General concepts of neurobiology

28 important questions on General concepts of neurobiology

What is potential difference?

-E
-difference in voltage between 2 points

What is the definition of membrane potential and how does this process works?

-Vm, the difference in voltage across the plasma membrane
-voltage inside the cell relative to the voltage outside the cell

What is a graded potential?

small change in the membrane potential produced by some type of stimulus that triggers the opening/closing of ion channels
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What is a synaptic potential?

Graded potential produced in the post-synaptic cell in respons to neurotransmitters binding to receptors

What is a receptor potential?

graded potential produced in respons to a stimulus action on a sensory receptor

What is an action potential?

a large rapid change in the membrane potential produced by depolarization of an excitable cell's plasma membrane to threshold

A graded potential can be decremental or depolarization. what do they mean?

-decremental: signal weakens by diffusion throughout and leakage through cell membrane
-depolarization: bring the membrane potential closer to the threshold to generate an action potential -> hyperpolarization = kuiltje, depolarization = bolletje

What is the all or none principal of an action potential?

amplitude of AP does not change, only generated the the threshold is reached.
always the same magnetude of +30mV

What is the definition of a threshold?

a stimulus must depolarize the membrane potential up to a critical level to have generation of an AP

What are the 2 refractory periods and what do they mean?

refractory period: after een AP temporary inactivation of Na+ channels
-absolute refractory period: impossible to generate AP, Na+ channels closed
-> stage 1/2/3 of AP

-relative refractory period: some Na+ channels closed, K+ channels starting to close -> lead to repolarization/hyperpolarization
-> stage 4 of AP

What are the 4 stages of the action potential?

1. resting state
2. depolarization, na+ channels open (bolletje)
3. repolarization, na+ inactivating, K+ channels opens
4. hyperpolarization, k+ channels opens, na+ resetting (kuiltje)

When a domino effect of an AP leads to electrochemical gradient in the extra- and intracellular fluid leads to low resistance we are talking about:

propagation of an action potential

Are action potentials in myelinated axons the same as in unmyelinated axons?

no, myeline isolates. the AP goes directly to the 'node of Ranvier' (space between the myeline)

What is a electrical synaps?

plasma membranes of cells are linked by gap junctions for fast conduction, bidirectional

What is a chemical synaps in relation to neurotransmitters?

one neuron secretes a neurotransmitter into the extracellular fluid in respons to an AP arriving at its axon terminal. the neurotransmitter binds to receptors on the plasma membrane of the second cell. this leads to an action potential

What are chemicals released into interstitial fluid by neurons and released from the axon terminal?

neurotransmitters

What is an ionotropic receptor?

fast respons, channel linked receptor. it opens the ion channel, allowing one or more specific ions to permeate the plasma membrane and change the electrical properties of the post synaptic neuron

What is a metabotropic receptor?

slow respons, G-protein linked receptors.
triggers the opening/closing of ion channels, depending on the specific synaps

Where is acetylcholine released from?

neurons in the central and peripheral nervous system and it is synthesized in the cytosol of the axon terminal of neurons

What are (fast/slow) excitatory synapses in the central nervous system and what is released?

-depolarizes postsynaptic membrane
-fast: opening na+ channel, fast influx na+
-slow: activation via G-protein, closure k+ channel, decrease K+ efflux
- neurotransmitter glutamate is released (bind 3 main classes of receptors)

What are inhibitor synapses in the central nervous system and what is released?

-hyperpolarizes postsynaptic potential (IPSP)
-decreases change of generating action potential
-neurotransmitter GABA is released

What are neuropeptides and what are 2 examples?

-short chains of amino acids that are synthesized in the same manner as proteins
-vasopressin: regulates urine output by the kidney
-oxytocin: regulates contractions of the uterus and the flow of milk from the breasts

What is the difference between divergence and convergence in neural integration?

by divergence a single neuron communicates to several other neurons and by convergence a single neuron receives communication from other neurons

What is postsynaptic modulation?

the sum of all signals, derived from multiple synaps

There are 2 types of summation, spatial and temporal summation. what is the difference between these 2?

temporal: 2 or more post synaptic potentials are generated in rapid succesion at the same synaps, such that a postsynaptic potential does not have time to fully dissipate before the next one is generated

spatial: 2 or more post synaptic potentials originating from different synapses are generated at the same time, such that when they spread to the axon hillock, they overlap and sum

What are presynaptic facilitation and inhibition by neural integration?

facilitation: activating modulation neuron enhances synaptic transmission
inhibition: activating modulation neuron inhibits/decreases synaptic transmission

What are Glial Cells?





-the second class of cell found in the nervous system, account for 90% of all cells in the nervous system.
-Their main functions include providing structural integrity to the nervous system (glia is Latin for “glue”) and chemical and anatomical support that permits neurons to carry out




their functions. Recent studies suggest that glial cells may also play important roles in intercellular communication.

What are 4 types of glial cells?

-astrocytes, microglia, oligo- dendrocytes, and Schwann cells.
->only Schwann cells are located in the peripheral nervous system, the rest are found in the central nervous system
-the functions of oligodendrocytes (forming myeline sheet in CNS) and Schwann cells (or neurolemmocytes, forming myeline sheet around axons) are crucial to electrical transmission in neurons

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