Brain anatomy Flashcards
(159 cards)
1
Q
What is a receptor protein?
A
- A protein that is sensitive to signals and is able to transfer a signal
- They are either ionotropic or metabotropic
2
Q
What is an ionotropic receptor?
A
- Receptor protein that is an ion channel
3
Q
What is a metabotropic receptor?
A
- receptor protein
- IS NOT AN ION CHANNEL
4
Q
What is the mode of operation of a metabotropic receptor?
A
- Triggers an intracellular signaling cascade that involves G Proteins
- triggers intracellular signals to catalyze chemical reactions
5
Q
What are the most frequent effects of the action of metabotropic receptors?
A
- change in gene expression
- opening or closing of g protein-gated ion channels
- secretion of substance from the cell
- Cell division
6
Q
What is the metabolism?
A
- ensemble of chemical reactions that occur inside of the cell
7
Q
What is a G-Protein?
A
- A protein that uses GTP instead of GDP as a source of energy
8
Q
What does it mean for a g protein to be “on”?
A
- bound to GDP
- Can trigger chemical reactions
9
Q
When is a g-protein considered as being “off”?
A
- when it has transformed the GDP in GTP
10
Q
How does GTP become GDP?
A
The g-protein pries off the third phosphate groupe to use it as a source of energy
11
Q
What is the course of action of metabotropic receptor signaling?
A
1) A metabotropic receptor binds to its ligand
2) the conformation of the receptor changes and it becomes favorable for the g-protein’s exhange of GDP for GTP
3) exchange occurs
4) the g-protein dissociates its alpha subunit, which bears the GTP
5) The alpha unit diffuses away
6) the alpha unit now activates downstream enzymes to allow metabolic reactions. It can also activate g-protein gated ion channels
7) the gtp molecule is metabolized into gdp
8) Deprieved of its supply of energy, the alpha subunit goes back to the rest of the molecule
12
Q
What is a g-protein ion channel?
A
- ion channel that is gated by g proteins
13
Q
How is a g-protein gated ion channel opened?
A
1) a neurotransmitter binds to the metabotropic recepor
2)Activated g proteins transmit the message intracellularly
3) The neighbouring ions channels therefore know they need to open
14
Q
Where can the different types of synapses form?
A
1) dendrites (dendritic shafts)
2) dendritic spines
3) soma (cell body)
4) axoaxonic synapses
15
Q
Where are situated the synapses that can have the greater impact on neuronal activity?
A
- on the soma (can override everything that happens in the axon)
16
Q
Which emplacement of synapses have as a goal to cause an action potential?
A
- dendrites
- dendritic spine
- soma
17
Q
What are axoaxonic synapses?
A
- synapses that are created by the apposition of one neuron’s terminal button on another neuron’s terminal button
18
Q
What is the purpose of an axoaxonic synapse?
A
- Regulate the amount of neurotransmitters the second neuron will release (the one on whose terminal button of the other neuron is appositioned)
19
Q
What are the two possible effects of an axoaxonic neuron?
A
- Presynaptic inhibition
- Presynaptic facilitation
20
Q
What is presynaptic inhibition?
A
- hyperpolarization of the axon terminal of the neuron that is supposed to independently release neurotransmitters
- voltage gated calcium channels either do not open or open much less than normally when an action potential arrives
21
Q
What is the net effect of presynaptic inhibition?
A
- reduce neurotransmitter release when the downstream terminal button receives action potential
22
Q
What is the metod of action of presynaptic inhibition?
A
Entry of Cl-
23
Q
What is presynaptic facilitation?
A
- depolarization of the axon terminal of the neuron supposed to independently release neurotransmitters
- voltage-gated calcium channels are more likely to open when an action potential arrives
24
Q
What is the net effect of presynaptic facilitation?
A
- increase neurotransmitter release
25
What is the method of action of presynaptic facilitation?
- entry of sodium ions
- facilitates the entry of calcium ions
26
What is an autoreceptor?
- receptor located on the presynaptic membrane
27
When does an autoreceptor get activated?
- the cell releases its own neurotransmitter
28
What type of protein are autoreceptors?
- metabotropic receptors
- inhibitory
29
What is the function of autoreceptors?
- presynaptic inhibition
- detect when the cell has released enough neurotransmitters
30
What is the method of action of autoreceptors?
