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chapter 13 neuronal communication Flashcards

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1
Q

what systems do animals use to respond to external and internal changes in environment

A

neural and hormonal communication systems to bring about the correct response

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2
Q

what systems do plants use to respond to external and internal changes in environment

A

hormonal systems

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3
Q

in multicellular organisms, organs and organ systems cannot live isolated they need to be …

A

coordinated with other organs and organ systems

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4
Q

what is homeostasis

A

the coordination of organs to maintain a relatively constant internal environment

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5
Q

what does homeostasis allow: the optimal functioning …

A

the optimal functioning for the organism and includes many variables being kept within certain pre-set limits or within homeostatic ranges

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6
Q

what variables are controlled in homeostasis

A

core temp
blood glucose conc
blood Fe conc
glood gases (co2, 02)
arterial pressure (mmHg)
blood Ca conc
blood Na and K conc
blood water potential (osmotic pressure)
blood pH
cerebrospinal fluid conc
neurotransmitter conc (acetylcholine)

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7
Q

cell signalling is the …. and …. at a cellular level

A

communication and coordination

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8
Q

how do cells communicate with each other

A

by releasing chemicals that affect a target cell or cells

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9
Q

cell signalling can be … and … (distance)

A

between cells locally eg within a tissue or synapse

between cells at greater distances eg a cell in the pancreas controlling a cell in the liver (insulin)

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10
Q

cell signals are carried by …… that are released by one cell and move to make …… with …..

A

signal molecules
make contact
with another cell

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11
Q

what are the common properties of signalling molecules that bind to cell surface receptors

A

large and hydrophillic

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12
Q

example of signalling molecule that bind to cell surface receptor

A

adh

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13
Q

what are the common properties of signalling molecules that enter the cell

A

small and hydrophobic

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14
Q

eg of signalling molecule that enter the cell

A

thyroxine hormone

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15
Q

signalling molecules are excreted by the cell via …

A

exocytosis

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16
Q

how are cell signalling molecules transported

A

they DIFFUSE into the bloodstream and then are transported in the circulatory system

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17
Q

cell signals/signalling molecules are detected by

A

receptors

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18
Q

a way receptors can operate: receptor is a …. and it operates with … or …. or …

A

protein
light
mechanical pressure
temperature

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19
Q

a way receptors can operate: they are ….. …. that change …. of….. when

A

transmembrane proteins
change shape of conformation when their specific signal binds to them

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20
Q

transmembrane proteins (receptors) that
change shape of conformation when their specific signal binds to them could lead to…

A

ions crossing the cell surface

receptor becoming a catalyst on the cytoplasmic side and causes cAMP to be made as a second messenger/a new chemical

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21
Q

what is cAMP

A

cyclic adenosine mono phosphate

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22
Q

what are intracellular receptors

A

proteins that change shape when their signal molecules bind to them, they are for signal molecules that cross the surface membrane

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23
Q

an electrical impulse is also known as a

A

wave of depolarisation

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24
Q

a neurone or nerve cell is a cell that can..

A

transmit electrical impulses/pass on nerve impulses and communicates with other cells via specialised connections called synapses

specialised cells

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25
Q

a neurone is the main component of nervous tissue in all animals except

A

sponges

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26
Q

do plants and fungi have neurones

A

no

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27
Q

what is the function of neurones

A

rapidly transmit electrical impulses to allow coordination

undirectional

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28
Q

difference between a nerve, nerve cell and a neurone

A

a neurone and a nerve cell are the same, a nerve is a collection of neurones

nerve is an enclosed, cable like bundle of axons in the psn

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29
Q

what are the 3 features of every mammalian neurone

A

cell body
dendrons
axons

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30
Q

what is in the cell body

A

nucleus
mitochondria
RER

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31
Q

why to neurones have rer

A

to allow protein synthesis of neurotransmitters

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32
Q

what are dendrons

A

transmits electrical impulses towards the cell body, they form a branching pattern with smaller dendrites

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33
Q

role of axons

A

they transmit electrical impulses away from the cell body

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34
Q

structure of an axon

A

often very long
narrow cytoplasm called an axoplasm covered by plasma membrane with microtubule support

end in many extensions called axon terminals

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35
Q

what is different about sensory neurones

A

they have a side branch with the cell body attached on the end of it

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36
Q

role of sensory neurones

A

they transmit electrical impulses from a receptor cell to a relay neurone/cns the brain or motor neurone

