Exam 2 Flashcards
(171 cards)
1
Q
Ionotropic (Ligand-Gated) receptors (Neurotransmitter systems)
A
-Nicotine Acetylcholine Receptors
-GABA-A Receptors- Shunting Inhibition
-Ionotropic Glutamate Receptors
2
Q
Metabotropic ( G-coupled) Receptors (neurotransmitter system)
A
Gs, Gi, GQ alpha subunit
Shortcut pathway (beta, gamma subunits)
3
Q
What are the types of neurotransmitters?
A
Amino acids
Monoamines
Acetylcholine
Unconventional
4
Q
What are the amino acids?
A
Glutamate
aspArtate
Glycine
Gamma-aminobytytic acid (GABA)
5
Q
What are the monoamines?
A
Dopamine (catecholamines) synthesized in the midbrain
Epinephrine
Norepinephrine synthesized in the pons
Serotonin ( indolamines)
6
Q
How does catecholamine synthesize the monoamines?
A
It synthesizes phenylalanine into tyrosine to L-Dopa to Dopamine to norepinephrine to epinephrine
7
Q
Where serotonin synthesis from?
A
Tryptophan
8
Q
What are the unconventional neurotransmitters?
A
Nitric oxide
Carbon monoxide
9
Q
What stimulate the production of second messenger membrane?
A
The unconventional neurotransmitters
10
Q
What is involved in retrograde transmission? And what is it?
A
The unconventional neurotransmitters
Retrograde transmission is when neurotransmitters go from the post synaptic cell to the presynaptic
11
Q
What are the neuropeptides?
A
Pituitary peptides in the pituitary gland
Hypothalamic peptides in the hypothalamus
Brain gut peptides in the gut
Opioid peptides in the resemble opium
Miscellaneous
12
Q
What can neurotransmitters cause? And are direct actions as neurotransmitters?
A
Excitation
Inhibition
13
Q
What are excitatory responses? ( glutamate)
A
They results in depolarization, the cell became more positive of the post synaptic neuron
14
Q
What are inhibitory responses cause? (Glycine and GABA)
A
They cause hyper-polarization of the post synaptic neuron, making it more negative
15
Q
Is acetylcholine excitatory or inhibitory?
A
Excitatory for skeletal muscles
Inhibitory for cardiac muscle
16
Q
Explain direct action?
A
Neurotransmitters binding causes receptors to open up so that ions can pass through
17
Q
What can be involved in direct action?
A
Acetylcholine and amino acids
18
Q
Explain indirect action
A
When the action is promoted through second messenger molecules
19
Q
What initiated indirected action? What else work that way?
A
It is initiated by metabotropic receptors and hormones work that way
20
Q
What are amino acids?
A
They are small molecules containing amine( NH2) and carboxyl (-COOH)
21
Q
What are the most abundant type of neurotransmitters? ( 70% of all neurons in CNS utilize AANTs)
Act as both Ionotropic and metabotropic?
Have a fastest effects due to change in resting membrane potential?
A
GABA
GLUTAMATE
22
Q
What is synthesized from glutamine? The enzyme being glutaminase
A
Glutamate
23
Q
What happens if GABA-A receptors are blocked?
A
Convulsions and Death can result
24
Q
What synthesized GABA?
A
GABA is synthesized only by GABAergic neurons
25
Where does GABA from and what catalyzed it?
GABA is made from glutamate, synthesized by glutamic acid decarboxylase (GAD)
26
The catecholamine Systems
Dopamine and movement
Dopamine and reward
Dopamine and cognition
27
Dopamine and movement
Nigrostriatal tract: axons in the substantia nigra extend to the basal ganglia
28
Dopamine and reward
Mesolimbic dopamine pathway: from the ventral tegmental area to various structure of the limbic system
29
What are mesolimbic dopamine pathway and mesocortical dopamine pathway
though of as? Explain it.
It is though of as the primary reward pathway
It is though to contribute to the development of addiction
30
Dopamine and cognition
Mesocortical dopamine pathway from the VTA to the prefrontal cortex, cognition of reward
31
What is the catecholamine systems?
