Ch+48+Collaboration+period+2

** Collaboration Teams ** - Members share responsibility for posting refined answers to the guided readings - succinct, relevant, clear, and with pictures or a ** video ** to compliment. When contributing to the reading guide, follow these steps: 1) First complete the reading guide on your own from the Nervous System unit page.   2) Write your response to a question in word and then copy it. Be sure to upload pictures and/or video for each question. 3) Click on the edit button and then go to the appropriate question and paste your answer below it.  Sign your contribution with your first name and last initial and TEAM COLOR  4)  Scroll to the very bottom and in the Optional comment box, place a summary of what you did and sign it (e.g. "I answered chp 26 question 3" - Tom S.) Th en click Save.


 * Collaboration Teams ** - Members share responsibility for posting refined answers to the guided readings - succinct, relevant, clear, and with pictures or a video to compliment.
 * **Blue ** 1-5 || **Purple ** 6-10 || **Green ** 11-15 || **Pink ** 16-20 || **Yellow ** 21-25 || **Orange 26-30 ** || **Red ** 31-35 ||

AP Biology Chapter 48 Guided Reading Assignment

1. What is a nerve net? A nerve net is a weblike system of neurons, characteristic of radically symmetrical animals, such as hydra. In simplistic terms, it is a system of arranged neurons that control the contraction and expanisoni of gastrovascular cavity.

2. Compare and contrast the central and peripheral nervous systems. The peripheral nervous system is the sensory and motor neurons that connect to the central nervous system. It sends messages to the peripheral nervous system. The is the brain and longitudinal spinal cords in vertebrate animals. Ganglia are neurons that regulate behavior in the CNS.

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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 The hydra nervous system consists of only a nerve net. The insect nervoys system has a brain, a ventral nerve cord, and a segmental ganglia.

b. Hydra and flatworm The hydra nervous system consists of only a nerve net. The flatworm's nervous system has an eyespot, a brain, a nerve cord, and a transverse nerve.

c. Leech and salamander The nervous system of the leech has a brain, a ventral nerve cord, and a segmental ganglion. The nervous system of the salamander has a brain, a spinal cord (dorsal nerve cord), and a sensory ganglion.

4. What are the functions of the following: a. Sensory neurons They transmit information from sensors that detect external stimuli and internal conditions. They send information to interneurons (see below). media type="youtube" key="KdD2-0tGjAc" height="344" width="425"

b. Interneurons The interneurons integrate and analyze the information input by the sensory neurons. They form synapses with sensory and motor neurons. c. Motor neurons The motor nuerons communicate with the effector cells. This is also where the motor output leaves the CNS via this area. They transmit signals from the brain or spinal cord to muscles or glands. media type="youtube" key="r5nMVAjz0d0" height="385" width="480" d. Effector cells The effector cells are muscle cells or endocrine cells. They communicate with the motor neurons. They perform the body's responses to simuli and respond to signals from the brain or other processing center of the nervous system.

5. Use the diagram below to demonstrate the activity surrounding a reflex response. <span style="color: #0869d9; font-family: 'Trebuchet MS',Helvetica,sans-serif; font-size: 130%;">

6. Label the neuron below - be prepared to label this on a quiz the day that this is due.

7. Why are glial cells important? **Glial cells are important for the structural integrity of the nervous system. Astrocytes provide nutrients, support, and insulation for neurons of the central** ** nervous system. Radial glia are a pivotal cell type in the developing central nervous system involved in key developmental processes. Oligodendroctes are a type of support cell in the brain that produces myelin, the fatty sheath that surrounds and insulates axons.** ** Schwann cells are nerve cells in the peripheral nervous system that wrap around nerve fibers with myelin. **

8. What are astrocytes?
 * Astocytes are glial cells that provide nutrients, support, and insulation for neurons of the central nervous system. **

9. What is the blood brain barrier and why is it important? <span style="color: #1b9d06; font-family: Arial,Helvetica,sans-serif; font-size: 120%;">A specialized capillary arrangement in the brain that restricts the passage of most substances into the CNS (central nervous system) allowing the extracellular chemical environment of the CNS to be tightly controlled.

