1. Chapter 48 Reading Quiz 1.Which part of the neuron receives messages? 2.Which part of the neuron sends messages? 3.What is the period called during which a neuron is insensitive to depolarization? 4.Which group of molecules message within the synapse? 5.How many hemispheres does the mammal brain have?

2. 1. List and describe the three functions of the nervous system. 1.Sensory input (sensory neurons) 2.Integration (interneurons) 3.Motor output (motor neurons)

4. 2. Identify: neuron, cell body, dendrites, axons, myelin sheath, Schwann cells, oligodendrocytes, synaptic terminals, and synapse. How do they relate? Neuron  structural and functional unit of the nervous system (nerve cell); made up of the cell body, dendrites, and axons. Myelin sheath  insulating layer surrounding many axons (made of oligodendrocytes in the CNS and Schwann cells in the PNS) Synaptic terminals  the specialized endings of axons that release neurotransmitters into the synapse (site of contact between that and the receiving cell)

6. 3. Distinguish among the three classes of neurons. Sensory neuron  receives information from a sensory receptor Interneuron  in the spinal cord; receive information from sensory neurons (helpful in reflexes) Motor neuron  also receives information from the sensory neuron and signals an effector cell to respond (muscle or gland typically)

9. 4. Define reflex, ganglion, and nuclei (in reference to the nervous system). Reflex  the simplest type of nerve circuit; automatic response Ganglion  a cluster of nerve cell bodies, often with similar function, located in the PNS; these are called nuclei in vertebrate brains

10. 5. Describe what supporting cells (glia) are used for. Supporting cells are essential for the structure and function of neurons Help to “glue” neurons together A type called “astrocytes” form tight junctions between cells lining the capillaries in the brain, leading to the blood-brain barrier 

11. 6. What is the purpose of the blood-brain barrier? This restricts the passage of most substances into the brain Allows the chemical environment of the CNS to be well controlled

12. 7. Describe what membrane potential is, and how this concept is important in the nervous system and it’s function. All cells have voltage across their plasma membranes (membrane potential) The signal transmission along the length of a neuron depends on voltages created by ionic fluxes across neuron plasma membranes - inside the cell: lots of K + - outside the cell: lots of Na + and Cl -

14. 8. In describing action potential, define resting potential, gated ion channels, hyperpolarization, depolarization, threshold potential, voltage-gated ion channels, and the refractory period. Action potential  the all-or-none change in the membrane potential (voltage) Resting potential  the membrane potential of an excitable cell in an unexcited state Gated ion channels  special ion channels that allow the cell to change its membrane potential in response to the stimuli it receives Hyperpolarization  an increase in the electrical gradient across the membrane (ex: opening a K + channel, causing outflow) Depolarization  a reduction in the electrical gradient across the membrane (ex: opening a sodium channel, causing inflow) 

16. #8 continued… Threshold potential  each excitable cell has a threshold to which depolarizing stimuli are graded (usually more positive than the resting potential) - if depolarization reaches the threshold, an action potential will be triggered Voltage-gated ion channels  these open and close in response to changes in membrane potential Refractory period  the period after the first action potential when the neuron is insensitive to a second depolarizing stimulus (limits action potential rate)

18. 9. How do action potentials travel? Describe saltatory conduction. Action potentials “travel” along an axon; it is regenerated at each position along the membrane Neuron is stimulated at the dendrites or cell body Saltatory conduction  the action potential “jumps” the gaps in the myelin sheath between successive cells - results in faster transmission of nerve impulses

21. 10. Where does chemical or electrical communication occur? Distinguish between the presynaptic and postsynaptic cells. Electrical  allows action potentials to spread directly from presynaptic to postsynaptic cell, which are connected by gap junctions ( no delay) Chemical  more common; the synaptic cleft between cells prevents action potential from spreading –The electrical signal is converted to chemical, it travels the space, and is converted back to electrical

23. 11. Describe the two types of synapses: electrical and chemical. Define synaptic cleft, synaptic vesicles, neurotransmitter, presynaptic membrane, and postsynaptic membrane. Electrical  allow action potentials to spread directly from pre- to postsynaptic cells via gap junctions (less common) Chemical  pre- and post- cells are not electrically coupled, use neurotransmitters to transmit nerve impulses in only one direction Synaptic cleft  the narrow gap that separates the presynaptic cell from the postsynaptic cell Synaptic vesicles  sacs in the cytoplasm at the tip of the presynaptic axon that contain molecules of neurotransmitters 

25. #11 continued… Neurotransmitter  a substance used as an intercellular messenger Presynaptic membrane  the surface of the synaptic terminal that faces the cleft (gap) Postsynaptic membrane  the plasma membrane of the cell body or dendrite on the other side of the synapse (receives the neurotransmitters)

27. 12. Define both EPSP and IPSP. EPSP  excitatory postsynaptic potentials - occur when excitatory synapses release a neurotransmitter that opens gated channels allowing Na + to enter the cell and K + to leave (depolarization) IPSP  inhibitory postsynaptic potentials - occur when neurotransmitters released from inhibitory synapses bind to receptors that open ion gates, which make the membrane more permeable to K + (leaves) and/or Cl - (enters) causing hyperpolarization