Dopamine to norepinephrine to epinephrine
32
How is amino acid converted to L-dopa?
It is converted by the enzyme tyrosine hydrolase ( addition of an hydroxyl group to tyrosine, considered as the rate limiting enzyme)
33
How is dopa converted into dopamine?
By the enzyme aromatic amino acid decarboxylase ( removal of carboxyl group from dopa)
34
How is dopamine converted to norepinephrine?
By the enzyme dopamine beta hydroxylase ( addition of OH group to dopamine)
35
How is epinephrine is converted to norepinephrine?
By the enzyme phenyl-ethanonolamine-N-methyltransferase ( addition of a methyl group to norepinephrine)
36
Where is acetylcholine found at?
Neuromuscular junction
Autonomic nervous systems
Isolated within the brain (fibers originate and stay in brain )
37
What are the 3 primary areas where the ACh is found?
Projecting ACh cell bodies: basal forebrain and brainstem
ACh interneurons: Striatum
38
Where is ACh synthesized?
In two discrete brain regions: basal forebrain and medulla
The main neurotransmitter at the muscular junction
39
How is ACh formed?
It is formed from choline and acetyl coenzyme A
Most choline comes from the consumed foods with natural fats( meats, eggs, vegetables…)
Actively transported across BBB
Acetylcholine CoA is produced during metabolism of sugars
40
What catalyze the synthesis of ACh and where is it found?
Choline Acetyltransferase catalyzes the synthesis of ACh and is found in neurons that use ACh as their transmitter
41
What is the role of CHAT?
It transferse the acetyl group from acetyl CoA to choline
42
What inactivate acetylcholine? And How does it breaks it down?
ACh is inactivated by acetylcholinesterase, which breaks it down to choline and acetyl acid
43
Where can we find ACHE?
We can find it in the presynaptic and post synaptic cell
44
Explanation
Most choline in the cleft after ACh breakdown by ACHE is taken back into the cholinergic nerve terminal by a choline transporter.
45
Where is Serotonin synthesized?
In several nuclei in the midbrain and brainstem
The clusters project to broadly and are mostly inhibitory
46
What are the Rostral raphe group?
Dorsal
Linear
Median
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What are the caudal raphe group?
Magnus
Obscurus
Pallidus
48
What is Serotonin?
Known as indoleamine, it is a neurotransmitter that has a wide range of behavioral and physiological functions including regulation of mood, sleep, hunger,anxiety, pain, and learning and memory
49
Formation of serotonin?
L-Tryptophan to L-5-Hydroxytryptophan by trytophydrolase
L-5-Hydroxytryptophan to serotonin by aromatic L-amino acid decarboxylase (COOH is gone)
50
How do we call neurotransmitters that bind to more than one type of receptors?
Receptors subtypes
51
What results in fewer side effects?
When drugs are designed to affect specific subtypes.
52
What are the major categories of transmitters receptors ?
Ionotropic and metabotropic
53
What can be qualified as Ionotropic receptor?
Ligand gated ion channel
Transmitter gated ion gated
54
How does Ionotropic neurotransmitter receptors work?
Ion influx changes the membrane potential into excitatory or inhibitory
55
What is an important second messenger for many developmental and environmental responses?
Calcium
56
How does metabotropic receptors work?
Act more slowly but responses last longer
Consists with one subunit with seven transmembrane domains
Work by activating G proteins ( G proteins coupled receptors)
57
How does G proteins act?
