The Nervous System Flashcards
(303 cards)
1
Q
What is the nervous system in charge of?
A
interaction between the body and the environment
2
Q
What is the nervous system the main coordinator of?
A
body functions
3
Q
What additional system does the nervous system work alongside with in order to coordinate body functions?
A
endocrine system
4
Q
What are the 2 main components of the nervous system?
A
central and peripheral
5
Q
What do neurons communicate between?
A
themselves and with other cells
6
Q
What signals do neurons use to communicate between themselves and other cells?
A
electrical and chemical signals
7
Q
What so dendrites do?
A
receive information that signals to the specific neurone
8
Q
What is an axon?
A
pathway through which neurone signals to the next one in the chain
9
Q
What do presynaptic terminals face into?
A
the synapse
10
Q
Why are neurons excitable?
A
membranes have charges which change when they become activated and generate action potential
11
Q
What is meant by directional flow of charge?
A
neurons only allow charge to flow in one direction through them
12
Q
How do neurones communicate with each other and target cells using chemicals?
A
they release small quantities of chemical across the synaptic cleft from a presynaptic neurone to the post synaptic cell
13
Q
What is the name of the chemicals used across synapses?
A
neurotransmitters/transmitters
14
Q
Where are neurotransmitters stored?
A
vesicles in the presynaptic cell
15
Q
What do synapses enable?
A
quick transfer of signal
16
Q
How do synapses help with directional flow?
A
neurotransmitters only move one way
17
Q
What are afferent neurons?
A
neurons towards the brain
18
Q
What are efferent neurons?
A
neurons moving away from the brain towards effectors
19
Q
What do interneurones do?
A
receive signals and process them within the brain or peripheral ganglia
20
Q
How are structures which receive/process sensory information located anatomically in relation to structures that control efferent output?
A
posterior
21
Q
What is the CNS composed of?
A
brain and spinal chord
22
Q
What divisions is the PNS composed of?
A
afferent and efferent divisions
23
Q
What are the 3 branches of the afferent division of the PNS?
A
somatic sensory, visceral sensory (autonomic), special sensory
24
Q
What are the 2 branches of the efferent division of the PNS?
A
somatic motor, autonomic (visceral)
25
What are the 3 divisions of the efferent autonomic system of the PNS?
sympathetic, parasympathetic, entric
26
What are the 4 lobes of the brain (human)?
frontal, occipital, parietal, temporal
27
What are the 2 key areas of the forebrain?
cerebrum, diencephalon
28
What is the brain stem the centre for?
information essential to life (e.g. respiration/heart rate)
29
What are the 3 key elements of the brainstem?
midbrain, Pons, medulla oblongata
30
What is the cerebellum used for?
balance and posture (bigger in quadrupeds)
31
What is the vagus nerve?
key nerve in autonomic nervous system
32
Where does information enter the spine via afferent nerves?
dorsal horn
33
Where does information leave the spine via efferent nerves?
ventral horns
34
What are the ventral horns composed of?
long axons of neurons located in the grey matter
35
Why do nerves not correspond to the segments of the spinal chord once we reach adulthood?
are an exact match when we are born, as we grow the spinal column grows more than nerve tissue so the exits no longer match the locations of the nerves
36
What are the 4 areas of the spine?
cervical, thoracic, lumbar, sacral
37
What are high density clusters of neurones called in the brain?
nuclei
38
What are high density clusters of neurons called in the peripheral nervous system?
ganglia
39
why is the phospholipid bilayer a good electrical insulator?
impermeable to ions
40
Is the concentration of sodium ions higher inside the cell or outside?
outside (145 mM)
41
is the concentration of potassium ions higher inside or outside the cell?
inside (140 mM)
42
What is an example of an active ion transporter?
sodium potassium pump
43
how many potassium ions are moved for 3 sodium ions?
