week 5 - neurons Flashcards
neuron
Neurons - brain cells
dendrite
Dendrites - part that extends away from the cell body and is the main input to the neuron
soma
Soma - Cell body of a neuron that contains the nucleus and genetic information, and directs protein synthesis.
nucleus -
Nucleus - Collection of nerve cells found in the brain which typically serve a specific function.
axon
Axon - Part of the neuron that extends off the soma, splitting several times to connect with other neurons; main output of the neuron.
synapse
Synapse - Junction between the presynaptic terminal button of one neuron and the dendrite, axon, or soma of another postsynaptic neuron.
myelin sheath
Myelin sheath - Substance around the axon of a neuron that serves as insulation to allow the action potential to conduct rapidly toward the terminal buttons.
terminal button
Terminal button - The part of the end of the axon that forms synapses with postsynaptic dendrite, axon, or soma.
spines
Spines - Protrusions on the dendrite of a neuron that form synapses with terminal buttons of the presynaptic axon.
synaptic gap
Synaptic gap - Also known as the synaptic cleft; the small space between the presynaptic terminal button and the postsynaptic dendritic spine, axon, or soma
synaptic vessels
Synaptic vessels - Groups of neurotransmitters packaged together and located within the terminal button.
neurotransmitters
Neurotransmitters - Chemical substance released by the presynaptic terminal button that acts on the postsynaptic cell.
sensory neurons
Sensory neurons - neurons that help us receive information about the world around us.
motor neurons
Motor neurons - allow us to initiate movement and behaviour
interneurons
Interneurons - which process the sensory input from our environment into meaningful representations, plan the appropriate behavioral response, and connect to the motor neurons to execute these behavioral plans
unipolar neurons
Unipolar neurons - are structured in such a way that is ideal for relaying information forward, so they have one neurite (axon) and no dendrites. They are involved in transmission of physiological information from the body’s periphery such as communicating body temperature through the spinal cord up to the brain.
bipolar neurons
Bipolar neurons - involved in sensory perception such as perception of light in the retina of the eye. They have one axon and one dendrite which help acquire and pass sensory information to various centers in the brain
multipolar neurons
Multipolar - most common and they communicate sensory and motor information in the brain. For example, their firing causes muscles in the body to contract. Multipolar neurons have one axon and many dendrites which allows them to communicate with other neurons.
the second type of brain cells are called the …
The second type of brain cell are called the glia cells - they have several functions
Oligodendroglia form myelin sheath & Wrap their dendritic around axons many times to form myelin sheath
Microglia & astrocytes digest debris of dead neurons, carry nutritional support from blood vessels to the neurons, and help to regulate the ionic composition of the extracellular fluid.
While glial cells play a vital role in neuronal support, they do not participate in the communication between cells in the same fashion as neurons do.
The intracellular (inside the cell) fluid and extracellular (outside the cell) fluid of neurons is composed of a combination of ions
Proteins span the membrane that form ion channels that allow particular ions to pass between intra and extracellular fluid
cell membrane
Cell membrane is composed of the lipid bilayer of fat molecules which separate the cell from surrounding extracellular fluid
cations and anions
Cations = + charged ions
Anions = - charged ions
Anions (A-): Anions are highly concentrated inside the cell and contribute to the negative charge of the resting membrane potential. Diffusion and electrostatic pressure are not forces that determine A– concentration because A– is impermeable to the cell membrane. There are no ion channels that allow for A– to move between the intracellular and extracellular fluid.
diffusion
Diffusion - the force on molecules to move from high concentration to low concentration areas
electrostatic pressure
Electrostatic pressure - the force on two ions with similar charge to repel each other and the force of two ions with similar charge to attract to one another
resting membrane potential
Resting membrane potential - The voltage inside the cell relative to the voltage outside the cell while the cell is at rest (approximately -70 mV).
potassium
Potassium (K+): The cell membrane is very permeable to potassium at rest, but potassium remains in high concentrations inside the cell. Diffusion pushes K+ outside the cell because it is in high concentration inside the cell. However, electrostatic pressure pushes K+ inside the cell because the positive charge of K+ is attracted to the negative charge inside the cell. In combination, these forces oppose one another with respect to K+.
