week 5 - neurons

Question 1

neuron

Answer 1

Neurons - brain cells

Question 2

dendrite

Answer 2

Dendrites - part that extends away from the cell body and is the main input to the neuron

Question 3

soma

Answer 3

Soma - Cell body of a neuron that contains the nucleus and genetic information, and directs protein synthesis.

Question 4

nucleus -

Answer 4

Nucleus - Collection of nerve cells found in the brain which typically serve a specific function.

Question 5

axon

Answer 5

Axon - Part of the neuron that extends off the soma, splitting several times to connect with other neurons; main output of the neuron.

Question 6

synapse

Answer 6

Synapse - Junction between the presynaptic terminal button of one neuron and the dendrite, axon, or soma of another postsynaptic neuron.

Question 7

myelin sheath

Answer 7

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.

Question 8

terminal button

Answer 8

Terminal button - The part of the end of the axon that forms synapses with postsynaptic dendrite, axon, or soma.

Question 9

spines

Answer 9

Spines - Protrusions on the dendrite of a neuron that form synapses with terminal buttons of the presynaptic axon.

Question 10

synaptic gap

Answer 10

Synaptic gap - Also known as the synaptic cleft; the small space between the presynaptic terminal button and the postsynaptic dendritic spine, axon, or soma

Question 11

synaptic vessels

Answer 11

Synaptic vessels - Groups of neurotransmitters packaged together and located within the terminal button.

Question 12

neurotransmitters

Answer 12

Neurotransmitters - Chemical substance released by the presynaptic terminal button that acts on the postsynaptic cell.

Question 13

sensory neurons

Answer 13

Sensory neurons - neurons that help us receive information about the world around us.

Question 14

motor neurons

Answer 14

Motor neurons - allow us to initiate movement and behaviour

Question 15

interneurons

Answer 15

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

Question 16

unipolar neurons

Answer 16

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.

Question 17

bipolar neurons

Answer 17

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

Question 18

multipolar neurons

Answer 18

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.

Question 19

the second type of brain cells are called the …

Answer 19

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

Question 20

cell membrane

Answer 20

Cell membrane is composed of the lipid bilayer of fat molecules which separate the cell from surrounding extracellular fluid

Question 21

cations and anions

Answer 21

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.

Question 22

diffusion

Answer 22

Diffusion - the force on molecules to move from high concentration to low concentration areas

Question 23

electrostatic pressure

Answer 23

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

Question 24

resting membrane potential

Answer 24

Resting membrane potential - The voltage inside the cell relative to the voltage outside the cell while the cell is at rest (approximately -70 mV).

Question 25

potassium

Answer 25

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+.

Question 26

chloride

Answer 26

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–.

Question 27

sodium

Answer 27

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.

Question 28

action potential

Answer 28

Action potential - A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation.

Question 29

threshold of excitation

Answer 29

Threshold of excitation - Specific membrane potential that the neuron must reach to initiate an action potential

Question 30

epsp and ipsp

Answer 30

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.

Question 31

hormones

Answer 31

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

Question 32

5a-reductase

Answer 32

5α-reductase - An enzyme required to convert testosterone to 5α-dihydrotestosterone.

Question 33

aromatase

Answer 33

Aromatase - An enzyme that converts androgens into estrogens.

Question 34

dihydrotestosterone

Answer 34

Dihydrotestosterone (DHT) - A primary androgen that is an androgenic steroid product of testosterone and binds strongly to androgen receptors.

Question 35

endocrine gland

Answer 35

Endocrine gland - A ductless gland from which hormones are released into the blood system in response to specific biological signals.

Question 36

estrogen

Answer 36

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.

Question 37

feminization and masculinization

Answer 37

Masculinization - The induction of male traits.

Feminization - The induction of female traits.

Question 38

gonadel sex

Answer 38

Gonadal sex - The sex of an individual as determined by the possession of either ovaries or testes. Females have ovaries, whereas males have testes.

Question 39

hormone

Answer 39

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.

Question 40

neurotransmitter

Answer 40

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.

Question 41

oxytocin

Answer 41

Oxytocin - A peptide hormone secreted by the pituitary gland to trigger lactation, as well as social bonding.

Question 42

parental and paternal behaviour

Answer 42

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.

Question 43

progesterone and progestin

Answer 43

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.

Question 44

prohormone

Answer 44

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.

Question 45

prolactin

Answer 45

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.

Question 46

receptor

Answer 46

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.

Question 47

sex determination

Answer 47

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.

Question 48

sex differentiation

Answer 48

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.

Question 49

target cell

Answer 49

Target cell - A cell that has receptors for a specific chemical messenger (hormone or neurotransmitter).

Question 50

testosterone

Answer 50

Testosterone - The primary androgen secreted by the testes of most vertebrate animals, including men.

Question 51

agonists vs antagonists

Answer 51

Agonists - A drug that increases or enhances a neurotransmitter’s effect.
Antagonist - A drug that blocks a neurotransmitter’s effect.

Question 52

enzymes and enzyme induction

Answer 52

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.

Question 53

metabolism

Answer 53

Metabolism - Breakdown of substances.

Question 54

polypharmacy

Answer 54

Polypharmacy - The use of many medications.

Question 55

psychoactive drug

Answer 55

Psychoactive drugs - A drug that changes mood or the way someone feels.

Question 56

psychotropic drug

Answer 56

Psychotropic drug - A drug that changes mood or emotion, usually used when talking about drugs prescribed for various mental conditions (depression, anxiety, schizophrenia, etc.).

Question 57

synapse

Answer 57

Synapse - The tiny space separating neurons.

Question 58

action potential

Answer 58

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.

Question 59

nodes of ranvier

Answer 59

Nodes of Ranvier - Gaps in the myelin sheath. Where most of the action happens.

Question 60

resting membrane potential

Answer 60

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.

Question 61

electrostatic pressure

Answer 61

Electrostatic pressure - the force on two ions with similar charge to repel each other. Opposites attract.

Question 62

chemicals inside the cell

Answer 62

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.

Question 63

when the threshold is met

Answer 63

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

Question 64

resting potential

Answer 64

1. 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.

Question 65

concentration gradient

Answer 65

. 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.

Question 66

sodium potassium pump

Answer 66

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

Question 67

postsynaptic neuron

Answer 67

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).

Question 68

presynaptic neuron

Answer 68

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.

Question 69

ionotropic receptors

Answer 69

have sites for neurotransmitters to bind which opens a receptor and allows ions to flow into the neuron, manipulating the charge of the neurone