Exam Three: Learning Objectives Flashcards
(206 cards)
1
Q
What are the two broad types of synapes?
A
Chemical and electrical
2
Q
Chemical synapses are __ and electrical synapses are __
A
complex, simple
3
Q
Describe the current flow at a chemical synapse.
A
flows our of presynaptic cell and spac e in between presynaptic and postsynaptic cell
4
Q
Describe the current flow at an electrical synapse.
A
Current flows out of the presynaptic cells and through the gap junction to continue out of the post synaptic cell
5
Q
Electrical synapses: relatively __ action, almost always __. Present where __ and __ are paramount. Present in circuits that control __ __ or _
A
simple; excitatory
speed; synchronization
rapid behaviors; responses
6
Q
Describe step one: arrival of action potential at terminal
A
arrival of the AP at terminal stimulates the opening of voltage-gated Ca channels, which results in the influx of Ca into the cytosol from outside of the cell, takes place in the presynaptic cell
7
Q
Describe step two: Ca triggers vesicle fusion and neurotransmitter release
A
increased cytosolic Ca activates vesicle fusion and exocytosis of synaptic vesicles
prior to ca activation, the synaptic vesicles are already docked at the active zones filled with neurotransmitter
The neurotransmitter molecules begin to diffuse across the synaptic cleft towards the post-synaptic membrane
8
Q
Describe step three: neurotransmitter binds to post-synaptic receptor
A
neurotransmitters diffuse across the cleft and bind to specific receptors on the post-synaptic membrane of the effector cell
9
Q
What are the two steps that can result from the neurotransmitter binding to a post-synaptic receptor?
A
fast chemical synaptic transmission
slow chemical synaptic transmission
10
Q
Describe the fast chemical synaptic transmission
A
binding to ionotropic receptors which directly increases membrane permeability of ions
11
Q
Ionotropic receptors are…
A
ligand-gated ion channels
12
Q
Describe the slow chemical synaptic transmission
A
binding to metabotropic receptors which results in activation of a signaling cascade and usually results in the opening of an ion channel
13
Q
Metabotropic receptors are…
A
G-protein coupled receptors
14
Q
In a chemical synapse, an action potential first triggers __ in the presynaptic neuron membrane.
A
Ca influx
15
Q
Synaptic potentials can be __ or __
A
excitatory; inhibitory
16
Q
What is a synaptic potential?
A
graded change in the postsynaptic cell in response to neurotransmitter binding, lasting 10-20 ms
17
Q
What is an EPSP?
A
A synaptic potential that depolarizes the membrane (excitatory) increasing the probability of an action potential
18
Q
What is an IPSP?
A
a synaptic potential that hyperpolarizes the membrane (inhibitory), decreasing the likelihood of an action potential
19
Q
If the post-synaptic channels that are opened allow cations to enter the cell or anions to exit, the post-synaptic membrane will become __
A
depolarized
20
Q
What are the two most common neurotransmitters that elicit EPSPs (excitatory neurotransmitters)
A
Acetylcholine (Ach) and glutamate
21
Q
T/F: The local change in the membrane is termed an EPSP, and this IS an action potential
A
FALSE: this is not an action potential, it just increases the likelihood one will happen
22
Q
What conditions would cause the post-synaptic membrane to become hyperpolarized?
A
if the post-synaptic channels that are opened allow anions to enter the cell or cations to leave
23
Q
The local change in the membrane potential when a hyperpolarization occurs is termed a?
A
IPSP - inhibitory post-synaptic potential
24
Q
What are the two common inhibitory neurotransmitters (ones that elict an IPSP)
A
gamma-aminobutryic acid (GABA) and glycine
25
Multiple EPSPs can trigger an __ __
action potential
26
T/F: A single EPSP is sufficient enough to bring the axon hillock to threshold
false, more than one EPSP is required to initiate a post-synaptic action potential
27
Define spatial summation:
if a number of EPSPs occur simultaneously, at different locations of the dendritic arbor of a neuron, their summed EPSPs (net change in potential at the hillock) may bring the axon hillock membrane to threshold
28
Define temporal summation
stimulation may also occur if multiple EPSPs occur within a short duration (before the previous EPSP has dissipated, roughly 50 ms)
29
The excitatory/ inhibitory neurons __ to the axon hillock are the most powerful
closest
30
Multiple receptors, with __ functions, may bind a __ type of neurotransmitter
different; single
31
ACh is excitatory in __ muscle ( __ receptors) and inhibitory in __ muscle (__ receptors)
skeletal - nicotinic
cardiac- muscarinic
32
Which neurotransmitter binds to both nicotinic and muscarinic receptors?
acetylcholine
33
Ach slows the heart rate by ___
hyperpolarizing
34
For most skeletal muscles, each fiber is only innervated by __ neuron
one
35
Acetylcholine is the __ neurotransmitter at the __ junction
excitatory; neuromuscular
36
The nicotinic Ach receptor is a single __ gated channel for both __ and __
ligand
Na and K
37
Discuss how Ach directly generates a muscle contraction
opens ligand-gated channels for Na and K which depolarizes the muscle Vm, generating an AP and causing muscle contraction
38
What are the two types of neurotransmitters?