Inhibit or activate ion channels ( potassium moves out of the cell and hyperpolarization results)
Stimulate or inhibit effector enzymes in the cell membrane, that synthesize or breakdown second messenger molecules
58
Good summary ( seven steps in neurotransmitters action)
1-Synthesis
2- Storage of vesicles
3- Breakdown of any neurotransmitters leaking from the vesicle
4- Exocytosis
5- Inhibitory feedback via auto receptors
6- Activation of post synaptic receptors
7- Deactivation
59
Step of sensory input
Receptors
Thalamic Relay Nuclei
Primary Motor Cortex
Secondary Motor Cortex
Association Cortex
60
Step of motor output
Association Motor Cortex
Secondary Motor Cortex
Primary Motor Cortex
Brain Stem Motor Cortex
Muscles
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Sensorimotor Association Cortex
Posterior Parietal Association Cortex
Dorsolateral Prefrontal Association Cortex
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The Posterior Parietal Association cortex
Receive messages from the visual, auditory, somatosensory system
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The dorsolateral prefrontal association cortex
Receives information from the posterior parietal cortex and send information to the primary and secondary motor cortex and the frontal eye field
64
Secondary Motor cortex
Receives information from the posterior parietal association cortex and the dorsolateral prefrontal association cortex. It send information largely to the primary motor cortex.
65
What does the primary motor cortex consist of?
The supplementary motor area
The premotor Cortex
66
The role of the secondary motor cortex
It involves the programs patterned movement
67
Where can we find the primary motor cortex?
In the precentral gurus of the frontal lobe
68
What are important sensorimotor structures?
The cerebellum
Basal Ganglia
69
What does the cerebellum contain?
A majority of the neurons in the brain
70
Where does the cerebellum get the inputs from?
The motor cortex
The brain stem
The motor nuclei
The somatosensory system
71
What is the cerebellum used for?
Motor learning and skills with precise timing
72
The role of the basal ganglia
Receives cortical input, then transmit it to the thalamus and finally the cortex.
It facilitates wanted movements and inhibits unwanted movements
73
What are the 4 main paths through the spinal cord?
2 within the dorsolateral region ( dorsolateral corticospinal tract, and the dorsolateral corticorubrospinal tract)
2 within the ventromedial region (ventromedial corticosteroid-brainstem-spinal tract and ventromedial corticospinal tract)
74
What comprise the motor unit?
1 neuron (alpha-Lower motor neuron )and all of the muscles fibers it innervates
75
What comprise the motor systems?
Somatic motor system
Skeletal muscle
Neuromuscular junction
Graded control of muscle contraction
76
What are the parts of the somatic motor system?
Upper motor neurons
Lower motor neurons
77
What are the parts of the lower motor neurons?
Alpha (fast and slow)
Gamma motor neurons
Motor unit
Motor neuron pool
78
Role of the somatic motor system
Voluntary movement
Skeletal muscle and the parts of the nervous system them
Striated (grooved muscle)
79
Somatic motor system expanded
Descending systems (upper motor neurons )
Basal Ganglia(gating proper initiation of movements) to the motor cortex
80
What is the role of the motor cortex?
Planning, initiating,and directing voluntary movement
81
How does the ventral horn of the spinal cord innervate skeletal muscle fibers?
The ventral horn of the spinal cord contains motor neurons that innervate skeletal muscle fibers
82
Proximal-Distal Organization
Proximal muscles to Distal muscle (shoulder muscle to hands muscles)
83
How are the muscle fiber innervate?
Each muscle fiber is innervate by a single axon.
84
What are the role of the flexors and extensors?
The flexors cause contraction of the joint, while the extensors extend the joint.
Muscles can only pull on a joint(contract), they cannot pull.
85
What is the role of the alpha lower motor neurons?
Trigger muscle contraction
Innervate extrafusal muscle fibers
86
What is the role of the gamma lower neurons?
Sensation of movement
87
What is the role of the Motor Neuron Pool?
All of the alpha motor neurons that innervate one muscle
88
What is the role of the motor unit?
Alpha motor neuron and the muscle fibers it innervates.
89
What is the neuromuscular junction?
All or none: action potential always trigger muscle contraction
90
Where is the transmitter in neuromuscular junction?
Transmitter is acetylcholine
91
Where are located the Nicotinic ACh receptors?
They are located within folds in the motor end-plate
92
The role of alpha-Bungarotoxin
It binds to and blocks the nicotinic receptor at the neuromuscular junction
93
How does graded control of muscle contraction happen?
Via frequency of the action potentials in a single motor unit.
Single action potentials- twitch
Multiple action potentials- substained contraction
94
How does the graded control of muscle contraction?
