Ch 4- Nervous System

Question 1

“specialized cells capable of transmitting electrical impulses and then translating those electrical impulses to chemical signals”

Answer 1

Neurons

Question 2

“Myelin is produced by_________ in the central nervous system and ___________ in the peripheral nervous system”

Answer 2

oligodendrocytes

Schwann cells

Question 3

“Between the neurons, there is a small space into which the terminal portion of the axon releases neurotransmitters, which bind to the dendrites of the postsynaptic neuron. This space is known as the ”

Answer 3

Synaptic cleft

Question 4

“In the central nervous system, axons may be bundled together to form

Answer 4

tracts

Question 5

“The cell bodies of neurons in the same tract are grouped into ”

Answer 5

Nuclei

Question 6

“nourish neurons and form the blood–brain barrier, which controls the transmission of solutes from the bloodstream into nervous tissue.”

Answer 6

Astrocytes

Question 7

“line the ventricles of the brain and produce cerebrospinal fluid, which physically supports the brain and serves as a shock absorber.”

Answer 7

Ependymal Cells

Question 8

“are phagocytic cells that ingest and break down waste products and pathogens in the central nervous system.”

Answer 8

Microglia

Question 9

“Neurons use all-or-nothing messages called _______ to relay electrical impulses down the axon to the synaptic bouton.”

Answer 9

action potentials

Question 10

“The Na+/K+ ATPase maintains a resting membrane potential of ______ by moving ______ Na+ ions out of the cell for every _______ K+ ions moved into the cell at the expense of ____ATP

Answer 10

-70 mV, 3, 2, 1

Question 11

“If the axon hillock receives enough excitatory input to be depolarized to the threshold value (usually in the range of –55 to –40 mV), an _________ will be triggered.”

Answer 11

Action potential

Question 12

“ In __________ multiple signals are integrated during a relatively short period of time. A number of small excitatory signals firing at nearly the same moment could bring a postsynaptic cell to threshold, enabling an action potential.”

Answer 12

temporal summation

Question 13

“In _________ the additive effects are based on the number and location of the incoming signals”

Answer 13

spatial summation

Question 14

“If the cell is brought to threshold, ___________ open in the membrane”

Answer 14

Voltage gated sodium channells

Question 15

“There is a strong __________ that promotes the migration of sodium into the cell. From an electric standpoint, the interior of the cell is more negative. Sodium is positive. From chemical standpoint, higher concentration of sodium out than in

Answer 15

Electrochemical Gradient

Question 16

“When Vm approaches +35 mV, the sodium channels are _________ and will have to be brought back near the resting potential to be ________”

Answer 16

inactivated, activated

“Thus, these sodium channels can exist in three states: CLOSED (before the cell reaches threshold, and after inactivation has been reversed), OPEN (from threshold to approximately +35 mV), and INACTIVE (from approximately +35 mV to the resting potential).”

Question 17

“The positive potential inside the cell not only triggers the voltage-gated sodium channels to inactivate, but also triggers the voltage-gated potassium channels to”

Answer 17

Open

Question 18

“As positively charged potassium cations are driven out of the cell, there will be a restoration of the negative membrane potential called”

Answer 18

repolarization

Question 19

“The speed at which action potentials move depends on

Answer 19

the length and cross-sectional area of the axon”

The effect of cross section is more significant than the effect of length

Question 20

Myelin is so effective that the membrane is only permeable to ion movement at

Answer 20

The nodes of Ranvier

Question 21

“It is important to note that all action potentials within the same type of neuron have the same”

Answer 21

Potential difference during depolarization

Question 22

“Increased intensity of a stimulus does not result in an increased potential difference of the action potential, but rather

Answer 22

an increased frequency of firing.”

Question 23

“the neuron preceding the synaptic cleft is called the”

Answer 23

presynaptic neuron

Question 24

“the neuron after the synaptic cleft is called the”

Answer 24

Postsynaptic neuron

Question 25

“If a neuron signals to a gland or muscle, rather than another neuron, the postsynaptic cell is termed an”

Answer 25

effector

Question 26

“Prior to release, neurotransmitter molecules are stored in

Answer 26

membrane-bound vesicles in the nerve terminal.”