- enables g-protein to open metabotropic inhibitory receptors to hyperpolarize the neurone and stop the release of neurotransmitters
31
What is the neuraxis?
imaginary line that cuts the CNS in half
32
What are the only senses that are ipsilateral?
- Taste
- Smell
33
What are the brain nuclei?
Collection of neurons that are clusteres together and all work together to serve some brain function
34
What composes the central nervous system?
Everything in the brain, as well as the spinal chord
35
What composes the peripheral nervous system?
Any part of the nervous system that isnt inside the brain or the spinal chord (nerves)
36
Where are situated sensory neurons and motor neurons?
Span on both regions
37
What are the main differences between the CNS and the PNS?
- in the cns, myelin is created by oligodendrocytes, whereas it is created by schwann cells in the pns
- The CNS is protected by the blood-brain barrier
38
What are the differences between schwann cells and oligodendrocytes?
- schwann cells only myelinate one axon each
- schwann cells are in the pns
39
What is the extracellular fluid of the brain?
the cerebrospinal fluid
40
What is particular of the blood capillaries that pass through the brain and spinal chord?
the do not have gaps in them (blood brain barrier)
41
What are the meninges?
- protective connective tissues that surround the brain
42
What are the layers of the meninges?
- pia mater
- arachnoid membrane
- dura mater
43
What is the dura mater?
- outer layer of the meninges
- thick, tough, unstretchable tissue
44
What is the arachnoid membrane?
- middle layer of the meninges
- soft and spongy
- web-like appearance
45
What is the pia mater?
- layer of the meninges that is closest to the brain
- filled with blood vessels
46
What is the subarachnoid space?
- between the arachnoid membrane and the pia matter
- filled with CSF and blood vessels
47
What is the choroid plexus?
- tissue found in each of the brain ventricles
- found in all of the ventricles
- makes CSF
48
What is the half-life of CSF?
- 3 hours (it is half replaced every three hours)
49
Where are the lateral ventricles?
under the cerebrum
50
Where is the third ventricle?
Between the two thalamic nuclei
51
Where is the fourth ventricle?
between the pons and the cerebellum
52
What is the cerebral aqueduct?
- long, tube-like structure
- connects the third and fourth ventricle
53
What is an interneuron?
- A neuron of the CNS
- ONLY in the CNS
- The axon stays local
- communicates with cells in the vicinity
54
What are motor neurons?
- neurons that have a cell body in the spinal chord and the axon in the PNS
- efferent fibers
55
What are the functions of motor neurons?
- control muscle contractions
- control gland secretions
56
What are sensory neurons?
- afferent fibers
- cell bodies are just outside of the spinal chord
- detect changes in the external and internal environment
- send the info about the changes in the environment to the CNS
57
What are efferent fibers?
- brings information away from the CNS
58
What are the afferent fibers?
- brings information toward the CNS
59
What is a nerve?
- sheath of tissue that encases a bundle of individual nerve fibers
- peripheral nervous system
60
How do the brain and spinal chord communicate with the rest of the body?
via nerves
61
What are the spinal nerves?
- attach to the spinal chord
- one pair for each vertebrae
62
What are the cranial nerves?
- Serve sensory and motor functions of head and neck region
63
What is the structure of the spinal chord?
- long conical structure
- white matter outside, grey matter inside
64
What are the functions of the spinal chord?
- collect sensory information to be passed on to the brain
- distribute motor fibers to effector organs throughout the body
- reflexive control circuits located there
65
What are the subdivisions of the peripheral nervous system?
- somatic nervous system
- autonomic nervous system
66
What is the purpose of the somatic nervous system?
- Interacts with the external environment
- controls skeletal muscle movements
- processes sensory information relating to the outside world
67
What is the task of the afferent nerves of the somatic system?
- Carry sensory signals from eyes, ears, skin, etc. TO the CNS
68
What is the task of the efferent nerves of the somatic system?
- Carry motor signals from the CNS to skeletal muscles
69
What is the purpose of the autonomic nervous system?
- regulates the body's internal environment
- senses and regulates smooth muscles, cardiac muscles, and glands
70
What is the purpose of the afferent nerves of the autonomic nervous system?
- carry sensory signals from the internal organs to the CNS
71
What is the purpose of the efferent nerves od the autonomic nervous system?