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37
Q

do sensory neurones detect a stimulus

A

NO

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38
Q

how many dendrons does a sensory neurone have

A

1 that may branch into several dendrites

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39
Q

the dendron carries the impulse to the

A

cell body

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40
Q

how many axons does a sensory neurone have

A

one that may have many branches at its terminal

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41
Q

where does coordination occur

A

in the cns

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42
Q

what is a sensory ganglion

A

a region where all the cell bodies are found and it creates a bulge eg funny bone

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43
Q

what do relay neurones do

A

they transmit electrical impulses between neurones (sensory and motor)

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44
Q

where is the cell body on a relay neurone

A

it is central

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45
Q

how many dendrons do relay neurones have

A

many small dendrons that branch into several dendrites

relay neurones dont need long dendrites and axons because they are in the cns

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46
Q

how many axons do relay neurones have

A

many but less than dendons ?

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47
Q

all of the neurones are

A

interconnected

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48
Q

what do motor neurones do

A

transmitt electrical signals from a relay neurone or a sensory neurone/cns to an effector

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49
Q

effectors can be.. or ….

A

muscles or glands

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50
Q

glands come from

A

the endo or exocrine system

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51
Q

how many dendrites do motor neurones have

A

many that carry the impulse towards the cell body

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52
Q

how many axons do motor neurones have

A

one long axon that may have branches that may have branches at its terminal

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53
Q

what is at the end of an axon terminal

A

synaptic bulb or synaptic knob

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54
Q

what is at the end of the axon extensions of motor neurones

A

motor end plates

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55
Q

electrical signals from the motor neurone trigger ….. at the ……. causing the ….. to contract

A

chemical changes at the motor end plate causing the muscle fibres to contract

(produces a grandulated effect on a light micrograph

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56
Q

where are myelinated neurones mostly located and why

A

peripheral nervous system and not cns as cns is dense and compact and so rarely needed

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57
Q

what is special about the plasma membrane of myleinated neurones

A

it is an electrical insulator
non polar
based on LIPID
made from schwann cells

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58
Q

what is myelin made from when in the pns

A

schwann cells when the neurone is in the pns

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59
Q

What is the name for the sleeve of protein and fatty material which covers some neurones?

A

myelin sheath

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60
Q

What effect does the insulating layer of protein and fatty material have on the impulse conduction speed of neurones?

A

Nerve impulses are conducted at a higher speed.

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61
Q

State the name of the cell which produces the sleeve of protein and fatty material which covers some neurones.

A

schwann cell

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62
Q

what is myelin made from when in the cns

A

oligodendorcytes

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63
Q

how do schwann cells produce many layers of plasma

A

by growing around and around the axon of neurones in pns (making myelin sheath)

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64
Q

what is the outer layer of the schwann cell called

A

the neurilemma

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65
Q

what is the band of bunger

A

the schwann cells have a role in allowing dead neurones to reform inside the tunnel created by the SC

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66
Q

how do oligodendrocytes form myelin sheath

A

perform the same as schwann cells but on neurones of cns and do not have a neurilemma because they wrap around multiple axons, up to 50

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67
Q

what type of cells are oligodendrocytes and schwann cells

A

gial cells

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68
Q

What is the name of the gaps found in the sleeve of protein and fatty material which covers some neurones?

A

Nodes of ranvier.

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69
Q

what are the nodes of ranvier

A

small gaps between the myelin sheath and the axolemma which are exposed to the extracellular space

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70
Q

what do the nodes of ranvier allow

A

saltatory conduction

the electrical impulse to jump from one node to hte next increasing the speed of transmission of the impulse

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71
Q

what speed can the transmission of an impulse reach in a myelinated neurone

A

100ms-1

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72
Q

what speed can the transmission of an impulse reach in a non myelinated neurone

A

1ms-1
like in giant squid

73
Q

in humans how often are the nodes of ranvier

A

1-3 mm

74
Q

symptoms of charcot marie tooth disease

A

loss of muscle tissue, loss of touch sensation mainly in feet and legs extending to arms and hands in advanced stages

it is incurable
one of the most common inheited neurological disorders

75
Q

what happens in MS

A

a demyelinating disease in which the myelin sheath of nerve cell axons in the brain and spinal cord are damaged

affects schwann cells

this disrupts the ability of parts of the ns to transmit signals

76
Q

what is thought to be the cause of ms

A

either destruction by the immune system (autoimmune) or failure of hte myelin producing cells- schwann cell