chloride
Chloride (Cl-): The cell membrane is also very permeable to chloride at rest, but chloride remains in high concentration outside the cell. Diffusion pushes Cl– inside the cell because it is in high concentration outside the cell. However, electrostatic pressure pushes Cl– outside the cell because the negative charge of Cl– is attracted to the positive charge outside the cell. Similar to K+, these forces oppose one another with respect to Cl–.
sodium
Sodium (Na+): The cell membrane is not very permeable to sodium at rest. Diffusion pushes Na+ inside the cell because it is in high concentration outside the cell. Electrostatic pressure also pushes Na+ inside the cell because the positive charge of Na+is attracted to the negative charge inside the cell. Both of these forces push Na+ inside the cell; however, Na+ cannot permeate the cell membrane and remains in high concentration outside the cell. The small amounts of Na+ inside the cell are removed by a sodium-potassium pump, which uses the neuron’s energy (adenosine triphosphate, ATP) to pump 3 Na+ ions out of the cell in exchange for bringing 2 K+ ions inside the cell.
action potential
Action potential - A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation.
threshold of excitation
Threshold of excitation - Specific membrane potential that the neuron must reach to initiate an action potential
epsp and ipsp
excitatory postsynaptic potentials (EPSPs): a depolarizing current that causes the membrane potential to become more positive and closer to the threshold of excitation; or
inhibitory postsynaptic potentials (IPSPs): a hyperpolarizing current that causes the membrane potential to become more negative and further away from the threshold of excitation.
hormones
Hormones coordinate the physiology and behavior of individuals by regulating, integrating, and controlling bodily functions.
hormones change the probability that a particular behavior will be emitted in the appropriate situation
5a-reductase
5α-reductase - An enzyme required to convert testosterone to 5α-dihydrotestosterone.
aromatase
Aromatase - An enzyme that converts androgens into estrogens.
dihydrotestosterone
Dihydrotestosterone (DHT) - A primary androgen that is an androgenic steroid product of testosterone and binds strongly to androgen receptors.
endocrine gland
Endocrine gland - A ductless gland from which hormones are released into the blood system in response to specific biological signals.
estrogen
Estrogen - Any of the C18 class of steroid hormones, so named because of the estrus-generating properties in females. Biologically important estrogens include estradiol and estriol.
feminization and masculinization
Masculinization - The induction of male traits.
Feminization - The induction of female traits.
gonadel sex
Gonadal sex - The sex of an individual as determined by the possession of either ovaries or testes. Females have ovaries, whereas males have testes.
hormone
Hormone - An organic chemical messenger released from endocrine cells that travels through the blood to interact with target cells at some distance to cause a biological response.
neurotransmitter
Neurotransmitter - A chemical messenger that travels between neurons to provide communication. Some neurotransmitters, such as norepinephrine, can leak into the blood system and act as hormones.
Virtually any drug that changes the way you feel does this by altering how neurons communicate with each other. Neurons (more than 100 billion in your nervous system) communicate with each other by releasing a chemical (neurotransmitter) across a tiny space between two neurons (the synapse)
Neurotransmitter - A chemical substance produced by a neuron that is used for communication between neurons.
Pharmacokinetics - The action of a drug through the body, including absorption, distribution, metabolism, and excretion.
oxytocin
Oxytocin - A peptide hormone secreted by the pituitary gland to trigger lactation, as well as social bonding.
parental and paternal behaviour
Parental behavior - Behaviors performed in relation to one’s offspring that contributes directly to the survival of those offspring
Paternal behavior - Parental behavior performed by the father or other male.
progesterone and progestin
Progesterone - A primary progestin that is involved in pregnancy and mating behaviors. Progestin - A class of C21 steroid hormones named for their progestational (pregnancy-supporting) effects. Progesterone is a common progestin.
prohormone
Prohormone - A molecule that can act as a hormone itself or be converted into another hormone with different properties. For example, testosterone can serve as a hormone or as a prohormone for either dihydrotestosterone or estradiol.
prolactin
Prolactin - A protein hormone that is highly conserved throughout the animal kingdom. It has many biological functions associated with reproduction and synergistic actions with steroid hormones.
receptor
Receptor - A chemical structure on the cell surface or inside of a cell that has an affinity for a specific chemical configuration of a hormone, neurotransmitter, or other compound.
