Transport in animals Flashcards
Why do animals need specialised transport systems?
STATE THE FIVE MAIN REASONS!!
- Metabolic demands of most multicellular animals are (i.e. food, water and lots of waste product is produced) so diffusion over long distances is not sufficient to maintain this.
- SA:V ratio becomes smaller the more larger an animal so diffusion distance gets bigger and SA available to absorb or remove substances becomes relatively smaller.
- Molecules like enzymes and hormones made in one area of the body but needed in another part.
- Food digested by organ needs to transported for respiration and other aspects of cell metabolism.
- Waste products need to be removed from cells and transported into excretory organs.
How would explain the term a mass transport system to a person?
- A system that uses a mechanism to carry a large amount of fluid around the body.
What do most circulatory systems have in common?
- A transport medium to circulate around system (i.e. blood).
- Vessels that carry the transport medium around the organisms body.
- A pumping mechanism to move ‘blood’ around the body.
Can you name the types of systems large, multicellular animals use?
- Open circulatory system (OCS)
- Closed circulatory system (CCS)
What is an example of an OCS, what is it’s pathway and what is the transport medium called?
- A OCS is commonly found in invertebrates and there are few vessels to contain transport medium, which is under low pressure.
- Pumped straight from heart to the rest of the body which means cells and tissue are in direct contact with transport medium.
- This open body cavity called ‘haemocoel’ is split by a membrane and heart extends along length of thorax and abdomen of thorax.
- Carries insects blood called ‘haemolymph’.
- Haemolymph can be circulated around body but steep diffusion gradients cannot be maintained for efficient diffusion.
CONS: Amount of haemolymph flowing to a tissue cannot be varied to meet changing demands
What does a haemolymph carry?
- NOT CO2 OR O2!!!!!
- Transports food, nitrogenous food waste and cells involved in defence against disease.
What features does a CCS have?
- Blood is enclosed in blood vessels and doesnt come into direct contact with cells so substances diffuse through walls of blood vessels.
- Heart is able to pump around body under pressure and relatively quickly returns directly back to heart.
- Unlike OCS, amount of blood travellingto a particular tissue can be adjusted by widening/narrowing of blood vessels.
- Most CCS contain a blood pigment that carries respirator gases.
What type of animals have an OCS?
Most invertebraes, insects and molluscs
Why don’t you try naming a few animals who have a CCS?
Echinoderms - starfish
Cephalopod molluscs - octopus
Annelid - common earthworm
Do you think you can explain a single closed system and it’s pathway in a body?
- Blood flows through heart and pumped out to flow through rest of the body, only travels around body once to complete one full circulation.
- Has only two sets of capillaries, one in the ‘lungs’ where CO2, O2 are exchanged and the other in the rest of the body where substances are exchanged.
- These narrow vessels moving in only one continuous direction results in blood pressure dropping so blood returns back to heart rather slowly.
- Low blood pressure = slow blood flow = lack of efficiency in exchange processes
- Most of animals end up having low activity levels.
Why do are fish the exception in the single closed circulatory system?
- Have a counter-current gaseous exchange mechanism, this allows a lot of oxygen to be diffused into cells from water.
- Their body weight is supported by water, the environment they live in.
- Do not need to maintain their body temperature, this reduces the metabolic demands of their body.
Do you want to explain the double CCS?
- Commonly seen in very active animals such as land animals like humans, birds that maintain their own body temperature.
- This is most efficient form of gaseous mechanism to pump blood around the body.
- Has two separate circulations: - pulmonary/systemic circulation.
- Blood travels twice through heart for each circuit in body and travels through one capillary network, so relatively high pressure and fast flow of blood can be maintained
What are the different components used in blood vessels?
- Elastic fibres - Composed of elastin and can stretch/recoil, provides vessel walls with flexibility.
- Smooth muscle - contracts/relaxes, this changes size of lumen.
- Collagen - Provides structural support to maintain shape and volume of vessel.
Why is the blood in the arteries under higher pressure than the blood in the veins?
- Elastic fibres allow larger volumes of blood to be taken in the arteries and enable them to withstand the force of it being pushed through. They recoil back to original shape after blood is pushed through until the next heart contraction.
- Collagen works to maintain structure and limits elastin in walls to not ‘overstretch’.
- Endothelium is also smooth so blood flows through it.
How do the arterioles function and how does it concern vasoconstriction/dilation?
- Links the arteries and capillaries and has more smooth muscle than elastin walls in the artieries.
- This is due to the way it can constrict/dilate to control the blood flow into individual organs.
- Vasoconstriction - Smooth muscle contracts and constricts the vessels to prevent blood flow into capillary.
- Vasodilation - Smooth muscle relaxes and dilates the vessels this lets blood flow into capillary.
