Transport in Animals

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  • Created by: Chloe
  • Created on: 19-03-17 18:11
Open system
Blood isn't enclosed in the blood vessels all the time, it can flow freely through the body cavity. E.g. Insects.
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Closed system
Blood is enclosed inside blood vessels. It can't flow freely throughout the body cavity. E.g. Fish and mammals.
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Single system
Blood only passes through the heart once for each complete circuit. E.g. Fish.
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Double system
Blood passes through the heart twice for each complete circuit of the body. E.g. Humans.
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Why do multicellular organisms usually need a transport system?
They have a high metabolic demand and a small surface area to volume ratio.
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What are the two loops of the circulatory system?
The pulmonary system - send blood to the lungs. The systematic system - sends blood to the rest of the body.
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Why is the mammalian system described a a double circulatory system?
The blood passes through the heart twice. The right sight pumps the blood to the lungs (pulmonary system)
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What is the role of the arteries?
They carry blood from the heart to the rest of the body.
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What is the composition of the arteries?
Thick muscle layer, elastic tissue for recoil, folded endothelium to allow the artery to expand.
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What type of blood do the arteries carry? What is the exception?
Oxygenated blood. Except from the pulmonary arteries which carry deoxygenated blood to the lungs.
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What are arterioles?
They are branches of the arteries (they are much smaller than the arteries). Smooth muscle layer allows them to contract and expand. They have less elastic tissue than arteries.
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What are capillaries?
Smallest of the blood vessels. They are one cell thick. They are made of endothelum.
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What are veins?
They take blood back to the heart. Carry low pressure blood. Thin elastic and muscle layers. Veins contain valves to prevent back flow.
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What type of blood do veins carry? What is the exception?
Veins carry deoxygenated blood. Except for the pulmonary which carries oxygenated blood to the heart from the lungs.
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What is the function of the blood?
It is a transport medium primarily.
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What substances does the blood carry?
Oxygen, carbon dioxide, glucose, urea, hormones, white blood cells and platelets.
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What is tissue fluid?
It is extracellular fluid which the cells and capillaries sit in.
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What substances move into the blood plasma?
Carbon dioxide, water and urea.
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What substances move out of the blood?
Ions, oxygen, water, glucose and hormones.
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What substances don't leave the blood plasma?
Proteins, white blood cells and red blood cells.
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What effect do plasma proteins have?
An osmotic effect. This is because they give the blood in the capillaries a high solute potential. As a result, water moves out of the capillaries by osmosis.
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What happens at the arterial end?
Hydrostatic pressure forces fluid out of the capillaries. The pressure is about 4.6kPa. Since it is higher than oncotic pressure, fluid is forced out. The fluid is called tissue fluid.
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What happens at the venous end?
Hydrostatic pressure falls below oncotic pressure to around 2.3 kPa. This means that water moves back into the capillaries via osmosis. By the time the blood returns to the veins, 90% of the tissue fluid is back in the blood vessels.
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What is oncotic pressure?
It is a form of osmotic pressure exerted by proteins. It has a pressure of -3.3 kPa.
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What are the components of the tissue fluid?
Water, dissolved solutes. Very few proteins and very few white blood cells. Fatty acids and carbon dioxide.
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What is the lymph?
The 10% of tissue fluid which doesn't make it back into the blood vessels drains off into the lymph vessels.
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Composition of the lymph
Very similar to plasma and tissue fluid, except it has less oxygen and fewer nutrients. It does contain white blood cells, water and dissolved solutes.
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How does lymph fluid move?
By the contraction of muscles.
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Do lymph vessels have valves?
Yes, to aid the one way flow.
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Do lymph nodes contain lymphocytes?
Yes. These swell when the body has an infection. The lymphocytes build up and produce antibodies when necessary. The lymphatic system plays a key role in the defence system. Enlarged lymph nodes are a sign of infection.
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Why does lymph fluid contain fatty acids?
It absorbs it in the villi.
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Does lymph ever return to the blood plasma?
Yes, near the heart.
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How is oxygen and carbon dioxide transported in the blood plasma?
Erythrocytes (rbcs) carry oxygen and carbon dioxide.
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What are the key characteristics of a red blood cell?
They have a biconcave shape, no cell components/or very few. This maximises the volume of oxygen it can carry. Biconcave shape increases surface area for diffusion and gives it flexibility.
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What is haemoglobin?
It is a protein made up of 4 polypeptide chains. Each chain has an iron-haem group. 300 million per ham group.
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What is special about haemoglobin?
It has a high affinity for oxygen. This means that when the first oxygen binds, it makes binding of subsequent oxygen molecules easier.
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What does an oxygen dissociation graph show?
It shows the partial pressure of oxygen agains the percentage saturation of haemoglobin. As partial pressure increase, the percentage saturation increases. Rate is slow to start with then dramatically increases.
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What is Bohr shift?
It occurs when carbon dioxide levels increases, haemoglobin.
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Why does haemoglobin give oxygen up more easily with high levels of carbon dioxide?
Respiring tissues produce a lot of carbon dioxide as a by product meaning more oxygen is delivered. Also CO2 levels are low in the lungs, so there is more oxygen uptake.
