Chapter 6 (Midterm 1)

Question 1

What are neurotransmitters?

Answer 1

chemical messenger used by neurons to communicate with each other or with effectors

Question 2

What are types of neurotransmitters?

Answer 2

Biogenic amines, Acetylcholine, Gases, Neuropeptides, Amino acids, Purines (BAG-NAP)

Question 3

What is an excitatory neurotransmitter synapse?

Answer 3

increases the likelihood that postsynaptic neuron will undergo APs (increases frequency of existing APs)

Question 4

What is an inhibitory neurotransmitter synapse?

Answer 4

decreases the likelihood that postsynaptic neuron will fire an AP ( decreases the frequency of exisiting APs) – hyperpolarization

Question 5

Where are neurotransmitters released?

Answer 5

presynaptic cleft

Question 6

What is acetylcholine?

Answer 6

major nuerotransmitter in the PNS at the neuromuscular junction

Question 7

What are biogenic amines?

Answer 7

neurotransmitters that are small charged molecules made from amino acids containing an amino group

Question 8

What are amino acids as neurotransmitters?

Answer 8

most prevalent neurotransmitters in the CNS

Question 9

What are neuropeptides as neurotransmitters?

Answer 9

short chains of amino acids with peptide bonds can be prepackaged as precursor proteins and is activated when cleaved

Question 10

What are gases as neurotransmitters?

Answer 10

can diffuse from original cell into the intracellular fluid of other neurons/effector cells and bind to proteins to activate them

Question 11

What are purines as neurotransmitters?

Answer 11

act as neuromodulators

Question 12

What is spatial summation?

Answer 12

simultaneous inputs to different places on neuron are added together

Question 13

What is temporal summation?

Answer 13

two or more inputs occurring at different times are added together

Question 14

What is a synapse?

Answer 14

junction between two neurons where electrical activity in one neuron influences the excitability of the second

Question 15

Excitatory Postsynaptic Potentials

Answer 15

depolarizing graded potential in postsynaptic neuron due to activated excitatory synapse

Question 16

Inhibitory Postsynaptic Potentials

Answer 16

hyperpolarizing graded potential in postsynaptic neuron due to activated inhibitory synapse

Question 17

What are electrochemical gradients?

Answer 17

differences in charges and ion concentrations across the membrane

Question 18

What is the threshold level? (mV)

Answer 18

-55mV

Question 19

What is the resting membrane potential? (mV)

Answer 19

-70mV

Question 20

What is the refractory period?

Answer 20

the period when the axon (during an AP) cannot respond to any/another stimulus

Question 21

What is the purpose of the refractory period?

Answer 21

help prevent signals from traveling in both directions down the axon at once

Question 22

What are electrochemical forces?

Answer 22

the two forces that drive the diffusion of ions across the plasma membrane

Question 23

What is equilibrium potential?

Answer 23

when the chemical force and the electrical force become equal in magnitude (cancel each other out in a sense)

Question 24

What is an action potential?

Answer 24

large alterations in membrane potential, generally very rapid

Question 25

What is a graded potential?

Answer 25

changes to a membrane potential that is confined to a relatively small region of the plasma membrane

Question 26

What consists or doesn’t consist in a graded potential?

Answer 26

a refractory period and a threshold, does not meet threshold, may include ligand-gated ion channels and leak channels

Question 27

Examples of graded potentials

Answer 27

synaptic, receptor, pacemaker

Question 28

What determines the magnitude of membrane depolarization in a graded potential?

Answer 28

intensity of the initial stimulus

Question 29

What mechanism does the nervous system use to communicate over long distances?

Answer 29

action potential

Question 30

Where are graded potentials found within the neuron?

Answer 30

generally in the dendrites/soma part of the neuron

Question 31

Where are action potentials found within the neuron?

Answer 31

occur in parts of neuron where Na/K voltage gated channels are abundant on the membrane

Question 32

What are electrical synapses (junctions)?

Answer 32

the presynaptic neuron is DIRECTLY connected to the post-synaptic neuron || gap junctions

Question 33

What are chemical synapses?

Answer 33

use neurotransmitters to communicate = INDIRECTLY connected

Question 34

What is the relative permeability of the membrane to Na and K at rest?

Answer 34

much more permeable to K

Question 35

Under action potential conditions, how does the relative permeability of the membrane change?

Answer 35

It is more permeable to Na since a bunch of Na voltage-gated channels open due to the AP

Question 36

How do changes in the stimulus be presented to the CNS

Answer 36

information to the CNS is transmitted by the changing frequency of the APs

Question 37

What is an absolute refractory period?

Answer 37

during an AP, second stimulus does not produce a second AP, inactivated Na channel contributes to this

Question 38

What is a relative refractory period?

Answer 38

after absolute refractory period, second AP potential can be produced if the stimulus strength is greater

Question 39

What is the effect of myelination?

Answer 39

reduces the amount of current “leaking” through membrane = improves electrotonic conduction

Question 40

What is the main role of calcium ions at chemical synapses?

Answer 40

cause fusion of synaptic vesicles with the plasma membrane of the axon terminal

Question 41

How do graded potentials end?

Answer 41

diffusion of ions via leak channels

Question 42

How do action potentials end?

Answer 42

closure of voltage-gated Na channels post-inactivation, opening of K+ vg channels and activation of Na/K ATPase – return membrane potential to rest