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6.5 Study Guide the Nervous System Instructions: Read pages 173 to 184 in you IB Biology Textbook. Then define all the vocabulary words and Address all the assessment statements below: Vocabulary Words: Central Nervous system Peripheral Nervous system Nerves Neurons Dendrites Axon Myelin sheath Nodes of Ranvier Motor end plates Nerve Impulse Resting potential Action Potential Depolarization Repolarization Relay neurons Motor neurons Synapsis Synaptic transmission Protein Channels Sodium ions Potassium ions Active transport Facilitated diffusion Neurotransmitter Ion channel Vesicles Exocytosis Presynaptic neuron Postsynaptic neuron Homeostasis Hypothalamus Glucose Glucagon Insulin Glycogen Pancreas Alpha Cells Beta cells Hydrolysis Diabetes type I Diabetes type 2 Practice Questions (options): 1. Define the following: Central nervous system The brain and spinal cord. (1) Peripheral nervous system Neuron Synapse Neurotransmitter Resting potential Action potential 2. State the name and function of each of the labeled structures of this motor neuron. A = Dendrite Function: B= Function: C= Function: D= Function: E= Function: speeds up propagation of action potential and saves energy F= Function: Essential Biology 6.5 Nerves, Hormones, Homeostasis Due Date: Candidate Number: 002171- Student Name: 3. This diagram shows a simple reflex arc. Identify the structures labeled A-D and state the actions 1-3. A B C D 1 2 3 4. Resting potential is the electrical potential across the membrane of a neuron that is not conducting an impulse. It is used to repolarize (reset) a neuron in between impulses. a. List two ions used in neurons. b. Define electrical potential c. State the specific method of membrane transport used to maintain resting potential d. Explain how a resting potential is maintained, including why it is negative. Sodium ions are pumped out of the neuron By Stephen Taylor Bandung International School http://sciencevideos.wordpress.com Essential Biology 6.5 Nerves, Hormones, Homeostasis Student Name: Due Date: Candidate Number: 002171- 5. Action potential (AP) is the depolarization and repolarization of the neuron to conduct an electrical impulse. a. Use the following cues to explain how an AP is transmitted along the neuron. Resting potential Is maintained through... Depolarisation Is trigged by… Which causes Voltage-gated Na+ channels “all or nothing response” K+ channels Refractory period b. Explain the significance of the labeled features of this graph, showing an action potential. 1 2 3 4 5 c. Outline how a one-way direction of nerve impulse is maintained. d. Compare resting potential and action potentials. Resting potential Also known as… -polarisation Action potential - polarisation Internal potential is… (positive/ negative) Stephen Taylor Bandung International School http://sciencevideos.wordpress.com Essential Biology 6.5 Nerves, Hormones, Homeostasis Due Date: Candidate Number: 002171- Student Name: Sodium ions are… Potassium ions are… Membrane proteins used (voltage-gated sodium channels or sodium potassium pump?) 6. A synapse is a junction between neurons. This is a small gap between the terminal end of the pre-synaptic neuron and the dendritic end of the post-synaptic neuron. The electrical signal of the action potential is converted to a chemical signal, which passes across the synapse and stimulates an action potential in the post-synaptic neuron. Whew. a. Label these features of the synapse. A B C D E F G H b. Explain the process of synaptic transmission, referring to all of the labeled structures above. AP reaches terminal end of pre-synaptic neuron This causes voltage-gated Ca2+ channels to open Stephen Taylor Bandung International School http://sciencevideos.wordpress.com Essential Biology 6.5 Nerves, Hormones, Homeostasis Due Date: Candidate Number: 002171- Student Name: c. Explain the need for high numbers of mitochondria in the pre-synaptic neuron. d. Predict the effect of a drug which acts as a competitive inhibitor of a neurotransmitter. Data-based question practice, from the QuestionBank CDRom 7. The sense of taste is normally caused by the stimulation of chemoreceptors in the taste buds of the tongue. There are four main 'tastes': sweet, salty, bitter and sour. The tongue also has receptors for temperature. It is known that the taste of food can vary according to whether it is cold, warm or hot. Scientists discovered that just warming or cooling parts of the tongue, even when no food was present, also caused a sensation of taste. Scientists experimented with a group of people. They gradually cooled the tips of their tongues and measured the intensity of the taste felt by each member of the group. The experiment was repeated, this time warming the tip of the tongue. The graphs show the average values for the group. Cooling the tongue tip Warming the tongue tip Taste intensity felt / arbitrary units moderate weak just detectable 35 25 35 20 35 15 35 10 35 5 20 25 Decrease in temperature from 35 ºC Key: Salty Bitter 20 30 20 35 20 40 Increase in temperature from 20 ºC Sweet Sour [Source: modified from Cruz and Green, Nature (2003) 403, page 889] (a) Identify which taste was felt most strongly when the tip of the tongue was (i) cooled: (ii) warmed: Stephen Taylor Bandung International School http://sciencevideos.wordpress.com Essential Biology 6.5 Nerves, Hormones, Homeostasis Due Date: Candidate Number: 002171- Student Name: (1) (b) Compare the effects on the taste of sweetness, of warming and cooling the tip of the tongue. (2) (c) It is important that such experiments use a population sample that is representative. Suggest two biological criteria the scientists would have used to select the people to be tested. (1) (d) Explain whether cooling or warming the tip of the tongue has the greater effect on the sensation of taste. (2) The scientists discovered that there were two types of chemoreceptor in the tongue tip. They called these A and B. They tested these chemoreceptors using solutions of sucrose to find out the type of taste and the intensity felt. The results are shown in the bar chart. moderate weak Taste intensity felt / arbitrary units just detectable sweet detected Key: Stephen Taylor sour detected A Bandung International School B http://sciencevideos.wordpress.com Essential Biology 6.5 Nerves, Hormones, Homeostasis Student Name: (e) Due Date: Candidate Number: 002171- Compare the effects of sucrose on the A and B chemoreceptors by giving two similarities and two differences. Similarities Differences (4) (Total 10 marks) Stephen Taylor Bandung International School http://sciencevideos.wordpress.com Essential Biology 6.5 Nerves, Hormones, Homeostasis Student Name: Due Date: Candidate Number: 002171- Works Cited 1. Taylor, Stephen. Nerves, Hormones and Homeostasis (presentation). Science Video Resources. [Online] Wordpress, 2010. http://sciencevideos.wordpress.com/bis-ib-diploma-programme-biology/06human-health-physiology/nerves-hormones-homeostasis/. 2. Allott, Andrew. IB Study Guide: Biology for the IB Diploma. s.l. : Oxford University Press, 2007. 978-019-915143-1. 3. Mindorff, D and Allott, A. Biology Course Companion. Oxford : Oxford University Press, 2007. 978099151240. 4. Clegg, CJ. Biology for the IB Diploma. London : Hodder Murray, 2007. 978-0340926529. 5. Campbell N., Reece J., Taylor M., Simon. E. Biology Concepts and Connections. San Fransisco : Pearson Benjamin Cummings, 2006. 0-8053-7160-5. 6. Burrell, John. Click4Biology. [Online] 2010. http://click4biology.info/. 7. IBO. Biology Subject Guide. [Online] 2007. http://xmltwo.ibo.org/publications/migrated/productionapp2.ibo.org/publication/7/part/2/chapter/1.html. Stephen Taylor Bandung International School http://sciencevideos.wordpress.com