Lab 14 Introduction to Nervous System Hamilton ANSWERS TO PRE- LAB ASSIGNMENTS Pre-Lab Activity 1: 1. a. orbicularis oculi b. sternocleidomastoid c. deltoid d. pectoralis major e. biceps brachii f. rectus abdominis g. flexor carpi radialis h. rectus femoris i. tibialis anterior j. epicranius occipital belly k. trapezius l. infraspinatus m. triceps brachii n. latissimus dorsi o. extensor digitorum p. gluteus maximus q. biceps femoris r. gastrocnemius Pre-Lab Activity 2: 1. a. 2 b. 7 c. 1 d. 8 e. 9 f. 4 g. 6 h. 10 i. 3 j. 5 Pre-Lab Activity 3: 1. a. 6 b. 4 c. 7 d. 8 e. 5 f. 9 g. 3 h. 2 i. 1
Pre-Lab Activity 4: 1. c 2. triceps brachii posterior arm; extends forearm; biceps brachii anterior arm; flexes forearm 3. a. A Flexes wrist b. P Extends wrist c. P Extends digits d. A Flexes wrist e. A Pronates forearm Pre-Lab Activity 5: 1. a. A Extends b. P Flexes c. A Extends d. P Flexes e. A Extends 2. a. 4 b. 6 c. 1 d. 3 e. 2 f. 5
ANSWERS TO ACTIVITY QUESTIONS Activity 1 11. Trial Distance Meter Stick Dropped (in cm) Visual Stimulus Auditory Stimulus Tactile Stimulus 1 Student data Student data Student data 2 Student data Student data Student data 3 Student data Student data Student data 4 Student data Student data Student data 5 Student data Student data Student data Average distance dropped (cm) Student data Student data Student data Reaction time Student data Student data Student data 12. student data 13. a. The thalamus is the largest component of the diencephalon and it serves as a sensory relay station for all sensory impulses except smell. b. The visual association area is located in the occipital lobe of the cerebrum and it functions to interpret visual input. c. The precentral gyrus is located in the frontal lobe and it controls skeletal muscle activity. Activity 2 A. Components of the Motor Neuron Feature Function Connections to Things I Have Already Learned Cell body (soma) Contains nucleus; biosynthetic center Clusters of cell bodies in the CNS = nuclei; clusters of cell bodies in the PNS = ganglia Nissl bodies Synthesize proteins Specialized RER Neurofibrils Dendrites Components of the cytoskeleton that help to support the cell; function in intracellular transport Short, branched projections from the cell body that typically transmit electrical messages to- Form railroad tracks that transport materials within cell; for example, synaptic vesicles filled with neurotransmitter are transported from the cell body to the axon terminal via neurofibrils Dendros = tree
Axon Axon hillock Axolemma Telodendria Axon terminals Myelin sheath Nodes of Ranvier ward the cell body Transmits electrical messages away from the cell body Cone-shaped region of the cell body from which the axon arises Plasma membrane surrounding the axon of the cell Terminal branches of axons Bulbous endings of axon terminals containing neurotransmitter-filled synaptic vesicles White, fatty substance surrounding some axons Gaps in the myelin sheaths surrounding an axon Also referred to as a nerve fiber Hillock = small elevation Sarcolemma = plasma membrane surrounding a skeletal muscle fiber Telos = end Also called synaptic knobs Myelin is produced by Schwann cells in the PNS and by oligodendrocytes in the CNS. Also called myelin sheath gaps; allow for saltatory conduction B. Demonstrating the Effect of the Myelin Sheath 6. Student prediction 7. Trial Which Axon Is Faster (Axon 1 or Axon 2)? 1 Student data 2 Student data 3 Student data 4 Student data 8. a. axon 2 because there are fewer people and therefore less space on the axon through which the impulse must travel b. transmission of an electrical impulse c. saltatory conduction Activity 3 1. a. calcium channel b. synaptic vesicle c. neurotransmitters d. axon terminal e. synaptic cleft
f. neurotransmitter receptor g. postsynaptic neuron h. ions 1 action potential reaches axon terminal 2 action potential triggers influx of calcium ions, which triggers neurotransmitter release 3 neurotransmitter diffuses across synapse and binds to receptor on postsysynaptic membrane 4 ions enter the postsynaptic neuron causing a graded potential 2. a. arrival of action potential at axon terminal b. fusion of synaptic vesicle with presynaptic membrane and neurotransmitter release c. it is degraded or removed from the synapse d. chloride rushes in, causing IPSP e. potassium rushes out, causing IPSP f. sodium rushes in, causing EPSP g. when threshold is met h. 1. It could stimulate the release of an excitatory NT from the axon terminal. 2. It could mimic an excitatory NT. i. 1. It could stimulate the release of an inhibitory NT from the axon terminal. 2. It could mimic an inhibitory NT. Activity 4 1. dendrites carry electrical impulses toward the cell body and axons carry electrical impulses away from the cell body they insulate, help nourish, protect, and anchor neurons to capillaries multipolar it has many dendrites and a single axon 2. they protect and electrically insulate neurons 3. allows impulse to jump along the length of the axon oligodendrocyte ANSWERS TO POST- LAB ASSIGNMENTS PART I. Check Your Understanding Activity 1: Calculating Reaction Time 1. Based on the neural pathway involved in the reaction time experiment, match each of the following structures with its function. 3 a. sensory neuron 5 b. effector 4 c. thalamus 6 d. motor neuron 1 e. visual association area 2 f. primary motor area 1. interprets meaning of stimulus 2. initiates efferent message to the muscle 3. transmits information from the receptor to the brain
