Lecture 6: Brain Anatomy ll & Neurotransmitters Flashcards
neural tube
a hollow enclosed tube that forms in the first weeks of embryonic development
neural progenitor cells
make up the neural tube
cell division of neural progenitor cells
asymmetrical cell division starts 40 days after conception and occurs over the next 85 days. by day 125, there are over 100 billion neurons in the human brain.
when do humans have the most neurons
125 days after conception
neurogenesis
the production of new neurons
when does neurogenesis stop?
4 months after conception
apoptosis
a process of programmed cell death that occurs in multicellular organisms. ensures a dying cell doesn’t cause problems for its neighbours
when do human neural progenitor cells undergo apoptosis?`
125 days after conception
the midbrain
a colleciton of nuclei that orchestrate complex reflex behaviour
what ventricle is the midbrain found in
the cerebral aqueduct
two major parts of the midbrain
the tectum & the tegmentum
the tectum
appears as two pairs of bumps on the surface of the brain (the superior colliculi and the inferior colliculi)
the superior colliculi
the two top bumps of the tectum that is involved in peripheral vision
the inferior colliculi
the bottom two bumps of the tectum that are involved in orienting to unexpected sounds
the tegmentum
part of the midbrain. includes several structures that coordinate and motivate complex species-typical movements. some areas of the tegmentum process pain and orchestrate responses to threats
parts of the forebrain
the hypothalamus, thalamus, limbic system, cerebral cortex, and basal ganglia
the role of the hypothalamus is similar to that of what hindbrain structure
medulla
the role of the thalamus is similar to the role which hindbrain structure
pons
the role of the cerebral cortex is similar to that of what hinbrain structure
cerebellum
the hypotalamus and thalamus are found in which ventricle
3rd
the limbic system, cerebral cortex, and basal ganglia are found in which ventricle
lateral ventricles
hypothalamus function
a bilateral structure made up of several nuclei that regulate the autonomic nervous system activity. critically involved in the 4 Fs (feeding, fighting, fleeing, fucking)
hormone
chemical substance that is released by an endocrine gland and that has effects on target cells in other organs
endocrine gland
secretes chemical signals (hormones) into the bloodstream. much of the endocrine system is controlled by hormones produced by cells in the hypothalamus
pituitary gland
master hormone gland
thalamus function & location
bilateral structure that is divided into several nuclei that relay sensory information to different regions of the cerebral cortex. found above the hypothalamus
what is the cerebrum
term referring to the cerebral cortex, basal ganglia, and limbic system.
where is the cerebrum found?
in the lateral ventricles
what is the cerebral cortex made of?
multi-layered structure with interconnected neurons between layers to give rise to cortical columns which are thought to be partially distinct functions
what animal’s cerebral cortex is made of nuclei?
birds
what is the stie of neural integration in the CNS?
cerebral cortex
cerebral cortex function
attention, perception, awareness, thought, memory, consciousness, decision-making
gray matter
the outermost portions of the cerbreal cortex where the cell bodies are
white matter
the part beneath the gray matter that has a large concentration of myelinated axons
sulci
small grooves
fissures
large or major grooves
gyri
ridges between sulci or fissures
longitudinal fissure
large groove that separates the two hemispheres
lateral fissure
large groove that separates the frontal lobe from the temporal lobe
central sulcus
provides a good landmark separating the rostral and caudal divisions of the cerebral hemisphere
corpus callosum
a large band of axons that connects the corresponding parts of the association cortex to the right and left hemispheres
4 lobes of the cerebral cortex
frontal, parietal, occipital, temporal
frontal lobe function
controls movement
parietal lobe function
processes touch information
occipital lobe
processes visual information
temporal lobe
processes auditory information
insular cortex
located in the lateral fissure. processes taste
piriform cortex
located in the lateral fissure. processes smell
primary motor cortex
in the frontal lobe. contains the motor neurons that synapse in the spinal cord
somatosensory cortex
in the parietal lobe. where touch information first enters the cerebral cortex
primary visual cortex
in the occipital lobe. where the visual information first enters the cerebral cortex
primary auditory cortex
in the temporal lobe. where the auditory information first enters the cerebral crotex
insular cortex
hidden in the lateral fissure. where gustatory information first enters the cerebral cortex
sensory association cortex
where each primary sensory area sends information. perception takes place there and memories are stored there
basal ganglia
a collection of nuclei in the forebrain that regulates intentional movements, motivation, reinforcement learning and habits
limbic system functions
important for emotions and episodic memroies
3 components of the limbic system
hippocampus, amygdala and cingulate cortex
hippocampus
crucial for explicit and memory formation
amygdala
important for feeling and recognizing emotions
cingulate cortex
a large area that overlies the corpus callosum. This region interconnects many limbic areas of the brain
what are conventional neurotransmitters made of
amino acid derivatives
how are conventional neurotransmitters synthesized
locally synthesized in axon terminals
how are conventional neurotransmitters secreted?
