Transport In Animals Flashcards
state 5 reasons why some animals need a specialized transport system.
- the metabolic demands (waste produced and oxygen/food required) is high so cannot be achieved by diffusion
- surface area to volume ratio is too small in larger organisms.
- hormones and enzymes are made in one location but needed in another
- food needs to be transported to every cell to use for respiration
- waste products of metabolism need to be removed.
define the term mass flow.
when a mass of liquid is moved around a transport system using some kind of mechanism.
define the term diffusion.
the net movement of particles/substance from an area of high concentration to an area of lower concentration across a partially permeable membrane until equilibrium is reached.
define the term circulatory system.
a transport system which carries gases such as oxygen and carbon dioxide, nutrients, waste products and hormones around the body.
what is an open circulatory system?
a system where there are very few vessels to contain the transport medium. it is pumped straight from the heart into the body cavity of the animal called the haemocoel - where the transport medium is under low pressure. it comes into direct contact with tissues and cells, this is where exchange takes place. the transport medium returns to the heart through an open ended vessel.
what features do most circulatory systems have in common?
- liquid transport medium that circulates around the system.
- vessels that carry the transport medium
- pumping mechanism to move the fluid around the system.
describe when and how open circulation happens in insects.
in invertebrate animals like insects, gas exchange takes place in the tracheal system. insect blood is called haemolymph and doesn’t carry oxygen or carbon dioxide. it transports food, nitrogenous waste and cells involved in defense against disease. the body cavity is split by a membrane and the heart extends along the length of the thorax and abdomen. the haemolymph circulates but steep diffusion gradients cannot be maintained.
describe a closed circulatory system.
the blood is enclosed by vessels and does not come into direct contact with cells. the heart pumps the blood around the body fast and at high pressure. the blood returns directly to the heart. substances enter and leave the blood by diffusing across vessel walls. blood contains respiratory gases. the amount of blood flowing can be adjusted by narrowing blood vessels.
where are closed circulatory systems found?
all vertebrate groups including mammals, as well as a few other randos like earthworms.
what is a single circulatory system?
blood flows through the heart and is pumped out to travel around the body before returning to the heart. the blood travels only once through the heart. found in fish
what is a double circulatory system?
the most efficient system for transporting substances around the body. found in mammals and birds. it consists of two circuits - the pulmonary circuit where blood is pumped to the lungs to pick up oxygen and the systemic circuit which takes blood to the body. blood flows through the heart twice in each circuit. relatively high speed and pressure are maintained throughout.
list the order of blood vessels in the body.
arteries, arterioles, capillaries, venules, veins.
define the term lumen
the space in the middle of the blood vessel through which the blood itself travels.
state the names of the layers of a blood vessel.
- endothelium lining the lumen
- tunica intima containing elastic fibres
- tunica media containing smooth muscle
- tunica externa containing collagen
describe why the properties of a blood vessel wall are useful.
endothelium - lines the lumen reducing friction in the blood, some folds which allow it to expand when the heart beats.
tunica intima containing elastic fibres - allow the blood vessel to expand and return to it’s normal shape when put under pressure.
tunica media containing smooth muscle - allows for vasocostriction when needed
tunica externa containing collagen - provides structural support and maintains the shape of the vessel.
