Nervous System Flashcards
(397 cards)
1
Q
Neurons
A
specialized cells that transmit and process information from one part of the body to another
2
Q
what form does the information transmitted by neurons take
A
form of electrochemical impulses known as action potentials
3
Q
action potential
A
is a localized area of depolarization of the plasma membrane that in a wave-like manner along an axon
4
Q
what happens when the action potential reaches the end of an axon at the synapses?
A
the signal is transformed into a chemical signal with the release of neurotransmitter into the synaptic cleft a process known as synaptic transmission
5
Q
bipolar neurons
A
neurons that have one dendrite
6
Q
mutlipolar neurons
A
neurons with more than one dendrite
7
Q
role of dendrites
A
receiving signals
8
Q
role of axons
A
carrying action potentials away from cell body (soma)
9
Q
axons
A
can branch multiple times and terminate in synaptic knobs that form connections with target cells, after chemical messengers are released and travel across a very small gap called the synaptic cleft to the target cell
10
Q
Kinesin
A
motor protein, drive movement of vesicles and organelles along microtubules in axons
11
Q
what kind of movement does motor protein kinesin drive
A
anterograde (movement from the soma toward the axon terminus)
12
Q
what does kinesin NOT do
A
- does not have anything to do with action potentials
- neurons in general do not divide and kinesin therefore has nothing to do with cell division
- when inhibiting kinesin it will prevent materials from accumulating at the synaptic knobs
13
Q
nerve
A
large bundle of many different axons from different neurons
14
Q
resting membrane potential
A
electric potential across the plasma membrane of approximately -70mV, with the interior of the cell negatively charged with respect to exterior of the cell
15
Q
two primary membrane proteins that are required to establish the resting membrane potential
A
Na+/K+ ATPase
Leak channels
16
Q
Na+/K+ ATPase
A
pumps 3 sodium ions out of the cells and 2 potassium ions into the cell with the hydrolysis of one ATP molecule
17
Q
what form of transport is carried out by Na+/K+ ATPase?
A
It drives transport against gradient, therefore it is primary transport
18
Q
Leak channels
A
channels that are open all the time, and that simply allows ions to leak across the membrane according to their gradient. (ie: potassium leak channels allow only potassium and no other ions to flow DOWN their gradient OUT of the cell)
19
Q
what happens when there are many positive ions leaving the cells through the Na+/K+ ATPase and the leak channels?
A
it leaves the interior of the cell with a net negative charge, approximately 70mV more negative than the exterior of the cell (resting membrane potential)
20
Q
are there any SODIUM leak channels in the cell (ie: neurons)
A
Yes, but very few in comparison to potassium leak channels with a ratio of 100:1. Therefore the cell is virtually IMPERMEABLE TO SODIUM.
21
Q
are neurons the only cells with a resting membrane potential?
A
no, all cells have the resting membrane potential.
22
Q
whats unique about neurons and muscles when it comes to resting membrane potential
A
neurons and muscle tissue are unique in using the resting membrane potential to generate ACTION POTENTIALS
23
Q
What would happen if potassium channels are blocked, what will happen to the membrane potential?
A
potassium usually leaves the cell, making the interior of the cell more negative and reduce the magnitude of the resting membrane potential. Blocking it would therefore do the opposite where a build up of it inside the cell would make the cell less negative (ie: more positive)
24
Q
what would happen to the membrane potential if sodium ions were allowed to flow down their concentration gradient?
A
sodium ions would flow into the cell and reduce the potential across the plasma membrane, making the interior of the cell less negative and even relatively positive if enough ions flow into the cell
25
the resting membrane potential and interior of neuron
RMP establishes a negative charge along the interior, making it polarized
26
polarized neuron
when a neuron is negative on the inside and positive on the outside (ie: when Na+/K+ ATPase and potassium form their gradient)
27
depolarization
as a result of action potentials disturbing the membrane potential a wave of depolarization of the plasma membrane travels along an axon
28
what happens as a result of action potentials to the polarization of neurons
as a result of action potentials disturbing the membrane potential a wave of depolarization of the plasma membrane travels along an axon
29
depolarization
change in the membrane potential from the resting membrane potential of -70mV to a less negative or even positive potential
30
repolarization
follows depolarization returns the membrane potential to normal
31
Key protein in the propagation of action potentials
voltage gated sodium chanels located in the plasma membrane of the AXON
32
what happens to voltage gated sodium channels in response to a change in membrane potential
ion channels open to allow sodium ions to flow down their gradient into the cell and depolarize that section of membrane
33
what is the effect of opening the voltage gated sodium channels on the membrane potential?
sodium (positively charged) flows into the cell, down its concentration gradient, making the interior of the cell less negatively charged or even positively charged
34
threshold potential
what can trigger the voltage gated sodium channels to open through depolarization of the RMP making interior of the cell from -70mV (RMP) to -50mV (TP) to allows channels to open
35
what happens once voltage gated sodium channels open and allow sodium ions to go into the cells
they continue to depolarize that section of the membrane to about +35mV before inactivating
36
what do some sodium ions do during the opening of the voltage gated ions channels
they can sometimes flow down the interior of the axon, slightly depolarizing the neighbouring section of the membrane, once the next section reaches threshold potential, the nearby voltage gated sodium channels are open as well, passing the depolarization down the axon
37
if an action potential starts at one end of an axon, can it run out of energy and not reach the other end?
no, it cannot. action potential are continually RENEWED at each point in the axon. Assuming there are enough voltage gated channels, once an action potential starts, it will propagate without a change in amplitude (size) until it reaches a synapse
38
what cannot cause the interior of the neuron to have a momentary positive charge
- opening of potassium leak channels
- activity of the Na+/K+ ATPase
- Opening of voltage-gated potassium channels
39
what would be the response of voltage gated sodium channels to a membrane depolarization of -70mV to -60mV
none of the channels would open because the interior of the cell needs to reach a threshold potential (threshold depolarization) of -50mV for it to actually open
40
factors that cause the membrane to repolarize (go back to -70mV)
1. voltage gated sodium channels inactivate very quickly after opening, shutting off the flow of sodium into the cell. The channels remain inactivated until the membrane potential nears resting values again
2. voltage gated POTASSIUM channels open more slowly than the voltage gated sodium channels and stay open longer. they open in response to membrane depolarization. As potassium leaves the cell down its concentration gradient , the membrane potential returns to negative values, actually overshooting the resting potential by about 20mV to about -90mV. at this point they begin to close
3. potassium leak channels and the Na+/K+ ATPase continue to function (as they always do) to bring the membrane back to resting potential. These factors ALONE would bring the RMP back but it would take MUCH LONGER
41
What would happen to the Na+/K+ ATPase if voltage gated sodium channels did not close
they would work harder than ever (the point of it is to move sodium out to make the interior more negative)
42
myelin
- insulating sheath that wraps around many neurons
- created by schwann cells
43
where can no ions enter or exit a neuron?