10. Explain why myelin is important in nerve conduction? As a signal moves down the axon each channel only opens after the one before it does. Myelin sets up local circuits, which means the spaces between the channels are further apart. This allows a signal to jump between them faster.

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11. Define the following terms: a. Membrane potential- Electrical potential difference voltage across their plasma membrane. b. Resting potential- membrane potential of the neuron that is not transmitting signals

<span style="color: #219000; font-family: Arial,Helvetica,sans-serif; font-size: 16pt;">12. Discuss the three types of gated ion channels below: a. Stretch- found in cells taht sense stretch and open when membranes are mechanically deformed. b. Voltage- found in axons and open or close when the membrane potential energies. c. Ligand- found at synapses and open or close when a specific chemical binds to the channel. media type="youtube" key="Du-BwT0Ul2M" height="345" width="584"

13. Define the following terms: a. Hyperpolarization Electrical state in which the inside of the cell is more negative relative to the outside than at the resting membrane potential b. Depolarization Electrical state in an excitable cell wher by the inside of the cell is made less negative relative to the outside that at the resting membrane potential c. Graded potentials A local voltage change in a neuron membrane inuced by stimulation of a neuron with the strength proportional to the strength of the stimulus and lasting about a milisecond. d. Threshold The potential an excitable cell memebrane must reach for an action potential to be initiated e. Action potential Rapid change in the membrane potential of an excitable cell caused by stimulus triggered selective opening and closing of voltage sensitive gates in sodium potassium channels

14. Use the diagram to describe the generation of an action potential.


 * 1) Resting state- The activaion gates on the Na+ and K+ 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 those channels depolarizes the membrane
 * 3) Rising phase of the action potential-Depolarization opens the activation gates on most Na+ channels while K+ channels activation remains closed. Na+ influx makes the inside of the membrane positive with respect to the outside
 * 4) Falling phase of the action potential- The inactivation 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 reurns to its resting rate

15. How do the various factors affect the speed of an action potential? a. Larger axon The larger the axon's diameter, the faster the conduction. This is because resistance to the flow of electrical current is increasingly proportional to the cross-sectional area of a conductor

b. Myelination and salutatory conduction Myelin increases the conduction speed of action potential by insulating the axon membrane, Insulation has the same effect as increaing the axon's diameter

16. Use the diagram below to describe the conduction of the action potential.


 * 1) 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 if the membrane re-initiating the action potential there
 * 3) The depolarization-repolarization process is repeated in the next region of the membrane. In this way, local currents of ions cross the plasma membrane cause the action potential to be propagated along the length of the axon

17. What happens at the synaptic cleft? The neurotransmitter diffuses across the synaptic cleft, a narrow gap that separates the presynaptic neuron from the postsynaptic cell. The effect of the neurotransmitter on the postsynaptic cell may be either direct or indirect. Information transfer is much more modifiable at chemical synapses than at electrical synapses. ​

18. Contrast excitatory and inhibitory postsynaptic potentials. Excitatory Postsynaptic Potentials (EPSPs): An electrical charge (depolarization) in the membrane of a postsynaptic neuron caused by the binding of an excitatroy neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more likely for a postsynaptic neuron to generate an action potential.

Inhibitory Postsynaptic Potentials (IPSPs): An electrical charge (hyperpolarization) in the membrane of a postsynaptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more difficult for a postsynaptic neuron to generate an action potential.

19. Contrast temporal and spatial summation. Temporal Summination: A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is determined by the combined effect of EPSPs or IPSPs produced in rapid succession.

Spatial Summination: A phenomenon of neural integration in which the membrane potential of the postsynaptic cell is determined by the combined effect of EPSPs IPSPs produced nearly simultaneously by different synapses.

