Life 45- Neurons And Nervous Systems

Question 1

Spatial summation

Answer 1

In the production or inhibition of action potentials in a post synaptic cell, the interaction of depolarisations and hyper polarisation produced at different sites on the post synaptic cell.

Question 2

Patch clamping

Answer 2

A technique for isolating a tiny patch of membrane to allow the study of ion movement through a particular channel.

Question 3

Motor end plate

Answer 3

The modified area on a muscle cell membrane where a synapse is formed with a motor neuron

Question 4

Neuron

Answer 4

A nervous system cell that can generate and conduct action potentials along an axon to a synapse with another cell.

Question 5

Presynaptic neuron

Answer 5

The neuron that transmits information to another cell at a synapse

Question 6

Neuromuscular junction

Answer 6

Synapse (point of contact) where a motor neuron axon stimulates a muscle fibre cell.

Question 7

Voltage-gated channel.

Answer 7

A type of gated channel that opens or closes when a certain voltage exists across the membrane in which it is inserted.

Question 8

Depolarization

Answer 8

A change in the resting potential across a membrane so that the inside of the cell becomes less negative, or even positive, compared with the outside of the cell.

Question 9

Long-term potentiation (LTP)

Answer 9

A long-lasting increase in the responsiveness of a neuron resulting from a period of intense stimulation.

Question 10

Refractory period

Answer 10

The time interval after an action potential during which another action potential cannot be elicited from an excitable membrane.

Question 11

Central nervous system (CNS)

Answer 11

That portion of the nervous system that is the site of most information processing, storage, and retrieval; in vertebrates, the brain and spinal cord.

Question 12

Saltatory conduction

Answer 12

The rapid conduction of action potentials in myelinated axons; so called because action potentials appear to “jump” between nodes of Ranvier along the axon.

Question 13

Glia

Answer 13

Cells of the nervous system that do not conduct action potentials.

Question 14

Electrochemical gradient

Answer 14

The concentration gradient of an ion across a membrane plus the voltage difference across that membrane.

Question 15

Schwann cell

Answer 15

A type of glia cell that myelinated axons in the peripheral nervous system

Question 16

Temporal summation

Answer 16

In the production or inhibition of action potentials in a postsynaptic cell, the interaction of depolarisations or hyperpolarisations produced by rapidly repeated stimulation of a single point on the postsynaptic cell

Question 17

Neural network

Answer 17

An organised group of neurons that contains three functional categories of neurons- afferent neurons, inter neurons, and efferent neurons- and is capable of processing information.

Question 18

Interneuron

Answer 18

A neuron that communicates information between two other neurons.

Question 19

Microglia

Answer 19

Glia cells that act as macrophages and mediators of inflammatory responses in the central nervous system

Question 20

Node of Ranvier

Answer 20

A gap in the myelin sheath covering an axon; the point where the axonal membrane can fire action potentials.

Question 21

Axon

Answer 21

The part of a neuron that conducts action potentials always from the cell body

Question 22

Ganglion

Answer 22

A cluster of neurons that have similar characteristics or function.

Question 23

Acetylcholine (ACh)

Answer 23

A neurotransmitter that carries information across vertebrate neuromuscular junctions and some other synapses

Question 24

Peripheral nervous system (PNS)

Answer 24

The portion of the nervous system that consists of neurons that extend or reside outside the brain or spinal cord and their supporting cells.

Question 25

Membrane potential

Answer 25

The difference in electrical charge between the inside and the outside of a cell, caused by a difference in the distribution of ions

Question 26

Afferent

Answer 26

Carrying to, as in a neuron that carries impulses to the central nervous system, or a blood vessel that carries blood to a structure.

Question 27

Astrocyte.

Answer 27

A type of glial cell that contributes to the blood-brain barrier by surrounding the smallest, most permeable blood vessels in the brain

Question 28

Dendrite

Answer 28

A fibre of a neuron which often cannot carry action potentials, is usually much branched and relatively short, and commonly carries information to the cell body of the neuron

Question 29

Action potential

Answer 29

An impulse in a neuron taking the form of a wave of depolarisation or hyperpolarisation.

Question 30

Threshold

Answer 30

The level of depolarisations that causes an electrically excitable membrane to fire an action potential.

Question 31

Synapse

Answer 31

A specialised type of junction where a neuron meets its target cell (which can be another neuron or some other type of cell) and information in the form of neurotransmitter molecules is exchanged

Question 32

Mechanically gated channel

Answer 32

A molecular channel that opens or closes in response to mechanical force applied to the plasma membrane in which it is inserted.

Question 33

Myelin

Answer 33

Concentric layers of plasma membrane that form a sheath around some axons; provides the axon with electrical insulation and increases the rate of transmission of action potentials.

Question 34

Nerve

Answer 34

A structure consisting of many neuronal axons and connective tissue.

Question 35

Electrical synapse

Answer 35

A type of synapse at which action potentials spread directly from presynaptic cell to postsynaptic cell.

Question 36

Hyperpolarization

Answer 36

A change in the resting potential across a membrane so that the inside of a cell becomes more negative compared with the outside of the cell.

Question 37

Oligodendrocyte

Answer 37

A type of glial cell that myelinated axons in the central nervous system

Question 38

Sodium-potassium pump

Answer 38

Antiporter responsible for primary active transport; it pumps sodium ions out of the cell and potassium ions into the cell, both against their concentration gradient.

Question 39

Axon terminals.

Answer 39

The endings of an axon; they form synapses an release neurotransmitter.

Question 40

Metabotropic receptor

Answer 40

A receptor that indirectly alters membrane permeability to a type of ion when it combines with its ligand

Question 41

Nernst equation

Answer 41

A mathematical statement that calculates the potential across a membrane potential permeable to a single type of ion that differs in concentration on the two sides of the membrane.

Question 42

Brain

Answer 42

The centralised integrative centre of a nervous system

Question 43

Sensory neuron

Answer 43

A specialised neuron that transducers a particular type of sensory stimulus into action potentials

Question 44

Efferent

Answer 44

Carrying outward or away from, as in a neuron that carries impulses outward from the central nervous system, or a blood vessel that carries blood away from a structure

Question 45

Ionotropic receptors

Answer 45

A receptor that directly alters membrane permeability to a type of ions when it combines with is Ligand.

Question 46

Resting potential

Answer 46

The membrane potential of a living cell at rest.

Question 47

Axon hillock

Answer 47

The junction between an axon and its cell body, where action potentials are generated.

Question 48

Chemically gated channel

Answer 48

A type of gated channel that opens of closes depending on the presence or absence of a specific molecule, which binds to the channel protein or to a separate receptor that in turn alters the three-dimensional shape of channel protein.

Question 49

Neurotransmitter

Answer 49

A substance produced in and released by a neuron (the presynaptic cell) that diffuses across a synapse and excites or inhibits another cell (the postsynaptic cell)

Question 50

Chemical synapse

Answer 50

Neural junction at which neurotransmitter molecules released from a presynaptic cell induce changes in a postsynaptic cell.

Question 51

Blood-brain barrier

Answer 51

A property of blood vessels in the brain that prevents most chemicals from diffusing from the blood into the brain.