Organising Animals and Plants

Blood

- the blood, blood vessels and heart make up the human circulatory system which transports substances to and from the body cells

- plasma has blood cells suspended in it and transports proteins and other chemicals around the body

- red blood cells contain haemoglobin that binds to oxygen to transport it from the lungs to the tissues

- white blood cells help to protect the body against infection

- platelets are cell fragments that start the clotting process at wound sites

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Blood Vessels

- blood flows around the body in the blood vessels, the main types of blood vessels are arteries, veins and capillaries

- substances diffuse in and out of the blood in the capillaries

- the valves prevent backflow, ensuring that blood flows in the right direction

- human beings have a double circulatory system

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Heart

- the heart is an organ that pumps blood around the body

- heart valves keep the blood flowing in the right direction

- stents can be used to keep narrowed or blocked arteries open

- statins reduce cholesterol levels in the blood, reducing the risk of coronary heart disease

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Helping the Heart

- damaged heart valves can be replaced using biological or mechanical valves

- the resting heart rate is controlled by a group of cells in the right atrium that form a natural pacemaker

- artificial pacemakers are electrical devices used to correct irregularities in the heart rhythm

- artificial hearts are occasionally used to keep patients alive while they wait for a transplant, or for their heart to rest as an aid to recovery

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Breathing and Gas Exchange

- the lungs are in your chest cavity, protected by your ribcage and separated from your abdomen by the diaphragm

- the alveoli provide a very large surface area and a rich supply of blood capillaries, this means gases can diffuse into and out of the blood as efficiently as possible

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Tissues and Organs in Plants

- plant tissues are collections of cells specialised to carry out specific functions

- the structure of the tissues in plant organs is related to their functions

- the roots, stem and leaves form a plant organ system for the transport of substances around the plant

- many plants have specialised defence tissues and organs

    e.g special hairs that act like hypodermic needles that inject poison into any animal touching them

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Transport System in Plants

- plants have separate transport systems

- xylem tissue transports water and mineral ions from the roots to the stems and leaves

- phloem tissue transports dissolved sugars from the leaves to the rest of of the plant, including the growing regions and storage organs

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Evaporation and Transpiration

- the loss of water vapour form the surface of plant leaves is known as transpiration

- water is lost through the stomata, which open to let in carbon dioxide for photsynthesis

- the stomata and guard cells control gas exchange and water loss

- transpiration stream is driven by loss of water by evaporation out of the stomata

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Factors Affecting Transpiration

- factors that increase the rate of photosynthesis or increase the total stomatal opening will increase the rate of transpiration

- these factors include:

    temperature

    air flow

    humidity

    light intensity

- transpiration is more rapid in hot, dry, windy or bright conditions

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