Man Test(s) conducted with the eyes of the patients blindfoldedObservations X X’s fingertip was pricked by a pin X felt the pain but he did not withdraw his hand Y Y’s finger tip was pricked by a pin Y could not feel the pain and did not withdraw his hand Y was asked to move his hand Y could move his hand Z Z’s finger tip was pricked by a pin Z withdrew his hand but he was unaware of the touch and the withdrawal of his hand Which part of the nervous system was most likely damaged in X, Y and Z respectively? Explain your answer in each case. (8 marks)
16 Coordination in Humans Last update: 2019-12-24- 22 - CE930103a Two patterns of response shown by the human body towards stimuli of different nature are outlined below: Pattern A stimuluscentralnervoussystemreceptoreffectorresponsee.g. stepping e.g. withdrawal on a sharp nail of foot Pattern Bhormonestimulusresponsee.g. increase in e.g. decrease in blood glucose blood glucose level level(i) Referring to the specific cell types involved, describe the sequence of events that leads to the withdrawal of the foot. (4 marks) (ii) Referring to the specific organs and hormone involved, describe the sequence of events that leads to a decrease in blood glucose level. (4 marks) (iii) With reference to the mechanisms involved, explain why the response in pattern A occurs much faster than that in pattern B. (2 marks) (iv) Regulation of the blood glucose level is an example of the feedback mechanism in the body. State another example. What is the importance of the feedback mechanism to the body? (2 marks)
16 Coordination in Humans Last update: 2019-12-24- 23 - CE950103b3. (b) The diagram below shows the arrangement of some neurones in man : (i) Using numbers in the diagram, indicate the pathway of nerve impulses that bring about (1) the withdrawal reflex of the arm. (1 mark) (2) the voluntary action of the arm. (1 mark) (ii) State twodifferences between reflex actions and voluntary actions. (2 marks) (iii) For parts A, B and C of the brain, stateand explainonerole that eachplays when a man is riding a bicycle. (6 marks)
16 Coordination in Humans Last update: 2019-12-24- 24 - CE040202cIrritability is the ability of an organism to respond to an external stimulus. Most cases of irritability work in the following pattern : Below are three examples of irritability in humans: (I)Secretion of saliva when food is ingested (II)Constriction of pupil under bright light (III) Running out of the classroom upon hearing the fire alarm (i) For case I, state the receptor and effector involved. (2 marks) (ii) Based on the above pattern, use a flowchart to show the nervous pathway for case II, including the types of neurones involved. (3 marks) (iii) (1) Name the region of the brain where the coordinating centre for case III is located. (1 mark) (2) State twofeatures of the responses controlled by this region. (2 marks)
16 Coordination in Humans Last update: 2019-12-24- 25 - CE060103 3. The figure below shows a magnetic resonance image of the lateral side of the upper body of a person: (a) Name structure X and state its function. (2 marks) (b) What is the importance of structure Z to structure Y?