28. 13. What is summation? Describe the two types. It is the additive (cumulative) effect of postsynaptic potentials that can raise the membrane potential to threshold 1.Temporal summation  chemical transmissions occur so close together in time that the voltage doesn’t go to resting 2.Spatial summation  several different terminals stimulate a postsynaptic cell and have the additive effect

29. 14. Describe the various types of neurotransmitters, and why they can have different effects on different types of cells. The same neurotransmitter can produce different effects on different types of cells 1.Acetylcholine  may be excitatory or inhibitory depending on the receptor, functions in the vertebrate neuromuscular junction and the CNS 2.Biogenic amines  epinephrine, norepinephrine, dopamine, serotonin; function primarily in the CNS 3.Amino acids  glycine, glutamate, aspartate, and gamma aminobutyric acid; CNS 4.Neuropeptides  short chains of amino acids; mediate pain perception Elicit different responses by binding to a different receptor or initiating a different signal-transduction pathway

31. 15. Review what a nerve net is, what cephalization refers to, and what a nerve cord is. Nerve net  neurons controlling activities of the organism are arranged in a diffuse pattern (hydra) Cephalization  the clustering of sensory neurons and other nerve cells toward the anterior end of the organism in a brain Nerve cord  longitudinal down the animal’s body; work with the brain in a clearly defined CNS to control movement

33. 16. What is special about vertebrate nervous systems? Distinguish between gray and white matter. Vertebrate systems have distinct central and peripheral elements and a high degree of cephalization Gray matter  mostly dendrites, unmyelinated axons, and nuclei White matter  neurons whose axons are coated with myelin

35. 17. Describe the various components of the vertebrate PNS. Sensory division Sensing the: 1.external environment 2.Internal environment Motor division 1.Somatic NS  carries signals to skeletal muscles; usually considered voluntary 2.Autonomic NS  Parasymapthetic Sympathetic

37. 18. Distinguish between the parasympathetic division and the sympathetic division of the autonomic nervous system. Autonomic  controls primarily involuntary, automatic, visceral functions of smooth and cardiac muscles and organs of the gastrointestinal, excretory, cardiovascular, and endocrine systems 1.Parasympathetic  enhances activities that gain and conserve energy 2.Sympathetic  increases energy expenditures The two act antagonistically

39. 19. Outline the regions of the brain from embryo through adult. The brain develops from the anterior region of the neural tube  differentiates into the forebrain, midbrain, and hindbrain At 6 weeks, fetuses have developed five regions out of the three above 1.Brain stem  mesencephalon, metencephalon, and myelencephalon 2.Cerebellum  from part of the metencephalon 3.Thalamus & hypothalamus  diencephalon 4.Cerebrum  derived from telencephalon

41. 20. Describe the function of the three parts of the brainstem: the medulla oblongata, the pons, and the midbrain. 1.Medulla oblongata & pons  control visceral functions including breathing, heart and blood vessel activity, swallowing, vomiting, and digestion; also coordinate large-scale body movements such as walking 2.Midbrain  contains centers for the receipt and integration of several types of sensory information

43. 21. What does the cerebellum do? Functions in coordination Receives sensory information (both internal and external) to provide automatic coordination

44. 22. Describe the function of the thalamus. Main input center for sensory information going to the cerebrum & main output center for motor information leaving the cerebrum –Contains many different nuclei dedicated to specific senses

45. 23. Describe the function of the hypothalamus, and how it is involved in circadian rhythms. One of the most important brain regions for homeostasis Contains the body’s thermostat, centers for hunger, thirst, sexual and mating behaviors, the fight-or-flight response, and pleasure

48. 24. Describe why the cerebrum is the most sophisticated integrating center, and the various functions it controls. Two hemispheres –Left: controls right side of body; more adept at language, math, logic, processing sequences of information –Right: controls left side of body; more adept at pattern recognition, faces, spatial stuff, emotional processing Corpus callosum  thick band of fibers that communicates between left and right Specialized regions (that picture)

49. 25. Briefly outline how arousal, sleep, lateralization, language, speech, emotions, memory, learning, and consciousness are carried out by the brain. Arousal & sleep  controlled by centers in the cerebrum and brain stem, particularly the reticular formation (filter to what reaches cortex) Lateralization, language, & speech  each side controls different functions - left: speech, language, details, calculations - right: creativity, spatial perceptions - corpus callosum transfers info between halves Emotions  thalamus, hypothalamus, cerebral cortex, amygdala, hippocampus 

51. #25 continued… Memory & learning  short-term vs long-term - fact memory  conscious retrieval of data - skill memory  motor activities, repetition, conscious not needed for recall Memories are stored in certain association areas of the cortex Consciousness  still a mystery to science - may involve simultaneous cooperation of extensive areas of the cerebral cortex