2
44
What do ion channels allow?
ions to pass through plasma membrane down a concentration gradient
45
What are leaky ion channels?
channels that always allow ion movement
46
What are gated ion channels?
ion channels that remain closed until a threshold is reached which causes them to open
47
What are 2 examples of gated ion channels?
voltage gated and ligand gated
48
Does potassium diffuse into or out of the cell down it's concentration gradient?
out of the cell
49
What happens when positively charged potassium leaves the cell?
takes charge with it so cell becomes more negatively charged compared to the outside of the cell
50
What sort of potential can the movement of K+ ions out of the cell create?
negative membrane potential
51
What happens when movement of K+ ions out of the cell causes the cell to reach a threshold of electrochemical gradient?
no more net movement of potassium ions out of the cell
52
What happens at the balanced equilibrium potential?
concentration gradient one way is equal to the electrochemical gradient the other
53
What does the Nernst equation predict?
equilibrium potential for a particular type of ion
54
What is the RMP of a neuron?
-70 mV
55
What is the equilibrium potential of K+?
-95mV
56
What is the equilibrium potential of Na+?
+61mV
57
What is the equilibrium potential of Cl-?
-90mV
58
Which of the three main ions resting potential is the main determinant of resting membrane potential?
K+
59
What can be used to predict membrane potential?
relative permeabilities of ions
60
What does a relative permeability of 1 mean for ions?
high, flow through channels all the time
61
What does a relative permeability of 0 mean for ions?
very low, ions barely passing through channels
62
What happens to the membrane potential of a cell during an action potential?
fast changes in the membrane potential of the cell from positive to negative and back
63
What is an action potential?
brief 'all or nothing' depolarisation of neuronal membrane
64
How is the signal information encoded in an action potential?
by frequency and pattern of signal not by amplitude
65
What happens to the signal as it is propagated along cell membrane and axon?
the signal will remain the same
66
Once threshold has been reached what changes occur in the amplitude of the action potential?
none, even if a stronger signal is given the amplitude will stay the same
67
If the threshold is not reached will the signal be transferred?
no
68
What are fluxes of Na+ and K+ ions coordinated by?
voltage gated ion channels
69
What sort of polarisation of the cell membrane are Na+ ions involved with?
depolarisation
70
What sort of polarisation of the cell membrane are K+ ions involved with?
repolarisation
71
What is the Na+ ion channel controlled by?
potential of the membrane
72
What is the Na+ ion channel closed by?
flexible protein in the mouth of the channel
73
What does the charge of the amino acid/protein closing the Na+ ion channel react with?
charge inside the cell membrane
74
What must happen in order to initiate AP?
membrane must be depolarized
75
What does the need for membrane depolarization explain?
the threshold required before an AP is propogated
76
What feedback mechanism is responsible for the dynamic and speed of an action potential?
positive feedback mechanism
77
What effect does depolarization of the membrane have on Na
| + channels?
opening of voltage gated Na+ channels which results in sodium currents depolarizing membrane further
78
What can be done to stop the positive feedback mechanism and ensure an action potential comes to an end?
when channel is depolarized an inactivation gate covers the end of the sodium channel found in the cell
79
What stroke of the action potential are sodium channels responsible for?
upstroke
80
What happens to K+ ion channels in response to the depolarization of membrane?
delayed response results in K+ channels opening so K+ rapidly exits cell and so cell becomes more negative (polarized) again
81
What are the 3 states a sodium channel can be in?
closed, open, inactivated
82
What are the 2 states a potassium channel can be in?
closed or open
83
During depolarisation what happens to Na+ and K+ ion channels?
Na+: closed to open to inactivated
| K+: closed to open
84
During repolarisation what happens to Na+ and K+ ion channels?
Na+: inactivated to open to closed
| K+: open to closed
85
What is needed to reverse the inactivation of sodium channels?
negative membrane potential
86
What are the 2 factors responsible for the termination of action potential?
inactivation of Na+ channels
| delayed activation of K+ channels
87
What are the K+ channels also known as when opening after the depolarization of the membrane?
delayed rectifiers
88
What is the structure of the protein the Na+ channel made of?
single protein with 4 subunits
89
What is the structure of the protein the K+ channel is made of?
