Organising animals and plants (The blood vessel (Substances diffuse in…
Organising animals and plants
The circulatory system 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 tissue
Blood is made from about 55% plasma, 45% red blood cells and less than 1% white blood cells and platelets
The plasma transports waste carbon dioxide, urea, and small soluble products from the digestive system.
Red blood cells pick up oxygen from the air that we breathe in and carry it to where it's needed
They are concave to increase their surface area.
White blood cells are larger and contain a nucleus. Some form antibodies to prevent illness and others engulf invading bacteria.
Platelets are small fragments of cells. Despite having no nucleus they are very important in helping the blood to clot at the site of wounds.
The blood vessel
Substances diffuse in and out of the blood in the capillaries
The valves protect back flow ensuring blood flows forward
We have a double circulatory system
Arteries carry oxygenated blood away from the heart to the rest of the body. This is the pulse you can feel. They have thick walls containing muscle and fibres - this is to prevent the arteries getting damaged.
Veins carry blood away from the organs towards the heart. They have thinner walls because damage is less dangerous and this helps prevent backflow because of the weak pulse.
Capillaries form huge networks of tiny vessels linking the arteries and the veins. They are narrow and with very thin walls.
Stents can be used to keep narrowed or blocked arteries open.
Statins reduce cholesterol levels in the blood, reducing the risk of coronary heart diseases
Diagram of heart
Helping the heart
Damaged heart valves can be replaced using biological or mechanical valves
The resting heart is controlled by a group of cells in the right atrium that form a natural pacemaker
Artificial pacemakers are used to correct irregularities in the hearts rhythm
Artificial hearts are occasionally used to keep people alive waiting for a transplant
Because heart valves have to withstand a lot of pressure, they may start to leak or not open fully. This could be fatal.
Breathing and gas exchange
The lungs are in your chest cavity, protected by your rib cage and separated from your abdominal by the diaphragm
The alveolar provide a very large surface area and a rich supply of blood capillaries
This allows gasses to diffuse in and out efficiently
Tissues and organs in plants
Plant tissues are collection of cells specialised to carry out specific functions
The roots, stem and leaves form the plant organ system for transport of substances around the body
Transport systems in plants
Xylem tissue transports water and mineral ions from the roots to the leaves and stems
Phloem tissue transports dissolved sugars from the leaves to the rest of the plant
Evaporation and transpiration
The loss pf water vapour from the plant leaves is known as transpiration
Water is lost through the stomata which open to let in CO2 for photosynthesis
The stomata and guard cells control gas exchange and water loss
Factors affecting transpiration
Factors that increase the rate of it include temperature, humidity, air flow and light intercity