it cannot enter or exist past the neuron where the axonal membrane is covered with myelin
44
would an axon be able to conduct action potentials if its entire length were wrapped in myelin sheath?
no, the action potential requires the movement of the ions across the plasma membrane to create a wave of depolarizaiton
45
schwann cells
found in the peripheral nervous system (PNS). forrm myelin, increase speed of conduction of APs along axon
46
oligodendrocytes
found in central nervous system (CNS), simialr to schwann cells in that they myelinate axons of the CNS, increase speed of conduction of APs along axon
47
where does the Na+/K+ ATPase use less energy
in myelinated axons as the area of the membrane is much less, the Na+/K+ ATPase therefoe only works to maintain the RMP in the nodes of ranvier
48
what does the length of the refractory period (frequency of action potentials) depend on
the characteristics of the voltage-gated sodium and potassium channels, which do not change whether axon is myelinated or not
49
True/False, the size of action potential depolarization is much greater in myelinated axons than in unmyelinated axons
False, the size of depolarization in an action potential does not vary greatly; action potentials are an all or nothing response
50
Glial Cells
specialized, non-neuronal cells that typically provide structural and metabolic support to neurons. They maintain RMP but DO NOT generate action potentials
51
types of glial cells
- schwann cells (PNS)
- oligodendrytes (CNS)
- astrocytes (CNS)
- microglia (CNS)
- ependymal cells (CNS)
52
astrocytes
found in CNS, guide neuronal development, regulate synaptic communication via regulation of neurotransmitter levels
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microglia
found in CNS, remove dead cells and debris
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ependymal cells
found in CNS, produce and circulate cerebrospinal fluid
55
is the only role of glial cells to produce myelin
no, there are also glial cells that are involved in metabolic support to neurons and perform other functions
56
during action potentials are Na+ and K+ ions that move membrane through the VOLTAGE GATED channels active or passive
passive, driven by gradients
57
equilibrium potential
the membrane potential at which the driving force (gradient for action potentials) does not exist, there would be no net movement of ions across the membrane
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Na+ equilibrium potential
positive, +50mV.
59
what are Na+ driven by
they are driven inward by their concentration gradient, however if the interior of the cell is too positive, the positively charged ions are repelled, the electrical gradient would drive sodium out. therefore the CHEMICAL gradient driving sodium in and the electrochemical gradient driving sodium out balance each other to equilibrium potential
60
K+ equilibrium potential
negative equilibrium potential, K+ ions are driveat -90mV
61
K+ ions are driven outward by their concentration gradient
if the interior cell is too negative, the positively charged ions cannot escape the attraction, the electrochemical gradient drive potassium in. The chemical gradient driving potassium out and the electrochemical gradient driving potassium in balance at -90mV (EP)
62
Nernst equation for equilibrium potential for any ion is baed on the electrochemical gradient for that ion across the membrane
Eion= RT/zF ln [X]outside/[X]inside
Eion = equilibrium potential for the ion,
R= universal gas constant
T= temperature (in kelvin)
z= valence of the ion - electrochemical gradient
F= Faradays constant
X= the concentration of the ion on each side of the plasma membrane - chemical gradient
63
the resting membrane potential -70mV can be understood
also as through EP of Na+ (+50mV), and EP of K+ (-90mV)
64
you can remember that there are more potassium leak channels than sodium because of
the fact that RMP (-70mV) is closer to the EP of K+ (-90mV), rather than Na+ (+50mV). If it was completely permeable to K+ than it would be at about -90mV
65
the cell at rest is
completely permeable to K+, however the fact that the RMP is less negative than EP of K+ indicates that there are a few Na+ leak channels allowing Na+ in
66
when does the cell become more permeable to Na+ resulting in a more positive membrane potential
at the beginning of the action potential; the membrane potential shoots upward to +35mV, where its closer to Na+ EP
67
The refractory period
when the passage of one action potential makes the neurn nonresponsive to membrane depolarization and unable to transmit another action potential (for a short period of time)
happens in two phases the absolute and the relative
68
is there an upper limit to how soon a neuron can conduct an action potential after another has passed
yes
69
absolute refractory period
a neuron will not fite another action potential no matter how strong a membrane depolarization is induced
70
what happens during the absolute refractory period
the voltage gated sodium channels have been inactivated (not the same as closed) after depolarization, they will not be able to be opened again until the membrane potential reaches the RMP and the Na+ channels have returned to their closed state
71
Relative refractory period
a neuron can be induced to transmit an action potential, but the depolarization required is greater than normal because the membrane is hyperpolarized
72
what happens when repolarization occurs during a hyperpolarized state (ie: during a relative refractory period)
there is a brief period in which the membrane potential is more negative than the resting potential caused by voltage gated potassium channels that have not closed yet, because it is further from the threshhold (-50mV) greater stimulus is required to open the voltage gated sodium channels to start an action potential
73
if a fruit fly mutant is found that has a voltage-gated potassium channels that shut more quickly after repolarization, how would this affect the refractory period in the fly
the absolute refractory period would not be altered, but the relative refractory period would be decreased
74
synapse
a junction between the axon terminus of a neuron and the dendrites, soma, or axon of a second neuron.
