Neuro Flashcards
vesicular transport is used for macromolecules that are too large to fit through channel or carrier
ya
ATP is required to move the cytoskeleton during phagocytosis as well as to move the phagosome into the cytoplasm
ya
how does endocytosis differ from phagocytosis?
the membrane indents instead the the cytoskeleton pushing outwards; also vesicles are much smaller in endocytosis that phago
endocytosis still requires ATP
ya
what are the two types of endocytosis?
non-selective–pinocytosis (ECF is move into the ICF); selective: receptor-mediated transport
what is the equilibrium potential?
the membrane potential that exactly opposes the concentration gradient of any ion
where is visceral sensory info integrated?
in the brainstem and spinal cord
where are special sense integrated?
at their respective cortical regions
where are somatic senses integrated?
primary somatosensory cortex
most special senses go through thalamus, and are then sent to their respective cortical regions–except olfactory sense, which is sent straight to the olfactory cortex
ya
what are the four properties the CNS distinguishes from each signal?
modality; location; duration; intensity
what is modality?
the type of stimuli–touch vs temp–>will go to a different area in the brain
what is an electrical synapse?
a synapse where positive ions flow through ion channels (gap junctions) –>no synaptic cleft
what are the glial cells found in the CNS?
ependymal cells; astrocytes; microglia (modified immune cells); oligodendrocytes
what are the glial cells found in the PNS?
schwann cells and satellite cells
what is thought to be the cause of MS?
demyelination (immune cells attack it) or inability of myelin-producing cells (oligodendrocytes in the CNS or schwann cells in the PNS) to myeline nerve fibre/axons
function of satellite cells
exist in ganglia in the PNS; support neurons, provide protection and support
what are the functions of astrocytes?
–take up and release chems at synapses; provide neurons with substrates for ATP productions; help maintain homeostasis in the ECF (take up K and H2O); surround vessel (part of the BBB & influence vascular dynamics)
what is conductance?
the ease with which ions flow through a channel–high conductance=lots of ions passing through
general info about voltage gated
selective–allow 1 ion to pass through`
where are mechanically-gated ion channels found?
sensory neurons; allow both Ca and Na to pass through
chem gated ion channels
allow K, Na, and Ca to pass through
what are the types of mutations that can lead to channelopathies?
mutations causing channel to be impermeable to ion even if it’s open; mutation causing altered channel activation; mutation in inactivation processes
movement of AP along axon is referred to as conduction of AP
ya
describe an action potential
a wave of depol reaches the axon hillock, causing voltage-gated Na and K channels to open; Na rushes into the cell, causing the membrane to depol to +30 mV, where the channels inactivate; K channels are slowly opening and allowing K to rush out of the cell; past -70 mV, the channels begin to close but K still leaves, causing membrane to hyperpol. The channels fully close and leak channels allow to K to come back in, restoring membrane potential to -70mV
ions involved in a graded potential vs AP
Na, K, Ca, Cl vs Na an K
how does the Na inactivation gate stop positive feedback cycle?
depol past -55mV causing Na channels to open, allows Na to rush in, creating more depol, which would allow more to open/stay open–> inactivation gate closes the channels to prevent Na from coming in and causing further depol
what is hyperkalemia?
excess K in the plasma; less K will leave through leak channels–>makes membrane more positive–>will be more excitable
What is hypokalemia?
less K in plasma–>more K will leave the cell, making RPM more negative–> harder to initiate an action potential
where are electrical synapses located?
in some CNS neurons, cardiac muscle, smooth muscle
where are chem synapses located?
in the majority of neurons in the NS
what is a neurocrine?
a chem substance released from neurons to be used in the cell-cell communication; neurohormone, neurotransmitter, neuromodulator
what is a neurotransmitter?
a chemical that is released by the presyn cell and acts on the post syn cell (inclose vicinity) causing a FAST response in the post syn cell
what is a neuromodulator?
similar to neurotrans but causes a SLOW response in the post syn cell
what is a neurohormone?
a chemical released into the blood and act on targets in the body
a neuromod in one cell can act as a neurotrans in another, depending on the receptors present
ya
describe the two types of neurocrine receptors
ionotropic receptors–ligand/chem gated ion channels; ligand binds, causes conformational change, allows either 1 cation or multiple types of cations through; mediate fast postsyn responses
metabotropic receptors: GPCR; ligand binds to metabotropic receptor which leads to a GPCR response; –>can interact directly with ion channels or activate membrane bound enzymes; involved in slovwer postsyn response
where are large peptide neurotrans synthesized?
in the soma, transported via fast axonal transport to the axon terminal
where are small neurotransmitters synthesized?
right at the axon terminal and packaged there too, from vesicles from soma or recycle vesicles (enzymes for synthesis brought to terminal by slow axonal transport)
subthreshold graded potentials can generated APs by summating either spatially or temporally
ya
what is an axo-axonic synapse?
a synapse wehre the presyn cell synapses on the axon instead of the dendrite of the post-syn cell
desribe presynaptic inhibition and facilitation
presyn inhib: prevents as many neurontrans from being released; facil: allows more neurotrans to be released
what does the size of receptive field depend on?
number of primary receptors and the convergence of the primary receptors onto secondary receptors
location of stimulus–coded based on what receptive fields are being stim; most sensory stimuli for specific regions of the body are projected to specific areas in the somatic sensory cortex–except for sound; localized based on which ear’s mechanoreceptor/hair cells are stimulated first
ya
what is lateral inhibition?
when large APs inhibit other, less-stimualted secondary receptors via axo-axonic inhibition–helps brain in pinpointing location of stim
tonic response
continues to generate APs as long as the stim is applied–slowly adapting
phasic response
quickly adapt and do not generate APs for the length of the stim
the hypothal, medulla, and pons, initiate autonomic, endocrine, and behavioural responses
ya
autonomic system works closely with endocrine and behavioural systems to maintain homeostasis
ya
what is the sympathetic system?
fight-or-flight
what is the parasympathetic system?
rest or digest
self-contained neurons in the autonom ganglia can act as mini integrating centres
ya
where are the sympathetic autonom ganglia found?
in two chains running alongside the vertebral column
where do sym preganglionic neurons originate?
in the thoracic and lumbar regions
symp pre and postganglionic neurons
short pre, long post
parasymp ganglia
originate in brainstem and exit via cranial nerves or from sacral region of spine; long pre, short post; vagus nerve (cranial nerve x) contains 75% of all vagus nerves
what is the the synapse between an autonomic neuron and tissue?
neuroeffector junction
what do autonomic pathways target?
smooth and cardiac muscle, many exocrine glands, a few endocrine glands, lymphoid tissue, and some adipose tissue
autonomic ganglia swell near target tissue–>create varicosities–>neurotrans leave, diffuse to receptors
ya
acetylcholine and NE can be synthesized in the varicosities
ya
NE diffuses out of syn cleft or is taken back up into the varicosity; Ach is broken down to Acetate + choline and choline is taken up while acetate diffuses into postsyn cell
ya
