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AP Biology Chapter 48 Guided Reading Assignment

1. What is a nerve net?

2. Compare and contrast the central and peripheral nervous systems.

3. How does the organization of the nervous system of a _ compare with the organization of the nervous system of a ?

a. Hydra and insect

b. Hydra and flatworm

c. Leech and salamande

4. What are the functions of the following: a. Sensory neurons

b. Interneurons

c. Motor neurons

d. Effector cells - Muscle cells or endocrine cells that actually respond to the stimulus of motor neurons to perform the intended action.

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5. Use the diagram below to demonstrate the activity surrounding a reflex response.



6. Label the neuron below.



7. Why are glial cells important?

Glial cells are supporting cells that are essential for maintaining the structure of the nervous system and for the normal functioning of neurons.

8. What are astrocytes?

A glial cell that provides structural and metabolic support for neurons.



9. What is the blood brain #|barrier and why is it important?

A specialized capillary arrangement in the brain that restricts passage of most substances in the brain. It stops the dramatic changes in the brain’s environment.



10. Explain why myelin is important in nerve conduction?

It helps protect neurons and more importantly speeds up the signals sent across its neuron for better conduction and message relaying.



11. Define the following terms: a. Membrane potential- The charge difference between a cell’s cytoplasm and the extracellular fluid, due to the different distribution of ions.

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b. Resting potential- The membrane potential of a neuron that is not transmitting signals.

12. Discuss the three types of gated ion channels below: a. Stretch- Found in cells that sense stretch and open when the membrane is mechanically deformed.

b. Ligand- Found at synapses and open or close when a specific chemical, such as a neurotransmitter, binds to the channel.

(Top two ligand, bottom two voltage)

c. Voltage- Found in axons (and in the dendrites and cell body of some neurons, as well as in some other types of cells) and open or close when the membrane potential changes.

13. Define the following terms: a. Hyperpolarization- Stimuli triggered, an increased in the magnitude of the membrane potential (the inside of the membrane becomes more negative). May be caused by the opening of the K+ channels, which increases the membrane's permeability to K+ and causes the potential to approach Ek(-92 mV at 37C ) b. Depolarization- stimuli triggered, a reduction in the magnitude of the membrane potential (the inside of the membrane becomes less negative). Maybe due to the opening of gated Na+ channels, which increases the membrane’s permeability to Na+

c. Graded potential -the changes in membrane potential

d. Threshold -the potential an excitable cell membrane must reach for an action potential to be initiated

e. Action potential - a strong stimulus enough to produce a depolarization that reaches threshold

14. Use the diagram to describe the generation of an action potential. 1. Resting State- the activation gates on the Na+ and K+ channels are closed, and the membrane's resting potential is maintained. 2.Depolarization- A stimulus opens the activation gates on some Na+ channels. Na+ influx through through those channels depolarizes the membrane. If the depolarization reaches the threshold, it triggers an action potential. 3. Rising phase of the action potential- Depolarization opens the activation gates on most Na+ channels, while the K+ channels' activation gates remain closed. Na+ influx makes the inside of the membrane positive with respect to the outside. 4.Falling phase of the action potential- The inactivation gates on most Na+ channels close, blocking Na+ influx. The activation gates on most K+ channels open, permitting K+ efflux which again makes the inside of the cell negative. 5.Undershoot- Both gates of the Na+ channels are closed, but the activation gates on some K+ channels are still open. As these gates close on most K+ channels, and the inactivation gates open on Na+ channels, the membrane returns to its resting state.

15. How do the various factors affect the speed of an action potential? a. Larger axon- the wider an axon's diamete r, the faster the signal with pass through it

b. Myelination and salutatory conduction- Myelin increases the conduction speed of action potentials by insulating the axon membrane. Insulation has the same result as the axon's diameter increaing. Salutatory Conduction is when signals jump across the nodes of ranvier. When the action potential, passes down the myelinated axon, at the nodes of Ranvier the signal jumps across the nodes and this helps the signal to travel faster than if it were to travel down a non-myelinated axon.



16. Use the diagram below to describe the conduction of the action potential. 1. An action potential is generated as Na+ flows inward across the membrane at one location 2. The depolarization of the action potential spreads to the neighboring region of the membrane, re-initiating, the action potential there. to the left to this region, the membrane is repolarizing as K+ flows outward 3. The depolarization- repolarization process is repeated in he action potential to the next region of the membrane. In this way, local currents of ions across the plasma membrane causes the action potential to be propagated along the length of the axon.