it can also be a junction between the axon terminus of a neuron and an organ
two type: eletrical and chemical
75
electrical synapses
occur when the cytoplasms of two cells are joined by gap junctions. if two cells are joined this way, an action potential will spread directly from one cell to the other
76
what kind of synapses are NOT common in the nervous system
electrical synapses
77
where are electrical synapses found the MOST
important in propagating action potentials in smooth muscle and cardiac muscle
78
chemical synapses in the nervous system
found at the ends of axons where they meet their target cell, here an action potential is CONVERTED into a chemical signal
79
steps involved in the transmission of a signal across a chemical synapse in the nervous system as well as the junction of neurons with other cell types, such as skeletal muscle cells
1. an action potential reaches the end of an axon, the synaptic knob
2. depolarization of the presynaptic membrane open voltage-gated calcium channels
3. calcium influx into the presynaptic cell causes exocytosis of the neurotransmitter stored in secretory vesicles
4. Neurotransmitter molecules diffuse across the narrow synaptic cleft (small space between cells)
5. Neurotransmitter binds to receptor proteins in the postsynaptic membrane. These recepetors are ligand-gated ion channels
6. the opening of these ion channels in the postsynaptic cell alters the membrane polarization
7. if the membrane depolarization of the postsynaptic cell reaches the threshold of voltage-gated sodium channels, an action potential is initaiated
8. Neurotransmitter in the synaptic cleft is degraded and/or removed to terminate the signal
80
common example of a chemical synapse
the neuromuscular junction between neurons and skeletal muscle
81
what is released as a neurotransmitter at the neuromuscular junction
aceytlcholine (ACh)
82
what degrades acetylcholine in the synaptic cleft
acetylcholinesterase (AChE)
83
steps of how acetylcholine acts as a neurotransmitter in the neuromuscular junction
1. when an action potential reaches the synpase
2. acetylcholine released into the synaptic cleft
3. ACh binds to the ACh RECEPTOR on the surface of the POSTSYNAPTIC cell membrane
4. when ACh binds to its receptor, the receptors opens its associated sodium channel, allowing sodium to flow down a gradient into the cell, depolarizing the postsynaptic cell membrane
5. ACh in the synaptic cleft is degraded by the enzyme AChe
84
other neurotransmitter examples
- Gamma-amino acid (GABA)
- serotonin
-dopamine
-norepinephrine
85
excitatory
when a neurotransmitter (ie: acetylcholine etc..), opens a channel that depolarizes the postsynaptic membrane (ie: making it more positive)
86
inhibitory
when neurotransmitters have the opposite effect, making the postsynaptic membrane potential more negative than the resting potential, or hyperpolarized
87
what determines if a neurotransmitter is excitatory or inhibitory
it is NOT the neurotransmitter itself, but it is the receptor for that neurotransmitter and its associated channel that determines this
88
can postsynaptic receptors bind many different neurotransmitters
yes, they can have different receptors for different neurotransmitters and can respond accordingly
89
if a neurotransmitter causes the entry of chloride into the postsynaptic cell, is the neurotransmitter excitatory or inhibitory
it would be inhibitory because chloride ion are negatively charged, so as they enter the postsynaptic cell the cell potential becomes more negative or hyperpolarized
90
what if an inhibitor of acetylcholinesterase is added to a neuromuscular junction
it will be depolarized longer with each action potential because acetylcholine gated sodium channels will remain open longer with each action potential that reaches the synapse. if sodium channels are open longer, the depolarization of the postsynaptic membrane will last longer
91
why is there unidirectional signaling at synapses?
because only the presynaptic cell has vesicles of neurotransmitter that are released in response to action potentials and only the postsynaptic neuron has receptors to bind neurotransmitters that are released in response to action potentials
92
what can be confused for the reasons why the signals between synapses is unidirectional but is not true on unrelated to it
- the degradation of neurotransmitters
- axons are capable of propagating action potentials in both directions (not related to synapses unidirectionality)
- all cells have a resting membrane potential so it has nothing to do with the RMP
93
summation
is the decision by a postsynaptic neuron whether to fire an action potential is determined by adding the effect of all synapses impinging on a neuron, both excitatory and inhibitory
forms of summation
- temporal
- spatial
94
excitatory neurotransmitter cause post synaptic potentials (EPSPs)
excitatory post synaptic potentials (EPSPs)cause postsynaptic depolarization
95
inhibitory neurotransmitters cause
inhibitory postsynaptic potentials (IPSPs)
96
temporal summation
presynaptic neuron fires action potentials so rapdily that the EPSPs or IPSPs pile up on top of one another. if they are EPSPs the additive effect might be enough to reach the threshold depolarization required to start a postsynaptic action potential
- if they are IPSPs, the postsynaptic cell will hyperpolarize, moving further and further away from the threshold, effectively becoming inhibited
97
spatial summation
the EPSPs and IPSPs from all of the synapses on the postsynaptic membrane are summed at a given moment in time. if the total of all EPSPs and IPSPs cause the postsynaptic membrane to reach the threshold voltage, an action potential will be fired
98
misconceptions that may arise for summation
- a neuron CANNOT change the size of action potentials it transmits
- action potentials are all-or-nothing once they are started, the magnitude of membrane depolarization during propagation of action potential does not change
- a neuron does not change the neurotransmitter it releases
- speed cannot be varied from one action potential to the next
99
frequency of action potentials
the number of action potentials transmitted in a given time
100
what does the nervous system do
receive information, decide what to do with it, and cause muscles or glands to act upon that decision
101
sensory function
receiving information part of the nervous system done by the PNS
102
integrative function
processing information part of the nervous system carried out by the CNS
103
motor function
acting on information received carried out by PNS
104
motor neurons
carry information from the nervous system towards organs which can act upon that information, known as effectors
THEY DO NOT only lead to muscles, can be efferent
105
two types of effectors
muscles and glands
106
efferent neurons
type of motor neuron that carry information away from the nervous system and innvervate effectors to effectors
efferents go to effectors
107
afferent neuron
type of sensory neuron that carry information TOWARD the central nervous system
108
Reflex
direct motor response to sensory input, which occurs without concsious thought, in fact, it usually occurs without any involvement of the brain at all
109
how do reflexes work
sensory neuron (PNS) transmits an action potential to a synapse with a motor neuron in the spinal cord which causes action to occur
110
muscle stretch reflex
a sensory neuron detects stretching of a muscle
111
sensory neurons and motor neuron together
long dendrite and a long axon, which transmits an impulse to a motor neuron cell body in the spinal cord, the motor neurons long axon synapses with the muscle that was stretched and causes it to contract
112
example of reflex response
when quadriceps (thigh) muscle contract when the patellar tendon is stretched by tapping with a reflex hammer
113
monosynaptic reflex arc
involves two neurons and one synapse (ie: reflex hammer on patellar tendon and quadriceps)
114
inhibitory interneuron
what sensory neuron uses to detect stretch in addition to the motor neuron
ie: when the sensory neuron is stimulated by stretch, it stimulates both the quadriceps motor neuron and the inhibitory interneuron to the hamstring motor neuron, as a result the quadriceps contracts and the hamstrings relax
115
an exampe of reciprocal inhibition
concurrent relaxtion of the hamstring and contraction of the quadriceps
116
if a reflex occurs without the involvement of the brain, how are we are of the action
