Transport Systems - The Blood, Heart and Transport in Plants

This section allows transport systems to be examined. The need for transport systems in large organisms is considered, together with the ways in which the major transport systems of plants and mammals function.

Red Blood Cells - Erethrocytes

• Carry oxygen around the body (haemoglobin)
• No nucleus (More oxygen carrying possible)
• Biconcave - maximum surface area
• Haemoglobin combines with oxygen - oxyhaemoglobin
• lack of haemoglobin - anemic
• 5 million Red Blood Cells per mm³

White Blood Cells - Leukocytes

• Irregular shape
• 7000 per mm³

• Phagocytes (engulf the bacteria)
  • bacteria into vacuole
  • enzymes destroy it
• Lymphocyes
  • Produces antibodies which recognise anitgen on bacteria membrane
  • disable bacteria
  • finally ingested by phagocytes
  • immunity

Platelets

• fragments of cells
• 250000 per mm³
• they clump together to clot blood
• make chemical that converts fibrinogen into fibrin - strands across wound.

Plasma

• contains fibrinogin
• contains serum, water, salts, gasses, hormones, glucose and wastes
• It is made up of 90% water.

Substances Transported by the Blood

Substance	From	To
Oxygen	Lungs	Body Cells
Carbon Dioxide	Body Cells	Lungs
Urea	Liver	Kidney
Food (Glucose)	Intestine	Body Cells
Hormones	Glnds	Target Organds
Heat	Muscles/Liver	Whole Body

Transport Systems - Veins, Arteries, Capilleries

• Arteries carry oxygenated blood away from the heart around the body
• Veins carry deoxygenated blood from the body to the heart and then to the lungs
• Capillaries link arteries to veins. They are the site of diffusion with tissue
• Veins have valves to prevent backflow of blood
• Veins have a thin wall
• Arteries have thick walls, this allows from streching (pulse)
• Arteries have a narrow lumen, allowing for high pressure
• Coronary arteries are around the heart
• The heart has double circulation, meaning blood goes through the heart twice, once oxygenated, and once deoxygenated.
• Cholestrol can cause blocking of the coronary arteries
• It can also cause blood pressure to increase.

 

Transport In Plants

Water and minerals are absorbed by the root hairs and then into the xylem

Xylem and Phloem

xylem transports water from root hairs to leaves

phloem transports glucose from leaves to the rest of the plant

Transpiration- it is the movement of water from root hairs to leaves where it evporated and is released through the stomata

• The evaporation causes a suction due to the difference in poressure, and pulls water up through the leaves.
• This continuous cycle is known as a transpiration stream.

Functions of transpiration

• Cools plant
• Brings water and minerals to the plant

 Differences between the Xylem and Phloem

Xylem	Phloem
Dead tissue make it up	living tissue
vessels lined with lignin	vessels lined with cellulose
Transports Water	Trasnports glucose

 

Environmental Factors Affecting Transpiration

• Light
  • opens the stomata, therefore more evaporation
• temperature
  • on a hot day evaporation occurs more rapidly
• Air Movement
  • Wind removed water vapour around the leaf
• Humidity
  • Low humidity, therefore higher concentration of water vapour in leaf the air. (diffusion high)

Potometer - measures water uptake by roots

 

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