3.1.2: transport in animals Flashcards
why are specialised transport systems needed?
- metabolic demands demands of most multicellular animals are high so diffusion over long distances isn’t enough
- sa:v is small
- molecules may be needed in one place but needed in another
- food will be digested but needs too be transported to every cell for respiration
- waste products need to be removed from cells and transported to excretory organs
what is an open circulatory system?
the transport medium isn’t carried in vessels and is pumped straight from the heart into the body cavity of the animal
what is an example of an animal with an open circulatory system?
in insects
how does an insects circulatory system work?
they don’t have blood but they have a fluid called haemolymph. it is pumped out of the heart and and passes into the body cavity, haemocoel. molecules are transferred between haemolymph and body cells then the haemolymph goes back to the heart
what is a closed circulatory system?
the blood is enclosed in blood vessels and doesn’t come directly into contact with the body cells. substances leave and enter the blood by diffusion through the walls of the blood vessels
is an open circulatory system rapid or slow?
slow
is a closed circulatory system rapid or slow?
rapid
true or false: the amount of blood flowing in an open circulatory system can be adjusted
false
true or false: the amount of blood flowing in an closed circulatory system can be adjusted
true
what is an example of an animal that has a closed circulatory system?
in mammals and in fish
what are 3 different components of blood vessels?
elastic fibres, smooth muscle and collagen
what is the function of elastic fibres in blood vessels?
provide flexibility because they can stretch and recoil
what is the function of smooth muscle in blood vessels?
contracts and relaxes, changing the size of the lumen
what is the function of collagen in blood vessels?
provides structural support to maintain the shape and volume of the vessel
what do arteries do?
carry mainly oxygenated blood away from the heart to the tissues of the body
what are the 2 arteries that carry deoxygenated blood?
pulmonary artery and the umbilical artery
what do the elastic fibres in arteries do?
enable them to withstand the force of blood and take the blood at greater volumes. these also recoil which helps to even out surges of blood pumped
what does the smooth muscle in arteries do?
allows the blood to flow easily
what does the collagen in arteries do?
maintains the stretch when blood is pumped at a high pressure
what are arterioles?
they link arteries and capillaries together
what are capillaries?
microscopic blood vessels that link the arterioles to the venules, forming an extensive network through the tissues and used for gas exchange
what are the adaptations of the capillaries?
- large surface area for diffusion in and out of blood
- total cross-sectional area is greater than the arteriole, slowing down blood flow, giving more times to exchange substances
- one cell thick wall so their is less distance for diffusion
what do veins do?
they carry deoxygenated blood, apart from 2 veins, towards the heart from the cells to the heart