77
Q

what sort of signs and symptoms could someone with ms have

A

a range including physical, mental and psychiatric problems

78
Q

ms is an autoimmune disease that damages the nervous system

suggest how the immune system causes damage to the nervous system
(2/3)

A

schwann cells activate immune system (are the self cells)

antibodies against schwann cells are produced

phagocytes/macrophages etc break down schwann cells

79
Q

what can be concluded about how ms causes a reduction in the speed of nervous impulses (2)

A

fewer/damaged schwann cells
so damaged/no myelin sheath
no saltatory conduction

80
Q

state the function of the myelin sheath

A

saltatory conduction
increases speed of impulse/action potential/transmission
insulates axon

81
Q

outline the ways in which the structures of a sensory neurone and a motor neurone are similar (4)

A

dendrite(s)
an axon
a cell body with a nucleus and eg mitchondria
have myelin sheath made of schwann cells and have nodes of ranvier
voltage gated channels/K+Na pump

82
Q

what do sensory receptor cells do

A

convert a stimulus they detetct into an electrical impulse

83
Q

feature of sensory receptor cells: they are ….to a single type f …

A

SPECIFIC to a single type of stimulus

84
Q

feature of sensory receptor cells: they are ….. because

A

they are transducers because they transduce the stimulus energy into (trigger) electrical energy impilse

85
Q

what are the 4 types of mammalian receptor cells

A

mechanoreceptors
chemoreceptors
thermoreceptors
photoreceptors

86
Q

what is the stimulus for mechanoreceptors

A

pressure
movement
pain

87
Q

what is the stimulus for chemoreceptors

A

chemicals (external and internal)

88
Q

what is the stimulus for thermoreceptors

A

heat

89
Q

what is the stimulus for photoreceptors

A

light

90
Q

sense organ for photoreceptors

A

eye

91
Q

example of photoreceptors

A

cone cells (detect different wavelengths of light)

92
Q

what does a chemoreceptor cell do

A

transduce a chemical substance to generate and electrical impulse

93
Q

chemoreceptors can detect chemicals that are ……. and ……… give examples

A

external eg odurs in the oldactory system
internal eg blood pH/H+ conc in carotid body

94
Q

what are pacinian carpuscles and what do they detect

A

pressure receptor cells that are found in mammalian skin

for sensitivity to vibrations or surface texture

aka lamellar corpuscles

95
Q

what do pacinian corpuscles transduce

A

mechanical energy into an electrical energy impulse in the sensory neurone

96
Q

link sensory neurone of pacinian corpuscle

why is what special

A

the SN that ends inside the PC has a special plasma membrane that contains stretch mediated sodium channel proteins

97
Q

in their normal state (not stretched) the sodium channel proteins have a high …. to ……. because

A

high impermeability to sodium ions because the channel is simply too small for sodium ions

98
Q

when the plasma membrane at the end of the SN in the PC is stretched or pressurised what happens to the sodium channel proteins

A

they increase their permeability to sodium ions because the channel gets wider

99
Q

what are the names of the other 3 pressure receptors in mammalian skin and what are they for

A

meissner’s corpuscles for sensitivity to light touch

merkel cells sensitivity to light touch

ruffini corpuscles sensitivity to skin stretching vital for finger grip (relative to touch)

100
Q

when the PC has pressure or stretch applied, the plasma membrane of the SN is….. and the ……… change from …… to …….

and what does this allow

A

deformed and the sodium channel proteins change from closed to opened

allowing Na+ to be transported into the SN through the sodium channels by facilitated diffusion

101
Q

when Na+ entre the SN what happens

A

it changes the localised polarity of the voltage locally and so that part of the membrane becomes depolarised

102
Q

what is the all or nothing principal

A

an action potential is only created if sufficient sodium ions enter the SN

103
Q

when part of the SN membrane becomes depolarised what happens

results in …… causing

A

it results in a generator potential which causes an action potential/electrical impulse which then travels down the SN

a wave of depolarisaiton

104
Q

when the Na+ enter the SN what is the difference is charges

A

the inside becomes (more) positive relative to the outside

there are no negative ions involved

105
Q

what does a stimulus cause in relation to movement of charge

A

a gradual movement of charge down the nerve called a nerve impulse

106
Q

In an axon, a nerve impulse is defined as a

A

a moving area of charge

107
Q

A nerve impulse always travels in one direction, which is…

A

away from a receptor, towards an effector where it triggers a response

108
Q

the charge/nerve impulse is always….. positve/negative

A

positive

109
Q

what are the 2 ions involved in a nerve impulse

A

potassium ions and sodium ions

110
Q

Generally, there is a higher combined concentration of potassium and sodium ions…
why?

