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Transport in Animals
Transcript of Transport in Animals
Transport in Animals Types of Transport systems All living cells need a supply of nutrients such as glucose and a constant supply of oxygen, they also need waste disposal:
Small organisms do this by diffusion
Bigger organisms need a transport system to do this Small Organisms Very small organisms such as single cellular organisms can use DIFFUSION as it produces an adequate amount of nutrients and oxygen and the speed of the supply is sufficient for their needs (their needs aren't great because these organisms do not move as much as bigger organisms and therefore need less energy)
This is because they have a very large SURFACE AREA: VOLUME ratio meaning that there is a bigger area for gases to diffuse across Open and Closed Circulatory Systems Most vertebrates have a CLOSED Circulatory System and this means that their blood is within blood vessels such as arteries. This maintains the HIGH PRESSURE needed to reach the extremities of the body and also keeps the OXYGENATED and DEOXYGENATED blood apart An OPEN circulatory system is when the blood is not encapsuled within blood vessels and animals which have an open circulatory systems have limited ability to control blood flow and usually have relatively low metabolic rates. Large Organisms Larger organisms cannot rely just on diffusion, this is because they are often more active and will therefore need a fast rate of oxygen and nutrients to their muscles. These organisms have transport systems which are either single or double circulatory.
This is because they have a small SURFACE AREA:VOLUME ratio meaning that diffusion is not sufficient Open Circulatory System Insects The blood is pumped around the body by numerous hearts The blood flows out of the arteries The blood then fills the haemocoel oxygenating the cells Insects don't have a circulatory system like mammal', they have an arrangement of tubes called TRACHEAE which carry oxygen throughout the body The exchange surfaces are close to the cells creating the CO2 so they are more efficient to the cell's needs Closed Circulatory systems Fish- Single Circulatory System A fish has a single circulatory system as they have ONE ATRIUM and ONE VENTRICLE which pumps blood to the body and is oxygenated by the gills.
This is not as efficient as a double circulatory system because as it approaches the gills it loses pressure (going through the capillaries) Amphibian- Double Circulatory System A Frog has a double circulatory but they have TWO ATRIA and ONE VENTRICLE which has a pulmonary and systemic system to the lungs and body:
Having a malformed SEPTUM and one ventricle means that the oxygenated blood and deoxygenated blood mix making the process less efficient. Human- Double Circulatory System A human and other mammals have a double circulatory with TWO ATRIA and TWO VENTRICLES which has a pulmonary and systemic system to the lungs and body:
This circulatory system is very efficient as oxygenated and deoxygenated blood is separated making oxygen get to the cells efficiently The Mammalian Heart The Cardiac Cycle Atrial Systole The atrio-ventricular valves are closed and this prevents blood from going through into the ventricles, the INCREASES the pressure in the atria
Atrial systole occurs when the two atria contract (stimulated by excitations from the SAN) forcing the blood into the ventricles
The Venus semi-lunar valves are closed to prevent the backflow of blood Ventricular systole As the blood flows into the ventricles this puts pressure on the papillary muscles making the AV valves close and the arterial semi-lunar valves are pushed open.
A contraction caused by the AVN node makes the blood go up the arteries in what is know as ventricular systole Diastole The pressure in both the ventricles and the atria drops and the heart relaxes, blood from the veins flows in at low pressure. Some blood reaches the ventricles.
Both the AV valves and the Venus semi lunar are open but the arterial semi lunar are closed to prevent the backflow of blood Valves Atrio-Ventricular Valve