sex determination
Sex determination - The point at which an individual begins to develop as either a male or a female. In animals that have sex chromosomes, this occurs at fertilization. Females are XX and males are XY. All eggs bear X chromosomes, whereas sperm can either bear X or Y chromosomes. Thus, it is the males that determine the sex of the offspring.
sex differentiation
Sex differentiation - The process by which individuals develop the characteristics associated with being male or female. Differential exposure to gonadal steroids during early development causes sexual differentiation of several structures including the brain.
target cell
Target cell - A cell that has receptors for a specific chemical messenger (hormone or neurotransmitter).
testosterone
Testosterone - The primary androgen secreted by the testes of most vertebrate animals, including men.
agonists vs antagonists
Agonists - A drug that increases or enhances a neurotransmitter’s effect.
Antagonist - A drug that blocks a neurotransmitter’s effect.
enzymes and enzyme induction
Enzyme - A protein produced by a living organism that allows or helps a chemical reaction to occur.
Enzyme induction - Process through which a drug can enhance the production of an enzyme.
metabolism
Metabolism - Breakdown of substances.
polypharmacy
Polypharmacy - The use of many medications.
psychoactive drug
Psychoactive drugs - A drug that changes mood or the way someone feels.
psychotropic drug
Psychotropic drug - A drug that changes mood or emotion, usually used when talking about drugs prescribed for various mental conditions (depression, anxiety, schizophrenia, etc.).
synapse
Synapse - The tiny space separating neurons.
action potential
Action potential - A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation. Send a signal down the axon.
nodes of ranvier
Nodes of Ranvier - Gaps in the myelin sheath. Where most of the action happens.
resting membrane potential
Resting membrane potential - A bi-lipid layer of molecules that separates the cell from the surrounding extracellular fluid. Cell membrane (lipid bilayer) layers of fat. Separates the intracellular from extracellular fluid. Hydrophilic heads.
electrostatic pressure
Electrostatic pressure - the force on two ions with similar charge to repel each other. Opposites attract.
chemicals inside the cell
Potassium (K+) is high in concentration inside cells. Cell membrane highly permeable to K+. Flows freely from in to out.
Chloride (Cl-) is in high concentration outside cells. Cell membrane is highly permeable to Cl-. Pushes outside of the cell because of attraction. Because of diffusion, Cl- gets pushed back into the cell.
Sodium (Na+) in high concentration outside cells. Not easily transferred across the membrane. Not permeable to sodium. -70mV inside relative to outside of the cells.
Sodium-potassium pump : An ion channel that uses the neuron’s energy (adenosine triphosphate, ATP) to pump three Na+ ions outside the cell in exchange for bringing two K+ ions inside the cell. Maintains neuron levels at around -70mV.
when the threshold is met
When threshold is met:
Voltage-dependent sodium (Na+) channels are opened electrostatic pressure and diffusion
Na+ rushes in, making the cell highly depolarized/positive
K+ channels open
K+ rushes out via electrostatic pressure (more + inside than outside)
Na+ channels close, K+ gradually close
resting potential
- When a neuron is at rest, the neuron maintains an electrical polarization (i.e., a negative electrical potential exists inside the neuron’s membrane with respect to the outside). This difference in electrical potential or voltage is known as the resting potential. At rest, this potential is around -70mV.
concentration gradient
. Concentration gradient (difference in distribution of ions between the inside and the outside of the membrane): During the resting potential, a difference in the distribution of ions is established with sodium (Na+) 10 times more concentrated outside the membrane than inside and potassium (K+) 20 times more concentrated inside than outside.
sodium potassium pump
Sodium-potassium pump, in cellular physiology, a protein that has been identified in many cells that maintains the internal concentration of potassium ions [K+] higher than that in the surrounding medium (blood, body fluid, water) and maintains the internal concentration of sodium ions [Na+] lower
postsynaptic neuron
The postsynaptic neuron is the cell that receives information (i.e., receives chemical messages). The synaptic cleft is the small space separating the presynaptic membrane and postsynaptic membrane (usually the dendritic spine).
presynaptic neuron
A presynaptic neuron is a neuron (nerve cell) that fires the neurotransmitter as a result of an action potential entering its axon terminal. In both the central and peripheral nervous systems in mammals, presynaptic terminals operate mostly in the same way.
ionotropic receptors
have sites for neurotransmitters to bind which opens a receptor and allows ions to flow into the neuron, manipulating the charge of the neurone
