Nervous System Study Guide

Nervous System Study Guide 1. Identify the main function of the nervous system. –To control the body’s activities by relaying messages 2. Identify the main divisions of the nervous system and list the body parts included in each division. a) central nervous system = brain and spinal cord b) peripheral nervous system = nerves 3. Label the main parts of the neuron (dendrites, cell body, nucleus, axon, axon tips). 4. List the function of each part of a neuron. a) dendrites—carry a nerve impulse to the cell body b) cell body—contains the nucleus c) nucleus—control center of the cell d) axon—carry a nerve impulse away from the cell body e) axon tips—release the nerve impulse 5. Describe how two neurons are always joined. (_______ end to ________ end). Neurons are always joined axon end to dendrite end. 6. Identify what a synapse is and how two joined neurons overcome a synapse. A synapse is the gap between two neurons. The nerve impulse travels as an electrical impulse through the neuron. However, the nerve impulse becomes a chemical impulse as it travels across the synapse. 7. What is membrane potential? Membrane potential is the electrical charge that exits on the membranes of every cell. 8. What creates this membrane potential? Membrane potential is created by different concentrations of ions on the inside and the outside of the cell. 9. Describe or draw the membrane potential of the cell membrane. Cell membranes are positive to the outside and negative to the inside 10. What ions are primarily involved in establishing membrane potential? Na+ and K+ 11. Explain how the cell maintains this membrane potential. There is a higher concentration of K+ inside the cell than outside. The membrane is “leaky” to K+ so these ions tend to move down the concentration gradient to the outside of the cell. There is a higher concentration of Na+ outside the cell, and Na+ does not readily diffuse through the membrane. The combination of these factors causes the cell to be negative to the inside and positive to the outside. 12. What is an “impulse”, and in what direction do impulses always travel across a neuron? The nerve impulse is simply the message that is being sent. A nerve impulse always travels from dendrite end to axon end across a neuron. 13. Before an action potential can occur, a “threshold” must be reached. What is the threshold? The threshold is the minimum level of a stimulus that is required to activate a neuron. A neuron follows the “all or none” principal. Either the stimulus will produce an impulse or it will not. 14. What is meant by the term “resting potential”? The “resting potential” is the condition of the neuron when the neuron is at rest, and not conducting a nerve impulse. 15. What causes the transmission of a nerve impulse? Transmission of an impulse is caused by rapid changes in membrane potential along the axon of the neuron. 16. Distinguish between a sensory, motor, and interneuron. a) sensory neurons—nerve cells that carry a nerve impulse to the central nervous system b) motor neurons—nerve cells that carry a nerve impulse away from the central nervous system and towards the muscle or gland that needs to respond c) interneurons—nerve cells found only in the brain and spinal cord 17. List the eight main parts of the brain and identify what each part controls. a) cerebrum—largest part of the brain; controls thinking, personality, the senses, memory b) cerebellum—part of the brain that controls balance and muscle coordination c) brain stem/medulla olongata—part of the brain that controls involuntary actions such as breathing and heart rate d) corpus callosum- a think band of nerves that connects the two hemispheres of the cerebrum e) thalamus- receives messages from all of the sensory receptors of the body and relays the information to the proper region of the brain f) hypothalamus- coordinates the nervous system with the endocrine system g) pituitary gland- secretes 9 hormones that directly regulate many body functions and controls the actions of several other endocrine glands h) pons18. Each hemisphere of the cerebrum is divided into what four lobes? Each lobe is the control center for what functions? Front lobe: intellectual function, speech, reasoning, and problem solving Parietal lobe: Motor function, body sensations, touch information Temporal lobe: Hearing, memory and speech Occipital lobe: Vision 19. What is the “white matter”? The whie matter is found below the wrinkled surface of the cerebral cortex. It is composed of the axons of cortical neurons. These axons link specific regions of the cortex with each other and with other neural centers. 20. What is the “gray matter”? The gray matter consists of densely packed nerve cell bodies. It process information from the sense organs and controls body movements. 21. A person falls backward, hitting the back of their head in the process. What part of the brain would be damaged and how might the person be impaired if damage is done to this part of the brain? The injury affects the cerebellum. It will result in movements that are slow and uncoordinated. The person may stagger and tend to fall. There may be some slurred speech and abnormal eye movements. 22. What is a reflex, and why does it occur quickly and automatically? A reflex is caused by a nerve impulse that bypasses the brain. Bypassing the brain allows the muscle or gland to respond quickly. 23. What is the limbic system? The limbic system includes the thalamus, the hypothalamus, and some deeper parts of the cerebral cortex. It plays a role in emotion, memory and motivation. 24. The neurons of the brain and spinal cord are surrounded by three protective layers. What name is given to these protective layers? The meninges 25. List and describe the three individual layers of protective membranes. Dura Mater: the outer layer consisting of connective tissue, blood vessels, and neurons. Arachnoid Layer: The middle layer. It is elastic and web-like. Pia Mater: The thin inner layer that adheres to the brain and spinal cord. It contains many blood vessels and neurons. 26. What is the cerebrospinal fluid and what are its functions? It is a clear fluid that provides a cushion to protect the brain and spinal cord from injury. It separates the middle and inner meninges, and acts as a transport medium for substances that are important to brain function. 27. How many pairs of spinal nerves branch out to the body from the spinal cord? 31 pairs 28. How many pairs of cranial nerves branch out of the cranium? 12 pairs 29. What role does the autonomic nervous system have? What role does the somatic nervous system have? autonomic nervous system—division of the peripheral nervous system that controls involuntary actions somatic nervous system—division of the peripheral nervous system that controls voluntary actions 30. The autonomic nervous system is subdivided into the sympathetic division and the parasympathetic division. Describe each: Sympathetic Nervous System: Speeds up the body processes, flight or flight reaction, prepares the body for intense, energy consuming activities Parasympathetic Nervous System: Slows the body processes, Primes the body for rest and conservation of energy 31. List the five sense organs and identify what “sense” they detect. a) eye—sight b) ear—hearing c) tongue—taste d) nose—smell e) skin—touch 32. Indicate what effect the sympathetic nervous system has on each numbered structure seen below: 33. Indicate what effect the parasympathetic nervous system has on each numbered structure seen below: