Study Guide Questions 1-15

Question 1

1.) Describe the structure and functions of the glia cells and neurons. (pp. 86-87)

Answer 1

Glia Cells: Much smaller and about 10x as many as neurons. Make up about 50% of the brain’s total volume. Neurons: Structures: Axon: Part of a neuron designed to send information. Insulated with myelin sheaths made of gial cells. Soma: The cell body of a neuron. It includes the normal structures of a cell such as the nucleus and the mitochondria. Dendrites:Part of the neuron designed to receive information. Terminal Buttons: Terminal buttons are the structures that secrete neurotransmitters at the synapse of a neuron. Synaptic cleft - the microscopic gap between the terminal button of the pre-synaptic neuron and the cell membrane of the post-synaptic neuron.

Question 2

1. What is a neural impulse?
2. Describe what happens when a neuron is stimulated.
3. Describe how sodium and potassium ions contribute to the neural impulse. (pp. 88-89)

Answer 2

1. Neural Impulse:
   
   1. The firing of an action potential that releases neurotransmitters from terminal buttons on axons. (the signal the moves through a neuron.)
2. What happens when a neuron is stimulated?:
   
   1. channels in its cell membrane open.
   2. Positively charged ions flood into the cell.
   3. The near instantaneous change in voltage is the firing of an action potential 89.
3. How do sodium and potassium ions contribute to the neural impulse?:
   
   1. ​Sodium and potassium are the positively charged ions that rush in through the channels of the cell membrane when the neuron is stimulated to create an action potential.

Question 3

1. Describe the “battery-like” features of a neuron at rest.
2. Define the resting potential of a neuron.
3. How many millivolts is the resting potential in most neurons? (p. 88)

Answer 3

1. Battery-like features of a neuron at rest: Because negatively charged chloride ions and positively charged potassium and sodium flow across the cell membrane of a neuron at different rates, a neuron at rest has a negetive charge of about -70millivolts. This default negetive charge is a store of energy similar to a battery.
2. Resting potential of a neuron: the stable, negative charge when a cell ins inactive.
3. millivolts of the resting potential in most neurons: -70millivolts

Question 4

Define the action potential of a neuron. (p. 88)

Answer 4

Action Potential 88 – a very brief shift in electrical charge that travels along the axon of a neuron.

Question 5

What is the absolute refractory period?

Answer 5

Absolute refractory period – is the minimum amount of time after a neuron fires an action potential before it can fire another one.

Question 6

1. Describe the all-or-none law of the neural impulse.
2. Explain how neurons convey information about the strength or intensity of a stimulus. (p. 89)

Answer 6

1. The all-or-none law of the neural impulse refers to the binary nature of action potentials. A neuron is either firing an action potential or it is not.
2. Neurons convey information about the strength or intensity of a stimulus with PSP or post-synaptic-potentials. PSPs are the voltage changes at the receptor site of a postsynaptic cell membrane that can either increase decrease or have neutral effect on the likelihood of a neuron to fire action potentials. The stronger or more intense the stimulus the more likely the cell is to fire action potentials.

Question 7

1. What is a synapse?
2. Explain how neural impulses travel at the synapses. (pp. 89-90)

Answer 7

1. Synapse: is the junction at which information from the presynaptic neuron is passed to the postsynaptic neuron.
2. Neural Impulses travel at the synapse by: The postive voltage shift travels along the axon of a neuron like a wire. the “wire” is insulated with a myelin sheath - a fatty substance made up of glial cells.

Question 8

1. describe a synaptic cleft.
2. Define presynaptic neuron and postsynaptic neuron. (p. 89)

Answer 8

Synaptic Celft – the microscopic gap between the terminal button of the presynaptic neuron and the cell membrane of the postsynaptic neuron. Define presynaptic neuron and postsynaptic neuron:

Presynaptic neuron: the neuron that is firing the action potential that secretes the neurotransmitters from the terminal buttons on a axon across the synaptic cleft into the receptor sites on the cell membrane of the dendrite of the

postsynaptic cell – the cell that is receiving the information.

