Exam 3 Review Sheet Chapter 35 Animal Nervous Systems 1 What are the two types of cells that make up the nervous system o Brain Spinal Cord One or more main trunks of nerve cell and centralized Central Nervous System ganglia Peripheral Nervous System o Sensory Neurons Interneuron and Motor Neurons send to CNS 2 What are all the parts of a neuron What is the function of each 1 Sensory Neurons 2 Interneurons 3 Motor Neurons Which respond to physical features such as temperature light and touch or to chemical signals such as odor and taste Which process the information received by the sensory neurons and transmit it to different body regions Which are at the end of the pathway and produce a suitable response based on the information from the sensory and interneurons 3 Which direction does information flow in a neuron 4 What are the functions of glial cells Information flows in one direction Action potential propagate only in one direction normally from the cell body at the axon hillock to the axon terminal A neuron cannot fire a second action potential during the refractory period when the inner membrane voltage falls below and then returns to resting potential The action potential is propagated along the axon in only a single direction because the refractory period prevents the membrane from reaching its threshold too quickly after an action potential and firing an action potential in the reverse direction Do not transmit electrical signals Support the neurons Surround the neurons and provide them with nutrition physical support Astrocytes o Blood brain barrier Myelin o Provides electrical insulation to vertebrate neurons o Schwann Cells motor and sensory neurons and oligodendrocytes brain and the spinal cord o Increase the speed of action potential transmission 5 What are the two types of proteins that help ions move across membranes How does each of them work 1 Receptors 2 Inside the cell 6 Which ions are at a higher concentration outside the cell when a neuron is at rest Sodium ions are at a higher concentration outside the cell when a neuron is at rest Potassium ions are at a higher concentration inside the cell when a neuron is at rest 7 Explain how the resting potential is established Which ion is involved Microelectrode is inserted into the axon A reference electrode is placed outside of the cell in contact with the solution bathing the axon Sodium ion is involved Na 8 Explain how an action potential is generated beginning to end all details It reaches a threshold and an action potential is generated by the opening of Na channels causing depolarization Hyperpolarization then happens in response to the closing of Na channels and the opening of Cl and K 9 What is a synapse How is information communicated across one A Synapse is a communication between neurons o 1 Action potential is generated o 2 Depolarization opens Ca2 channels o 3 The Ca2 triggers the opening of the vesicles which hold acetylcholine or neurotransmitters it releases the neurotransmitters to the post synaptic cleft o 4 Neurotransmitters bind with receptors on the postsynaptic cell causing a change in membrane potential o 5 After inactivation neurotransmitter molecules are re absorbed into the presynaptic terminal and stored in the vesicles until the next action potential arrives 10 Explain summation of information within a neuron No Summation o Multiple EPSP s widely spaced in time do not set off an action potential Temporal Summation Spatial Summation Cancellation o Multiple EPSP s arrive quickly at a single synapse and set off an action potential o Single EPSP s at two or more different synapses set off an action potential o An EPSP and IPSP may cancel each other so no action potential is set off Chapter 36 Animal Sensory Systems 1 What are sensory cells Sensory receptors that detect environmental stimuli embedded in specialized membranes of sensory neurons Animal sensory receptors detect physical and chemical stimuli by changes in membrane potential Sensory neurons include chemoreceptors mechanoreceptors thermoreceptors pain receptors electromagnetic receptors photoreceptors Action potential firing rate correlates with the strength of a stimulus Generally strong stimuli induce high firing rates and weak stimuli induce low firing rates Animal sensory receptors increase their sensitivity to stimuli by temporal and spatial summation enhance their acuity by lateral inhibition and adapt to continuous stimuli 2 How do sensory cells adapt 3 How do we smell things Sensory cells adapted if the stimulus continues over a longer time period sensory receptors typically reduce their firing rate through process called adaption Olfaction The odor molecules are captured by nasal mucus and sensed by long thin hair like extensions which project into the mucus They are chemoreceptors Odor molecules then bind to a receptor cell When bound molecules produce excitatory post synaptic potentials EPSP s If summation is high enough an action potential is fired which sends signals to the brain for processing How do we taste things Gustation Taste Buds Papillae It goes from the microvilli to the sensory neuron the action potential is fired in the axon Receptors bind to specific chemical compounds that give the food its taste Sensory cells synapse on interneurons to the brain Humans have 5 categories of taste buds Sour sweet bitter salty and savory or umami protein flavor 4 How do hair cells respond to stimuli Mechanoreceptors Sense movement and vibrations Sterocillia Sense motion and gravity Basis for the sense of hearing What is a statocyst o Movement causes depolarization of the hair cell s membrane Are made up of an internal chamber lined by hair cells with stereocilia that project into the chamber They are gravity sensing organs What is the vestibular system in humans 2 statocyst chambers and 3 semicircular canals The 2 statocyt chambers o Info about gravity and sense of direction of movement 3 Semicirculatory canals o Sense angular motions of the head 5 How are hair cells involved in our sense of hearing The hair cells located within the semicircular canal sense angular motions proving a sense of balance 1 No sounds vibrations are present The basilar membrane is immobile 2 Sound vibrations push the basilar membrane upward The hair cell stereocilia bend against the tectorial membrane setting off an action potential 3 The downward motion of the basilar motion of the basilar membrane relative to the tectorial membrane bends
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