Transport in Animals Flashcards
Why are specialised transport systems needed in animals?
Maintain metabolic demands, small SA:V, transport of necessary molecules like hormones, removal of waste products like carbon dioxide
What are the different types of circulatory systems?
Open circulatory systems and closed circulatory systems (single and double)
What are the features most circulatory systems have in common?
Liquid transport medium (blood), vessels that carry the transport medium, pumping mechanism to move the fluid around the system
What is an open circulatory system?
When there are very few vessels in a system that pumps blood directly into a body cavity of an organism
How do open circulatory systems work?
The blood in the body cavity is transported under a low pressure, comes into contact with cells and tissues for gas exchange etc, the blood returns to the heart through an open ended vessel
Name some organisms that may have an open circulatory system
Invertebrates, some insects, some molluscs, arthropods
What is a closed circulatory system?
Blood is enclosed in vessels and does not come into direct contact with cells and tissues. Blood is pumped under high pressure and exchanges substances via diffusion before returning to the heart
What are single closed circulatory systems?
Blood only travels through the heart once for a complete circulation of the body
How do single closed circulatory systems work?
Blood passes through 2 sets of capillaries before it enters the heart; the first set exchanges oxygen and carbon dioxide (from respiratory system) and the second substances are exchanged between all the other organs in the body. This happens at a low pressure so therefore is very slow
Name some examples of what organisms may have a single closed circulatory system
Fish and annelid worms
How is the single closed circulatory system different in fish?
They have an efficient respiratory system because they have countercurrent gas exchanged systems that allow the gills to absorb a lot of oxygen. They also do not have to maintain their body temperature or support their body against gravity, which decreases metabolic demand
What are double closed circulatory systems?
Blood travels through two separate circulations; to the lungs and to the rest of the body
How do double closed circulatory systems work?
Blood is pumped to the lungs to load oxygen and unload carbon dioxide, blood is the pumped back to the heart, then pumped to the rest of the body to transport oxygen and other substances to organs, tissues and cells, then pumped back to the heart for a complete circulation. Each circuit only passes through one capillary network at a high pressure to maintain a high blood flow
Name some examples of what organisms may have a double closed circulatory system
Birds and most mammals
What are the components present in blood vessels?
Elastic fibers, smooth muscle and collagen
What is the advantage of having elastic fibers in blood vessels?
Able to stretch and recoil for flexibility
What is the advantage of having smooth muscle in blood vessels?
Contraction and relaxation changes size of lumen
What is the advantage of having collagen in blood vessels?
Provides structural support to maintain volume/shape of the vessel
What are arteries?
Vessels that carry oxygenated blood away from the heart (A for Away), EXCEPT the pulmonary artery and the umbilical artery. Blood in the arteries is under a higher pressure than blood in the veins
What are arterioles?
Link arteries with capillaries. They have more smooth muscle and less elastic fibers, due to the decreased pressure but also controls the volume of blood going into the capillary bed