Via recruitment of additional motor units
95
What does most muscles have?
They have a range of motor unit sizes:
Single alpha motor neuron can innervate 3-1000 muscles fibers
Recruited in order of smallest first and largest last
Provides fine control over contraction force
96
What are the two types of motor units?
Slow:
Slow to contract
Slowly fatiguing
Found in antigravity muscles in leg( maintenance of posture), also fight muscles in birds
Innervates by slow motor neurons(10-20Hz)
Fast:
Fast to contract
Rapidly fatiguing
Found in muscles important for brief, strong exertion such as running or jumping
Innervates by fast motor neurons(30-60Hz)
97
What is ataxia
Affecting regions of the brain that are responsible for movement coordination; altered balance, speech or limb movements. Can be both genetic or through neurodegenerative conditions
98
What is chorea?
Movements are very repetitive, brief/ episodic(more often voluntary )
99
What is dystonia?
Substained involuntary movements; can be whole body or isolated to particular limb/area
100
Define restless leg
Uncomfortable feeling in the legs when someone is remaining; sometimes relieved by getting up and moving.
101
Define tardive dyskinesia?
More often the result of a chronic use of certain drugs for psychiatric disorders; repetitive and involuntary movement of the face
102
Define Tremor
Rhythmic shaking of parts of the body; typically in the limb/extremities
103
Why should we care about specific neurotransmitters?
The inability for the correct (environmentally cued)release of specific neurotransmitters in the basal ganglia are linked with a variety of movement disorders
104
What is direct pathway in movement disorder?
Disinhibition of the thalamus and activation of motor areas, increased movement
105
What is indirect pathway in movement disorder?
Disinhibition of the subthalamic nuc. (STN) and as a result a inhibition of the thalamus, decreased movement
106
What is the anatomy of common movements disorders?
Abnormal movements can be elicited anywhere in the complex hierarchical motor network
However, when clinicians talk about movement disorders, they are often referring to abnormal movements related to basal ganglia pathology
107
What are the keys symptoms and signs of hemibalismus?
Involuntary, wild flinging movements of the right arm and leg
Relatively slow worsening (relative to a stroke/ infarct)
HIV infection(toxoplasmosis)
108
What are keys symptoms and signs of Huntington’s disease?
Irregular jerking, slightly decreased tone, and unsteady gait
Moderately slowed saccadic eye movements
Flat affect, argumentative, and denied having any involuntary movements
109
What are the cognitive disorders associated with HD?
Difficulty organizing, prioritizing or focusing on tasks
Lack of flexibility or the tendency to get stuck on a thought, behavior or action
Lack of impulse control that can result in outbursts, acting without thinking and sexual promiscuity
Lack of awareness of one’s own behaviors and abilities
Slowness in processing thoughts or finding words
Difficulty in learning new information
110
Psychology disorders associatied with HD?
Feelings of irritability, sadness, or apathy
Social withdrawal
Insomnia
Fatigue and loss of energy
111
What are the key symptoms and signs of Parkinson’s disease?
Asymmetrical bradykinesia, cogwheel rigidity, and resting tremor, all more severe on the right side
Stooped gait with short steps, decreased arm swing, en bloc turning, and retropulsion
Significant benefit from levodopa
Gradual progression over a period of years
112
What is now called a blastocyte?
Pluripotent cells
113
What is pluripotent cell(blastocyte)?
New stem cells have the ability to develop into any of the 3 early layers of an embryo.
Blastocyte implants in the uterine wall around day 6-9 after fertilization
114
Early embryological development
Ectoterm(superior)
Mesoderm(middle)
Endoderm(inferior)
115
What leads to the development of the neural plate?
The thickening of the ectoderm leads to the development of the neural plate
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When does the neural groove develop?
The neural groove begins to develop at 20 days
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What happens to the neural groove at 22 days?
At 22 days, the neural groove closes along the length of the embryo making neural tube.
118
The what will happen to the neural tube?
The neural tube will become the brain and the spinal cord
119
What will happen a few days later?
A few days later, major divisions of the brain are observable: forebrain, midbrain, hindbrain
120
What is the homeobox genes (HOX)?
