9. Transport in Animals

Anmerkungen:

• Describe the circulatory system as a system of blood vessels with a pump and valves to ensure one-way flow of blood

Anmerkungen:

• Fish have a two chambered heart and a single circulation. This means that for every one circuit of the body, the blood passes through the heart once.

Anmerkungen:

• Mammals have a four chambered heart and a double circulation. This means that for every one circuit of the body, the blood passes through the heart twice. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs (the pulmonary circulation) The left side of the heart receives oxygenated blood from the lungs and pumps it to the body (the systemic circulation)

Anmerkungen:

• Blood traveling through the small capillaries in the lungs loses a lot of pressure that was given to it by the pumping of the heart, meaning it cannot travel as fast. By returning the blood to the heart after going through the lungs its pressure can be raised again before sending it to the body, meaning cells can be supplied with the oxygen and glucose they need for respiration faster and more frequently. 

1. the muscular wall

   Anmerkungen:

   • Supplied with blood by the coronary arteries
   1. explain the relative thickness of the muscle walls
      1. left and right ventricles

         Anmerkungen:

         • left ventricle has a thicker muscle than the right as it has to pump blood at higher pressure around the entire body, whereas the right ventricle is pumping blood at lower pressure to the lungs
      2. atria compared to ventricles

         Anmerkungen:

         • The ventricles have thicker muscle walls than the atria as they are pumping blood out of the heart and so need to generate a higher pressure
2. the septum

   Anmerkungen:

   • Explain the importance of the septum in separating oxygenated and deoxygenated blood
3. the left and right ventricles and atria

   Anmerkungen:

   • Remember: you are looking at the heart as if in a person on an operating table, hence the right side is on the left of the diagram
4. one-way valves

   Anmerkungen:

   • Name and identify the atrioventricular (separate the atria from the ventricles) and semilunar (found in the two arteries that come out of the top of the heart) valves in the mammalian heart.  (Theses are the only two arteries in the body that contain valves)
5. coronary arteries

Anmerkungen:

• Remember: A for Away from the heart

1. away from the heart into arteries
2. returns to the heart in veins

1. ECG
2. pulse rate

   Anmerkungen:

   • Measured in beats per minute (bpm)
3. listening to sounds of valves closing

Anmerkungen:

• To investigate effects of exercise: Record the pulse rate at rest for a minute. Immediately after exercise, record the pulse rate every minute until it returns to resting rate. This experiment shows that during exercise the heart rate increases and may take several minutes to return to normal.  (go to page 2 > to read why)
• Heart rate increases during exercise so that sufficient blood is taken to the working muscles to provide them with enough nutrients and oxygen for increased respiration.  An increase in heart rate also allows for waste products to be removed at a faster rate.  Following exercise, the heart continues to beat faster for a while to ensure that all excess waste products are removed from muscle cells. It is also likely that muscle cells have been respiring anaerobically during exercise and so have built up an oxygen debt. the heart continues to beat faster to ensure that extra oxygen is still being delivered to muscle cells. 

1. describe in terms of the blockage of coronary arteries

   Anmerkungen:

   • The heart muscle cells get blood supplied to them by the coronary arteries, delivering oxygen, glucose and other nutrients and removing carbon dioxide and other waste products. If a coronary artery becomes partially or completely blocked by fatty deposits called 'plaques' (mainly formed from cholesterol), the arteries are not as elastic as they should be and therefore cannot stretch to accommodate the blood which is being forced through them - leading to coronary heart disease. Partial blockages result in sever chest pains known as angina. Complete blockage means cells in that area of the heart will not be able to respire and can no longer contract, leading to a heart attack.
2. risk factors

   Anmerkungen:

   • State possible risk factors as: Diet (too high in saturated fats and cholesterol) Stress (hormones can increase blood pressure, increasing chance of a blockage) Smoking (Nicotine causes blood vessels to become narrower, increasing blood pressure) Genetic predisposition (family history, more likely to develop it) Age (risk increases as you get older) Gender (males more likely to develop it than females)
3. prevention

   Anmerkungen:

   • Discuss the roles of diet and exercise in the prevention of coronary heart disease: Quit smoking Reduce animal fats in diet and eat more fruits and vegetables to reduce cholesterol levels in blood. Exercise regularly to lose weight, decrease stress, blood pressure and cholesterol.
4. treatment

   Anmerkungen:

   • Describe ways in which coronary heart disease may be treated, limited to drug treatment with aspirin and surgery (stents, angioplasty and by-pass) Aspirin reduces the risk of blood clots forming. Angioplasty : a narrow catheter (tube) is threaded through the groin up to the blocked vessel. A tiny balloon  inserted into the catheter is pushed up to the blocked vessel and then inflated. This flattens the plaque against the wall of the artery, clearing the blockage. To keep the artery clear, a stent is also inserted which pushes against the wall of the artery.  Coronary bypass surgery: A piece of blood vessel is taken from the patient's leg, arm or chest and used to create a new passage for the flow of blood to the cardiac muscle, bypassing the blocked area.  The number of bypass grafts gives rise to the name of the surgery, so a 'triple heart bypass' would mean three new bypass grafts being attached. 

Anmerkungen:

• Describe the functioning of the heart in terms of the contraction of muscles in the atria and ventricles and the action of the valves.