20. What happens when indirect synaptic transmission takes place? In indirect synaptic transmission, a neurotransmitter binds to a receptor that is not part of an ion channel. This activated a signal transduction pathway involving a second messenger in the postsynaptic cell. Compared to the postsynaptic potentials produced by direct synaptic transmission, the effects of indirect synaptic transmission have a slower onset but last longer (up to several minutes).

<span style="background-color: #ffff00; color: #007dff; font-family: Tahoma,Geneva,sans-serif; font-size: 90%;"> 21. Discuss the neurotransmitters listed below: a. Acetylcholine ACh is commonly secreted at neuromuscular junctions, the gaps between motor neurons and muscle cells, where it stimulates the muscle(s) to contract. At other junctions it produces an inhibitary post synaptic potential.

b. Biogenic amines i. Epinephrine and norepinephrine

ii. Dopamine

iii. Serotonin

c. GABA <span style="background-color: #ffff00; color: #53afee; font-family: Georgia,serif;">An inhibitory neurotransmitter amoung neurons in the brain. d. Endorphins Secreted by the hypothalamus/pituitary, causes a good mood e. Nitrous oxide An anesthetic, ex: "Laughing Gas"

22. What is the difference between gray matter and white matter? Gray- Cell bodies of nerve cells Whie- Filaments that extend from the cell bodies

23. Define the following terms: a. Central nervous system (CNS) Includes the brain and spinal cord. b. Peripheral nervous system (PNS) Includes sensory neurons that transit to the CNS c. Somatic nervous system Directs the contraction of skeletal muschles d. Autonomic nervous system Controls organs and involuntary muscles (such as the heart)

24. Contrast the core functions of the parasympathetic and sympathetic nervous system. Sympathetic nervous system- The stimulation of activities that prepare the body for action, by increasing heart rate as well as the release of sugar. This is also known as the fight or flight responce.

Parasympathetic- This activates tranquil functions, such as stimulating the secretion of salvia/digestive enzymes into the stomach.

25. What are the three brain region during embryonic development? The forebrain, the midbrain, and the hindbrain.

26. What are the parts of the brainstem and what are its functions? Medulla oblongata: Centers that control several visceral (automatic) functions (breathing, heart, vomiting, swallowing) Pons: Some of the functions of the medulla oblongata, like breathing. Midbrain: Centers for receipt and integration of types of sensory information. Inferiot/Superior Colliculi: auditory and visual systems respectively

27. What is the reticular formation? A diffused network of neurons.

28. What are the core functions of the cerebellum Coordination and error checking during motor, perceptual, and cognitive functions. Remembering/learning motor skills, hand-eye control.

29. What are the parts of the diencephalons and what are its functions? Epithalamus: pineal gland and capillaries that produce cerebrospinal fluid from blood. Thalmus: main input for sensory into going to cerebellum and output info from cerebellum Hypothalmus: Homeostatic regulation, body's thermostat, centers of hunger, thirst, sexual and mating behaviors, "fight or flight", and pleasure.

30. What are circadian rhythms? Daily rhythms; like sleep/wake cycle. Biological clock.

31. Describe the cerebral hemispheres. The cerebrum is divided into the right and left hemispheres. Each hemisphere consists of an outer covering of gray matter, the cerebal cortext, internal white matter, and groups of neurons collectively located deep within the white matter.



32. What is the corpus callosum? It is a thick band of axons that enables communication between the right and left cerebral cortices.



33. What is the limbic system and what is its function? It is a ring of structures around the brainstem. It includes 3 parts: amygdala, hippocampus, and olfactory bulb. The function of the limbic system is to control emotions and behaviors.


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

34. Explain how the nervous system produces graded contractions of whole muscles. In 2 basic ways, by varying the number of muscle fibers that contract and by varying the rate at which muscle fibers are stimulated.

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