3.2 Transport in Animals
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- Created by: elbungay1
- Created on: 22-03-19 18:01
What three factors influence the need for a transport system?
Size, surface area to volume ratio and level of metabolic activity
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Why do large organisms need a transport system?
Cells inside the organism are too far from its surface, the diffusion pathway is increased. the diffusin rate is decreased and diffusion is too slow to supply all requirements
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Why do organisms with a very large surface area to volume ratio not need a transport system?
They have sufficient area of the body surface which exchange can occur
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If an organism completes high levels of metabolic acitivty, what nutrients does it need to supply cells?
The cells require high levels of oxygen and glucose in which it can synthesise ATP in aerobic respiration
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What features will an effective transport system include?
A fluid/medium to carry molecules around the body. A pump to create pressure taht will push the fluid around the body. Exchange surfaces that enable substances to enter and leave the blood
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What route does blood take in a single circulatory system of a fish
Heart to Gills to Body to Heart
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Mammalian double circulatory systems consist of what two separate circuits?
Pulmonary circulation which carries blood to the lungs to pick up oxygen. Systemic circulation which carries oxygen and nutrients around the body to tissues
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What are the disadvantages of a single circulatory system?
Blood has low pressure after leaving heart and passing gills, and will not flow very quickly. the rate at which oxygena dn nutrients are delivered to respiring tissues, and carbon dioxide and urea are removed, is limited
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What are the advantages of a double circulatory system?
Blood pressure needs to be low in lungs to protect delicate capillaries, the heart can increase pressure of oxygenated blood so it flows flow quickly around the body. Systemic circulation can carry blood at higher pressure than pulmonary circulation
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What are the disadvantages of an open circulatory system?
Blood pressure is low and blood flow is slow. Circulation of blood may be affected by body movements or lack of body movements
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What advantages do closed circulatory systems have over open circulatory systems?
Higher pressure, faster blood flow. More rapid delivery of oxygen and nutrients. More rapid removal of carbon dioxide and other wastes. Transport is independent of body movements
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What is the innermost lining of a blood vessel called and whats its role?
Endothelium, single layer cells which is particularly smooth in order to reduce friction with the flowing blood.
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What are the three layers of an artery wall?
Inner layer (tunica intima) conists of elastic tissue which allows wall to stretch and recoil to maintain BP. Middle (tunica media) thick layer smooth muscle. Outer (tunica adventitia) Thick layer of collagen and elastic, provides strength for highBP
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What are arterioles?
Small blood vessels that distribute blood from an artery to a capillary. Arteriole wall contains smooth muscle that can contract, decreasing pressure and redistributing blood to tissues which demand more Oxygen
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What are the properties of Capillaries?
Narrow lumen squeezes RBCs against wall which decreases diffusion distance and rate of flow. Wall consist fo singlew layer of flattened endothelial cells, reduces dissusion distance. Leaky walls allow blood plasma and dissolves substances to leave
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What are the properties of veins?
Wide lumen to ease flow of blood. Thinner layers of collagen, elastic and smooth muscle as they dont need to constrict or recoil. Contain valves to prevent back flow of blood
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How is tissue fluid formed?
At arterial end of capillary bed, relatively high hydrostatic pressure, whoch pushes plasma and dissolved nutrents out of leaky gaps. gaseous exchange can then occur between surrounding tissues
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Why doesnt all tissue fluid re-enter blood
Some fluid is directed into lymphatic system
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Describe how hydrostatic and oncotic pressure determine the movement of fluids
Hydrostatic pressure of lood pushes fluid into tissues, hydrostatic pressure of tissue fluid pushs fluid back into blood. oncotic pressure of bvlood tends to pull water back into blood. Oncotic pressure of tissue fluid pulls water into tissue fluid.
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What are the roles of atrio-ventricular vales?
Ensure the correct movement of blood from the atria to the ventricles
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What are the roles of semilunar valves?
Valves that prevent blood re-entering the heart from the arteries
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Why are the walls of the left ventricle two to three times as thick as the right ventricle?
Right ventricle only needs to push blood to nearby alveoli which cnat withstand high pressure due to thin capillaries. Left ventricles need thicker smooth muscle to contract to overcome the resistance of systemic circulation
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Role of atrio-ventricular valves in cardiac cycle
After systole, pressure in ventricles decrease, blood in atria push valves open during atria systole. Close in diastole due to ventricle full of blood. in systole pressure in ventricle increases and blood pushed up, remain closed, prevent backflow
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Role of semilunar valves in cardiac cycle
before ventricle systole, pressure in artery higher, keeping vale closed. In systole, as soon as venbtriuclar pressure rises above artery pressure the valves are pushed open. In diastole ventricle pressure drops, blood flows back and the valves close
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Why is the cardiac muscle described as myogenic?
It can initiate it's own contraction, it will contract and relax rhythmically even if its not connected to the body
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Why is the Sino-atrial node known as the pacemaker?
It initiates a wave of excitation across cardiac muscles at regular intervals
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Describe how the atria contract
SAN initiates a wave of excitation which quickly spreads over the walls of both atria. It travels along membranes of muscle tissue and as it passes causes cardiac tissue to contract. Atrial systole
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Describe ventricular systole
After a delay AVN sends a wave of excitation down Purkyne Tissue. At base of septum, excitation spreads out over walls of ventricles, causing contraction from apex upwards, pushing blood up to arteries
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Describe the structure of haemoglobin
complex protein with 4 subunits. Each subunit conist of a polypeptide chain and a haem (non-protein) group. haem group contains a single iron ion which can attract and hold an oxygen molecule. it has a string affinity for oxygen.
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Why does fetal haemoglobin have a higher affinity to oxygen than adult haemoglobin?
Because the fetal haemoglobin must be able to associate with oxygen in an environment (placenta) where the oxygen tension is low enough to make adult haemoglobin release oxygen
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How is carbon dioxide transported in the body?
5% dissolved directly in the blood plasma. 10% is combined directly with haemoglobin to form carbinohaemoglobin. 85% is transported in the form of hydrogencarbonate ions
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Carbon Dioxide forms weak acid Carbonic acid with help of what enzyme
Carbonic Anhydrase
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What is the purpose of Chloride Shift
The movement of chloride ions from the plasma into the erythrocyte maintains the charge inside the cell. this causes hydrogencarbonate ions to diffuse out of the cell into the plasma
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Describe the Bohr Effect
increasing concentration of CO2 forms more H+ ions which decreases pH of cytoplasm. This affects the tertiary structure of haemoglobin, reducing affintiy to oxygen. haemoglobin can hold less O2 and O2 is released to tissues.
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Other cards in this set
Card 2
Front
Why do large organisms need a transport system?
Back
Cells inside the organism are too far from its surface, the diffusion pathway is increased. the diffusin rate is decreased and diffusion is too slow to supply all requirements
Card 3
Front
Why do organisms with a very large surface area to volume ratio not need a transport system?
Back
Card 4
Front
If an organism completes high levels of metabolic acitivty, what nutrients does it need to supply cells?
Back
Card 5
Front
What features will an effective transport system include?
Back
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