4 subunits are made from separate proteins
90
Where is the action potential generated in central neurons?
initial segment
91
What is found in large quantities in the initial segment of central neurons?
many Na+ channels
92
What does tetrodotoxin do?
blocks voltage gated sodium channels
93
What are the 2 phases of the refractory period?
Absolute and relative
94
Can action potential be generated in a cell in absolute refractory period?
no AP cannot occur under any circumstances
95
Can action potential be generated in a cell in relative refractory period?
a stronger than normal stimulus may evoke AP
96
What does sodium/potassium ATPase maintain and restore?
ion gradient and restores ion concentrations after action potential
97
what is sodium/potassium ATPase dependent on as an ion transporter?
ATP
98
Why is sodium/potassium ATPase electrogenic?
generates negative charge within cell
99
Where is AP propagated in mylinated cells?
nodes of ranvier
100
What is saltatory conduction?
AP jumps from one node of ranvier to next
101
How does saltatory conduction improve AP propagation?
increases the speed and saves energy
102
How does saltatory conduction save energy?
ion concentration does not have to be restored along the whole length of the cell
103
How quickly do thick, well myelinated axons conduct?
fast
104
How quickly do unmyelinated axons conduct?
slower
105
What is the neuromuscular junction?
synapse between presynaptic motor neuron and postsynaptic muscle
106
What does a chemical synapse do?
mediates signal propagation from neuron to posy synaptic cell
107
What is the synaptic cleft?
gap between pre and post synaptic cells
108
What direction does the electrical signal travel across a synapse?
from presynaptic terminal to post synaptic cell
109
What must happen in order for the electrical signal to cross the synaptic cleft?
must be converted into a chemical signal
110
What is the neurotransmitter found at neuromuscular junctions?
Acetylcholine
111
Where is acetylcholine produced?
presynaptic terminal
112
What enzyme produces acetylcholine?
choline acetyl transfurase
113
What does choline acetyl transfurase do in order to form acetylcholine?
attaches acetyl group to from acetyl-CoA to choline
114
Where is acetylcholine stored in the presynaptic cell?
vesicles
115
What transporters move acetylcholine into vesicles in the presynaptic cell?
uptake transporters
116
Where on a muscle cell is the neuromuscular junction usually found?
towards the middle of the cell
117
Why are there lots of mitochondria present in the presynaptic cell?
synaptic transmission requires a lot of metabolic energy
118
What type of ion channel is found in the presynaptic membrane?
voltage gated Ca2+
119
what types of ion channels are found in the post synaptic membrane?
voltage gated Na+ channels
| ligand gated channels
120
Is the intracellular concentration of Ca2+ in the cell high or low compared to outside the cell?
low
121
by what process is the neurotransmitter released from the presynaptic cell?
Ca2+ dependent exocytosis
122
What happens when a membrane is depolarized?
there is a positive shift in the membrane potential
123
What happens in the presynaptic cell when the action potential arrives at presynaptic terminal?
membrane is depolarized
124
What does the depolarization of the presynaptic membrane trigger?
Ca2+ channels to open so that calcium levels in the cell begin to rise
125
As calcium diffuses into the presynaptic cell what does it signal to?
elements that cause transmitter vesicles to dock to the presynaptic membrane
126
What is the name of the proteins in the presynaptic membrane which enable the transmitter vesicles to dock?
snare proteins
127
When a transmitter vesicle membrane fuses with the presynaptic membrane by what process does the transmitter then exit the vesicle and cell into the synaptic cleft?
exocytosis
128
Once in the synaptic cleft what happens to neurotransmitter?
diffuses to post synaptic cell and the acetylcholine receptors in it's surface
129
What postsynaptic ion channels are acetylcholine receptors examples of?
ligand gated ion channels
130
What is the name of the acetylcholine receptor?
nicotinic acetylcholine receptor (nAChR)
131
Is nicotinic acetylcholine receptor (nAChR) a selective or non-selective ion channel?
non-selective
132
How many binding sites for acetylcholine does nAChR have?
2
133
What happens to nAChR when 2 acetylcholine molecules have bound to it?
becomes activated and opens to allow ions to pass through such as Na+
134
How many different sub-units is nAChR formed of?