1. the sensory neuron branches to form a synapse with a neuron leading to the brain
2. other sensory information is received after the action is taken
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somatic division
a part of the PNS, concerned with the conscious sensation and deliberate, voluntary movement of skeletal muscle
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autonomic division
concerned with digestion, metabolism, circulation, perspiration and other involuntary processes
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efferent - autonomic split into two subdivisions
sympathetic and parasympathetic
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sympathetic system
when activated, the body is prepared for fight or flight
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parasympathetic system
when activated, the body is prepared for to rest and digest
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example of sympathetic effects
result from release of epinephrine, adrenaline (on top of kidney) into the bloodstream by the adrenal medulla
123
nephr
renal
kidney
kidney
124
true/false, the somatic and autonomic divisions of PNS both have efferent and afferent neurons
TRUE, but the sensory input and the target of efferent nerves are different
125
digestive system AUPSPNS
glands
- PSPNS stimulation
motility
-PSPNS stimulation (digestion)
sphincters
- PSPNS relaxtion
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digestive system AUSPPNS
glands
- AUSPPNS inhibition
motility
-AUSPPNS inhibition (inhibits digestion)
sphincters
- contraction
127
urinary system PSPNS
bladder
-PSPNS contraction (stimulates urination)
urethral spincter
-PSPNS relaxation (stimulates urination)
128
urinary system AUSPPNS
bladder
- AUSPPNS relaxation (inhibits urination)
contraction
-AUSPPNS inhibits urination
129
bronchial smooth muscle PSPNS
PSPNS constriction (closes airways)
130
bronchial smooth muscle AUSPPNS
AUSPPNS relaxation (open airways)
131
cardiovascular system PSPNS
heart rate and contractility - PSPNS - decreased
132
cardiovascular system AUSPPNS
heart rate and contractility - AUSPPNS - increased
blood flow to skeletal muscle - AUSPPNS - increased
133
Skin PSPNS
NO impact
134
Skin AUSPPNS
sweating and general vasoconstriction
135
eye PSPNS
pupil
- PSPNS - constriction
muscle controlling lens
- accommodation for near vision
136
eye AUSPPNS
pupil
- dilation
muscle controlling lens
-accommodation for far vision
137
adrenal medulla AUSPPNS
release of epinephrine
138
genitals PSPNS
erection/lubrication
139
genitals AUSPPNS
ejaculation/organsm
140
white matter
the myelinated axons in the PNS and CNS
141
tract CNS
white matter in the brain
142
tract/column CNS
white matter in the spinal cord
143
nerve
white matter in the PNS
144
grey matter
unmyelinated cell bodies in both the CNS and PNS
145
nucleus
grey matter deep in the brain CNS
146
cortex
grey matter on the surface of the brain CNS
147
horn
grey matter in the spinal cord CNS
148
ganglion
the grey matter in the PNS
149
the brain 3 subdivisions
the hindbrain - rhombencephalon
the mid brain - mesencephalon
the forebrain - prosencephalon
150
four regions of the CNS
the hindbrain - rhombencephalon
the mid brain - mesencephalon
the forebrain - prosencephalon
spinal cord
151
cerebrospinal fluid (CSF)
what the spinal cord and brain float in, a clear liquid that serves varioud functions such as shock absportion and exchange of nutrients and waste with the CNS
152
what is the spinal cord connected to and protected by
connected to the brain, protected by CSF and the vertebral column
153
what functions do the spinal cord take part in
simple spinal reflexes, but also primitive processes such as walking, urination, sex organ function
154
The hind brain
includes the medulla, the pons, cerebellum
155
the medulla (medulla oblongata)
below the pons that connects to the spinal cord, functions in relaying information between other areas of the brain, and regulates vital autonomic functions such as blood pressure and digestive functions (including vomitting), also the respiratory rhythmicity centers are found here
156
the pons
located below the midbrain and above the medulla oblongata. it is the connection point between the brain stem and the cerebellum. controls SOME autonomic functions and coordinates movement; it plays a role in balance and antigravity posture
157
cerebellum (little brain)
located behind the pons and below the cerebral hemispheres. integrating center where complex movements are coordinated. an instruction for movement from the forebrain must be sent to the cerebellum, where the billions of decisions necessary for smooth execution of the movement are made
158
what happens if cerebellum is damaged
poor hand-eye coordination and balance
159
pons and cerebellum
both the cerebellum and the pons receive information from the vestibular appratus in the inner ear, which monitors accerlation and position relative to gravity
160
midbrain
relay for visual and auditory information and contains much of the reticular activating system (RAS), which is responsible for arousal or wakefulness
161
brainstem
medulla, pons and midbrain constitute the brainstem, which contains important processing centers and relays information to or from the cerebellum and cerebrum
162
forebrain
includes the diencephalon and the telencephalon
163
diencephalon
include thalamus and hypothalamus
164
thalamus
located near the middle of the brain below the cerebral hemispheres and above the midbrain. contains relay and processing centers for sensory information
165
hypothalamus (h for hormone to remember)
interacts directly with many parts of the brain, contains centers for controlling emotions and autonomic functions, and has a major role in hormone production and release. it is the primary link between the nervous and the endocrine systems, and by controlling the pituitary gland is the fundamental control center for the endocrine system
166
left hemisphere
controls the right side of the body, generally linked to speech
167
right hemisphere
controls the left side of the body, generally linked to visual-spatial reasoning
168
telencephalon
consists of two separate cerebral hemispheres
169
cerebral hemispheres
connected by thick bundle of axons called the corpus callosum
responsible for thought processes and intellectual functions, also play a role in somatic sensory and motor information
170
a person with a cut corpus callosum
has two independent cerebral cortices and to a certain extent two independent minds
171
cerebrum
the largest region of the human brain and consists of the cerebral cortex (an outer layer of gray matter) plus an inner core of white matter connecting the cortex to the diencephalon
- gray matter composed of millions of somas
- white matter composed of myelinated axons
172
cerebral cortex 4 lobes
frontal lobe
parietal
temporal
occipital
173
frontal lobes
initiate all voluntary movement and are involved in complex reasoning skills and problem solving
174
parietal lobes
involved in general sensations (touch, temperature, pressure, vibration) and gustation (taste)
175
temporal lobes
process auditory and olfactory sensation and are involved in short-term memory, language comprehension, and emotion
176
occipital lobes
process visual sensation
177
basal nuclei
composed of grey matter and are located deep within the cerebral hemipsheres. include several functional subdivisions, but broadly function in voluntary motor control and procedural learning related to habits
the basal nuclei and cerebellum work together to process and coordinate movement initiated by the primary motor cortex
they are inhibitory preventing excess movement, while cerebellum is excitatory
178
limbic system
is located between the cerebrum and the diencephalon, includes several substructures (such as amygdala, cingulate gyrus and hippocampus) and works closely with parts of the cerebrum, diencephalon and midbrain. important in emotion and memory
179
brocas
speech production
180
wernickes area
language comprehension
181
occipital lobe
visual processing
182
homunculus (little man)
distorted image
183
What are all neurons entering and exiting the CNS carried by
12 pairs of cranial nerves
31 pairs of spinal nerves
184
cranial nerves
convey sensory and motor information to and from the brain stem
185
spinal nerves
convey sensory and motor information to and from the spinal cord
186
vagus nerve mcat*
a part of the cranial nerve and one that you. the effects of this nerve upon the heart and GI tract are the decrese the heart rate and increase the GI activity, as such is a part of the parasympathetic division of the autonomic nervous system