Are usually secreted from small synaptic vesicles that dock very close to the site of Ca2+ entry in the axon terminal
what types of receptors do conventional neurotransmitters activate?
ionotropic and metabotropic
glutamate
main excitatory neurotransmitter (because all ionotropic glutamate receptors let sodium in). it reduces excitatory post-synaptic currents (EPSCs) and membrane depolarization
gaba
main inhibitory neurotransmitter (because all ionotropic GABA receptors let chloride in). it induces inhibitory post-synaptic currents (IPSCs) and membrane hyperpolarization
neuromodulator types
Dopamine, norepinephrine, acetylcholine, serotonin
differences between neuromodulators and gaba/glutamate
neuromodulators primarily act on metabotropic receptors and tend to exert more fo a modulatory influence on postsynaptic cell activity (rather than causing EPSPs or IPSPs)
t or f: more than 99% of neurons release either glutamate or gaba
true
glutamate agonists examples
often cause seizures and excitotoxitiy (ex. kainic acid, NMDA(
glutamate antagonists examples
dissociative anesthetics (ketamine, PCP)
GABA antagonists
often cause seizures
GABA agonists
anesthetics, anticonvulsants, muscle relaxants, sleeping pills, alcohol, anti-anxiety medication
how are neuromodulators made
in a small colection of neurons that send their axons out widely
t or f: neuromodulators are classical neurotransmitters
true
where are the neurons that make neuromodulators located?
in the midbrain and the hindbrain
what are the receptors for neuromodulators
mostly g-protein coupled receptors, not ion channels
acetylcholine
attention and memory
dopamine
fine motor movements
serotonin
mood and depression
noradrenaline
attention and cognition
neuropeptides
type of neurotransmitter. short string of amino acids, synthesized in the cell soma. are secreted from large vesicles
synaptic recycling in neuropeptides
does not occur
what type of receptor do neuropeptides activate
metabotropic
lipid-based signalling molecules
type of neurotransmitter synthesized and released on demand as needed. are secreted in a non-vesicular manner, typically for postsynaptic neurons.
what type of receptor do lipid-based signalling molecules activate
metabotropic
creation and recycling of classic neurotransmitters
all classic neurotransmitters get manufactured in axon terminals. the necessary enzymes float around freely in the axon terminal. after a neurotransmitter is made, it gets packaged into vesicles by transporter proteins which are on the membranes of synaptic vesicles
monoamines
serotonin, dopamine, and norepinephrine. they all have similar chemical and 3D structures and the protein that packages them into synaptic vesicles is the same (VMAT)
2 subcategories of monoamies
catecholamines and indoleamines
catecholamines
dopaine and norepinephrine
indoleamines
serotonin
agonist
increase of a particular neurotransmitter
antagonist
decrease of a particular neurotransmitter
how could you artificially widen (slow down) the action potential?
infusing a voltage-gated channel antagonist (by not bringing the action potential back to rest via the potassium channel, it will take longer)
if a mutation targeted to the DNA that codes for amino acids located in the pore of the voltage-gated potassium channel might be used to test ____
whether these amino acids are important fo the channel’s selectivity
ionotropic receptors are gated by what
ligands
what directions do ionotropic receptors go in?
multidirectional
what are ionotropic receptors made of?
strings of amino acids encoded by DNA
what are metabotropic receptors?
strings of amino acids encoded by DNA
nitrogenous bases creates
DNA
amino acids make
protein
where is the blood-brain barrier most permeable?
in the area postrema, which allows you to respond to toxic chemicals via vomiting
when/ where is cerebrospinal fluid made?
always being produced by choroid plexus (a tissue that is found in each brain ventricle)
what division of the PNS has affrent and efferent signalling?
trick quesiton: both of em do (somatic and autonomic)