5
135
What effect does Na+ entering the post synaptic cell through nAChR have on the muscle fibre membrane?
depolarization and creation of end plate potential
136
What has to happen at the post synaptic muscle cell in order for movement to occur?
threshold has to be reached so that action potential (end plate potential) can be propagated
137
What does the creation of end plate potential in muscle cells lead to?
muscle contraction
138
Where are sodium channels and nAChRs present in the muscle cell?
sodium channels: all along muscle cells
| nAChRs: only in post synaptic endplate
139
Why does transynaptic signal need to be controlled?
to keep endplate potential short and make the transmission meaningful/useful
140
What is used to terminate the transynaptic signal?
enzymes in the synaptic cleft
141
What do enzymes in the synaptic cleft do to ACh?
split ACh into acetyl and choline
142
What is the name of the enzyme which breaks down ACh in order to terminate transynaptic signal?
acetylcholine esterase
143
What happens to the acetyl and choline that are broken down by acetylcholine esterase in the synaptic cleft?
reabsorbed into terminals and used to create acetylcholine again
144
In the CNS what are pre and post synaptic cells fomed of?
neurons
145
What is neural convergence?
many neurons impart signal onto a single neuron
146
what is neural divergence?
single neuron can signal to many different postsynaptic neurons/cells
147
What do dendritic spines on dendrites do?
increase contact surface area for synaptic contacs
148
Is there chemical diversity in the neurotransmitters and neuromodulators of the CNS?
yes
149
Name 6 potential neurotransmitter/neuromodulator types in the CNS
```
amino acids
acetylcholine
biogenic amines
neuropeptides
purines
gases
```
150
What is an example of a amino acid neurotransmitter?
glutamate/GABBA
151
What does Dale's principal suggest?
single neurons will specialise, they will be exitatory or inhibitory and so use a specific neurotransmitter in all synapses
152
Can a presynaptic neuron contain more than one neurotransmitter?
yes, often an exitatory and inhibitory
153
What is the difference in appearance between excitatory and inhibitory synapses?
excitatory: densities on both sides of the synapse are asymmetrical
inhibitory: symmetrical synaptic density
154
Can you have both exitatory and inhibitory synapses on one dendrite?
yes
155
Where is glutamate stored in the presynaptic cell?
vesicles near the presynaptic membrane
156
What is one of the most abundant receptors in the central nervous system?
ionotropic glutamate receptor (AMPA)
157
What type of ion channel is ionotropic glutamate receptor (AMPA)?
ligand gated ion channel
158
how many subunits is ionotropic glutamate receptor (AMPA) made up of?
4
159
What ions is ionotropic glutamate receptor (AMPA) permeable to when activated?
Na+, K+ and sometimes Ca2+
160
What is ionotropic glutamate receptor (AMPA) activated by?
2-4 glutamate molecules
161
How is ionotropic glutamate receptor (AMPA) deactivated?
unbinding of glutamate that leads to the closing of the channels
162
What sort of depolarization is excitatory postsynaptic potential?
graded depolarization
163
What does graded deploarization by ESPS do to the membrane potential?
moves the membrane potential closer to the threshold for firing an action potential
164
What effect does deploarization always have on the membrane potential?
makes it more positive
165
What happens if action potential reached at initial axon segment?
action potential is created
166
What does the level of depolarization by EPSP depend on?
the number of AMPA receptors opened
167
What is the major central inhibitory receptor type?
GABA receptor
168
What is GABA?
gamma-amino-butyric acid
169
What does GABA have a simular structure to?
glutamate
170
What type of ion channel is GABA receptor?
ligand gated ion channel
171
How many subunits does GABA receptor have?
5
172
What is the GABA receptor structure similar to?
nAChR
173
How does GABA receptor differ from nAChR?
it only accepts negative ions
174
What is the GABA receptor activated by?