- carry motor signals from the CNS to the internal organs
72
What are the two components of the autonomic nervous system's efferent branch?
- sympathetic division
- parasympathetic division
73
What is the sympathetic division?
- Primes the body for action
- active specifically in life threatening situations
- flight-fight-freeze
74
What are some of the impacts of the sympathetic division?
- regulates heart rate, blood flow, organ's activity rates
- can shut away bloof from organs non necessary for immediate survival and send this blood through to the organs necessary for intense physical activity
75
What is the parasympathetic division?
- supports activities that occur when the body is in a relaxed state
76
What are some of the impacts of the parasympathetic division?
- increases the body's energy stores
- feed, breed, rest, digest
77
What is neurogenesis?
Production of new neurons
78
How does neurogenesis occur?
-neural progenitor cells unergo asymmetrical cell division
79
When are neurons created?
During the first four months of gestation
80
What is apoptosis?
Process of programes cell death
81
When do neural progenitor cell undergo apoptosis?
125 days after conception
82
What structure are the neural progenitor cells present in?
the neural tube (pre-brain in the embryo)
83
When does the period of symmetrical division end in the neural tube?
40 days after conception
84
how long does the period of asymetricla division in the neural tube last?
After 85 days (125 days after conception)
85
What is the most caudal division of the brain?
Hindbrain
86
What are the structures of the Hindbrain?
- Medulla Oblongata
- Pons
- Cerebellum
87
What are the three anatomical divisions of the brain?
- Forebrain (more rostral)
- Midbrain
- Hindbrain (more caudal)
88
What ventricles are associated with the hindbrain?
fourth
89
What ventricles are associated with the midbrain?
cerebral aqueduct
90
What ventricles are associates with the forebrain?
lateral and third
91
What are the functions of the medulla oblongata?
- regulates involuntary functions
- heart rate
- blood flow
- breathing
- vomiting
- sneezing
- contains part of the reticular formation
- contains the area postrema
92
What is the area postrema?
- part of the medulla where the blood-brain barrier is very weak
- poisons detected here cause vomiting
93
What is the function of the reticular formation?
Deals with sleep and arousal
94
What are the functions of the pons?
- relays information between the cerebrum and the cerebellum
- contains part of the reticual formation
- contains the nuclei of several cranial nerves
95
What are the functions of cranial nerves?
Control what happens in the neck and face
96
What are the medulla and pons mostly constituted of?
Myelinated axons
97
Where is the reticular formation?
In the brain stem
98
What composes the brain stem?
medulla, pons, mid-brain
99
What are the roles of the cerebellum?
- motor control
- motor learning
- coordination, precision, accurate timing
- Integration of sensory and motor information
- smoothing effect on movement
- smoothing effect on cognition
100
What is the structure of the cerebellum?
The cerebellar cortex (continuous thin layer of tissue) surrounds a collection of cerebellar nuclei, that send axons out of the cerebellum.
101
What are the impacts of cerebellar damage?
- poorly coordinated, jerky, exaggerated movements
102
What are the subdivisions of the midbrain?
- Tectum (roof)
- Tegmentum
103
What is are the functions of the midbrain?
- orchestrate complex reflexive behaviours
- orienting response to sounds and lights
104
What are the components of the tectum?
- two pairs of bumps on the dorsal surface of the midbrain
- superior and inferior colliculi
105
Where are the superior and inferior colliculi situated?
on the tectum in the midbrain
106
What is the function of the superior colliculi?
- orienting the animal to things seen in peripheral vision
107
What is the function of the inferior colliculi?
- involved in orienting to unexpected sounds
108
What are the functions of the tegmentum?
- coordinate and motivate complex species-typical movements
- processing of pain
- orchestration of behavioral responses to threats
109
What are the components of the forebrain?
- cerebral cortex
- basal ganglia
- limbic system
- thalamus
- hypothalamus
110
What are the main functions of the hypothalamus?
- Regulates autonomous nervous system activity
- links the nervous system to the endocrine system
111
What does the hypothalamus control?
- critical survival behaviors: the four f's
- Basic bodily signaling: temperature, sleep-wake cycles, hunger, sex, aggression
112
What links the nervous and endocrine systems?
the pituitary gland, which is situated inside the hypothalamus
113
What are the functions of the thalamus?
- relay ascending sensory information to the cerebral cortex
- plays a role in arousal and sleep
114
What are the three types of grooves of the cerebral cortex?
