chapter 13 neuronal communication Flashcards
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
2
Q
what systems do plants use to respond to external and internal changes in environment
A
hormonal systems
3
Q
in multicellular organisms, organs and organ systems cannot live isolated they need to be …
A
coordinated with other organs and organ systems
4
Q
what is homeostasis
A
the coordination of organs to maintain a relatively constant internal environment
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
6
Q
what variables are controlled in homeostasis (loads of things)
A
core temp
blood glucose conc
blood Fe conc
blood 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)
7
Q
cell signalling is the …. and …. at a cellular level
A
communication and coordination
8
Q
how do cells communicate with each other
A
by releasing chemicals that affect a target cell or cells
9
Q
cell signalling can be … and … (distance)
and egs
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)
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
11
Q
what are the common properties of signalling molecules that bind to cell surface receptors
A
large and hydrophillic
12
Q
example of signalling molecule that bind to cell surface receptor
A
adh
13
Q
what are the common properties of signalling molecules that enter the cell
A
small and hydrophobic
14
Q
eg of signalling molecule that enter the cell
A
thyroxine hormone
15
Q
signalling molecules are excreted by the cell via …
A
exocytosis
16
Q
how are cell signalling molecules transported
A
they DIFFUSE into the bloodstream and then are transported in the circulatory system
17
Q
cell signals/signalling molecules are detected by
A
receptors
18
Q
a way receptors can operate: receptor is a …. and it operates with … or …. or …
A
protein
light
mechanical pressure
temperature
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
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
21
Q
what is cAMP
A
cyclic adenosine mono phosphate
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
23
Q
an electrical impulse is also known as a
A
wave of depolarisation
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
25
a neurone is the main component of nervous tissue in all animals except
sponges
26
do plants and fungi have neurones
no
27
what is the function of neurones
rapidly transmit electrical impulses to allow coordination
undirectional
28
difference between a nerve, nerve cell and a neurone
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
29
what are the 3 features of every mammalian neurone
cell body
dendrons
axons
30
what is in the cell body
nucleus
mitochondria
RER
31
why to neurones have rer
to allow protein synthesis of neurotransmitters
32
what are dendrons
transmits electrical impulses towards the cell body, they form a branching pattern with smaller dendrites
33
role of axons
they transmit electrical impulses away from the cell body
34
structure of an axon
often very long
narrow cytoplasm called an axoplasm covered by plasma membrane with microtubule support
end in many extensions called axon terminals
35
what is different about sensory neurones
they have a side branch with the cell body attached on the end of it
36
role of sensory neurones
they transmit electrical impulses from a receptor cell to a relay neurone/cns the brain or motor neurone
37
do sensory neurones detect a stimulus
NO
38
how many dendrons does a sensory neurone have
1 that may branch into several dendrites
39
the dendron carries the impulse to the
cell body
40
how many axons does a sensory neurone have
one that may have many branches at its terminal
41
where does coordination occur
in the cns
42
what is a sensory ganglion
a region where all the cell bodies are found and it creates a bulge eg funny bone
43
what do relay neurones do
they transmit electrical impulses between neurones (sensory and motor)
44
where is the cell body on a relay neurone
it is central
45
how many dendrons do relay neurones have
many small dendrons that branch into several dendrites
relay neurones dont need long dendrites and axons because they are in the cns
46
how many axons do relay neurones have
many but less than dendons ?
47
all of the neurones are
interconnected
48
what do motor neurones do
transmitt electrical signals from a relay neurone or a sensory neurone/cns to an effector
49
effectors can be.. or ....
muscles or glands
50
glands come from
the endo or exocrine system
51
how many dendrites do motor neurones have
many that carry the impulse towards the cell body
52
how many axons do motor neurones have
one long axon that may have branches that may have branches at its terminal
53
what is at the end of an axon terminal
synaptic bulb or synaptic knob
54
what is at the end of the axon extensions of motor neurones
motor end plates
55
electrical signals from the motor neurone trigger ..... at the ....... causing the ..... to contract
chemical changes at the motor end plate causing the muscle fibres to contract
(produces a grandulated effect on a light micrograph
56
where are myelinated neurones mostly located and why
peripheral nervous system and not cns as cns is dense and compact and so rarely needed
57
what is special about the plasma membrane of myleinated neurones
it is an electrical insulator
non polar
based on LIPID
made from schwann cells
58
what cells is myelin formed from when in the pns
schwann cells when the neurone is in the pns
59
What is the name for the sleeve of protein and fatty material which covers some neurones?
myelin sheath
60
What effect does the insulating layer of protein and fatty material have on the impulse conduction speed of neurones?