4. relays sensory information to the association area 5. carries out the motor response 6. transmits electrical impulse to the muscle 2. Based on your data, which stimulus type led to the fastest reaction time? Provide a possible explanation for this result. student data and explanation Activity 2: Investigating the Motor Neuron 1. Name two factors that increase the speed of nerve impulse conduction.presence of myelin; diameter of axon 2. Match each of the following neuron structures with its correct description. 1 a. neurofibrils 4 b. Nissl bodies 5 c. telodendria 3 d. axon terminals 2 e. nodes of Ranvier 1. cytoskeletal elements 2. gaps between Schwann cells 3. contain synaptic vesicles 4. produce neurotransmitters 5. terminal branches of axon Activity 3: Investigating the Chemical Synapse 1. Which neuron structure stores neurotransmitters? a. neurofibrils b. synaptic vesicles c. axon hillock d. Nissl bodies e. telodendria 2. Put the following events that lead to the generation of an action potential in the postsynaptic neuron in the proper order in which they occur by assigning each a number from 1 (first event) to 6 (last event): 4 a. The neurotransmitter binds to a receptor. 5 b. Sodium enters the postsynaptic neuron, generating an EPSP. 1 c. An action potential reaches the axon terminal. 6 d. When the EPSP reaches threshold, an action potential fires. 2 e. An influx of calcium triggers the release of neurotransmitter. 3 f. The neurotransmitter diffuses across the synapse. 3. Drug X exerts a stimulatory effect at a synapse. Briefly describe two ways in which drug X might exert its stimulatory effect. It might directly open Na + channels. It might stimulate release of excitatory neurotransmitters. 4. Drug Y exerts an inhibitory effect at a synapse. Briefly describe two ways in which drug Y might exert its inhibitory effect. It might directly open K + or Cl channels. It might stimulate release of inhibitory neurotransmitters.
Activity 4: Exploring the Histology of Nervous Tissue 1. Identify each structure in this neuron smear. a. nucleolus b. nucleus c. neuroglial cell nucleus d. dendrites e. cell body f. axon 2. Identify the components of nerve shown in the photomicrograph (cross section). a. myelin b. axon c. perineurium d. endoneurium e. epineurium
3. Identify the components of nerve shown in the photomicrograph (longitudinal section). a. Schwann cell nucleus b. node of Ranvier
PART II. Putting It All Together A. Review Questions Answer the following questions using your lecture notes, your textbook, and your lab notes. 1. Which of the following structures is a component of the peripheral nervous system? a. brain b. spinal cord c. cranial nerves d. spinal nerves e. More than one of these answers is correct. 2. Which of the following cell types produces myelin? a. oligodendrocyte b. astrocyte c. ependymal cell d. schwann cell e. More than one of these answers is correct. 3. The nervous system is divided into the CNS and the PNS. The PNS is divided into the sensory and the motor divisions. The motor division is further divided into somatic and autonomic portions. The autonomic nervous system innervates cardiac muscle, smooth muscle, and glands, whereas the somatic nervous system innervates skeletal muscle.
4. Is a nerve an organ or a tissue? Explain. organ; it contains several tissue types 5. List the three categories of neurons based on structure. multipolor, bipolar, unipolar 6. List the three categories of neurons based on function. sensory, motor, interneuron 7. Multiple sclerosis is an autoimmune disease that affects the brain and spinal cord. It causes damage to the myelin surrounding nerve fibers as well as to the nerve fibers themselves. The damaged myelin forms scar tissue (a process called sclerosis), which gives the disease its name. How does this disease affect nerve impulse conduction? Why? It slows it down because the scar tissue interfers with nerve impulse conduction. 8. Does each description apply to an astrocyte (A) or to a satellite cell (S) or to both cell types (A and S)? A + S a. Maintains proper ionic environment A b. Anchors capillaries to neurons A c. Found in central nervous system 9. Does each description apply to a hormone (H) or to a neurotransmitter (N) or to both a hormone and a neurotransmitter (H and N)? H + N a. Function as chemical messengers H b. Released into the bloodstream H c. Produced by endocrine glands 10. Does each description apply to a bipolar neuron (B) or to a unipolar neuron (U) or to both neuron types (B and U)? U a. Classified as a sensory neuron B b. Consists of one dendrite and one axon B c. Found in the retina and olfactory mucosa 11. Does each description apply to a graded potential (G) or to an action potential (A) or to both potential types (G and A)? G + A a. Classified as an electrical event G b. Can vary in intensity A c. Classified as an all-or-none event
B. Concept Mapping 1. Fill in the blanks to complete this concept map outlining the organization of the nervous system. axon cerebrum nerve neuron Schwann cell 2. Construct a unit concept map to show the relationships among the following set of terms. Include all of the terms in your diagram. Your instructor may choose to assign additional terms. action potential arbor vitae axon brainstem cerebrum diencephalon epineurium gray matter lateral horn nerve nerve fiber neuron node of Ranvier Schwann cell synaptic cleft Answers will vary.