Question 27

“When the action potential reaches the nerve terminal, ___________ open, allowing calcium to flow into the cell.

Answer 27

voltage-gated calcium channels

-This sudden increase in intracellular calcium triggers fusion of the membrane-bound vesicles with the cell membrane at the synapse, causing exocytosis of the neurotransmitter.”

Question 28

“It is critical to understand the difference between______ and _______ transmission. Within a neuron, electricity is used to pass signals down the length of the axon. Between neurons, chemicals (neurotransmitters) are used to pass signals to the subsequent neuron (or gland or muscle).”

Answer 28

Chemical, Electrical

Question 29

“Once released into the synapse, the neurotransmitter molecules diffuse across the cleft and bind to ________ on the postsynaptic membrane”

Answer 29

Receptors

Question 30

“neurotransmitter receptors, which tend to be either________ or ________

Answer 30

ligand-gated ion channels or G protein-coupled receptors.”

Question 31

“If the receptor is a ligand-gated ion channel, the postsynaptic cell will either be ____________. If it is a G protein-coupled receptor, it will cause either _______or ________
Excerpt From: Kaplan. “Kaplan MCAT Biology Review: Created for MCAT 2015 (Kaplan Test Prep).” iBooks.

Answer 31

• Depolarized or hyper polarized

- changes in the levels of cyclic AMP (cAMP) or an influx of calcium”

Question 32

3 main mechanisms to remove neurotransmitters from synaptic cleft

Answer 32

1. Break it down with enzymes (Acetylchinesterase)
2. Bring it back into presynaptic neuron using REUPTAKE CARRIERS
   (Serotonin, Dopamin, Norepi)
   3.Neurotransmitters my diffuse out of synaptic cleft

Question 33

“Generally speaking, there are three kinds of nerve cells in the nervous system: ”

Answer 33

“sensory neurons, motor neurons, and interneurons”

Question 34

When an action requires brain or brainstem input

Answer 34

Supra spinal Circuits are used

Question 35

“The spinal cord extends downward from the brainstem and can be divided into four divisions:”

Answer 35

“cervical, thoracic, lumbar, and sacral. ”

Question 36

“Like the brain, the spinal cord also consists of white and grey matter. The ______ matter lies on the outside of the cord, and the ______ matter is deep within it”

Answer 36

White, Grey

Question 37

“The axons of motor and sensory neurons”

Answer 37

Are IN the spinal chord

Question 38

“The sensory neurons bring information in from the periphery and enter on the dorsal (back) side of the spinal cord. The cell bodies of these sensory neurons are found in the”

Answer 38

Dorsal Root ganglia

Question 39

“Motor neurons exit the spinal cord

Answer 39

Ventrally

Question 40

“consists of sensory and motor neurons distributed throughout the skin, joints, and muscles.”

Answer 40

Somatic Nervous System

Question 41

“One primary difference between the somatic and autonomic nervous systems is that the peripheral component of the autonomic nervous system contains

Answer 41

2 Neurons (preganglionic Neuron and Post-Ganglionic Neuron)

“The soma of the preganglionic neuron is in the CNS, and its axon travels to a ganglion in the PNS. Here it synapses on the cell body of the postganglionic neuron, which then affects the target tissue.”

“A motor neuron in the somatic nervous system goes directly from the spinal cord to the muscle without synapsing. ”

Question 42

____________ is the neurotransmitter responsible for parasympathetic responses in the body and is released by both preganglionic and postganglionic neurons.”

Answer 42

Acetylcholine

“In the sympathetic nervous system, preganglionic neurons release acetylcholine, while most postganglionic neurons release norepinephrine.”

Question 43

“There are two types of reflex arcs:

Answer 43

monosynaptic and polysynaptic.”

Question 44

“In a ___________, there is a single synapse between the sensory neuron that receives the stimulus and the motor neuron that responds to it”

Answer 44

monosynaptic reflex arc,
(no interneuron)
Classic Example is the knee-jerk reflex

Question 45

“In a __________ there is at least one interneuron between the sensory and motor neurons. ”

Answer 45

polysynaptic reflex arc

Stepping on a nail and involving the withdrawal reflex