A

outside the axon

more +ions outside because at resting potential Na+ gated channels are closed and K+ gated channels are open and the pump is working so most are outside creating the resting potential

111
Q

generally is it more positively charged inside or outside the axon

A

outside

112
Q

generally, where is a higher concentration of K+
why

A

inside the axon

113
Q

generally where is there a higher conc of Na+

why

A

outside the axon

3 go out from the pump

114
Q

can charged particles/ions simply diffuse through membranes, and what do they need

A

no

they need specific channel proteins that enable facilitated diffusion

115
Q
A
116
Q

what are the 2 ways that we can tell the difference between light and hard touch

A

the number of neurones stimulated relates to how many action potentials are created

the frequency of the action potentials

117
Q

what is the resting potential

A

[when the SN is not stimulated by the PC] in its resting state/not transmitting and impulse it has a voltage across the plasma membrane called the resting potential

is polarised because there is a potential difference across it (outside of the membrane is more postively charged than inside.

plasma membrane is between cytoplasm of axon and plasma membrane of axon

118
Q

what is the usual resting potential

A

around -70milivolts

inside relative to the outside

119
Q

what number mv is hyperpolarisation (the first time)

A

0 to +40

120
Q

what must be reached before an action potential/depolarisation occurs

and what number is this usually

A

the threshold

-55mv

121
Q

what 3 things happen to create the resting potential

A

the sodium channel proteins are closed so no Na+ enter

potassium channel proteins are open so potassium enter

the sodium potassium pump is active: 3Na+ out and 2K+ in

122
Q

at the resting potential, what is the permeability of the membrane like to sodium and potassium ions

A

virtually impermeable

123
Q

the resting potential is generated by which 3 transmembrane proteins

A

Na+/K+ ATPase aka sodium potassium pump, a carrier protein that requires atp because it does active transport and never stops working

N

124
Q

what does the CNS consist of

A

the brain and spinal cord

125
Q

what does the cns have instead of nerves

A

nerve tracts

126
Q

what does the pns consist of

A

nerves and ganglia outside of the brain and spinal cord

127
Q

what is the survival value of reflex actions

A

they are automatic without initial conscious thought so it reduces time for the stimulus to cause damage/prevents damage to the body

128
Q

the knee jerk reflex is also known as the and what is the other reflex we need to know

A

patella tendon reflex blinking reflex

129
Q

a reflex has a specific ….

A

stimulus

130
Q

is a reflex a voluntary or involuntary action

A

involuntary

131
Q

reflexes involves reflex ….. which do not involve the …..

A

reflex arc, a neural pathway which doesnt involve the brain/parts of the brain that are involved in decision making so the theyre able to deal with more complex responses

132
Q

reflexes are innate which is good because

A

they dont have to be learnt/present at birth so provide immediate protection

133
Q

in a reflex arc the impulse travels along the sensory neurone which enters the spinal cord via the

A

dorsal root ganglion

134
Q

in a reflex arc the relay neurone forms synapses with a motor neurone which leaves the spinal cord via the

A

ventral root

135
Q

a reflex has a nearly ……… response

A

instantaneous usually involving only 1 or 2 synapses which are the slowest part of synaptic transmission

136
Q

what is the spinal cord/what is it made up of

A

a long thin tubular structure made up of nervous tissue

137
Q

where is the spinal cord? it extends from…

A

it extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column

138
Q

the vertebral column encloses the central ….. of the spinal cord which contains …..

A

central canal which contains cerebrospinal fluid

139
Q

function of the spinal cord: ……… of nervous impulses from the …… cortex to the ……..

A

transmission from motor cortex to effectors

140
Q

function of the spinal cord: ……….. of nervous impulses from ….. neurons to ……… cortex

A

transmission from sensory neurons to sensory cortex

141
Q

function of the spinal cord: coordinating …

A

coordinating reflexes

142
Q

function of the spinal cord: controlling ……. instructions for ……. movement such as walking

A

motor instructions for rhythmic movement

143
Q

the knee jerk reflex tests what

A

functioning of the spinal cord it it as example of proprioception

144
Q

hitting the patella tendon with a reflex hammer initiates the ……… by acting as the ….