bundle of axons that end in a ganglia on the surface of the heart, stomach, and other visceral organs
187
axon on vagus nerve
preganglionic and come from cell bodies located in the CNS on the heart and stomach the synapse with postganglionic neurons
188
somatic MOTOR neurons
innervate skeletal muscle cells, use ACh as their neurotransmitter, and have their cell bodies in the brain stem or the ventral front portion of the spinal cord
189
somatic SENSORY neurons
- have long dendrite
- extend from a sensory receptor toward the soma located just outside the CNS in dorsal root ganglion
190
dorsal root ganglion
bunch of somatic (and autonomic) sensory neuron cell bodies located just dorsal of the spinal cord, form a chain along the dorsal aspect of the vertebral column
191
what are dorsal root ganglion protected within
within the vertebral column outside the meninges and outside the CNS
192
meninges
protective sheath of the brain and cord
193
where is the first synapse for the somatic sensory neurons
CNS, but depending on the type of sensory information conveyed the axon either synapses in the cord or stretches all the way up into the brain stem before its first synapse
194
preganglionic neuron
has its cell body in the brain stem or spinal cord, it sends an axon to an autonomic ganglion, located outside the spinal column, in the ganglion this synapses with the post ganglionic neuron
all autonomic release ACh as their neurotransmitter
195
postganglionic neuron
sends an axon to an effector (smooth muscle or gland)
all parasympathetic release ACh as their neurotransmitter
196
sympathetic postganglionic neuron
nearly all release norepinephrine (noreadrenaline) as their neurotransmitter
197
another name for sympathetic system
thoraco- lumbar system because all sympathetic preganglionic efferent neurons have their cell bodies in the thoarcic (chest) or lumbar (lower back)
198
another name for the parasympathetic system
craniosacral system, because all of its preganglionic neurons have cell bodies in the brainstem (which is in the head or cranium) or in the lowest portion of the spinal cord the sacral portion
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in the sympathetic system how do the preganglionic and ganglia postganglionic look like
preganglionic - relatively short
ganglia - is quite large
postganglionic - long to effector
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in parasympathetic system how do the preganglionic, ganglia and postganglionic look
preganglionic - long axon
ganglia - short (closer to target - effector)
postganglionic - short axon since the cell body is close to the target
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difference between autonomic afferent sensory neurons and somatic afferent neurons
autonomic can synapse in they can synapse in the PNS (at the autonomic ganglia) with autonomic neurons in what is known as a short reflex. first synapse of somatic is in CNS
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adrenal gland
-two
-above kidney
-inner portion, medulla
-outer portion, cortex
- part of the sympathetic nervous system
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cortex of adrenal gland
outer part, important endocrine gland, secreting glucocorticoids (cortisol), mineralocorticoids (aldosterone) and some sex hormones
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what happens when sympathetic system is activated
adrenal gland is stimulated to release epinephrine
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epinephrine
hormone because it is released into the bloodstream by a ductless gland, many ways behaves like a neurotransmitter
- rapid but short lived
-stimulation of heart
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sensation
act of receiving information
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perception
act of organizing, assimilating, and interpreting the sensory input into useful and meaningful information
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what are sensory receptors used to detect
from the interior of the body or the external environment, receives only one information and transmits that information to sensory neurons, which then convey it to the central nervous system
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exteroceptors
sensory receptors that detect stimuli from the outside world
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interoceptors
receptors that respond to internal stimuli
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mechanoreceptors
respond to mechanical disturbances
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pacinian corpuscles
pressure sensors located deep in skin
shaped like onion
composed of concentric layers of specialized membranes
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example of how pacinian corpuscles works
when the membranes are distored by firm presure on the skin, the nerve ending become depolarized and the signal travel up the dendrite (grade potential changes),
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auditory hair cell
specialized cell found in cochlea of the inner ear, detects vibrations caused by sound waves
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vestibular hair cells
located within special organs called semicircular canals, also found in the inner ear, role is to detect acceleration and position relative to gravity
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chemoreceptors
respond to particular chemicals
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olfactory receptors
detect airborne chemicals and allow us to smell things
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gustatory receptors
taste buds
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autonomic chemoreceptors
in the walls of the carotid and aortic arteries respond to changes in arterial pH, PCO2 and PO2 levels
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nociceptors
pain receptors
stimulated by tissue injury
consist of free nerve ending that detects chemical signs of tissue damage
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autonomic pain receptors
do not provide the concious mind with clear pain information, but give s ensation of dull, aching pain,
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referred pain
create illusion of pain on skin when their nerves cross paths with somatic afferents from the skin
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thermoreceptors
stimulated by changes in temperature
autonomic and somatic
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peripheral thermoreceptors
fall into three categories: cold-sensitive, warm-sensitive, thermal nociceptors, which detect painfully hot stimuli
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electromagenetic receptors
stimulated by electromagetic waves
rod and cone cells of retina (only examples in humans - photoreceptors)
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four properties that need to be communicated to the CNS when encoding sensory stimuli
1. modality
2. location
3. intensity
4. duration
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stimulus modality
type of stimulus, depending on which CNS is firing
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stimulus location
communicated by the receptive field of the sensory receptor sending the signal. localization of stimulus can be improved by overlapping receptive fields of neighboring receptors, allows brain to localize stimulus activating neighboring receptors to the area in which their receptive fields overlap
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lateral inhibition of neighboring receptors
helps to discriminate between two separate stimuli
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stimulus intensity
coded by the frequency of action potentials,
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how can the dynamic range be detected in the stimulus intensity
can be detected by sensory receptors, can be expanded by range fractionation (human cone cells responding to different but overlapping ranages of wavelengths to detect the full visual spectrum of light)
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stimulus duration
may or may not be coded
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tonic receptors