It explains why different species look so similar early in embryological development
The HOX genes are genes that control the development of different segments of the body(including brain)
121
What are the 8 phases in embryonic and fetal development at a cellular level?
1.Mitosis
2.Migration
3.differentiation
4.Aggregation
5.Synaptogenesis
6.Neuron Death
7.Synapse Rearrangement
8.Myelination
The 8 stages are sequential for a given neuron, but all are occurring simultaneously throughout fetal development
122
Explain Neural proliferation
Proliferation (neurogenesis): Occurs rapidly after neural tube is formed, cell division occurs at ventricular zone, from there cells migrate away
Controlled by chemical signals from organizer areas
Floor plate(glial layer separating left and )
Roof plate (Becomes spinal gray matter. And sensory fibers)
123
Explains Migration
Occurs in ventricular zone
Rate can be 250000/min
After mitosis “daughter” cells become fixed post mitotic
124
What are the 2 methods by which cells migrate in the developing neural tube?
Somal translocation and glia-mediated migration
125
Explain Differenciation
Neurons become fixed post mitotic and specialized
They develop processes (axons and dendrites)
they develop NT-making ability
They develop electrical conduction
126
Explain Aggregration
Like neurons move together and form layers
127
Explain synapse formation
Axon growth (once aggregation is complete, neurons grows axons and dendritres in preparation for
Synaptogenesis-formation of synapses with other neurons)
Accurate localization is due to growth cones(filipodia)
128
What chemoattractant and chemorepellant proteins?
Chemoattractant: attract growth cone migration towards them
Chemorepellant: repel grown cone migration
129
Explain neural death
Neural death(some maybe guided by accuracy of synaptic connections )
Apoptosis(triggers- genetic preprogramming, lack of survivals chemicals
Supporting evidence that neurotrophic are important)
130
Explain Synapse Rearrangement
How?-axonal sprouting
Why?-focus output of each neuron on fewer post synaptic cells
131
Explain Myelination
The cells begins to myelinated at birth
132
Explain postnatal growth of the human brain
Brain volume increases 4x between birth and adulthood
Why?
Synaptogenesis
Peaks in visual cortex at 4 months
Greater plasticity
Myelination
Speeds up transmission
Sensory and motor areas myelinated in first few months
Prefrontal cortex myelinated in adolescence
Dendritic branching
133
What develops to relative maturity first?
Limbic system(amygdala):fear, aversive emotions
Ventral Striatum (accumbens): reward, reinforcement
Prefrontal cortex: Executive function
134
What is the role of the Amygdala?
Emotion processing and fear assessment
135
What is the role of the Ventral Stratium?
Reward and Motivation
136
what is the prefrontal cortex?
Executive function/behavioral/control decision making
137
What is more activated by sucrose in adolescents than adults?
Ventral striatum
138
What do adolescents show greater in response to fearful face?
Greater amygdala activation
139
Presence of peers increases risk taking. Why that?
Peers increase activity in ventral striatum
140
What is the DLPFC?
It is part of a system originating in the primitive embryological hippocampus
141
What role do the Circuits play in?
Working Memory-control and manipulation of information
Declarative “episodic” memory
Attention
Executive functioning
Goal selection sequencing-The development of an action plan
Monitoring outcome
The inhibition of distracting stimuli for completion of complex task
142
What is Orbitofrontal Cortex?
It is intimately connected with limbic nuclei involved in emotional processing
143
What area function in visceral and emotional activities?
Emotional self-regulation
Evaluating hedonic information
144
What are our primary senses?
Audition: hearing
Vision: seeing
Olfactory- smelling
Taste
Touch
145
What are the primary brain region of the senses?
Audition-temporal lobe
Vision-occipital lobe
Olfaction-olfactory bulbs
Taste-somatosensory cortex
Touch-somatosensory cortex
146
What are the senses that have a lot of brain tissue dedicated to them?
Audition
Vision
Olfaction
147
Define sensory transduction and sensory coding
Sensory transduction: Conversion of physical energy from the environmental into changes in electric potential
Sensory coding: what happens in the brain
148
What is transduced?
