Transport in animals Flashcards
Why do singled-celled organisms (like bacteria and amoeba) not need at transport sysem?
Because they are able to obtain nutrients and excrete waste simply by diffusion
Why do large multicellular organisms need a transport system?
Large multicellular organisms cannot rely on diffusion to move substances in and around the body. This is because of their:
Metabolic rate
Surface area to volume ratio
Transporting molecules (e.g. food, hormones, enzymes and waste products)
What about a large multicellular organism’s metabolic rate requires them to have a transport system?
They have a high metabolic rate
They requier high volume of substances and poduce a lot of waste
Diffusion alon would not be able to intake an expel all these substanes
What about a large multicellular organism’s surface area to volume ratio requires them to have a transport system?
In larger organisms, diffusio of substance would occur far too slowly to enable them to survive: the rate og diffudion increase with the square of distacne it has to travel.
This is not just because of its size, more important in an prganims surface area to volume ratio. Single celled organisms have a very large surface area to volume ratio becuase the diffusion path is so short
What about a large multicellular organism’s transporting of materialsrequires them to have a transport system?
Hormones and enzimes are often produced in a gland one part of the body and are required in another psart of the body.
The circulatory systems are used to transport these substances.
Digested food, absorbed in the intestine, is required by alll cells in the body.
Waste products of metabolism, produced by all cells need to remove and disposed of in a particular part of the body
What are the types of circulatory systems?
They are either open or closed and then they are single or double
What is an open circulatory system?
Haemolymph (blood) is not enclosed in blood vessels, it is pumped into large spaces into the body cavities, where tissues are surrounded in the blood
Give an example of an organism which has an open circulatory system
insects
What is a closed circulatory system?
Blood is enclosed in blood vessels. The blood is pumped by the heart throguh vessels and does not fill body cavities
What is a double circulatory system?
Two seperate pathwyss for blood: thorugh the heart twice and to circulate the body once. The blood is pumped to the lungs to pick up oxygen, it returns to the heart with oxygenated blood which is then pumped around the body
What are the two circutes know as and what do they do? (in a double circulatory system)
Pulmonary circute - blood is pumped to the lungs to pick up oxygen
Systamatic circute - oxygenated blood is pumped around the body
What is a mammaliean circulatory system?
A closed of the heart and blood vessels
The heart pumps blood around the body
The blood vessels allow blood to circulate to all parts of the body
What is a single circulatory system?
A single circulatory system occurs in fish in which the blood only passes once through the heart when it circultes the whole body.
Describe the circulatory system of a fish
It is a closed and single sirculatory system
Fish hearts have two chambers - atrium (to recieve blood) and ventricle (to pump blood)
Gas exchange occurs at the gills (they do not have lungs)
Blood is pumped to the gills to pick up oxygen and from then to the body
What are the function of the arteries?
To carry blood away from the heart to the lungs
What are the function of the arterioles?
To control blood flow from the arteries to capilaries
What are the structure to function of the capillaries?
Thin layer of cells – short diffusion distance
Numerous and highly branched – large SA for diffusion
Narrow diameter – keep all cells closed by
Narrow lumen – bring RBC closed to the cells = short diffusion distance
Space between cells –allow white blood cells o escape
What is the structure of an artery?
Thick muscle layer control the flow of blood
Thick elastic layer – smooth surges from the heart
What is the structure of an arterioles?
Thicker muscle layer than arteries – high pressure, have to be able to maintain pressure – they can constrict to make pressure go up
Thinner elastic layer than arteries
No valves
What si the structure of blood vessels?
Tough outer layer – resist pressure because the blood flowing through the arteries is at a high pressure
Muscular layer – can contract ad control the flow of blood because they are controlling the rate of delivery of blood to different organs and can control pressure
Elastic layer – can stretch and recoil to maintain blood pressure when the heart is contracting and allows it to cope with searches of blood
Endothelium – smooth layer to prevent friction (blood will flow smoothly), prevents turbulence which prevents blood clots
Lumen – not a layer –a cavity (the hole in the middle of the vessel)
Describe the capillaries
Found in the muscle and lungs
Microscopic one cell thick
Very low blood pressure
When gas exchange takes place. Oxygen passes though the capillary wall and into the tissues carbon dioxide asses from the tisues int the blood
What is the structure of the veins?
Thin muscle layer (by the time the blood travels here the pressure is very low) Thin elastic layer Valves Wide lumen Lower pressure
Structure to function of veins and ventricles?
Carry blood to the heart (always deoxygenated aprt form the pulmonary vein which goes from the lungs to the heart
Have thin walls – because the are carrying blood under low pressure
Have larger internal lumen so that they can accommodate any large amount of blood at any one time
Contain blood under low pressure
Have valves to prevent blood flowing backwards – the back flow of blood closes the valves – not enough pressure to keep blood flowing in one way
What are the main blood vessels in the circulatory system?
Aorta
Pulmonary arteries
Vena Cava -The superior vena cava (blood from upper body) and the inferior vena cava (blood from the lower body
Pulmonary veins
