Final neurobiology Flashcards by sophia rahman

lays down myelin around some axons

oligodendrocytes

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Specialized macrocyte cells in the brain that remove myelin and cellular debris

microglial cells

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maintain an appropriate chemical environment

astrocytes

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nerve cell bodies that reside in the PNS

ganglia

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bundles of peripheral axons

nerves

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local accumulations of neurons that have roughly similar connections and functions

nuclei

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sheet like arrays of nerve cells

cortex

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gathering of CNS axons

tracts

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tracts that cross the midline of the brain

commissures

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what his the resting (membrane) potential and what is the ionic basis underlying it

The resting membrane potential is largely determined by the K+ selective permeability and K+ concentration gradient

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Below is the Nernst equation for the electrochemical equilibrium of a permeant ion. Eion is the equilibrium potential (measured in units of mV) generated by the permeant ion across the membrane at electrochemical equilibrium; [ion]out and [ion ]in are permeant ion’s concentration outside and inside the cell. z is the electrical charge of the permeant ion (2 for Ca2+). Log10 = 1, Log100 = 2, Log1000 = 3, Log1/10 = -1, Log1/100 = -2, and Log1/1000 = -3. If a neuron has 10 mM Ca2+ inside the cell and 10000 mM Ca2+ outside the cell, the equilibrium potential of Ca2+ for this neuron would be? Eion = 58/Z log ion out/ion in

+87 mV

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A neuron’s resting potential is -65 mV and the threshold potential is -40 mV. The equilibrium potential for Na+ (ENa) of this neuron is +70 mV. You use a voltage clamp method to inject positive currents into a neuron at the resting potential to depolarize the membrane potential by 40 mV. The membrane potential for the neuron is now clamped at?

specific value -65 mV + 40 mV = -25 mV.

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A transient increase in Na+ conductance causes Na+ to enter the neuron and quickly depolarizes the membrane potential (PNa+↑).
Depolarization slowly activates the voltage‐dependent K+ conductance, causing K+ to leave the cell and repolarizing the membrane potential (PNa+↓ & PK+↑↑).
Undershoot: the K+ conductance becomes temporarily higher than it is resting, (hyperpolarization, PK+↑↑). Hyperpolarization causes the voltage‐dependent K+ conductance to turn off, and the membrane potential returns to the resting potential (PK+↑).
Refractory period: following an action potential, the axon becomes refractory to further excitation for a brief period.

reconstruction of action potential

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Which protein molecule generates sodium and potassium ion concentration gradients across neuronal membranes?

Sodium-Potassium ATPase Pump

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An action potential depolarizes the presynaptic axonal terminal.
Depolarization leads to the opening of voltage‐gated calcium channels.
The influx of Ca2+ allows synaptic vesicles to fuse with the presynaptic membrane.
Neurotransmitter is released into the synaptic cleft via exocytosis.
The neurotransmitters bind to receptors in the postsynaptic membrane, causing channels to open or close.
Neurotransmitter‐induced postsynaptic current increases or decreases the probability that the postsynaptic cells will fire an action potential (the excitability).

sequence of events involved in chemical synaptic transmission

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If the reversal potential is more ______ than the threshold potential then it is excitation

positive

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if reversal is more negative than threshold potential then it is _____

inhibitory

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-45 mV – (-65 mV) = 20 mV
EPSPs + IPSPs need to be greater or equal to 20 mV. 10mV – 4mV – 3mV + 15 mV = 18 mV

18 mV < 20 mV, so the neuron would not fire an action potential

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Enzymatic degradation (3)

Acetylcholine, Substance P, and Opioid Peptides

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Uptake through transporters (4)

Glutamate, GABA, Dopamine, and Serotonin

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ionotropic NT

Nicotinic acetylcholine receptor
AMPA
NMDA
P2X receptors

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Metabotropic NT

-Muscarinic acetylcholine receptor
-dopamine receptor
-α-adrenergic receptors
-β-adrenergic receptors

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ii. Peptide transmitters are made as propeptide precursors and packed in large dense-core vesicles
iii. Propeptides can give rise to more than one species of active neuropeptides.
iv. Peptide transmitters typically elicit complex postsynaptic responses

Understand synthesis and processing of peptide transmitters and they are packed in which types of vesicles?

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The mechanism for short-term synaptic depression

Depletion of the presynaptic vesicle

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what is the common btw LTP and LTP

both remove or internalize AMPARs from the surface

Differences between LTD:

Cerebellar: 1. uses kinases 2. coincidence detector: activation of mGluR + VCa2+ synapses Hippocampal: 1. uses phosphates 2. coincidence detector: NMDAR

How do receptor potentials encode the intensity of stimuli?