fire action potentials as long as the stimulus continues. These receptors are subject adaptation and the frequency of action potentails decreases as the stimulus begins decreases as the stimulus continues at the same level
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adaptation
decrease in firing frequency when the intensity of a stimulus remains constant
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proprioception (kinesthetic sense)
awareness of self (awareness of body part position)
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muscle spindle
mechanoreceptor an example of proprioception
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golgi tendon organs
monitor tension in the tendons
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joint capsule receptors
detect pressure, tension and movement in the joints
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what portion of the CNS would you expect to require input from proprioceptors
cerebellum, which is responsible for motor coordination
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taste bud (5 stimuli)
responds to 5 flavors
1. sweet (glucose)
2. salty (Na+)
3. bitter (basic)
4. sour (acidic)
5. umami (amino acids and nucleotides)
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nasopharnyx (nasal cavity)
detect airborne chemicals that dissolve in the mucus covering the nasal membrane
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olfactory bulbs
located in the temporal lobe of the brain near the limbic system, an area important for memory and emotion (why smell can bring back vivid memories)
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Phermones
chemical signals that cause a social response in members of the same species
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structure of the ear
outer ear
- auricle
- pinna
- external auditory canal
middle ear
- ossicles
- malleus (hammer)
- incus (anvil)
- stapes (stirrup)
inner ear
- cochlea
- semicircular canals
- utricle
- saccule
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sound to hearing
sound waves
auricle
external auditory canal
tympanic membrane
malleus
incus
stapes
oval window
perilymph
endolymph
basilar membrane
auditory hair cells
tectorial membrane
neurotransmitters stimulate bipolar auditory neurons
brain
perception
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what does a more rapid firing of action potentials in sensory neouron leading from the ear to the brain mean?
indicates an increased volume of sound
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what happens if the pitch of the sound we hear changes
a different set of neurons would fire more action potentials
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what happens if auditory nerve is severed?
no hearing of any kind is possible, even through conduction of vibration
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how can sound still be detected in a person who is deaf?
through conduction of vibration through the skull to the cochlea
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if bones of the middle ear are unable to move, would this impair the detection of sound by conductance through bone?
not involved directly in detecting sound. can stimulate the cochlea and result in hearing if the middle ear is non functional
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vestibular complex
contain 3 semicircular canals, utricle, saccule, ampullae
function is to NOT detect sound but the rotational acceleration of the head
innervated by afferent neurons which send balance information to the pons, cerebellum, and other areas
monitors both static equilibrium and linear acceleration which contribute to sense of balance
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what is retinas role
It detects light using photoreceptors (rods and cones) and converts it into electrical signals.
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What do rods and cones do in the retina?
Rods detect dim light and motion; cones detect color and fine detail.
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What happens to the signal after photoreceptors detect light?
The signal passes to bipolar cells, then to ganglion cells, whose axons form the optic nerve.
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Where does the optic nerve send visual signals?
To the occipital lobe of the brain for visual processing.
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What is the cornea?
The clear, curved front of the eye that bends (refracts) incoming light.
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What is the sclera?
The white part of the eye that protects and maintains the shape of the eyeball.
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What is the choroid?
A pigmented layer under the sclera that absorbs excess light.
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What is aqueous humor?
A clear fluid in the anterior and posterior chambers that nourishes the eye and maintains pressure.
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What are the iris and pupil?
The iris is the colored part of the eye that controls the size of the pupil, which regulates how much light enters.
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What does the lens do?
it fine-tunes the focus of light onto the retina; its shape is controlled by the ciliary muscle.
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What is vitreous humor?
A jelly-like substance that fills the vitreous chamber and helps maintain the eye’s shape.
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What is the retina?
The inner lining at the back of the eye that contains photoreceptors (rods and cones).
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What do bipolar cells do?
They relay signals from rods and cones to ganglion cells.
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What do ganglion cells and the optic nerve do?
Ganglion cells collect signals and their axons form the optic nerve, which sends visual info to the brain.
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What is the optic disc?
The point where the optic nerve exits the eye; no photoreceptors are here, so it's a blind spot.
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What are the macula and fovea centralis?
The macula is the central part of the retina; the fovea (its center) has only cones and is for sharp, detailed vision.
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How do we see? List the steps in order from light entering the eye to image processing in the brain.
Light enters the eye through the cornea, which bends (refracts) it.
Light passes through the aqueous humor and enters the pupil, controlled by the iris.
The lens adjusts shape (via the ciliary muscle) to focus light.
Light travels through the vitreous humor to the back of the eye.
The retina receives the light; rods and cones detect the signal.
The signal is passed to bipolar cells, then to ganglion cells.
Ganglion cell axons form the optic nerve, which carries the signal to the brain.
The occipital lobe of the brain interprets the signal, allowing us to see the image.
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Why are rods and cones named that way?
Because of their distinct shapes—rod-shaped and cone-shaped.
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What special proteins do rods and cones have?
Opsins, which are bound to a molecule of retinol (from vitamin A).
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What is the state of retinol and the sodium channel in the dark?
Retinol has a cis-double bond and keeps sodium channels open → the cell is depolarized.
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What does light do to retinol and the sodium channel?
Light converts retinol to the all-trans form, closing sodium channels → the cell hyperpolarizes.
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What do rods and cones release onto bipolar cells in the dark?
They release glutamate when they are depolarized (in the dark).
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What do on-center bipolar cells do in the dark vs. light?
In the dark: glutamate inhibits them → little or no neurotransmitter released.
In the light: less glutamate → inhibition stops → they release neurotransmitter.
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What do off-center bipolar cells do in the dark vs. light?
In the dark: glutamate stimulates them → they release neurotransmitter.
In the light: less glutamate → they are inhibited.