Question 9

1. Define neurotransmitter
2. synaptic vesicle.

Answer 9

1. Neurotransmitter 89 – chemicals that transmit information from one neuron to another.
2. 6 Nuerotransmitters discussed in the testbook:
   
   1. Acetylcholine
   2. Dopamine
   3. Norepranepherine
   4. Serotonin
   5. GABA
   6. Endorphins
3. Synaptic Vesicle 89 – sacs that contain neurotransmitters found within terminal buttons. When a neuron fires an action potential, synaptic vessicles fuse with the membrane of the terminal button and realease the neurotransmitters to difuse across the syanptic cleft.

Question 10

1. What are the postsynaptic potentials?
2. Do they follow the all-or-none law?
3. Explain. (p. 90)

Answer 10

1. Postsynaptic potentials (PSP) – when a neurotransmitter and a receptor molecule combine, the reaction creates a voltage shift known as a postsynaptic potential. These PSPs can either have and excitory nature: a PSP that increases the liklihood for the postsynaptic neuron to fire action potentials, or an inhibitory nature: a PSP that has either decereases or has a neutral effect on whether or not the postsynaptic neuron fires action potentials.
2. Do PSPs follow the all-or-none law? PSPs do not follow the all or none law as PSPs are graded.
3. Explain: Some PSPs have a greater influence on the liklihood of a postsynaptic neuron to fire action potentials than others.

Question 11

1. What are excitatory and inhibitory postsynaptic potentials?
2. Describe the process of re-uptake that occurs at the synapses. (p. 90)

Answer 11

1. Excitory PSP – a positive voltage shift that increases the liklihood that a postsynaptic neuron will nfire action potentials.g
2. Inhibitory PSP – a negative or neutral voltage shift that decreases the liklihood that a popstsynaptic neuron will fire action potentials.
3. Describe the process of reuptake that occurs at the synapses – nuerotransmitters that do not bind witha receptor site molecule and do not drift away are metabolized by enzimes and converted into inactive forms. These inactive neurotansmitters are reabsorbed by the presynaptic neuron.v

Question 12

1. describe the process in which the neuron integrates signals that arrive at the synapses.
2. Explain the sense in which our activities are due to patterns of neural activity. (pp. 90-91)

Answer 12

1. The process in which the neuron integrates signals that arrive at the syanpses: A neuron integrates signals that arrive at the synapses through the balance of excitory and inhibitory PSPs.
2. Our activities are due to patterns of neural activity in the sense that: Millions of neurons must organize and fire accurately in order to perform even basic funtions. When a neuron is repeatedly stimulated by another cell, the efficiency between the two neuron’s is increased. (Hebb. 1949, p. 62)

Question 13

1. Describe the process by which neural networks are formed.
2. What is synaptic pruning? (pp. 90-92)

Answer 13

1. Neural networks are formed by the process of: Creating a large amount of neural networks and the then eliminating unnecessary networks through the process of Synaptic Pruning.

Question 14

1. How many neurotransmitters are there?
2. Explain how neurotransmitters function and how they bind to receptor sites. (p. 92)

Answer 14

1. How many neurotransmitters are there?
   
   1. ​There are 9 classic, well-established (small molecule) transmitters.
   2. ~40 neuropeptide chemicals that function, atleast part time, as neurotransmitters.
   3. a handfull of recently recognized “novel” tansmitters.
2. Explain how neurotransmitters function and how they bind to receptor sites. (p. 92)
   
   1. ​Neurotransmitters funtion by binding to select reception site molecules. certain neurotranmitters can only bind to specific receptor molecules in order to reduce cross-talk. Differeent neurotranmitters are specialized to have specific functions.

Question 15

1. Describe the properties and functions of acetylcholine. (pp. 92-93)

Answer 15

1. Functions:
   
   1. ​Involved with muscular movement.
   2. contributes to:
      
      1. attention
      2. memory
      3. arousal
2. Properties:
   
   1. ​found throughout the nervous system
   2. only transmitter between motor neurons and voluntary muscles.