2 GABA molecules binding
175
How is the GABA receptor deactivated?
unbinding of GABA molecules which then return to their resting state
176
What sort of polarization is inhibitory postsynaptic potential?
graded hyperpolarization
177
What does the degree of graded hyperpolarization during IPSP depend on?
the number of GABA channels open
178
What does graded hyperpolarisation by IPSP do?
moves the membrane potential further from the threshold for firing an action potential
179
What does it mean if the membrane has become more polarized?
membrane is more negative
180
How is the membrane made more negative during IPSP?
influx of chloride ions
181
Compared to active transport how fast is synaptic transmission?
slow
182
What is good about synaptic transfur that cannot occur during the electrical transmission of action potential?
allows for multiple signal integration of incoming signals and this integration will them compute if active transport should be propagated
183
How does a neuron decide if an action potential will be propagated?
EPSP and IPSP are combined 'summed up' to decide if action potential will be triggered
184
What is spatial summation?
PSP's from different synaptic inputs arriving in the postsynaptic neuron at the same time
185
What is temporal summation?
PSP's from different synaptic inputs arriving in the postsynaptic neuron in quick succession
186
What happens if the sum of PSP's reaches the action potential threshold?
action potential can be triggered at axon hillock
187
Can combination of EPSP and IPSP lead to no response?
yes
188
Give an example of presynaptic inhibition
inhibition of presynaptic Ca2+ channels
189
give an example of presynaptic excitation?
increase of presynaptic Ca2+ levels
190
What can synaptic efficiency be modulated by?
metabotrophic receptors
191
What type of nervous structures are sensory receptors?
specialised
192
What do sensory receptors allow us to receive?
information about the external and internal environment
193
where is information from sensory receptors sent for processing?
CNS
194
What are specialized nerve cells able to detect?
one form of energy which triggers an action potential
195
What are the 2 types of sensory receptor?
specialised endings of afferent neurons or separate cells that signal to the afferent neuron
196
Sensory receptors that use specialised cells are not directly linked to the ___?
brain
197
Sensory receptors are ___ of energy?
transducers
198
What does a transducer do?
converts one form of energy (e.g. heat) into another form of energy (e.g. electrical energy)
199
what is depolarization at a sensory terminal called?
receptor potential
200
What does graded mean in terms of receptor potential?
proportional to stimulus strength
201
What does non-propagating mean in terms of receptor potential?
it is confined to the sensory terminal
202
What happens if the receptor potential in a sensory terminal is large enough?
it will evoke an action potential along the nerve fibre
203
What does an increase in stimulus strength mean for the amount of neurotransmitter released from the pre-synaptic neurone of the sensory organ?
increase in stimulus will lead to an increased amount of neurotransmitter released
204
What effect does the increased amount of neuro transmitter released by a more intense stimulus have on the CNS?
helps CNS to be aware of the intensity of the stimulus and so coordinate an appropriate response
205
If the stimulus is intense what effect does this have on action potential of the afferent sensory neurone?
more action potentials are produced the more intense the stimulus is
206
Does action potential frequency vary depending on the stimulus?
yes
207
What does adaption to a stimulus prevent?
sensory overload
208
what does the speed of adaption to stimuli depend on?
the receptor type as they vary in their speed of adaption to stimuli
209
What is reduced in the sensory organ by frequent exposure?
receptor potential
210
What sensory receptors are often fast acting?
pressure/touch
211
What does it mean if a receptor is fast adapting to a stimulus?
action potential firing reduces quickly during continued exposure to stimulus
212
What sensory receptors are often slow acting?
muscle stretch receptors
213
Why is it important that muscle stretch receptors are slow acting?
the body needs constant feedback in order to aid proprioception and prevent damage
214
When do fast adapting fibres often see a second spike in action potential?
when stimulus stops/is removed - the off response
215
What do temperature dependent ion channels open in response to?
temperature increase of membrane
216
How is an action potential created by temperature dependent ion channels?
channels permeable to positive ion (Na+), this depolarizes the membrane and an action potential is created
217
What can ion channels in sensory receptors be sensitive to?
different stimuli
218
Why is a receptor specific to one energy or stimulus?
it is most sensitive to that energy
219
Can receptors be stimulated by energy other than that which they are specific to?
yes but only if that stimulus is of very high intensity
220
Give 3 types of receptors
mechanoreceptors
photoreceptors
chemoreceptors
221
What helps to increase the precision of the detection of a stimulus?
