Chapter 5

Question 1

What is a Ionotropic receptor

Answer 1

• Embedded membrane protein with two parts:
• A binding site for a neurotransmitter + A pore that regulates ion flow to directly and rapidly change membrane voltage
• Allows the movement of ions such as Na+
  ,K+, and Ca2+ across a membrane

Question 2

What occurs when the Ionotropic receptor binds to the binding site?

Answer 2

When neurotransmitter attaches to binding site, the pore opens or closes, changing the flow of ions.

Question 3

What is a Metabotropic receptor and what is its function?

Answer 3

• Embedded membrane protein with a binding site for a neurotransmitter but no pore
• Indirectly produces changes in nearby ion channels or in the cell’s metabolic activity
• Linked to a G protein that can affect other receptors or act with second messengers to affect other cellular processes

Question 4

What is an Amplification Cascade?

Answer 4

• A single neurotransmitter binding to a metabotropic receptor can activate an escalating sequence of events. Proteins can
  be activated or deactivated

Question 5

Explain the role of receptor subtypes:

Answer 5

Each neurotransmitter may interact with a number of receptor subtypes specific to that neurotransmitter.
* Each subtype has slightly different properties, which
confer different activities.

Question 6

Explain how the relationship between a neurotransmitter and a behaviour is not simply a cause and effect

Answer 6

A single neuron may use one transmitter at one synapse and a different transmitter at another synapse.
* Different transmitters may coexist in the same terminal or synapse (even in a single vesicle!!)

Question 7

What is a cholinergic receptor? (motor neuron)

Answer 7

Neuron that uses acetylcholine (ACh) as its main neurotransmitter
* Excites skeletal muscles to cause contractions

Question 8

What is a Nicotinic ACh receptor (nAChr)?

Answer 8

When ACh or nicotine binds to this receptor, its pore opens to permit ion flow, thus depolarizing the muscle fiber
*The nicotinic receptor pore
permits the simultaneous
efflux of K+ and influx of Na

Question 9

What are the Dual Activating Systems of the Autonomic Nervous System (ANS)?

Answer 9

Parasympathetic and Autonomic Nervous System

Question 10

Explain the function of the parasympathetic nervous system

Answer 10

calms the body down, producing an essentially opposite rest-and-digest
response.
* Digestive functions ramp up; heart rate ramps down.

Question 11

Explain the function of the sympathetic nervous system

Answer 11

arouses the body for action,
producing the fight-or-flight response.
* Heart rate ramps up; digestive functions ramp down

Question 12

Explain which neurotransmitter is responsible for controlling the parasympathetic and sympathetic nervous system and how this process occurs:

Answer 12

CNS neurons synapse with parasympathetic neurons that contain Ach and with sympathetic neurons that contain
norepinephrine.
* Cholinergic neurons in the CNS synapse with sympathetic NE neurons to prepare the body’s organs for fight or flight
* Cholinergic neurons in the CNS synapse with autonomic ACh neurons in the parasympathetic division to prepare the body’s organs to rest and digest

Question 13

What is the role of norepinephrine in sympathetic arousal?

Answer 13

• During sympathetic arousal, norepinephrine turns up heart rate and turns down digestive functions
• NE receptors on the heart are excitatory, whereas NE receptors on the gut are inhibitory

Question 14

What is the role of acetylcholine in sympathetic arousal?

Answer 14

• acetylcholine turns down heart rate and turns up digestive functions because its receptors on these organs are reversed
• On the heart, inhibitory
• On the gut, excitatory

Question 15

Does the enteric nervous system need input from the CNS to function?

Answer 15

• ENS can act without input
  from the CNS

Question 16

Which classes of neurotransmitters are used by the enteric nervous system?

Answer 16

• Uses all four classes of
  neurotransmitters—more
  than 30 transmitters
• Mainly serotonin and
  dopamine

Question 17

What conditions do sensory neurons detect in the gastrointestinal tract?

Answer 17

Detect mechanical and
chemical conditions in the
gastrointestinal system.

Question 18

What are the four activating systems in the enteric nervous system?

Answer 18

Cholinergic, dopaminergic, noradrenergic, and serotonergic
* (one system for each small-molecule transmitter)

Question 19

What is an activating system?

Answer 19

Neural pathways that coordinate brain activity through a single neurotransmitter
* Cell bodies lie in a nucleus in the brainstem, and their axons are distributed through a wide region of the brain.