17. What happens at the synaptic cleft?

18. Contrast excitatory and inhibitory postsynaptic potentials. **Excitatory brings membrane potential more towards the threshol****d.** **Inhibitory takes membrance potential farther from the threshold**

19. Contrast temporal and spatial summation. **Temporal is two EPSP's in rapid succession at a single synapse, second can #|begin before the first goes back to resting** **Spatial two EPSP's produced simoltanoues****ly by different synapses and add together.**

20. What happens when indirect __#|synaptic transmission__ takes place? A neurotransmitter binds to a receptor that is not part of an ion channel. this activates a signal transduction pathway involving a second messenger in the postsynaptic cell.



21. Discuss the neurotransmitters listed below: a. Acetylcholine- one of the most common neurotransmitters in both invertabrates and vertebrates. Binds to receptors and alters permeability of postsynaptic membrane. b. Biogenic amines -neurotransmitters derived from amino acids i. Epinephrine and norepinephrine- involved in fight or flight response. Functions as both hormone and neurotransmitter. Closely related to dopamine. ii. #|Dopamine- closely related to epinephrine and norepinephrine. Affects sleep, mood, attention, and learning. iii. Serotonin- synthesized from the amino acid tryptophan c. GABA- produces IPSPs by increasing permeabilityof the postsynaptic membrane to Cl-. Believed to be at most inhibitory synapses d. Endorphins- decreases pain perception. e. Nitrous oxide

22. What is the difference between gray matter and white matter?

23. Define the following terms: a. Central nervous system

b. Peripheral nervous system

c. Somatic nervous system
 * carries signals to and from skeletal muscles, mainly in response to external stimuli **

d. Autonomic nervous system
 * regulates the internal environment by controlling smooth and cardiac muscles and the organs or the digestive, cardiovascular, excretory and endocrine systems-generally involuntary **

24. Contrast the core functions of the parasympathetic and sympathetic nervous system. media type="youtube" key="J968Wco1u0s" height="315" width="420"
 * The sympathetic system causes arousal and energy generation while parasympathetic system causes calming and a return to self maintenance functions **

25. What are the three brain region during embryonic development?
 * Forebrain - The most anterior of the three primary regions of the embryonic brain **
 * Midbrain - The portion of the vertebrate brain that develops from the middle section of the embryonic brain **
 * Hindbrain - The lower or hind region of the adult brain comprising the pons and medulla oblongata **

26. What are the parts of the brainstem and what are its functions?
 * Medulla Oblongata (myelencephalon) - controls homeostatic functions (HR, breathing) **
 * Pons - regulates breathing centers of medulla oblongata **
 * Midbrain - centers for receipt and intergration of sensory info **

27. What is the reticular formation? Almost 90 clusters of neurons seated within the center of the brain. It regulates sensory information and determines how much of that information is sent to the cortex. It is able to regulate our sleep and arousel.

28. What are the core functions of the cerebellum The cerebellum is located behind the brain stem. It is responsible for our coordination and checks and balances within our motor, perceptual, and cognative functions. The cerbellum uses auditory and visual information from the cerebrum combined with the sensory information from muscle movement to coordinate a function such as riding a bike.

29. What are the parts of the diencephalons and what are its functions? The diencephalons consists of three structures: epithalamas, thalamas, hypothalamas. Epithalamas: Contains the pineal gland and choroid plexus which is responsible for creating cerebrospinal fluid. Thalamas: The "Information Super Highway," all input sensory information is sent here before continuing into the cerebrum, while all motory information is sent from the cerebrum through the thalamas. Hypothalamas: Main structure in brain that supports homeostatic regulation. It regulates the body's temperature, hunger, thirst, and sexual behaviors.



30. What are circadian rhythms? Circadian rhythms are the bodies natural cycle that runs on a 24 hour day. It goes along with our waking and sleeping and our daily cycles such as day and night.

31. Describe the cerebral hemispheres. They are the two regions of the brain-the left and right. Each side receives signals from the opposite side-left brain receives stimulus from the right side of the body and vice versa. The left hemisphere is usually the analytic side of the brain and the right is the more creative side.

32. What is the corpus callosum? =The corpus callosum is a broad band of nerve fibers joining the two hemispheres of the brain. It allows for messages and signals to travel from the left to the right brain and visa versa. =

33. What is the limbic system and what is its function? The limbic system  is a complex system of nerves and networks in the brain that controls the basic emotions and drives. It includes the amygdala, hippocampus and the olfactory bulb. The limbic system structures form early in development.

 The amygdala mostly takes part in fear and aggression. The hippocampus mostly takes part in memory.


 * Skim ahead to Ch 49 and try to answer these: **

34. Explain how the nervous system produces graded contractions of whole muscles.

35. Labeling the diagram below, explain how a muscle contraction is controlled.