Transport in Animals Flashcards
Why are specialised transport systems needed in animals (5 things)…
The metabolic demands are high and diffusion won’t supply the quantities needed. Small SA:V ratio. Hormones/enzymes are made in one place but needed in another. Food is digested in one organ system but is needed in every cell for respiration. Waste products of metabolism need to be removed.
What do most circulatory systems have in common?
A transport medium, vessels and a pumping mechanism.
What is the haemocel?
The open body cavity of an animal in a open circulatory system.
Describe the haemolymph…
There are very few vessels to contain the haemolymph, the haemolymph is pumped straight from the heart to the haemocel. The haemolymph comes into direct contact with cells and tissues. Haemolymph Flowing to a particular area cannot be controlled.
How does the haemolymph return back to the heart?
Through an open ended vessel.
What does the haemolymph carry?
Food, nitrogenous wasteland defence cells.
What pressure is the haemolymph under?
Low
Where does the heart run through in an open circulatory system?
Through the thorax and abdomen
How is blood flowing to particular areas controlled in a closed circulatory system?
Vasoconstriction and vasodilation
Describe closed circulatory systems…
The blood is enclosed in vessels and does not come into direct contact with cells of the body. The heart pumps blood around the body under pressure and it returns to the heart. Substances enter /leave the blood by diffusion. Blood pigment carries the respiratory gases.
Describe single closed circulatory systems…
The blood flows through the heart and travels throughout the whole body before returning.
What type of animals have single closed circulatory systems…
Animals with low activity levels as blood is at low pressure and returns to the heart slowly as there are two sets of capillaries, the first for O2 and CO2 and the seconds for exchanges substances.
What is the exception for the type of animals that have single closed circulatory systems?
Fish have high activity levels but they have a countercurrent exchange system, their BMI is supported by the water and H2O regulates their body temperature.
What is a double closed circulatory system?
The blood travels through the heart twice for each circulatory of the body. Each circuit only passes through 1 capillary network maintaining high pressure and fast flow.
What are elastic fibres?
They are composed of elastin so can stretch hence they give vessel walls flexibility.
What is smooth muscle?
It contacts/relaxes changing the lumen size.
What is collagen?
It provides structural support to maintain vessel shape and volume.
What put of the 3 things do arteries contain?
Elastic fibres, smooth muscle and collagen.
What are the functions of arteries?
To carry blood away from the heart at high pressure
How do the 3 things work in an artery?
Elastic fibres enable arteries to withstand high blood pressure and stretch to limits maintained by collagen.
What is the purpose of elastic recoil in arteries?
To even out surges of blood, alas tic fibres return to their original length.
What do arteries have a smooth endothelium?
So blood flows easily over it
What do arterioles link?
Arteries and capillaries
What is the purpose of arterioles?
To constrict/dilate to control blood flow and pressure to capillary beds so Pitney don’t get damaged.
What is the composition of arterioles?
More smooth muscle than elastic fibres.
What do capillaries link?
Arterioles and venules
What is the lumen size of a capillary?
Very small, to allow one RBC at a time
What is the structure of capillaries?
There are large gaps between endothelial cells (fenestrations) where substances are exchanged into tissue fluid or directly through tissue cells.
Name 3 ways capillaries are adapted to their role…
They provide a large SA for diffusion, their total CSA is larger than arterioles so blood flow drops allowing time for exchange, the walls are a single endothelial cell thick.
What is the function of veins and venules?
They carry deoxygenated blood from capillaries to the two main veins (superior and inferior vena cava) to the heart.
What is the pressure in the venules/veins?
Low, no pulse.
What adaption do veins have do to low pressure?
Valves to prevent back flow.