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Why is the affinity for fetal haemoglobin greater than for adult haemoglobin?
If it wasn't this way, oxygen wouldn't be delivered to the foetus.
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Composition of the human heart
4 chambers. Deoxygenated blood enters on the right side of the heart. Oxygenated blood enters on the left.
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What 3 types of tissue make up the heart?
Cardiac muscle, smooth muscle and endothelial tissue.
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What is the role of the coronary artery?
Supplies the heart muscle with blood to provide oxygen for respiration and to remove carbon dioxide as a product.
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What happens in the right side of the heart?
The superior and inferior vena cava supply the heart with deoxygenated blood. Blood enters the right atrium. Atrioventricular valve is open so blood flows into the right ventricle. Right ventricle contracts, atrioventricular valve closes.
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From the right side to?
Semilunar valve opens, so blood flows into the pulmonary artery.
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Where does the pulmonary artery take the blood?
To the lungs to be oxygenated.
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What happens on the left side of the heart?
Blood enters the left atrium via the pulmonary vein. The atrioventricular valve is open so blood can flow into the left ventricle. Left ventricle contracts so the atrioventricular valve closes.
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From the left side to?
Semilunar valve opens allowing blood to flow into the aorta.
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Where does the aorta take blood to?
The rest of the body.
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Why is the left side of the heart thicker than the right?
Blood in the left side is under higher pressure meaning the heart has to provide significant force to overcome the resistance of the aorta and arterial system to move the blood.
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What lines the inner dividing wall of the heart?
Septum. The wall prevents the mixing of oxygenated and deoxygenated blood.
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How is carbon dioxide transported in the blood?
3 ways: 5% in the plasma, 10-20% combines with amino acids, 75-85% converted into hydrogencarbonate.
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What is the catalyst for the conversion of CO2 and water into carbonic acid?
Carbonic anhydrase
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What else is it the catalyst for?
Conversion of carbonic acid into hydrogen ions and hydrogen carbonate ions.
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Why is the release of H+ ions significant?
pH receptors detect high levels of this. During exercise, high levels of H+ stimulate the reaction to remove CO2.
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What happens to carbonic acid?
It dissociates to form H+ ions and hydrogen carbonate ions.
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What happens to the negatively charged hydrogen carbonate ions?
They move out into the plasma by diffusion down a concentration gradient.
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What is the role of chloride ions?
These move into the erythrocyte whilst hydrogen carbonate ions move out. This maintains the electrical balance of the cell. It is called chloride shift.
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What else do H+ ions do?
Act as a buffer, especially for haemoglobin.
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Benefit of breaking down CO2
Helps to maintain a steep concentration gradient, to prevent CO2 diffusing back into the tissues from the red blood cells without these reactions.
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What do buffers do?
Donate or accept + and - ions to maintain pH.
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What does myogenic mean?
Heart cells naturally beat on their own.
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What is the time for a normal heartbeat?
0.8 seconds.
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What does systole mean?
Contraction.
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What does diastole mean?
Relaxation.
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What happens during systole?
Heart contracts, blood is forced into the lungs and the rest of the body. Pressure falls at the end of systole.
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What happens during diastole?
The heart relaxes, atria and ventricles fill and the pressure and the volume increase.
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What does SAN stand for?
Sino-atrial node. It is the first wave of impulses across the atria.
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What does AVN stand for?
The atrio-ventricular nodes. They are activated by SAN.
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What does the Purkyne tissue do?
It is activated by SAN and causes contraction from the ventricles to the atria.
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SANs role in initiating heart activity
The action of the heart is initiated by the SAN. SAN sets a regular rhythm. It sends out regular waves of electrical activity to atrial walls. This action results in the simultaneous contraction of the left and right sides. This is called systole.
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What is the role of the non-conducting tissue?
Prevents the waves of electrical activity passing directly to the ventricles
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What is the role of AVN?
Waves of excitation are passed from non-conducting tissue to the AVN. There is a slight delay before AVN reacts. This allows time for the ventricles to contract and all of the blood to leave the atria. AVN stimulates bundle of HIS.
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What does HIS do?
Conducts the waves to the Purkyne tissue.
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What does Purkyne tissue do?
Carries the waves of electrical activity into the muscular walls of the ventricles causing simultaneous contraction from the bottom of the heart, up.
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What is the name of the product from the binding of CO2 with amino acids?
Carbaminohaemoglobin.
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Haemoglobin
It is a quaternary protein made from four polypeptides, 2 alpha and 2 beta subunits. Each subunit contains a prosthetic haem group. The iron II ions in the haem groups are able to combine reversibly with an oxygen molecule.
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Why is the structure of haemoglobin beneficial?
It allows it to transport oxygen.
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Other cards in this set

Card 2

Front

Closed system

Back

Blood is enclosed inside blood vessels. It can't flow freely throughout the body cavity. E.g. Fish and mammals.

Card 3

Front

Single system

Back

Preview of the front of card 3

Card 4

Front

Double system

Back

Preview of the front of card 4

Card 5

Front

Why do multicellular organisms usually need a transport system?

Back

Preview of the front of card 5
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