Chapter 4

Question 1

Channel

Answer 1

Opening in a protein embedded in the cell membrane that allows the passage of ions.

Question 2

Gate

Answer 2

Protein embedded in a cell membrane that allows substances to pass through the membrane on some occasions but not others.

Question 3

Pump

Answer 3

Protein in the cell membrane that actively transports a substance across the membrane.

Question 4

How many pairs of chromosomes foes the human somatic cell contain?

Answer 4

23

Question 5

Allele

Answer 5

Alternate form of a gene; a gene pair contains two

Question 6

Wild type

Answer 6

Refers to the most common phenotype or genotype in a population

Question 7

Tay-Sach’s Disease

Answer 7

Inherited birth defect caused by the loss of genes that encode the enzyme (Hex A) necessary for breaking down lipids in the brain

Question 8

Huntington’s Disease

Answer 8

Hereditary disease characterized by chorea and progressive dementia

Question 9

Down Syndrome

Answer 9

Chromosomal abnormality resulting in mental retardation and other abnormalities, caused by extra chromosome 21.

Question 10

Transgenic Animal

Answer 10

Genes from one species is introduced into the genome of another species and passed along and expressed in subsequent generations.

Question 11

Diffusion

Answer 11

Movement of ions from an area of higher concentration to an area of lower concentration through random motion

Question 12

Concentration Gradient

Answer 12

Different in concentration of a substance among regions of a container that allow the substance to diffuse from an area of higher concentration to an area of lower concentration.

Question 13

Voltage Gradient

Answer 13

Difference in charge between two regions that allows a flow of current.

Question 14

Resting Potential

Answer 14

Electrical charge across the cell membrane in the absence of stimulation.

A store of potential energy produced by a greater negative charge on the intracellular side relative to the extracellular side

Question 15

What charged particles are in higher concentration in the intracellular fluid?

Answer 15

Protein anions and K+ ions

Question 16

Which charged particles are in higher concentration in the extracellular fluid?

Answer 16

Cl- and Na+ ions

Question 17

Graded Potential

Answer 17

Small voltage fluctuations in the cell membrane restricted to the vicinity on the axon where ion concentration change to cause a brief increase or decrease in electrical across the cell membrane.

Question 18

Hyperpolarization

Answer 18

Increase in electrical charge across a membrane.

Usually due to the outward flow of K+

Question 19

Depolarization

Answer 19

Decrease in electrical charge across a membrane.

Usually due to the inward flow of Na+ ions.

Question 20

Action Potential

Answer 20

Large, brief reversal in the polarity of an axon.

Question 21

Threshold Potential

Answer 21

Voltage on a neural membrane at which an action potential is triggered by the opening of Na+ and K+ voltage sensitive channels.

-50 millivolts relative to extracellular channels.

Question 22

Voltage-Sensitive Channel

Answer 22

Gated protein channel that opens or closes only at specific membrane voltages

Question 23

Absolutely Refractory

Answer 23

The state of an axon in the repolarizing period during which a new action potential cannot be elicited because gate 2 of sodium channels, which is not voltage sensitive is closed.

Question 24

Nerve Impulse

Answer 24

Propagation of an action potential on the membrane of an axon.

Question 25

Relatively Refractory

Answer 25

The state of an axon in the later phase of an action potential during which increased electrical current is required to produce another action potential.

A phase during which potassium channels are still open.

Question 26

Nodes of Ranvier

Answer 26

The part of an axon that is not covered by myelin

Question 27

Saltatory Conduction

Answer 27

Propagation of an action potential at successive nodes of ranvier.

Saltatory means “jumping” or “dancing”.

Question 28

Excitatory Postsynaptic Potentials

Answer 28

Brief depolarization of a neuron membrane in response to stimulation making the neuron more likely to produce an action potential.

Question 29

Inhibitory Postsynaptic Potentials

Answer 29

Brief hyperpolarization of a neuron membrane in response to stimulation making the neuron less likely to produce an action potential.

Question 30

EPSPs are associated with the opening of

Answer 30

Sodium channels

Question 31

IPSPs are associated with the opening of

Answer 31

Potassium channels

Question 32

Temporal Summation

Answer 32

Graded potentials that occur at approximately the same time on a membrane are summed.

Question 33

Spatial Summation

Answer 33

Graded potentials that occur at approximately the same location and time on a membrane are summed.

Question 34

Where is the action potential initiated?

Answer 34

At the axon hillock

Question 35

Back Propagation

Answer 35

Reverse movement of an action potential into the dendritic field of a neuron.

Postulated to play a role in plastic changes that underlie learning.

Question 36

Stretch-Sensitive Channels

Answer 36

Ion channel on a tactile sensory neuron that activates in response to stretching of the membrane, initiating a nerve impulse.

Question 37

Transmitter-Sensitive Channel

Answer 37

Receptor complex that has both a receptor site for a chemical and a pore through which ions can flow.