Vision- electromagnetic radiation
Taste- chemicals in fluid
Hearing- sound waves
Touch- pressure, temperature changes, pain
Smell, chemical in air
149
What are the cells responsible for transduction?
Vision- rods and cones in retina
Taste- taste buds on tongue
Hearing- hair cells in inner ear (cochlea)
Touch- specialized receptors under skin
Smell- hair cells in olfactory epithelium
150
What is the general pathway for most sensory information
Sensory cells- spinal tracts- thalamus- primary cortex- higher association cortex
151
What is vision?
Most highly developed sense in human
Optic nerve for one eye- 1,000,000 axons
Auditory nerve contains about 30000 axons
152
What does the human eye see?
Light waves along the visual spectrum
153
What are the visible part of the eye?
Pupil: An opening that controls how much light gets into the back of the eye
Iris: largely a muscle that expends and contracts pupil in response to light
Sclera: tough tissue, provides structural support
154
What are the part of the eye that we can’t see?
Retina: structure of eye important for transduction (back wall of eye that is home to Rods and Cones)
Retina contains neurons, glial cells and two types of photoreceptors
Cornea: outmost covering, helps focus light onto the pupil attached to schlera
Iris: remember, a muscle that controls opening and closing of pupil
Lens: Behind the pupil, helps focus light onto retina
155
Why is opening/closing of pupil important?
Large pupil opening: more light gets in helps see in the dark
Small pupil opening: less light gets in helps prevent “overload” in light
156
What are rods and cones?
Types of cells that are sensitive to different types of light info
157
What are the role of the rods and cones?
Responsible for transduction
Numerous differences between rods and cones
158
What are rods?
Shaped like a rode
Insensitive to color
Work well under low illumination
20,000,000/eye
Location: found around the periphery of the retina
Takes awhile to transmit info to brain
Responsible for helping see when it’s dark or hard to see well
159
What are the cones?
Shaped like a cone
Sensitive to color
Work best in bright light
5,000,000/eye
Location:found around the fovea of the retina
Works very quickly
Responsible for sharp images and vision
160
Explain at least two levels of communication whithin the cells of the eye
1.Rods and cones- bipolar cells- ganglia cells(axons make up the optic nerve, they carry info to the brain)
2.rods synapse on other rods too, cones synapse on other cones,…
161
What are the roles of the Amacrine ells and horizontal cells?
Provide “lateral communication” between cells in the same layer
162
Explain the horizontal cells
GABAergic- appear to be important in fine tuning activity of rods and cones to improve contrast
163
Explain the Bipolar cells
10-13 different types
All having different patters of firing to connect the outer retina to retinal ganglion cells
An unusual 2nd layer helping to fine-tube/ improve definition of visual input
164
Explain the Amacrine cells
Inhibitory (GABA and other transmitters)
Carry rod signals to ganglion cells
Fine-tune vision provides in low-light conditions
165
What is convergence?
The number of 1 cell type that stimulates another cell type
166
What is low and high convergence?
For cones: only few cones stimulate 1 ganglion cells, low convergence
For rods: lots of rods stimulate 1 ganglion cell, high convergence’
167
Explanation for color vision
Trichromatic: occurs at level of cones, 3 different types of cones sensitive to different primary color (blue, red, and green)
Explains major type of color blindness: deficits in certain types of cones can explain major type of color blindness
168
What is the opponent process theory?
Occurs at level of retinal ganglion cells
Red/green; yellow/blue
One color excites bipolar cell, other color inhibits it
Our ability to see many colors is related to how the 3 types of cones interact with the ganglion cells
169
Explain Magnocellular layers:
Inner 2 layers, large cells
No color sensivity
Process high contrast images
Low resolution
Fast processing of visual stimuli
170
Explain Parvocellular layers
Outer 4 layers, smaller cells
Color sensitive
Low contrast
High resolution
Slow response to visual stimuli
171
Explain Koniocellular layers
Sublayers between 1 and 2
Color sensitive (blue only )
Low contrast, low resolution, slow