Receptor potential is grade so their amplitude will be correlated with their intensity (increase in amplitude with increasing intensity of the stimulus)

Senses mediated by dorsal root ganglion neurons

Touch, proprioception, nociception, and thermoception (heat or cold)

sense points

Merkel cells

sense skin motion

messiner corpuscles

sense vibration

pacinian corpuscles

cutaneous stretching

Ruffini corpuscles

the primary somatosensory cortex has _____ _____ that does not reflect

disproportional somatotopy

The neurons in the Primary SSC will cluster together to form _____ _____ _____

functional distinct columns

lesions to which area will cause the most severe deficit in primary somatic sensory cortex

C fibers convey what type of pain, 1st or second

second

injury to one side then the patient will lose tactile sensation and proprioception on that same side but will lose nociception on the opposite side of the injury.

Dissociated Sensory loss

convey a sharp pain first

A epsilon

-mediates tactile sensation and proprioception -is the axon bundle of the dorsal root ganglia neuron running in the spinal cord

dorsal column

-mediates nociception - pain -axon bundle of dorsal horn neurons in the spinal cord

anterolateral column

1) Photoreceptors absorb a photon of light and change 11-cis retinal to all-trans isomer. 2) Conformational change of rhodopsin leads to activation of transducin (Gt) 3) Transducin activates a phosphodiesterase that hydrolyzes cGMP 4) Lowering of cGMP concentration in the outer segment 5) cGMP-gated channel closure and hyperpolarization of the cell

The sequence of events of phototransduction

low acuity + scoptic vision

rod

-specialized for acuity -phototopic vision

cone

The spatial arrangement of different sounds and different frequencies are processed in different regions of the auditory system

tonotopy

what is the mechanoelectrical transduction: the process by which hair cells convert mechanical energy from sound waves to electrical signals what its the sequence for mechanical transduction

1. displace of the hair 2. opening (MET) channel 3. K+ influx generates a graded receptor potentiation to depolarize the hair cell (HAIR CELLS DO NOT FIRE ACTION POTENTIALS) 4. depolarizing + opening of VGIC Ca2+ and transmitters release

liner acceleration

otolith

rotational acceleration

semicircular canal

The olfactory system does require a thalamic relay from the receptor neurons to the pyriform cortex True or false

False it does NOT require thalamic relay

i. Odorant receptor proteins are encoded by the odorant receptor gene family ii. Each of the olfactory receptor neurons expresses only one of the two copies of the odorant receptor genes iii. Most mammalian olfactory receptor neurons express only one odorant receptor gene) **** iv. Odorant receptor proteins are G‐protein‐coupled receptors v. Odorant receptor proteins are found at the highest concentration in the olfactory cilia of the olfactory receptor neurons

odorant receptor proteins

1) Alpha subunit of Golf dissociates upon odorant binding to receptors 2) Activation of adenyl cyclase III (ACIII) 3) An increase in cAMP opens cAMP‐gated channels that permit entry of Na+ and Ca2+ 4) Depolarization is further amplified by Calcium‐activated Cl‐ channels 5) Action potential are generated via voltage‐gated sodium channels

The Sequence of events of odor transduction

TRPM5 channel is involved in sensory transductions for

sweet, bitter, and umami tastes

Sensory Epithelia for Visual

retina

Sensory Epithelia for Auditory

Organ of Corti

Sensory Epithelia for Otolith organs (Utricle and Saccule)

Macula

Sensory Epithelia for semicircular canals

crista

Reflex movement is the movement that does or doesn't involve Cortical upper motor neurons.

DOESNT

Cell types involved in reflex movements

Cells involved in reflex movements are sensory neurons, lower motor neurons, interneurons, brainstem upper motor neurons

-gradual increases in muscle tension (or force) results from the progressive recruitment of motor units in a fixed order (S → FR → FF), according to their size. --Low threshold S motor units are recruited first, then FR motor units, and finally, at the highest levels of activity, the FF motor units

Size principle

maintain muscle length at a desired level

muscle stretch reflex

maintain muscle tension (force) at a desired level

Autogenic Inhibition Reflex

without sensory feedback or descending UMN inputs

Central Pattern Generator

generates a feedback response to stabilize posture after existing unanticipated postural instability

Vestibulo-Spinal Reflex

generates a feedforward response to stabilize posture to anticipated postural instability.

