animal transport Flashcards
What are some reasons that transport systems are required in animals?
+ Most animals have high metabolic demands so diffusion over long distances is not enough to supply the things required
+ As organisms get bigger the SA:V ratio gets smaller, so the amount of SA available to absorb substances gets smaller
+ Molecules such as hormones or enzymes may be made in one place and required at another
+ Waste products of cells need to be removed from cells and transported to excretory organs
What are some features most circulatory systems have in common?
+ Have a liquid transport medium that circulates around the system
+ Have vessels that carry the transport medium
+ Have a pumping mechanism to move the fluid around the system
What is a mass transport system?
A mass transport system is when substances are transported around the body in a mass of fluid with a mechanism designed to move that mass of fluid
What are the main features of an open circulatory system?
What is the open body cavity called
+ Very few vessels which contain the transport medium
+ Pumped straight from the heart to the cavity of an animal and comes in direct contact with the tissues and cells where exchange takes place.
+ This occurs under low pressure
The open body cavity is called the haemocoel.
Where are open circulatory systems mainly found?
What is insect blood called and its properties?
Open ended circulatory systems are mainly found in invertebrate animals such as insects and molluscs.
Insect blood is called haemolymph and only transport food and nitrogenous waste products and cells against disease.
The amount of haemolymph reaching tissues cannot be controlled as steep diffusion gradients cannot be maintained.
What are the main features of a closed circulatory systems?
+ Blood is closed in blood vessels and do not directly come in contact with cells
+ The heart is able to pump the blood under pressure and works relatively quickly
+ Substances will leave and enter the blood by diffusion through the walls of the blood vessels
+ Amount of blood flow to tissues and cells can be controlled by widening and narrowing of blood vessels.
What is a singular closed circulatory system? Why are they limited in how they work and how do fish counteract this?
{Hint in the word counteract}
A system where the blood goes through the heart and is pumped out to travel all around the body before returning to the heart. Blood will only pass heart once for a full circulation.
In a single closed circulatory system , blood passes through two sets of capillaries before returning to the heart meaning the blood pressure in the system drops low so blood will return to heart slowly, limiting efficiency of exchange processes.
Fish counteract this as they have a counter-current flow system for gasesous exchange and their weight is supported by water , greatly reducing metabolic demands.
What is a double closed circulatory system? What are the two stages this system goes through?
This circulatory system is when the blood pumps through the heart twice for each circuit of the body. This all only passes through one capillary meaning it has a relatively high blood pressure and a fast flow of blood can be maintained.
1) Pumped from the heart to the lungs to pick up O2 and unload CO2 and then return to heart
2) Pass through the heart and pump all around the body before turning back
What are the main components in blood vessels and their functions?
Elastic fibres: Composed of elastin and can stretch and recoil , providing vessel walls with flex-ability
Smooth muscle: Can contract or relax to change the size of the lumen and relative amount of blood flow
Collagen: Provides structural support to maintain the shape and volume of the vessel
What are the structure and function of arteries?
Arteries generally carry oxygenated blood away from the heart to the tissues of the body under higher pressure than the veins.
Arteries are made from elastin to withstand the high pressures of blood being pumped.
Has smooth endothelium lining so the blood flows easily over it,
What are the structure and function of arterioles?
Link the arteries to the capillaries.
They have more smooth muscle and less elastin in their walls than arteries meaning they cannot withstand much force however can control blood flow via vasoconstriction effectively.
What are the structure and function of capillaries?
Capillaries are microscopic blood vessels that link arterioles and venules.
Capillaries are where substances are exchanged between tissue cells and the blood through the small fenestrations / pores.
+They have a large SA for diffusion of substances
+Walls are a single endothieal cell thick , thin layer for diffusion
+Cross-sectional area of capillaries is lower than the arteries meaning the rate of blood flow will fall to receive more time for exchange of materials.
What are the structure and functions of the veins?
Veins carry blood away from the cell towards the heart and usually carry deoxygenated blood.
Veins do not have a pulse but usually carry the most blood in your body.
Have low blood pressure compared to the arteries and have valves to prevent the back flow of blood.
Have a lot of collagen but little elastic fibre and a wide lumen with smooth lining for easy flow of blood.
What are the structure and function of the venules?
Venules link the capillaries with the veins and have very little smooth muscle .
Several venules link to join into a vein.
How do the veins transport blood even under low pressure?
Veins have one way valves which prevent the back flow of blood as they will close if the blood begins to backflow.
Bigger veins will run through active muscles as when muscle contract and squeeze, it will force the blood from the veins to the heart
Breathing movements from the chest act as a jump for veins