1. contraction of muscles of atria and ventricles

   Anmerkungen:

   • Deoxygenated blood coming from the body flows into the right atrium via the vena cava. Once the right atrium has filled with blood, the heart gives a beat and the blood is pushed through the tricuspid (atrioventricular) valve into the right ventricle. The walls of the ventricle contract and the blood is pushed into the pulmonary artery through the semi lunar valve which prevents blood flowing backwards into the heart. The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place (this is why there has to be low blood pressure on this side of the heart - blood is going directly to capillaries which would burst under high pressure)Oxygen rich blood returns to the left atrium via the pulmonary veinIt passes through the bicuspid (atrioventricular) valve into the left ventricle.The thicker muscle walls of the ventricle contract strongly to push the blood forcefully into the aorta and all the way around the body.The semi lunar valve in the aorta prevents the blood flowing back down into the heart.
2. action of the valves

   Anmerkungen:

   • The basic function of all valves is to prevent blood flowing backwards. The atrioventricular valves are pushed open when the atria contract, but when the ventricles contract they are pushed shut to prevent blood flowing back into the atria. The semilunar valves are found in the two blood arteries that come out of the top of the heart. These valves open when the ventricles contract so blood squeezes past them out of the heart, but then shut to avoid blood flowing back into the heart.

1. arteries

   Anmerkungen:

   • Arteries -carry blood at high pressure away from the heart -carry oxygenated blood (except the pulmonary artery) -have thick muscular walls which withstand the high pressure of blood. -elastic walls expand and relax as blood is forced out of the heart. This causes the pulse you feel, eg in wrist -have a narrow lumen -speed of flow is fast
2. veins

   Anmerkungen:

   • Veins -carry blood at low pressure to the heart -carry deoxygenated blood (except the pulmonary vein) -have thin walls and a large lumen to reduce resistance to the flow of blood -contain valves to prevent the backflow of blood -blood is at low pressure, but nearby muscles squeeze the veins and help push the blood back towards the heart -speed of flow is slow
3. capillaries

   Anmerkungen:

   • Capillaries carry blood at low pressure within tissues -networks of capillaries extend through all the tissues, so every body cell is near to a capillary-the walls are only one cell thick - substances don't have very far to diffuse through them-the capillaries are highly branched so they cover an enormous surface area, giving more surface for diffusion to occur-capillaries are constantly supplied with fresh blood, keeping up the concentration  gradients of dissolved substances between blood and tissues to allow diffusion to occur.  speed of flow is slow blood plasma leaks out of the capillaries to form tissue fluid surrounding cells

1. heart

   Anmerkungen:

   • limited to: vena cava, aorta, pulmonary artery and pulmonary vein
2. lungs

   Anmerkungen:

   • limited to the pulmonary artery and pulmonary vein
3. kidney

   Anmerkungen:

   • limited to the renal artery and renal vein

1. arterioles

   Anmerkungen:

   • as arteries divide more as they get further away from the heart, they get narrower the narrow vessels that connect arteries to capillaries are called arterioles
2. venules

   Anmerkungen:

   • Veins also get narrower as they branch, further away from the heart The narrow vessels that connect capillaries to veins are called venules
3. shunt vessels

   Anmerkungen:

   • sometimes the cardiovascular system needs to redistribute the blood to specific areas of the body for example: - during exercise more of it goes to the working muscles and less of it goes to other body organs such as the digestive system - when we are hot, more blood flows through the surface of the skin and when we are cold less blood flows through the surface of the skin This redirection of blood flow is caused by the use of a vascular shunt vessel The shunt vessel can open or close to control the amount of blood flowing to a specific area

1. lymphatic vessesl
2. lymph nodes

   Anmerkungen:

   • lymph nodes are small clusters of lymphatic tissue found throughout the lymphatic system, especially in the neck and armpits large numbers of lymphocytes are found in lymph nodes

1. circulation of body fluids
2. protection of the body from infection

   Anmerkungen:

   • large numbers of lymphocytes are found in lymph nodes tissues associated with the lymphatic system, such as bone marrow, produce these lymphocytes Lymphocytes play an important role in defending the body against infection

Anmerkungen:

• red blood cells, white blood cells, platelets and plasma

1. red blood cells

   Anmerkungen:

   • biconcave discs containing no nucleus but plenty of the protein haemoglobin
2. white blood cells

   Anmerkungen:

   • large cells containing a big nucleus, different types have slightly different structures and functions
   1. lymphocyte

      Anmerkungen:

      • can easily be identified by their large round nucleus which takes up nearly the whole cell and their clear, non-granular cytoplasm
   2. phagocyte

      Anmerkungen:

      • easily identified by their multi-lobed nucleus and granular cytoplasm

1. red blood cells

   Anmerkungen:

   • Transport oxygen,  they carry the oxygen in the form of oxyhaemoglobin
2. white blood cells

   Anmerkungen:

   • in phagocytosis and antibody production part of the body's immune system, defending against infection by pathogenic microorganisms
   1. lymphocytes

      Anmerkungen:

      • produce antibodies to destroy pathogenic cells and antitoxins to neutralise toxins released by pathogens
   2. phagocytes

      Anmerkungen:

      • carry out phagocytosis by engulfing and digesting pathogens
3. platelets

   Anmerkungen:

   • involved in blood clotting
4. plasma

   Anmerkungen:

   • transport of blood cells, mineral ions, soluble nutrients, urea, hormones, carbon dioxide and heat energy

Anmerkungen:

• when the skin is broken, platelets arrive to stop the bleeding. platelets release chemicals that cause the conversion of soluble fibrinogen proteins to insoluble fibrin to form a mesh across the wound, trapping red blood cells therefore forming a clot

Anmerkungen:

• as preventing blood loss and preventing the entry of pathogens

Anmerkungen:

• details of the roles of water potential and hydrostatic pressure are NOT required