The Nervous System | Topic 1

Question 1

The nervous system works with the
endocrine system to respond to both internal and
external environmental change,
maintaining ______ within the body.

Answer 1

Homeostasis

Question 2

The nervous system responds via ___________
messages relayed from the brain

Answer 2

Electrochemical

Question 3

The endocrine system responds via __________ messengers
relayed through the bloodstream

Answer 3

Chemical

Question 4

What are the messengers of the endocrine system?

Answer 4

Hormones

Question 5

What are the two main types of nerve cells found in the nervous
system?

Answer 5

Glial Cells and Neurons

Question 6

What are Glial Cells?

Answer 6

Used for structural and
nutritional support to the Neuron

Question 7

What are Neurons?

Answer 7

Conductors of nerve impulses
throughout the body

Question 8

What is the basic unit of the Nervous system?

Answer 8

Neurons

Question 9

What are Neurons composed of? (structure)

Answer 9

The Dendrite, Axon, Myelin Sheaths, Schwann Cells, Nodes of Ranvier, and an Axon Terminal

Question 10

What is a Dendrite?

Answer 10

Branches which
accept nerve impulses from
other neurons and carry them
towards the cell body

Question 11

What structure of a Neuron carries nerve impulses
TOWARDS the cell body?

Answer 11

The Dendrite

Question 12

What is an Axon?

Answer 12

The longer branch which
carries nerve impulses away
from the cell body

Question 13

What structure of a Neuron carries nerve impulses
AWAY from the cell body?

Answer 13

The Axon

Question 14

What is the Myelin Sheath?

Answer 14

Fat that surrounds each axon,
insulating the neuron and
speeding up the rate of
impulse transmission

Question 15

What are Schwann Cells?

Answer 15

A type of glial
cell, are responsible for producing
the myelin around each axon

Question 16

What are Nodes of Ranvier?

Answer 16

Gaps between Schwann cells

Question 17

What is Saltatory Conduction?

Answer 17

Electrical impulses
“jumping” from node to node (Nodes being nodes of Ranvier)

Question 18

What is the Axon Terminal?

Answer 18

The end part of a Neuron which passes impulses
onto the dendrites of the
adjoining neuron

Question 19

Why is Myelination important?

Answer 19

Its vital for proper signal
transduction within the nervous systems

Question 20

Myelinated Neurons make up the ______ matter of your
brain

Answer 20

White

Question 21

Un-myelinated Neurons make up the ______ matter of your
brain

Answer 21

Grey

Question 22

Myelinated Neurons are responsible for….

Answer 22

Conducting nerve
impulses

Question 23

Un-myelinated Neurons are responsible for….

Answer 23

Processing
information and
generating nerve
impulses

Question 24

Myelinated Neurons ______ (can/cannot) (regenerate after injury

Answer 24

Can

Question 25

Un-myelinated Neurons ______ (can/cannot) regenerate after injury

Answer 25

Cannot

Question 26

What are the types of Neurons?

Answer 26

Sensory Neurons, Interneurons and Motor Neurons

Question 27

What do Sensory Neurons do?

Answer 27

Gather information from sensory receptors (i.e. touch/sight/sound/taste receptors) and transmit these impulses to the brain

Question 28

What do Interneurons do?

Answer 28

Process and integrate incoming sensory info from sensory neurons and relay outgoing information to motor neurons

Question 29

What do Motor Neurons do?

Answer 29

Transmit information from the brain to muscles (effectors), glands, and other organs

Question 30

Are Sensory Neurons afferent or efferent?

Answer 30

Afferent

Question 31

Are Motor Neurons afferent or efferent?

Answer 31

Efferent

Question 32

Explain a Neural Circuit

Answer 32

- Sensory Neurons receive info from receptors of the skin - Information relayed to the brain by Interneurons - Brain tells appropriate muscle how to respond by transmitting a signal through Motor Neurons

Question 33

What is the Reflex Arc?

Answer 33

A neural circuit that passes through interneurons in the spinal cord for immediate response (involuntary & unconscious)

Question 34

What are the components of the Reflex Arc in order?

Answer 34

1. Receptor 2. sensory neuron 3. interneuron (in spinal cord) 4. motor neuron 5. effector

Question 35

What 2 things are the speed of an impulse along the nerve fiber is dependent on?

Answer 35

Myelin and the Diameter of the Axon

Question 36

How does Myelin effect the speed of an impulse along the nerve fiber?

Answer 36

myelinated axons send impulses faster than non-myelinated axons because the impulse jumps from node to node all along the axon

Question 37

How does the Diameter of the Axon effect the speed of an impulse along the nerve fiber?

Answer 37

bigger = faster

Question 38

What are the four stages of a nerve impulse in order?

Answer 38

1) Polarized / resting state 2) Depolarization 3) Repolarization 4) Refractory Period / Hyperpolarization

Question 39

Describe the Polarized/resting state

Answer 39

Outside slightly more positive (More Na^+) Inside slightly more negative (More K^+, -70mV)

Question 40

What is Membrane Potential?

Answer 40

The change separation across the membrane

Question 41

Describe Depolarization

Answer 41

- Stimulus causes SOME Na^+ gates to open (inside becomes slightly more +) - If stimulus is strong enough (enough Na^+ comes in) to hit -55mV, it causes action potential -> all Na^+ gates open!!

Question 42

Describe Repolarization

Answer 42

- Na^+ gates close (lots of Na^+ inside) - K^+ gates open -> K^+ rushes out causing neuron to be positive again

Question 43

Describe the Refractory period / Hyperpolarization

Answer 43

- Inside becomes more negative then resting potential (K^+ gates slow to close) - Na^+/K^+ pump restores balance back to resting (-70mV) - Na^+ gates shut during this time, causing no action potential during this period

Question 44

What does "All Or Nothing" describe in terms of the action potential?

Answer 44

If only little Na^+ and charge does not hit the -55mV threshold, NO DEPOLARIZATION OCCURS or no action potential!

Question 45

The intensity of a stimulus is experienced as an increased _________________

Answer 45

Frequency (number) of nerve impulses

Question 46

What is synapse / the synaptic cleft?

Answer 46

The space in which a signal is transferred from an Axon Terminal to a Dendrite of the subsequent cell

Question 47

What is a Neurotransmitter?

Answer 47

Things that carry a electric impulse from one neuron to another

Question 48

What does an Excitatory neurotransmitter do?

Answer 48

Causes the Na+ channels of the post-synaptic membrane to open, resulting in depolarization and continuing the action potential

Question 49

____________ is an excitatory neurotransmitter found in muscle cells; causes contraction of the muscle fibre

Answer 49

Acetylcholine

Question 50

What is Cholinesterase?

Answer 50

The enzyme required to break down acetylcholine after the action potential has occurred

Question 51

What does an Inhibitory neurotransmitter do?

Answer 51

Causes Trigger K+ channels to open, causing K+ to flow out and thus lowering the membrane potential

Question 52

What is Norepinepherine?

Answer 52

Produced by adrenal glands during flight or fight response. Excitatory or inhibitory (ie. Increase blood glucose levels, decrease digestion rate)

Question 53

What is Summation?

Answer 53

The effect produced by the accumulation of neurotransmitters from two or more neurons on the postsynaptic neuron.