A

reflex arc acting as stimulus

145
Q

the patella tendon becomes ……. which is detected by stretch …… this causes the ……… to contract and the knee to …

A

stretched, stretch receptors, quadriceps, knee extends

146
Q

the reflex blink is a ….. reflex involving the .. in the lower brain stem

A

cranial (neurones going to brain), involving the pons in the lower brain stem

147
Q

examples of stimuli that causes the blinking reflex

A

contact with the cornea or objects that appear rapidly infront of the eye or loud sounds

148
Q

response time for blinking reflex

A

0.1 seconds

149
Q

the blinking reflex response is …. because both eyelids blink together

A

consensual

150
Q

what are the 5 gross areas of the brain

A

cerebrum
cerebellum
medulla oblongata
hypothalamus
pituitary gland

151
Q

What term is used to describe the period of time when a neurone is unable to repeat an action potential?

A

refractory period

152
Q

Describe how voltage-gated channels and the movement of sodium ions prevent the generation of an action potential during the refractory period.

A

the voltage gated Na+ channels are closeed
preventing movement of Na+ into the axon
stopping generation of an action potential

153
Q

Give two reasons why a refractory period should follow an action potential.

A

It ensures action potentials are unidirectional and occur as discrete impulses

154
Q

Neurones always generate action potentials of the same size, no matter how large the stimulus. The stimulus must also reach a minimum threshold or no action potential is generated. What name is given to this type of response?

A

The all or nothing response

155
Q

What method of conduction in myelinated axons involves action potentials jumping from one node of Ranvier to the next?

A

saltatory conduction

156
Q

List three factors that affect the speed of conduction along an axon

A

myelin
axon diameter/thickness/width
temperature

157
Q

What name is given to the swollen end of a presynaptic neurone?

A

synaptic bulb or knob

158
Q

Which neurotransmitter is found in cholinergic synapses?

A

acetylcholine

159
Q

Name the two categories synapses can be placed in, based on how they affect the likelihood of an action potential occurring.

A

excitatory and inhibitory synapses

160
Q

What effect do inhibitory synapses have on the postsynaptic membrane?

A

hyperpolarisation

161
Q

What term describes the process in which more than one impulse is needed to generate an action potential at a synapse?

A

spatial summation

162
Q

Name the process by which an action potential is generated from a single presynaptic neurone releasing neurotransmitters a number of times.

A

temporal summation

163
Q

Name the process by which an action potential is generated from multiple presynaptic neurones releasing neurotransmitters.

A

spatial summation

164
Q

Which part of the brain controls learning, memory and conscious thoughts?

A

the cerebrum

165
Q

Which part of the brain controls unconscious actions including posture and balance?

A

the cerbellum

166
Q

Which part of the brain controls breathing rate and heart rate?

A

the medulla oblongata

167
Q

Which part of the brain is the regulatory centre for temperature and water balance?

A

the hypothalamus

168
Q

Which part of the brain stores and secretes hormones?

A

The pituitary gland

169
Q

injury to the parts of the brain (pituitary gland and hypothalamus) can lead to a range of symptoms:
fatigue
weight gain
menstrual irregularities
low bp or dizziness
increased sensitivity to cold

outline how injury to pt and h is able to cause such a wide range of symptoms (2)

A

produce a wide range of hormones

affect other endocrine/hormone producing glands

exp of damage
eg damage to themoregulatory centre in H leads to increased sensitivity to cold
eg damage to h and pt means reduction in reproductive hormones which leads to menstrual irregularities (oestrogen)

170
Q

What is the role of receptors in homeostasis?

to detect … in a specific ….. involved in a physiological process

A

To detect changes in a specific stimulus involved in a physiological process

171
Q

Why are receptors described as transducers? they convert a ……

A

they convert a stimulus into a nerve impulse/action potential

172
Q

Give a specific example of a mechanoreceptor which responds to pressure in the skin.

A

pacinian corpuscle

173
Q

What stimulus do rods and cones respond to?

A

light

174
Q

what is an electrochemical gradient

A

The difference in concentration and charge across the membrane is called the electrochemical gradient.

175
Q

what does GABA cause in relation to the post synaptic membrane

A

hyperpolarisation of it

176
Q

true or false: the automatic nervous system contains sensory and motor neurones

A

true

177
Q

true or false: somatic and parasympathetic motor neurones use different neurotransmitters

A

false

178
Q

true or false: somatic motor neurones stimulate skeletal muscles whereas autonomic motor neurones stimulate only glands

A

false

179
Q
A

alevel biology ocr (26 decks)

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