Nerve impulses are conducted at a higher speed.
61
State the name of the cell which produces the sleeve of protein and fatty material which covers some neurones.
schwann cell
62
what is myelin made from when in the cns
oligodendorcytes
63
how do schwann cells produce many layers of plasma
by growing around and around the axon of neurones in pns (making myelin sheath)
64
what is the outer layer of the schwann cell called
the neurilemma
65
what is the band of bunger
the schwann cells have a role in allowing dead neurones to reform inside the tunnel created by the SC
66
how do oligodendrocytes form myelin sheath
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
67
what type of cells are oligodendrocytes and schwann cells
gial cells
68
What is the name of the gaps found in the sleeve of protein and fatty material which covers some neurones?
Nodes of ranvier.
69
what are the nodes of ranvier
small gaps between the myelin sheath and the axolemma which are exposed to the extracellular space
70
what do the nodes of ranvier allow
saltatory conduction
the electrical impulse to jump from one node to hte next increasing the speed of transmission of the impulse
71
what speed can the transmission of an impulse reach in a myelinated neurone
100ms-1
72
what speed can the transmission of an impulse reach in a non myelinated neurone
1ms-1
like in giant squid
73
in humans how often are the nodes of ranvier
1-3 mm
74
symptoms of charcot marie tooth disease
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
what happens in MS
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
what is thought to be the cause of ms
either destruction by the immune system (autoimmune) or failure of hte myelin producing cells- schwann cell
77
what sort of signs and symptoms could someone with ms have
a range including physical, mental and psychiatric problems
78
ms is an autoimmune disease that damages the nervous system
suggest how the immune system causes damage to the nervous system
(2/3)
schwann cells activate immune system (are the self cells)
antibodies against schwann cells are produced
phagocytes/macrophages etc break down schwann cells
79
what can be concluded about how ms causes a reduction in the speed of nervous impulses (2)
fewer/damaged schwann cells
so damaged/no myelin sheath
no saltatory conduction
80
state the function of the myelin sheath
saltatory conduction
increases speed of impulse/action potential/transmission
insulates axon
81
outline the ways in which the structures of a sensory neurone and a motor neurone are similar (4)
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
what do sensory receptor cells do
convert a stimulus they detetct into an electrical impulse
83
feature of sensory receptor cells: they are ....to a single type f ...
SPECIFIC to a single type of stimulus
84
feature of sensory receptor cells: they are transducers because
they are transducers because they transduce the stimulus energy into (trigger) electrical energy impulse
Transducers are used in circuits to convert one form of energy to another.
In a living organism, a transducer is a cell or part of a cell that converts stimuli into signals for the organism to process. Sensory receptors convert a stimulus into an action potential.
85
what are the 4 types of mammalian receptor cells
mechanoreceptors
chemoreceptors
thermoreceptors
photoreceptors
86
what is the stimulus for mechanoreceptors
pressure
movement
pain
87
what is the stimulus for chemoreceptors
chemicals (external and internal)
88
what is the stimulus for thermoreceptors
heat
89
what is the stimulus for photoreceptors
light
90
sense organ for photoreceptors
eye
91
example of photoreceptors
cone cells (detect different wavelengths of light)
92
what does a chemoreceptor cell do
transduce a chemical substance to generate and electrical impulse
93
chemoreceptors can detect chemicals that are ....... and ......... give examples
external eg odurs in the oldactory system
internal eg blood pH/H+ conc in carotid body
94
There are ion channels in the membrane of the Pacinian corpuscle’s sensory neurone.
Describe how these facilitate an action potential being sent to the central nervous system.
First, the membrane of the sensory neurone contains stretch-mediated sodium ion channels.
When the Pacinian corpuscle experiences pressure, these ion channels open.
An influx of sodium ions causes the inside of the neurone to become depolarised. This is called a generator potential.
When many of these potentials build up, the threshold value is reached, triggering an action potential. This action potential is sent to the central nervous system.