Question 20

What is the function of the Cholinergic activating system?

Answer 20

Normal waking behavior; is thought to function in attention and memory

Question 21

What disease is the loss of Cholinergic neurons associated with?

Answer 21

Loss of cholinergic neurons is associated with Alzheimer disease.

Question 22

What are the two pathways in the Dopaminergic activating system?

Answer 22

-Nigrostriatal pathways
-Mesolimbic pathways

Question 23

What is the Nigrostriatal pathway responsible for?

Answer 23

Active in maintaining normal motor behavior (coordination)

Question 24

What disease is the loss of dopamine associated with?

Answer 24

Loss of DA is related to muscle rigidity and dyskinesia in Parkinson disease

Question 25

What is the function of the Mesolimbic pathways?

Answer 25

Dopamine release causes repetition of behaviors
* Most affected in addiction behaviors (food, drugs, etc.)
* Related to impulse control

Question 26

What impact does an increase or decrease of dopamine have on our behaviour?

Answer 26

• Increases in DA activity may be related to schizophrenia.
• Decreases in DA activity may be related to deficits of attention.

Question 27

What is the function of the Noradrenergic system?

Answer 27

Norepinephrine plays a role in learning by stimulating neurons to change structure
* may also facilitate normal development of the brain and organize movement

Question 28

What effects can imbalances of norepinephrine have?

Answer 28

Imbalances associated with depression, mania

Question 29

What is a decreased level of norepinephrine associated with?

Answer 29

• Decreased NE activity related to ADHD and hyperactivity

Question 30

What is the function of the Serotonergic system?

Answer 30

• Plays a role in wakefulness and learning

Question 31

What is an imbalance of serotonin associated with?

Answer 31

• Imbalances associated with depression,
  schizophrenia, obsessive-compulsive disorder, sleep apnea, sudden infant death syndrome (SIDS)

Question 32

What is learning?

Answer 32

• Relatively permanent change in behaviour that results from experience

Question 33

What is neuroplasticity?

Answer 33

The nervous system’s potential for change, which enhances its ability to adapt. Required for learning and memory

Question 34

What is the Hebb Synapse?

Answer 34

Cells that fire together wire together.

Question 35

Who was Eric Kendal and what was his experiment?

Answer 35

Studied the synaptic basis of learning
using Aplysia. He used enduring changes
in simple defensive behaviours to study
underlying changes in the nervous system.

Question 36

What is the habitual response?

Answer 36

• Learning behavior in which a response to a stimulus weakens with repeated presentations of the stimulus
  eg: Gill withdrawal response in the marine snail Aplysia californica

Question 37

What occurs at the level of the neurons for habituation to take place? What is the process?

Answer 37

As habituation develops, the excitatory postsynapticpotentials in the motor neuron become smaller.
* Motor neuron is receiving less neurotransmitter from the sensory neuron across the synapse.
* Habituation must take place in the axon terminal of the sensory neuron.
* Less activity from a habituated neuron relative to a nonhabituated one.
* As habituation takes place, Ca2+ influx decreases in response to voltage changes associated with an action potential.
* Reduced sensitivity of Ca2+ channels and
decreased release of neurotransmitter

Question 38

What is the sensitization response?

Answer 38

• Learning behavior in which the response to a stimulus strengthens with repeated presentations because the stimulus is novel or stronger than normal

Question 39

What occurs at the level of the neurons for sensitization to take place? What is the process?

Answer 39

• In response to an action potential on an axon of a sensory neuron, K+ channels are slow to open.
• K+ ions cannot repolarize the membrane quickly, so action potential lasts longer than normal.
• Prolongs the inflow of Ca2+, and more transmitter is released.
• Sensitization is the opposite of habituation at the molecular and behavioral levels.
• In sensitization, more Ca2+ influx results in more transmitter being released.
• In habituation, less Ca2+ influx results in less neurotransmitter being released.

Question 40

What needs to happen for neural changes to result in permanent behavioural changes?

Answer 40

• Neural changes associated with learning must last long enough to account for a relatively permanent change in an organism’s behavior.
• Repeated stimulation produces habituation and sensitization that can persist for months

Question 41

How does the number and size of sensory synapses change in well-trained, habituated, and sensitized Aplysia?

Answer 41

Habituation-less connections
Sensitization-more connections