- sulci
- fissures
- gyri
115
What is the general function of the cerebral cortex?
Creates a sensory representation of the world, tries to make sense of it and tries to figure out how to evolve in the world. It is the largest site of neural integration in the central nervous system.
116
What is the structure of the cerebral cortex?
- 6 layers of neurons
- presence of cortical columns
117
What are the functions of the cerebral cortex?
- attention
- perception
- awareness
- thought
- memory
- language
- decision making
- consciousness
118
What is the name of the fissure that separates the two hemispheres?
longitudinal fissure
119
What are the subdivisions of the cerebral cortex?
- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe
120
Where is taste processed?
insular cortex
121
Where is smell processed?
piriform cortex
122
What is the task of the frontal lobe?
control movement
123
What does the parietal lobe do?
processes touch information
124
What is the function of the occipital lobe?
processes visual information
125
What is the funtion of the temporal lobe?
processes auditory information
126
What separates the frontal lobe from the temporal lobe?
lateral fissure
127
What separates the frontal lobe from the parietal lobe?
central sulcus
128
What is the role of the primary motor cortex?
contains the motor neurons that synapse in the spinal chord
129
What is the role of the somatosensory cortex?
touch information first enters the cerebral cortex here
different regions of the cortex receive information from different parts of the body
130
What is the role of the primary visual cortex?
visual information first enters the cortex here
131
What is the role of the primary auditory cortex?
auditory information first enters the cerebral cortex here
132
What does a lesion in one of the primary cortexes have as an impact?
You lose your conscious link to that sense. This means that you will still have reflexes, but will not be conscious of why. It also means that you will lose all previous memories including that sense, because the neurons that safekept that information are gone.
133
What is the sensory association cortex?
The part of the brain where each primary sensory area of the cortex sends information
134
What are the functions of the sensory association cortex?
- perception
- memory
135
What is the role of the prefrontal cortex?
abstract thinking
136
What is the consequence of a lesion in the sensory association cortex?
Cannot make sense of the information, nor understand the sensory stimuli
137
Where are movements planned?
in the premotor cortex
138
How is it determined which is the area of the sensory association cortex that recevices information from which primary cortex?
Geographical proximity
139
What is the structure of the basal ganglia?
- collection of nuclei
140
What are the functions of the basal ganglia?
- regulates intentional movements
- regulates motivation
- regulates reinforcement learning
- regulates habits
141
Where do the input received by the basal ganglia come from?
- frontal lobe
- cerebral cortex
142
Where do the outputs from the basal ganglia go?
- midbrain, hindbrain, thalamus, cerebral cortex
143
How is the basal ganglia involved in reinforcement learning and habits?
- monitors your context and the actions you are taking in said context
- if the action is succesfull: reinforces the neuronal circuit
- if the action is unsuccefull: the basal ganglia punishes the "bad" neuronal circuit
144
What are the subcortical structures?
basal ganglia and limbic system
145
What composes the limbic system?
- cingulate cortex
- hippocampus
- amygdala
146
What is the cingulate cortex?
- large area that overlies the corpus callosum
- interconnects limbis areas of the brain
147
What are the functions of the limbic system?
- regulates emotion
- regulates the formation of episodic memory
148
What is the function of the hippocampus?
- formation of episodic memory
149
What are episodic memories?
- long-term memories
- involve conscious recollection of experience, context, time, place, associated, emotions
150
What is the funciton of the amygdala?
- feeling emotions
- recognizing emotions
especially active with fear
151
Where are situated the lateral ventricles?
- underneath the cerebrum
152
Where is situated the third ventricle?
- between the two thalamic nuclei
153
Where is situated the fourth ventricle?
- between the pons and cerebellum
154
Where is situated the cerebral aqueduct?
- connects the third and fourth ventricle
155
What is the choroid plexus?
- site of CSF production
- tissue that covers every ventricle
156
What is the glymphatic system?
- system that cleans up the brain, carries nutrients to the brain and brings out the waste.
- the brain's own immune system
157
What does the sympathetic nervous system prioritize?
Processes immediately necessary for survival
158
What is asymetrical division?
A progenitor cell divides, producing a progenitor cell and one neuron OR one glial cell
159
What is the central sulcus?
A little groove in the brain that divides the rostral and caudal parts of the brain