95
what are pacinian carpuscles and what do they detect
pressure receptor cells that are found in mammalian skin
for sensitivity to vibrations or surface texture
aka lamellar corpuscles
96
what do pacinian corpuscles transduce .... into
mechanical energy into an electrical energy impulse in the sensory neurone
97
link sensory neurone of pacinian corpuscle
why is what special
the SN that ends inside the PC has a special plasma membrane that contains stretch mediated sodium channel proteins
98
in their normal state (not stretched) the sodium channel proteins have a high .... to ....... because
high impermeability to sodium ions because the channel is simply too small for sodium ions
99
when the plasma membrane at the end of the SN in the PC is stretched or pressurised what happens to the sodium channel proteins
they increase their permeability to sodium ions because the channel gets wider
100
what are the names of the other 3 pressure receptors in mammalian skin and what are they for
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)
101
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
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
102
when Na+ enters the SN what happens
it changes the localised polarity of the voltage locally and so that part of the membrane becomes depolarised
103
what is the all or nothing principal
an action potential is only created if sufficient sodium ions enter the SN
104
when part of the SN membrane becomes depolarised what happens
results in ...... causing
it results in a generator potential which causes an action potential/electrical impulse which then travels down the SN
a wave of depolarisaiton
105
when the Na+ enter the SN what is the difference is charges
the inside becomes (more) positive relative to the outside
there are no negative ions involved
106
what does a stimulus cause in relation to movement of charge
a gradual movement of charge down the nerve called a nerve impulse
107
In an axon, a nerve impulse is defined as a
a moving area of charge
108
A nerve impulse always travels in one direction, which is…
away from a receptor, towards an effector where it triggers a response
109
the charge/nerve impulse is always..... positve/negative
positive
110
what are the 2 ions involved in a nerve impulse
potassium ions and sodium ions
111
Generally, there is a higher combined concentration of potassium and sodium ions…
why?
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
112
generally is it more positively charged inside or outside the axon
outside
113
generally, where is a higher concentration of K+
why
inside the axon
114
generally where is there a higher conc of Na+
why
outside the axon
3 go out from the pump
115
can charged particles/ions simply diffuse through membranes, and what do they need
no
they need specific channel proteins that enable facilitated diffusion
116
117
what are the 2 ways that we can tell the difference between light and hard touch
the number of neurones stimulated relates to how many action potentials are created
the frequency of the action potentials
118
what is the resting potential
[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
119
what is the usual resting potential
around -70milivolts
inside relative to the outside
120
what number mv is hyperpolarisation (the first time)
0 to +40
121
what must be reached before an action potential/depolarisation occurs
and what number is this usually
the threshold
-55mv
122
what 3 things happen to create the resting potential
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
123
at the resting potential, what is the permeability of the membrane like to sodium and potassium ions
virtually impermeable
124
the resting potential is generated by which 3 transmembrane proteins
Na+/K+ ATPase aka sodium potassium pump, a carrier protein that requires atp because it does active transport and never stops working
N
125
what does the CNS consist of
the brain and spinal cord
126
what does the cns have instead of nerves
nerve tracts
127
what does the pns consist of
nerves and ganglia outside of the brain and spinal cord
128
what is the survival value of reflex actions
they are automatic without initial conscious thought so it reduces time for the stimulus to cause damage/prevents damage to the body
129
the knee jerk reflex is also known as the and what is the other reflex we need to know
patella tendon reflex blinking reflex
130
a reflex has a specific ....
stimulus
131
is a reflex a voluntary or involuntary action
involuntary
132
reflexes involves reflex ..... which do not involve the .....
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
133
reflexes are innate which is good because
they dont have to be learnt/present at birth so provide immediate protection
134
in a reflex arc the impulse travels along the sensory neurone which enters the spinal cord via the
dorsal root ganglion
135
in a reflex arc the relay neurone forms synapses with a motor neurone which leaves the spinal cord via the
ventral root
136
a reflex has a nearly ......... response
instantaneous usually involving only 1 or 2 synapses which are the slowest part of synaptic transmission
137
what is the spinal cord/what is it made up of
a long thin tubular structure made up of nervous tissue
138
where is the spinal cord? it extends from...
it extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column
139
the vertebral column encloses the central ..... of the spinal cord which contains .....
