Module 3.2 Transport in animals. Flashcards
Why do larger animals need a transport system?: What factors influence a transport system?:
Because animals have a complex anatomy more than two cells thick diffusion will not be able to fufill the requirements. Factors affecting transport system are size, SA:V ratio, and level of metabolic activity.
What are features of a good transport system?:
- Fluid or a medium to carry the nutrients, oxygen and waste products around the body. (blood)
- A pump to create pressure that will push the fluid around the body. (the heart)
- Exchange surfaces that enable substances to enter and leave blood as needed. (capillaries)
An efficient system will also include: - tubes or vessels to carry the blood by mass flow
two circuits - one to pick up oxygen and another to deliver oxygen to the tissues.
What are the differences of single and double circulatory systems?:
Single circulatory system: (e.g fish) The blood flows through the heart once for each circuit of the body
Double circulatry system: (mammals) One circuit carries blood to the lungs and back (pulmonary circulation), while the other system carries the oxygen and nutrients around the body of the tissues. (systematic circulation)
What are the advantages of the double circulatory system?:
The heart is able to control the pressure it sends blood to the body and lungs, as it must not be too high in the lungs but needs to be high in order to get across the whole body. Leaving the lungs it is at a high pressure so flows through the body more quickly allowing for more metabolic activity. Cells are well supplied with nutrients and oxygen, with waste products also being removed.
What is the differences between an open and closed circulatory system?:
Open circulatory system: Blood is not always held within vessels, but instead the blood fluid circulates through the body cavity, so that the tissues and cells are bathed directly in blood.
Closed circulatory system: Blood stays entirely in the vessels, and instead a sperate fluid, tissue fluid, bathes the tissues and cells.
What are advantages of a closed circulatory system instead of an open system?:
Blood is at a higher pressure so that blood flows more quickly.
Oxygen and nutrients delivered more rapidly.
Carbon dioxide and other waste products and removed more rapidly.
Transport is independent of body movements.
What are the 5 types of blood vessels?:
Arteries, arterioles, capillaries, venules and veins.
What are the roles of arteries? How does their structure help with their function?:
Arteries: Carry blood away from the heart.
collagen fibres and elastic fibres: Provides strength to withstand pressure and recoil to maintain pressure.
Smooth muscle: helps to withstand pressure.
Inner elastic tissue: allows walls to stretch and recoil maintaining the pressure.
Endothelium: folded to allow the lumen to expand as blood flow increases.
Small lumen to maintain pressure.
How do arterioles function?:
Arterioles (small blood vessels) distribute the blood from the artery to the capillaries. Their walls contain a layer of smooth muscle which can contract and constrict the diameter of the arterioles to increase resistance of flow and rate of flow of blood. This can therefore allow arterioles to divert the flow of blood to regions of the body demanding more oxygen.
What do capilaries do? How does their structure help their function?:
Capillaries allow the exchange of materials between the blood and the tissue fluid due to its specialised thin walls.
Lumen is small so red blood cell are pushed up against the walls of capillaries, helping to transfer oxygen and reducing diffusion distance.
Wall consists of one layer of squamos endothelial cells, reducing the diffusion distance further.
Leaky walls to allowblood plasma and dissolved substances to leave the blood.
What do veins do? How is their structure adapted for their function?:
Veins carry blood back to the heart, in which blood is at a low pressure.
Lumen is relatively large to ease blood flow.
Thinner layers of collagen, smooth muscle and elastic tissue compared to artery walls, as they do no need to stretch and recoil to reduce blood flow.
Contain valves in order to help blood flow back in the right direction, preventing back flow.
Surrounding skeletal muscle contracting outside of the vein can apply pressure to the blood, forcing it t move in the direction determined by the valves.
What are venules? What do they do?:
Venules collect the blood from the capillaries, collecting it from the capillary bed and leading it to the veins.
The venule wall consists of thin layers of muscle and elastic tissue outside the endothelium, and a thin outer layer of collagen.
What makes up blood?:
Plasma: the fluid portion of blood. It contains may dissolved substances such as oxygen, carbon dioxide minerals, glucose, amino acids hormones and plasma proteins.
red blood cells (erythrocytes), white blood cells and platelets.
What is tissue fluid? How is it formed?:
Tissue fluid is similar to blood plasma but does not contain most of the cells found in blood along with no plasma proteins. It is formed by blood plasma leaking from the capillaries.
What is the purpose of tissue fluid?:
Tissue fluid surrounds the cells of tissues, and supplies them with the oxygen and nutrients they require. They also carry back waste products from cells metabolic activity as some tissue fluid is returned to the capillaries.