Reticular Formation

control the orientating head and eye movement

Superior Colliculus

encode intentions for movements in central personal space

UMNs Primary Motor Cortex

encode ***intentions for movements that are oriented toward extra personal space (***beyond arm’s length)

UMNs Premotor Cortex

initiate feedforward voluntary adjustments that stabilize posture to anticipated postural instability

UMNs Reticular Formation

The corticospinal tract is the axons of the UMNs in the motor cortex, which descend through the ____ white matter and terminate in _______ spinal cord

lateral; contralateral

A subset of UMNs in the premotor cortex fire when an animal observes and performs a particular movement

What are mirror motor neurons

What are the four major parts of the basal ganglia

i. The corpus striatum ii. The globus pallidus iii. The substantia nigra iv. The subthalamic nucleus

HYPOKINETIC (difficulty in expression of movement) movement disorder CAUSED by the loss of the dopaminergic neurons in substantia nigra pars compacta

parkinson's disease

Loss of _____ input → increased indirect pathway and diminished direct pathway → more tonic inhibition of thalamus → decreased excitation of motor cortex UMNs → reduced voluntary movement.

dopaminergic

Medium spiny neurons that project to the external globus pallidus degenerate

Huntington's disease

Cortical inhibitory loop is formed by _____ _____ cells that provide the only output from the cerebellar cortex

GABAergic Purkinje

formed by deep cerebellar nuclei neurons

Deep excitatory loop

Parallel fiber pathway conveys the main inputs and functions to _____ ____

correct motor errors for ongoing movements

Climbing fiber pathway convey the modulatory input and functions to encode

motor learning and memory

the folding process of ectoderm to develop the neural tube

Neurulation

the single‐layered blastula is reorganized into a multilayered structure known as the gastrula

Gastrulation

Prosencephalon

cerebral cortex, hippocampus, basal ganglia, thalamus and hypothalamus

midbrain tegmentum, superior colliculi

Mesencephalon

cerebellum, pons, and medulla

Rhombencephalon

dorsalizing signals to regulate specification of the neural tube and differentiation of dorsal part

BMP

secreted from notochord to block BMP signaling for neural induction

Noggin and Chordin

ventralizing

Sonic Hedgehog

neuronal differentiation during neurogenesis by regulating neural stem cell decisions to generate either additional stem cells or postmitotic neurons

Delta/Notch

What are the two major functions of radial glial cells in the developing CNS?

* Acting as migratory guides * They are neuronal progenitor (stem) cells in the developing cortex

regulate neuronal polarization

Par

axon guidance chemoattractant

Netrin

non-diffusible axon guidance molecules and constitutes cell-cell recognition codes

Eph/ephrin

1. Neurite outgrowth or retraction 2. Synapse stabilization or elimination for activity‐dependent plasticity 3. Cell survival or death

Neurotrophins

Neurotrophins receptors

1. Tyrosine kinase (Trk) receptors 2. P75 receptor

* Explain the cellular basis of the experience-dependent modification of neural circuits * Suggests that synaptic contacts between co-activated pre- and postsynaptic neurons will be strengthened and strengthening of synaptic connections * Strengthening of synaptic connections can be reflected in sprouting of new branches * Uncorrelated activities between pre- and postsynaptic neurons result in loss of synaptic connections

Hebb’s postulate

The temporal window when experience and the resulting neural activity have a maximal effect on the circuit connectivity and the acquisition or skilled execution of a particular behavior

critical period

key players of activity-dependent plasticity during the critical period?

Neurotransmitter receptor (NMDA receptor), CREB transcription factor, kinase, intracellular Ca2+, and neurotrophins

distinct anatomical and functional arrangement of neurons within the primary visual cortex of the brain.

Ocular dominance column

the column for the deprived eye becomes narrower, while the column for the intact eye becomes wider

monocular deprivation

early deficiencies of sensory experience (4)

ADHD, Autism, Amblyopia, and Schizophrenia

What is the underlying reason for improved functional recovery after mammalian CNS damage

Reorganization of intact undamaged circuits rather than the regrowth or replacement of damaged neurons

Describe the sequence of events during peripheral nerve regeneration

1. The distal portion of the injured axon degenerates. 2. Macrophage phagocytoses myelin and axonal debris. 3. Schwann cells proliferate and secrete molecules to guide and stimulate regeneration. 4. Injured neurons transform the proximal segment of the injured axon into a growth cone, express growth-related genes, and increase protein trafficking. 5. Axon regrows to the target.

the process that all three types of glial cells (astrocytes, oligodendroglia, and microglia) are activated by proliferation and hypertrophy in response to the CNS injury

Reactive Gliosis

formed by astrocytes prevents axon growth + physical barrier that inhibits axon growth

glial scar

What are the factors that inhibit the regrowth of CNS axons after injury

a) glial scar b) Chemorepellents c) Extracellular matrix components d) Myelin‐associated inhibitors

What are the two neurogenic areas in the adult mammalian brain?

Subventricular Zone (SVZ) and Subgranular Zone (SGZ)

Final neurobiology Flashcards

(104 cards)