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Answer all the questionsName_______Bolatova__Talshyn______________________ Tutor Group________________B__________ Coursework: Cardiovascular system Answer all the questions
Submit a hard copy in the box in front of reception block 2 By Friday November 30th 13.00hrs (1.0pm)
Answer all the questions 1
(a) Two of these vessels are arteries and two are veins. Place a tick in the box on the right of the table below that correctly identifies the row showing which two vessels are arteries and which two vessels are veins
(1 mark) (b) Blood moves towards the heart in the veins. Describe how blood is moved through the veins. Firstly,by the pumping of the heart. There is no high pressure in veins like in arteries, so mostly contraction of muscles enables blood in vein to move. If blood from legs is moving, contraction of muscles enables its movement. If it is flowing from upper part of body, then gravity helps blood achieve heart. When organisms respire, in thorax low pressure forms, which also enables blood to move towards heart. Valves inside the vein vessels prevent blood from flowing backward. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________(3 marks)
(c) Capillaries are involved in the exchange of materials between the blood and the surrounding body tissues. Give two structural features of a capillary that enable it to exchange materials rapidly between blood and the surrounding tissues 1.__ only one epithelial cell thick_____ 2. are very small, small diameter as of only 1 red blood cell_ (2 marks) (Total 6 marks)
2. Complete the table below to indicate, precisely, the direction of blood flow in each of the blood vessels.
(4 marks) 3. (a) Cardiac muscle is described as myogenic. What is meant by the term “myogenic”? Means that it does not require any neural (electrical) initiate contraction___ (1 mark) (b) The diagram below shows the spread of impulses through the heart and the time taken (in seconds) to reach various parts.
(i) Using the information in the diagram, suggest the time period during which systole takes place. _0.42_= 0.06+0.17+0.19___________________________________________________________________________________________________(1 mark)
(ii) The atria have completed contraction by the time that initial impulses are fired in the ventricles. What causes this delay in the transmission of the impulses to the ventricles? Delay is caused by the atrioventicular septum. Delay is needed for the wave of contraction pass over the whole both atriums, to ensure that all blood from atriums went to the ventricles ant they are empty ______________________________________________________________________________________________________(1 mark)
(iii) Describe the path of impulse transmission within the ventricles. after delay of 0.1 sec in atrioventricular septum, signal goes to the only transmission route atrioventricular node (AV), secon pacemaker region. Passing AV node signal goes through atrioventricular bundle, which then is brunched to specialized muscle fibers called Purkinje fibers, thereby contructing ventricles.______________________________(1 mark) (iv) What is the advantage of the path of excitation described in (iii) to the pumping of blood out of the ventricles? in a case sinoatrial node (SA node) does not work properly, AV can perform pacemaking over the whole cell, and can work independently SA node. _______________________________(1 mark) (Total 5 marks)
4. The graph below shows the oxygen dissociation curves for the haemoglobin from three different mammals.
(a) The haemoglobin of which mammal has the highest affinity for oxygen? Explain your reasoning. Elephant. Because at given partial pressure of 02 6kPa saturation of elephant’s haemoglobin was almost 90%, while this for dog and mouse were 60% and 36% respectively. It is seen that elephant has higher oxygen affinity, which means it is harder to elephant’s haemoglobin give up oxygen. Elephant has lower metabolic rate, which means it does not have demand to additional oxygen release to the tissues like animals with higher metabolic rate, it has smaller rate of oxygen consumption proportional to mass than smaller animals. Therefore elephant has higher saturation rate of haemoglobin with oxygen. _______(2 marks)
(b) The mouse has a higher metabolic rate than either the dog or the elephant. Explain how mouse haemoglobin is adapted for maintaining a high metabolic rate. Mouse has higher metabolism so it has higher demand of oxygen per gram of weight. Which means mouse must be supplied with oxygen faster. One way is to increase unloading pressure for oxygen. Its haemoglobin can easier release oxygen to tissues than those of larger animals. It caused by high level of 2,3 diphopsphoglycerate (DPG). Therefore curve is shifted to the right (Bohr effect). Another way is smaller animals have higher density of capillaries density, so the diffusion path is reduced, enabling higher rate of diffusion. _____________________________________(2 marks)
(c) The partial pressure of carbon dioxide will influence the oxygen dissociation curve for haemoglobin.
(i) Sketch on the graph the oxygen dissociation curve you would expect for dog haemoglobin when ppCO2 has increased. (1 mark)
(ii) Under what circumstances would the ppCO2 increase in a dog? In fever or physical exercises, when there is a high demand for oxygen in organism. If blood pH is low, DGP is high and temperature is high.
(1 mark)
(iii) Explain the advantages of the effect described. In fever or in physical exercises, when metabolic rate is higher, high temperature and low pH(acidic) enable haemoglobin more rapidly give up oxygen, decreasing oxygen affinity. Therefore more oxygen is given to tissues, satisfying high demand of oxygen. (2 marks) (Total 8 marks)
5. The diagrams A and B below show the heart at different stages during the cardiac cycle.
(a) Identify the stages of the cardiac cycle shown in diagrams A and B. Дата добавления: 2015-09-27 | Просмотры: 952 | Нарушение авторских прав 12 |
. The photograph below shows sections of two blood vessels labelled A and B. The diagram (below right) shows a human heart with two of the blood vessels numbered 1 and 2.
