8. Transport In Mammals Flashcards
What is the mammalian circulatory system?
A closed double circulation consisting of a heart, blood and blood vessels
Including arteries, arterials, capillaries, venules and veins.
Why are blood plasma and tissue fluid both mainly composed of water?
Because water is a small enough molecule to pass through the gaps in the capillary walls and into the tissue fluid.
What is the difference between blood plasma and tissue fluid? And why is that difference possible?
Blood plasma contains proteins, tissue fluid does not.
This is because proteins such as albumin, are too large to fit between the gaps in the capillary wall and so they remain in the blood
What are the vessels that carry blood away from the heart called?
Arteries
What are the vessels that carry blood towards the heart called?
Veins
Describe the structure of arteries
-narrow lumen to keep blood under high pressure.
-they have the thickest walls of any blood vessel, allow them to withstand the high pressure of blood.
-middle layer (tunica media) contains a large amount of elastic fibers and smooth muscle.
-an outer layer (tunica externa) containing collagen fibers and some elastic fibers.
Explain 3 reasons how an elastic artery is adapted for its function.
-»carry blood from the heart on the first part of its journey towards its final destination.
-important in allowing them to stretch which reduces the likelihood of them bursting.
-when blood at high pressure enter an artery, it becomes wider reducing the pressure a little.
-when blood at lower pressure enter an artery, the artery walls recoils inwards, giving the blood a small push and raising the pressure
Explain how carbon dioxide is transported in the form of hydrogen carbonate ions.
-carbon dioxide diffuses down a concentration gradient from respiring cells into the plasma, and diffuses again into red blood cells
-in the red blood cells some carbon dioxide combines with water to form carbonic acid, catalyzed by carbonic anhydrase enzyme.
-carbonic acid dissociates to form hydrogen carbonate ions and hydrogen ions.
-the hydrogen carbonate ions diffuse out of the red blood cells into the plasma, where they are transported to the lungs
What would happen if the chloride shift did not happen?
The inside of the red blood cell would develop an overall positive charge because hydrogen ions would accumulate.
Explain what happens during the chloride shift.
Negatively charged hydrogen carbonate ions diffuse out of the cells into the blood plasma, so then negatively charged chloride ions move from the blood plasma into the red blood cells to balance their movement.
State the three ways that blood transports carbon dioxide.
- as hydrogen carbonate ions in the blood plasma
- as dissolved carbon dioxide molecules in the blood plasma
- as carbaminohaemoglobin
Why is the mammal circulatory system called a closed blood system?
Because the blood always remains within the blood vessels.
Describe the systemic circulation.
Blood is pumped out of the left ventricle into the aorta and travels from there to all parts of the body except the lungs. It returns to the right side of the heart in the vena cava.
What is pulmonary circulation?
The blood is pumped out of the right ventricle into the pulmonary arteries which carry it to the lungs. Then the pulmonary veins return it to the left side of the heart.
Cardiac muscle differs from other muscles in our body because it is myogenic. What does this mean?
This means that it naturally contracts and relaxes without the need to receive impulses from a nerve to make it contract.
Why are the tiny gaps between individual cells of the capillary important?
They allow some components of the blood to seep through into the spaces between the cells in all the tissues of the body.
Function of veins
To return blood to the heart
Why is the fact that water makes up majority of the blood important?
Water is a solvent- Glucose is transported in solution in blood plasma, as well as urea transported from, the liver to kidneys.
Water has a high heat capacity- allows it absorb a lot of heat energy without altering its temperature very much.
This factor helps the whole body to maintain a relatively constant temperature
Explain how the structure of hemoglobin is adapted for its function.
-Red blood cells are shaped like a biconcave disc.
The dent in each side of the cell increases the surface area to volume ratio of the cell. The large surface area means that oxygen can diffuse quickly into and out of the cell.
-Red blood cells are very small.
This small size means that no hemoglobin molecule within the cell is very far from the cell surface membrane, and the hemoglobin molecules can therefore quickly exchange oxygen with the fluid outside the cell,
-Red blood cells are very flexible.
The cells are able to be squashed so that they can pass through these vessels, this is possible because they have a specialized cytoskeleton. This allows them to be squashed into different shapes but then spring back to produce the normal biconcave shape.
-Red blood cells have no nucleus, no mitochondria, and no ER.
The lack of these organelles means that there is more room for hemoglobin, so maximizing the amount of oxygen which can be carried by each red blood cell.
Describe how tissue fluid is formed.
As blood flows through capillaries within tissues some of the plasma leaks out through the gaps between the cells in the walls of the capillary and flows into the spaces between the cells of the tissues.