a narrow receptive field
222
What can overlapping stimulation between neighboring receptive fields help to provide?
general information about the location of a stimulus
223
What do specific ascending nervous pathways maintain with regards to modality of the stimulus?
modality from detection to processing. The stimulus is not mixed with others by convergence of neurons
224
What do non-specific ascending pathways do with stimulus information from sensory neurons?
it is combined with other stimuli at the spinal cord during convergence of neurons
225
What is the difference in clarity between specific and non-specific ascending pathways?
specific is very clear
| non-specific is less clear so we cannot be sure of the type of stimulus
226
What information do non-specific ascending pathways give?
background information
227
What is the main reason for referred pain from visceral organs?
convergence of sensory pathways
228
Give and example of referred pain
left arm pain during myocardial ischemia/infarction
229
Where is the final destination in the brain for sensory information?
somatosensory cortex
230
What will stimulation of the correct area o the cortex lead to?
sensation in the area body that corresponds to the area of the brain being stimulated
231
Where can afferent information be modulated prior to reaching the brain?
spinal cord
232
Why may the CNS suppress pain signals temporarily?
to increase survival chances in a fight/flight situation
233
What can happen in the dorsal horn to alter sensation of pain?
suppression of the action of neurotransmitters from the sensory afferent neuron
234
What part of the nervous system operates without conscious command?
ANS - autonomic nervous system
235
What sort of functions in the body is the ANS responsible for?
critical
236
What functions do the ANS and endocrine systems control in the body?
internal organs, biochemical composition of the body and metabolism
237
name 6 diseases which involve ANS imbalances
arterial hypertension
gastric ulcers
heart rhythm abnormalities
depression/anxiety/parkinsons
238
Give 2 examples of conditions treated by drugs which act via ANS synapses
```
nasal congestion (common cold)
bronchial asthma
```
239
In the parasympathetic system where does the preganglionic neuron synapse with the effector organ?
inside or on the surface of the effector organ
240
What is the name of the efferent neurons of the CNS before they synapse with effector organs?
preganglionic
241
In the sympathetic system where does the preganglionic neuron synapse with the effector organ?
outside the effector organ within the sympathetic chain
242
What is the entric nervous system?
located in the intestine, under partial control of ANS sympathetic and parasympathetic pathways
243
Where does the parasympathetic nervous system originate from the spinal cord?
caudal aspect of the medulla oblongata/cranial nerves and sacral nerves
244
What number cranial nerve is the vagus nerve?
10
245
What do the sacral nerves of the parasympathetic nervous system control?
lower intestine, bladder and genitalia
246
Where are the parasympathetic ganglia located?
next to/ in the wall of the target effector organ
247
Where does the sympathetic nervous system originate from the spinal cord?
thoracic and upper lumbar sections of the spine
248
Where are sympathetic chain ganglia located?
where the first neuron/ preganglionic neuron synapses with the second/ post ganglionic neuron, para medial to the spinal cord
249
Does the CNS direct the synapses in the parasympathetic and sympathetic nervous systems?
no, ganglion do
250
Where do sympathetic fibres of the ANS originate from in the spinal cord?
cell bodies located between dorsal and ventral horns (known as the lateral horn)
251
Where does the efferent part of the sympathetic fibres leave the spinal cord?
ventral horn into the sympathetic chain
252
What are the main neurotransmitters in autonomic synapses?
acetylcholine
| noradrenaline
253
What amino acid is noradrenaline a derivative of?
tyrosine
254
Where in the body does adrenaline originate?
the adrenal medulla
255
Is adrenaline released in sympathetic synapses?
no
256
In what synapses is acetylcholine used in the parasympathetic nervous system?
ganglionic synapse and effector organ synapse
257
In what synapses is acetylcholine used in the sympathetic nervous system?
ganglionic synapse
258
In what synapses is noradrenaline used in the sympathetic nervous system?
effector organ synapse with sympathetic post ganglionic neurons
259
What is the central organ of the adrenal gland?
adrenal medulla
260
Where is the adrenal gland located?
superior surface of the kidney
261
What system does the adrenal medulla supply endocrine output for?