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What type of vision do rods support?
Night vision, motion detection, and dim light. Mostly found in the retina’s periphery.
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What type of vision do cones support?
Color vision and sharp detail (acuity). Mostly found in the fovea.
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What colors do the three types of cones detect?
Blue light
Green light
Red light
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What is normal vision called?
Emmetropia – when light focuses correctly on the retina.
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What is myopia (nearsightedness)
Light is bent too much and focuses in front of the retina. You can see near but not far.
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What kind of lens corrects myopia?
A concave (diverging) lens – spreads out light rays before they hit the cornea.
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What is hyperopia (farsightedness)?
Light focuses behind the retina. You can see far but not near.
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What kind of lens corrects hyperopia?
A convex (converging) lens – brings light rays together before they hit the cornea.
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What is presbyopia?
Age-related loss of lens flexibility, making it hard to focus on close objects (loss of accommodation).
285
Which sense do humans rely on the most?
Vision – even if other senses contradict it, we tend to trust what we see.
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Is visual processing simple or complex?
It’s extremely complex and depends on expectations and past experiences.
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What do feature-detecting neurons do?
They fire in response to specific features like lines, edges, angles, and motion.
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Why does looking at a face vs. reading text activate different brain areas?
Because different neurons process different features – this is called feature detection theory.
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What is parallel processing in the brain?
It means the brain processes form, color, motion, and depth all at the same time (not one by one).
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What does the occipital lobe do in vision?
It combines all visual features to create a full image (a holistic picture).
291
How do we know we’re seeing something like our mom’s face?
The brain uses parallel processing and memory to identify complex images quickly.
292
How much of the brain’s cortex is used for vision?
About 30% – compared to only 8% for touch and 3% for hearing
293
What is an absolute threshold?
It’s the minimum stimulus intensity needed to activate a sensory receptor 50% of the time.
294
What does the "50% recognition point" mean in sensory testing?
It means the lowest level of a stimulus that can be detected half the time.
295
Is the absolute threshold the same for everyone?
No – it can vary between individuals and between different species.
296
Do humans and dogs have the same sense of smell?
No – dogs have a much lower absolute threshold for smell than humans, meaning they can detect much fainter odors.
297
What happens to our absolute threshold as we age?
It increases – for example, we lose the ability to detect high-pitched sounds as we get older.
298
What is the difference threshold?
It’s the smallest noticeable difference between two sensory stimuli 50% of the time.
299
What does JND mean?
Just Noticeable Difference – the smallest change in a stimulus you can detect.
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What influences whether we notice a difference in stimuli?
The size of the initial stimulus – bigger stimuli require bigger changes to notice.
301
Why can you feel a difference between 1 lb and 2 lbs but not 100 lbs and 101 lbs?
Because the relative difference is larger in the 1 vs. 2 lb case. JND depends on proportional change.
302
What does Weber’s Law say?
Two stimuli must differ by a constant proportion (not amount) to detect a difference.
303
According to Weber’s Law, what proportions do humans need to notice differences?
Weight: 2% difference
Light intensity: 8% difference
Tone frequency: 0.3% difference
304
Does detection rely only on the strength of the stimulus?
No — it also depends on psychological factors like alertness, expectation, motivation, and past experience.
305
What is Signal Detection Theory?
It’s a theory that explains how and when we detect a sensory signal among background noise.
306
What do "signal" and "noise" mean in this theory?
Signal = actual sensory input (e.g., tumor on a scan)
Noise = background or irrelevant stimuli
307
What are the four possible outcomes in signal detection theory?
Hit – Signal present & detected
Miss – Signal present but not detected
False alarm – Signal not present, but thought to be
Correct rejection – Signal not present & not detected
308
Why is signal detection theory important?
It’s crucial in high-stakes situations, like a doctor spotting a tumor on a CT scan.
309
What does the word Gestalt mean?
Gestalt is a German word meaning “whole.”
310
What do Gestalt psychologists believe about perception?
We perceive the whole object, not just individual parts like lines or colors.
311
How would Gestalt psychology explain seeing a dog?
Instead of seeing shapes and colors, your brain automatically sees a dog as a whole.
312
What is bottom-up processing?
It starts with sensory input and builds up to complex understanding in the brain.
313
What is top-down processing?
It’s when the brain uses past experiences and expectations to interpret what you sense.
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Does the brain use both bottom-up and top-down processing?
Yes! The brain combines sensory input (bottom-up) with assumptions and experience (top-down).
315
What are the two major control systems in the body?
The nervous system and the endocrine system.
316
How does the nervous system control the body?
It sends fast electrical signals with short-term effects.
317
How does the endocrine system control the body?
It sends slow chemical signals (hormones) with longer-lasting effects.
318
Can the nervous system affect the endocrine system?
Yes! Neurons can signal hormone release from endocrine glands.
319
What is the main connection between the two systems?
The hypothalamic-pituitary axis connects the nervous and endocrine systems.
320
What does the endocrine system regulate and how fast?
It controls physiology (like metabolism) over hours to days.
321
How does the nervous system send messages?
Through fast electrical signals called action potentials.
322
What does the endocrine system use to send messages?
It uses hormones that travel through the bloodstream.
323
What is a hormone?
A chemical messenger made by an endocrine gland that acts on distant target cells with the right receptor.
324
What is an endocrine gland?
A ductless gland that releases hormones directly into the blood.
325
What is an exocrine gland?
A gland that uses ducts to release substances to the outside (like sweat or saliva).
326
What is a hormone receptor?
A protein on or in a cell that binds a hormone and changes cell activity.
327
What makes a cell respond to a hormone?
The cell must have the correct receptor for that hormone
328
What is autocrine signaling?
When a cell responds to its own signals, like a T-cell activating itself with interleukin-2.
329
What are the two major hormone types?
Hydrophilic (water-loving): Bind to cell surface receptors (e.g. peptides)
Hydrophobic (fat-loving): Bind to inside the cell (e.g. steroid hormones)
330
Where are peptide hormones made and processed?
In the rough ER, modified in the Golgi, and stored in vesicles until needed.
331
How are peptide hormones released and transported in the body?
They are released by exocytosis and travel dissolved in the blood plasma.
332
Why can’t peptide hormones enter the cell?
Because they are hydrophilic (water-loving) and cannot cross cell membranes.
333
How do peptide hormones affect target cells?
By binding to surface receptors and triggering a second messenger cascade.