central canal which contains cerebrospinal fluid
140
function of the spinal cord: ......... of nervous impulses from the ...... cortex to the ........
transmission from motor cortex to effectors
141
function of the spinal cord: ........... of nervous impulses from ..... neurons to ......... cortex
transmission from sensory neurons to sensory cortex
142
function of the spinal cord: coordinating ...
coordinating reflexes
143
function of the spinal cord: controlling ....... instructions for ....... movement such as walking
motor instructions for rhythmic movement
144
the knee jerk reflex tests what
functioning of the spinal cord it it as example of proprioception
145
hitting the patella tendon with a reflex hammer initiates the ......... by acting as the ....
reflex arc acting as stimulus
146
the patella tendon becomes ....... which is detected by stretch ...... this causes the ......... to contract and the knee to ...
stretched, stretch receptors, quadriceps, knee extends
147
the reflex blink is a ..... reflex involving the .. in the lower brain stem
cranial (neurones going to brain), involving the pons in the lower brain stem
148
examples of stimuli that causes the blinking reflex
contact with the cornea or objects that appear rapidly infront of the eye or loud sounds
149
response time for blinking reflex
0.1 seconds
150
the blinking reflex response is .... because both eyelids blink together
consensual
151
what are the 5 gross areas of the brain
cerebrum
cerebellum
medulla oblongata
hypothalamus
pituitary gland
152
What term is used to describe the period of time when a neurone is unable to repeat an action potential?
refractory period
153
Describe how voltage-gated channels and the movement of sodium ions prevent the generation of an action potential during the refractory period.
the voltage gated Na+ channels are closeed
preventing movement of Na+ into the axon
stopping generation of an action potential
154
Give two reasons why a refractory period should follow an action potential.
It ensures action potentials are unidirectional and occur as discrete impulses
155
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?
The all or nothing response
156
What method of conduction in myelinated axons involves action potentials jumping from one node of Ranvier to the next?
saltatory conduction
157
List three factors that affect the speed of conduction along an axon
myelin
axon diameter/thickness/width
temperature
158
What name is given to the swollen end of a presynaptic neurone?
synaptic bulb or knob
159
Which neurotransmitter is found in cholinergic synapses?
acetylcholine
160
Name the two categories synapses can be placed in, based on how they affect the likelihood of an action potential occurring.
excitatory and inhibitory synapses
161
What effect do inhibitory synapses have on the postsynaptic membrane?
hyperpolarisation
162
What term describes the process in which more than one impulse is needed to generate an action potential at a synapse?
spatial summation
163
Name the process by which an action potential is generated from a single presynaptic neurone releasing neurotransmitters a number of times.
temporal summation
164
Name the process by which an action potential is generated from multiple presynaptic neurones releasing neurotransmitters.
spatial summation
165
Which part of the brain controls learning, memory and conscious thoughts? an area not a specific lobe
the cerebrum
166
Which part of the brain controls unconscious actions including posture and balance?
the cerbellum
167
Which part of the brain controls breathing rate and heart rate?
the medulla oblongata
168
Which part of the brain is the regulatory centre for temperature and water balance?
the hypothalamus
169
Which part of the brain stores and secretes hormones?
The pituitary gland
170
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)
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)
171
What is the role of receptors in homeostasis?
to detect ... in a specific ..... involved in a physiological process
To detect changes in a specific stimulus involved in a physiological process
172
Why are receptors described as transducers? they convert a ......
they convert a stimulus into a nerve impulse/action potential
173
Give a specific example of a mechanoreceptor which responds to pressure in the skin.
pacinian corpuscle
The Pacinian corpuscle is a mechanoreceptor cell that sits deep in the skin and is sensitive to pressure. It converts pressure into an action potential.
174
What stimulus do rods and cones respond to?
light
175
what is an electrochemical gradient
The difference in concentration and charge across the membrane is called the electrochemical gradient.
176
what does GABA cause in relation to the post synaptic membrane
hyperpolarisation of it
177
true or false: the automatic nervous system contains sensory and motor neurones
true
178
true or false: somatic and parasympathetic motor neurones use different neurotransmitters
false
179
true or false: somatic motor neurones stimulate skeletal muscles whereas autonomic motor neurones stimulate only glands
false
180
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