Bypsych (4.1, 4.2, 4.3, 4.4) Flashcards
What is the value of the resting potential?
-70mv (polarised state)
The name of the electrodes used at a cell level?
Microelectrodes
What does the plus signs of the ions indicate?
The ion carry a single positive charge.
What ions are mostly outside and inside?
NA mostly outside, K mostly inside
What are the specialized pores thorough which ions go?
Ion channels
How do you describe electrostatic pressure?
Opposites attract
What is the second factor that influences ion distribution?
Random motion for Na to move down their concentration gradient
What channels are open in resting state?
K channels
Who discovered the sodium-potassium pump?
Hodgkin and Huxley
What is the quantity distributed by the sodium-potassium pump?
For 3 ions of Na out, 2 ions of K in
The firing of neurons releases chemicals at their button terminals called?
Neurotransmitters
What are the two effects of neurotransmitters?
Depolarization or hyperpolarization
An action potential is elicited when the depolarization of the neuron reaches?
The threshold of excitation (-65mV)
What are the two characteristics of the transmission of postsynaptic potential?
It’s rapid and decremental
Where is the action potential generated?
Axon initial segment
What is a graded response?
If the signal is weak, the postsynaptic potential is small and vice versa
Action potentials are not graded responses, they are?
All or none responses
What is called the adding or combining a number of individual signal into an overall signal?
Integration
What are the two types of integration?
Spatial and temporal summations
Axoni nemielinizați sau…
Amielinici
Conducerea poate fi de 4 feluri
Continuă/saltatorie, pasivă cu decrement, activă fără decrement (pa)
Ce este conductanța selectivă?
Membrana are o permisivitate ridicată față de anumiți ioni: gK>gNa
Care e raportul dintre gradientul de concentrație și presiunea electrostatică?
Gradientul de concentrație mai puternic decat presiunea electrostatică.
Ce se întâmplă cu neurotransmițătorii după potențialul de acțiune?
Astrocitele îi reintroduc în butonii terminali.
What is overshoot?
Se închid cananlele de Na
What does it mean a graded response and who has this capacity?
Only EPSP and IPSP are graded responses which means that the amplitute of them is proporitonal to the signal that elicits them
If EPSP and IPSP are graded responses, then AP are…
all or none respone
Do ESPS and IPSP travel all the way on the axons?
No, only few of them manage to travel very far along an axon
WHat does substantia nigra produce?
A chemical called dopamine
How do you explain hyperpolarisation?
The K channels are gradually closing so there is still a constant efflux of K
How are reestablish the resting ion concentrations next to the membrane?
The random movement of the ionsș
What is the absolute refractory period?
A period of 1 to 2 milis after the initiation pf an AP during which is impossible to elicit a second one
What is the relative refractory period
A period after the absolute refractory period in which another ap can be determined if the stimulus is bigger than usual
What consequences does the relative refractory period have?
AP travelling in only one direction+ the rate of neural firing is related to the intensity of the stimulation
How do you call the way of a signal going from the axon to the cell body?
antidromic conduction, opposite of orthodromic conduction
Where are the sodium channels?
In the nodes of Ranvier
What is the maximum velocity of conduction in human motor neurons?
about 60 m/s
FUN FACT
Many of the neurons in mammalian brains have no axon or small axons and many of them do not normally display ap
What are the properties of cerebral neurons that are not found in motor neurons
1.Many cerebral neurons fire continually even when they receive no input
2.Axons of some cerebral neurons can actively conduct both graded signals and action potentials
3.Action potentials of diff classes of cerebral neurons vary greatly in duration, amplitude and frequency
4.Many cerebral neurons do not display ap
5. The dendrites of some cerebral neurons can actively conduct action potentials.
In which case of synapses do you find varicosities and how are the synapses called bcs of that?
Nondirected synapses, string-of-beads synapses
Where are small-molecule neurotransmitters synthetized?
The cytoplasm of the terminal button and packaged in synaptic vesicles by the button’s Golgi complex
Where are neuropeptides assembled?
In the cytoplasm of the cell body on ribosomes, and are transported by microtubules- they don’t gather as closely tot he presynaptic membrane as the other nt do.
What is coexistence?
The fact that many neurons contain two neurotransmitters
What is exocytosis?
The process of neurotransmitter release
What is a receptor
A protein that contains binding sites for only particular neurotransmitters
What is a ligand?
Any molecule that binds to another is referred to as its ligand
What is a receptor subtype?
The different type of receptors to which a particular neurot can bind
An advantage of the receptor subtype?
THey enable one neurotransmitter to transmit different kinds of messages to different parts of the brain
Potassium influx determines inhibition or exhibition?
inhibition
The G protein determines the synthesis of a second messenger which…
diffuses through the cytoplasm and for ex enter the nucleus and bind to the DNA and influencing genetic expression
One special type of metabotropic receptor?
Autoreceptor
What do autoreceptors do?
THe bind to their neuron’s own neurotransmitter molecules adn they are located in the presynaptic membrane. They monitor the number of neurotransmitter molecules in the synapse to reduce subsequent release when levels are high or increase when they are low
What is the role of the transporter mechanisms?
Taking back neurotransmitters in the presunaptic buttons
What are enzymes?
Proteins that stimulate or inhibit biochemical reactions without being affected by them
What’s the role of astrocytes in synaptic transmission?
Release chemical transmitters, contain receptors for neurotransmiters, to conduct signals, to influence synaptic transmission
What are gap junctions?
Narrow spaces between adjacent cells. SOmetimes called electrycal synapses
Unlike neurons, astrocytes are distributed…
evenly throughout a particular area
Amino acids are known for…
Fast-acting in directed synapses
Monoamines are synthetisized from
A single amino acid
Monoamines are then divided into two categories
Catecholamines and indolamines
Catecholamines are…
Dopamine Ephinephrine and Norepinephrine
Indolamines are…
Serotonin
Unconventional neurotransmitters are…
Soluble gases (nitric oxide and carbon monoxide)
Endocannabinoids (anandamide)
What are the five categories of neuropeptides?
Pituitary peptides, Hypothalamic peptides, Brain-gut peptides, opioid peptides, miscellaneous peptides
What are agonists?
Drugs that facilitate the effects of a particular neurotransmitter
What are the two acetylcholine receptors and what are they’re meaning
A receptor can respond to multiple neurotransmitter, nicotinic receptors (ionotropic) and muscarinic receptors(metabotropic)
Morphine is part of
Opium as a major psychoactive ingredient, is addictive
Endogenous means
Occurs naturally in the body
Enkephalins means
In the head