334
What is a second messenger?
A molecule inside the cell (like cAMP) activated by the hormone-receptor complex that changes cell activity.
335
What is amplification in hormone signaling?
A small number of hormones activate many enzymes, creating a big effect from a small signal.
336
Are peptide hormones fast or slow acting?
They act quickly—within minutes to hours—but their effects are short-lived.
337
Give an example of a peptide hormone and its function.
Insulin, secreted by pancreatic beta cells, lowers blood sugar by activating protein kinases.
338
What are amino acid-derived hormones made from?
Single amino acids, commonly tyrosine, and they have no peptide bonds.
339
What are the two types of amino acid-derived hormones?
Catecholamines (like epinephrine) and thyroid hormones.
340
How do catecholamines (like epinephrine) act?
Like peptide hormones—bind to cell surface receptors and activate second messengers.
341
How do thyroid hormones act?
Like steroid hormones—enter cells, bind to DNA, and activate gene transcription.
342
What do thyroid hormones require in their structure?
Iodine.
343
What are steroid hormones made from?
Cholesterol.
344
Where are steroid hormones synthesized?
In the smooth endoplasmic reticulum (SER).
345
Are steroid hormones stored in the body?
No. They are made when needed and immediately diffuse into the bloodstream.
346
Why can steroid hormones freely cross cell membranes?
Because they are hydrophobic (fat-soluble).
347
How do steroid hormones travel in the bloodstream?
Attached to plasma proteins like albumin, since they are not water-soluble.
348
Where do steroid hormones bind in a target cell?
To a receptor in the cytoplasm.
349
What happens after the steroid hormone binds its receptor?
The hormone-receptor complex enters the nucleus and regulates gene transcription.
350
How fast do steroid hormones work?
Slowly—effects take days to start but can last for days or weeks.
351
Which glands secrete steroid hormones for reproduction and development?
Testes, ovaries, and placenta.
352
Which gland secretes steroid hormones for water balance and metabolism?
The adrenal cortex.
353
Do all endocrine glands secrete steroid hormones?
No. All others (besides gonads, placenta, and adrenal cortex) secrete peptide hormones.
354
Which hormone acts like a steroid even though it’s made from an amino acid?
Thyroid hormone—it enters cells and binds to DNA like a steroid.
355
What are the two major control systems of the body?
The nervous system (fast, short-term) and the endocrine system (slow, long-lasting).
356
How does the nervous system communicate?
Through fast electrical signals called action potentials.
357
How does the endocrine system communicate?
Through hormones secreted into the blood that affect distant target cells.
358
What is an endocrine gland?
ductless gland that secretes hormones into the bloodstream.
359
What is a hormone receptor?
A specific protein that binds a hormone and changes cell activity.
360
What are the two types of hormones based on solubility?
Hydrophilic (e.g. peptides, amino acid derivatives) and hydrophobic (e.g. steroids).
361
Where are peptide hormones made and stored?
Made in the rough ER, modified in Golgi, stored in vesicles, released by exocytosis.
362
How do peptide hormones act on cells?
Bind to surface receptors and activate second messenger cascades (e.g. cAMP).
363
Are peptide hormone effects fast or slow?
Fast (minutes to hours), but short-lived.
364
Give an example of a polypeptide hormone.
Insulin.
365
Give an example of an amino acid derivative hormone.
Epinephrine (acts like peptide), thyroid hormones (act like steroids).
366
Where are steroid hormones made?
In the smooth ER from cholesterol.
367
How do steroid hormones travel in the blood?
Bound to carrier proteins like albumin.
368
How do steroid hormones act on cells?
Diffuse through membranes, bind to cytoplasmic receptors, and regulate gene transcription in the nucleus.
369
Are steroid hormone effects fast or slow?
Slow (days), but long-lasting.
370
What is feedback regulation?
Hormone levels adjust automatically based on what the body needs.
371
What is an example of negative feedback?
Calcitonin is secreted when blood calcium is high; it stops when calcium levels fall.
372
What is a tropic hormone?
A hormone that regulates another hormone (e.g. ACTH stimulates cortisol production).
373
What is the hypothalamic-pituitary axis?
The control system where the hypothalamus regulates the pituitary, which controls other glands.
374
What does CRH (corticotropin-releasing hormone) do?
It stimulates the anterior pituitary to release ACTH.
375
What is the hypothalamic-pituitary portal system?
A special blood supply that carries hormones from the hypothalamus to the anterior pituitary.
376
What are the two parts of the pituitary gland?
Anterior (adenohypophysis) and posterior (neurohypophysis).
377
How does the anterior pituitary work?
It’s a normal gland controlled by hypothalamic hormones.
378
How does the posterior pituitary work?
It releases hormones made by hypothalamic neurons (neuroendocrine cells).
379
What hormones are released by the posterior pituitary?
ADH (water retention) and oxytocin (milk letdown, labor contractions).
380
What hormones are important in reproductive biology?
Testosterone, estrogen, progesterone, FSH, and LH.
381
What hormone is part of the sympathetic nervous system response?
Epinephrine.
382
What is the general role of hormones in the body?
To support development and maintain homeostasis in adults.
383
Which two hormones broadly affect metabolism and energy use?
Thyroid hormone and cortisol.
384
Where is thyroid hormone produced and from what amino acid?
In the thyroid gland from the amino acid tyrosine.
385
What are the two forms of thyroid hormone?
T3 (3 iodine atoms) and T4 (4 iodine atoms).
386
What stimulates thyroid hormone production?
TSH (thyroid-stimulating hormone) from the anterior pituitary.
387
What controls TSH secretion?
The hypothalamus in the brain.
388
How does thyroid hormone act inside the cell?
It binds to a cytoplasmic receptor that affects transcription in the nucleus.
389
What are the effects of thyroid hormone?
Increases metabolism, body temperature, and stimulates growth in children.
390
What environmental condition increases thyroid hormone production?
Exposure to cold.
391
Where is cortisol produced?
In the adrenal cortex.
392
What stimulates cortisol release?
ACTH from the anterior pituitary.
393
What is the main function of cortisol?
To help the body handle stress by mobilizing energy stores.
394
What energy sources does cortisol help mobilize?
Glycogen, fats, and proteins.
395
What happens if the adrenal cortex is removed?
Even mild stress can be fatal due to lack of cortisol.
396
What are the negative effects of long-term high cortisol levels?
Suppression of the immune system.
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