CNS
262
What neurotransmitter is used between CNS ad adrenal medulla?
acetylcholine
263
When the adrenal medulla is signaled by acetylcholine what does it release?
adrenaline and noradrenaline
264
what is adrenaline directly released into from the adrenal medulla?
the bloodstream
265
How does the sympathetic nervous system affect the eye?
causes dilation of iris
266
How does the sympathetic nervous system cause dilation of the iris?
controls the radial fibres of the iris, the contraction of radial fibres pulls the inner circle muscles outwards
267
How does the sympathetic nervous system affect the trachea and bronchi?
dilate in order to increase air flow
268
How does the sympathetic nervous system affect the heart?
increase in heart rate and force of contraction
269
what does an increase in heart rate and force of contraction of the heart mean will happen?
more blood is pumped and more oxygen delivered to tissues
270
How does the sympathetic nervous system affect the circulatory system?
arterioles constrict to redirect blood in favor of critical organs
271
Where is there strong constriction of arterioles in response to the sympathetic nervous system?
skin, abdominal viscera and kidneys
272
Where is there weak constriction (relaxation) of arterioles in response to the sympathetic nervous system?
heart, brain, lungs and muscles
273
Why may veins also constrict in response to the sympathetic nervous system?
more blood returns to the heart for faster re-circulation
274
How does the sympathetic nervous system affect systemic blood pressure?
increase in cardiac output, increase in resistance to blood flow, increased return of venous blood
275
what effect does increased systemic blood pressure have on oxygen and CO2 levels?
oxygen is gained and CO2 removed from the body quicker
276
What are the 2 types of adrenoreceptor in the liver?
alpha and beta
277
What are the 2 ways that the liver releases glucose?
glucogenolysis and glyconeogenesis
278
which is faster: glucogenolysis and glyconeogenesis?
glycogenolysis
279
how does glucogenolysis release glucose?
from glycogen storage
280
how does glyconeogenesis release glucose?
new glucose is made from amino acids
281
What do glucogenolysis and glyconeogenesis lead to in the blood?
increase in blood glucose
282
What is the primary food for the brain?
glucose
283
what type of adrenoreceptor is found in skeletal muscle?
beta
284
What effect does the sympathetic nervous system have on skeletal muscle?
increased contractility, glycogenolysis (energy supply)
285
When is the parasympathetic nervous system dominant?
at rest and during sleep
286
is near vision an active or passive process?
active
287
How does the parasympathetic nervous system affect the eye?
contraction of circular muscle of the iris to contract pupil
288
What effect does the contraction if the iris have on the eye?
reduces the amount of light reaching the retina
289
What needs to happen to the lens of the eye in order to focus on near objects?
increase in curvature of the lens is needed in order to focus light from near objects onto the retina
290
What shape is the lens of the eye naturally?
round
291
What fibres keep the lens flat in the eye?
zonular fibres
292
What effect does cilliary muscle have on the lens?
contracts to counteract zonular fibres so lens becomes more round
293
How does the parasympathetic nervous system affect the glands of the salivary and GI tract?
increase in gland secretion
294
How does the parasympathetic nervous system affect the GI tract?
increased motility of stomach and intestine
295
How does the parasympathetic nervous system affect the respiratory system?
trachea and bronchi constrict
296
What is the benefit of the constriction of the trachea and bronchi by the parasympathetic nervous system?
inhaled air can be cleaned more easily and pollutants removed
297
How does the parasympathetic nervous system affect the cardiovascular system?
heart rate and force of contraction reduce
298
What does the afferent part of the ANS monitor?
condition of body
299
Where is afferent information of the ANS processed?
the brain, mainly the medulla
300
What is afferent information of the ANS supplied from?
receptors all around the body
301
How does the body compensate for any differences from set point?
activates ANS
302
What body process is the afferent part of the ANS a key part of?
homeostasis
303
What are visceral or autonomic reflexes?
triggering of responses via the ANS by visceral and somatic afferents
