going to the lungs and one going to all the other organs in the body.

Stents are devices used in medicine. If a person has a buildup of plaque in their arteries, the arteries can become narrower, restricting the blood flow. A stent can be inserted into the artery and opened up, keeping the artery open.

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Transport Systems in Plants and Animals

In most animals, substances are transported around the body by the circulatory system, which comprises the heart, blood vessels and blood. They are transported to and from cells, either from where they are taken in or to where they are disposed of. Thanks to modern developments in biomedical and technological research, we are able to provide medical help when the circulatory system is not functioning well.

Plants have separate transport systems for water and nutrients.

You should be able to use your skills, knowledge and understanding to:

Evaluate data on the production and use of artificial blood products

Evaluate the use of artificial hearts and heart valves and stents

Practical work to develop your skills and understanding:

Dissecting a heart

Watching computer simulations of the circulatory system

Observing arteries and veins on slides

Observing blood

Observing valves in veins preventing backflow of blood

Measuring blood pressure before, during and after exercise using sensors

Investigating flow rate in xylem using celery

Investigating the content of artificial xylem and phloem

Investigating the effect of temperature or wind speed on transpiration rate using a potometer