1 small molecule neurotransmitters and amino acids
2 neuroactive peptides
39
Small molecules neurotransmitters and amino acids are synthesized and released at the __ __
axon terminal
40
Neuroactive peptides are synthesized at the __ __ and transported to the __ __
cell body; axon terminal
41
T/F: A neuron may release more than one neurotransmitter
true - but it releases a characterisitic one
42
A neuron can respond to __ __ of neurotransmitters, not just __
many types; one
43
Define synaptic plasticity
ability to change synaptic strength overtime, believed to be an important mechanism in learning
44
What are two basic examples of synaptic plasticity in a sea slug?
Habituation and sensitization
45
Define habituation
decrease in intensity of a reflex response to a repeated stimulus (mechanism of synaptic plasticity)
46
Define sensitization
the prolonged enhancement of a reflex response to a stimulus, which results from a second stimulus that is novel of noxious (mechanism of synaptic plasticity)
47
Describe habituation and sensitization in Aplysia (sea slug)
h: Aplysia will initially withdraw its gills when something comes in contact with the siphon or mantle shelf, but after contact proceeds repeatedly, a. will decrease this withdrawal behavior
s: then, if it receives a shock to the head, the slug will once again retract its gils in response to stimulation by the siphon
48
Synaptic responses mirror the __ __ of the slug
behavior responses
49
The synapse between __ neuron and __ neuron is a key site
sensory and motor
50
Repeated stimulation of __ neuron leads to decrease in ___ ___, the mechanism of __
sensory
Ca influx
habituation
51
Shock to the tail or head causes ___; __ release, causing a prolonged __ and activated increase of __ __ and increased release of __
sensitization
serotonin
AP
Ca influx
neurotransmitter
52
EPSP magnitude increases over __ when neurons are __ stimulated via tetanus, this increase is ___
baseline; repeatedly
LTP (long term potentiation)
53
NMDA receptor only opens when both __ and __ synaptic neurons are firing after __ stimulation
pre + post
tetanic
54
All sensory stimuli are ultimately __ to action potentials, and sent to the CNS by __ __
transduced
labelled lines
55
How do labeled lines send sensory stimuli to the correct place?
the wires are kept straight by ordering specific sensory axons to different specific regions of the brain
56
Define sensory receptor cells
specialized cells which react to certain stimuli and in turn stimulate an afferent neuron
57
Receptor potential amplitude varies with _ __
stimulus strength
58
AP frequency varies with __ __ __
receptor potential amplitude
59
Describe the function of an afferent neuron
integrates the amplitude of the stimulus from receptor cells and either fails to generate and AP, generates and AP, or generates multiple APs
60
Movement of the steriocillia (hairs) to the right __ the membrane while movement to the left __ the membrane
depolarizes
hyperpolarizes
61
Where are sensory cells located for hearing?
semicircular canals of the inner ear
62
_ __ in the canals moves hair cells and causes depolarization/hyperpolarization dependent on the __ and gives CNS information on __
Fluid movement
direction
acceleration
63
What do hair cells transduce?
vibration/ acceleration
64
Describe the path of sound wave travel
waves travel through the auditory canal, across the tympanic membrane, and to the bonds of the middle ear to resonate the oval window. The resulting waves in the cochlear media fluid displace hairs at specific locations n the basilar membrane dependent on frequency
65
__ frequencies are found closest to the oval window and __ frequencies are found at the center of the cochlea
higher; lower
66
In vertebrate taster buds, the receptor cells are not __ but __ __
neurons
epithelial cells
67
Tastes are encoded by different __
receptors
68
Describe the way salt is tasted
increase in sodium ions in the mouth can depolarize salt receptors
69
Sour taste is likely mediated by _- __ deactivation of __ __ __ channels. With __ permeability vastly decreased, __ begins to dominate the resting membrane potential, resulting in a __
H+ ion
ionotropic K+ leak
K+
Na+
depolarization
70
Sweet, umami, and bitter tastes are all __; they have different __ but similar __ __ __
metabotropic
receptors
downstream second messengers
71
Olfactory GPCRs can depolarize the membrane though activation of __ dependent __ channels
Ca2+, Cl-
72
T/F: Rods are more numerous than cones
true
73
In humans, the fovea covers 0.01% of the visual field but has high density of __ cells
photoreceptor
74
Describe how light moves through the cells of the eye
rods and cones send information to bipolar cell to ganglion cell to the optic nerve. Sometimes an amacrine cell acts as an intermediate between a bipolar and ganglion cell
75
What are vertebrae photoreceptors?
rods and cones
76
Define rods
photoreceptors that are more sensitive and used for vision in dim light
77
Define cones
photoreceptors that are used in bright light to produce color vision
78
Discuss the composition of rods and cones
Rods: Rhodopsin = opsin protein + retinal
Cones: Photopsin = opsin protein + retinal
79
Retinal is derived from vitamin _ and is replenished in the __ __
A
pigment epithelium
80
In the cones, the opsin responds to different _-
wavelengths
81
In a dark current, more __ is released
glutamate
82
Under dark conditions: __-__ __ channels are always open, Thus, the permeability of __ in the dark rods is very high and the cell is in a constant state of __
cGMP-gated Na
Na
depolarization
83
Dark current is costly as ____ is needed to maintain a constant __
Na+/K+ ATPases
potential
84
__ activation hyperpolarizes the membrane
rhodopsin
85
1) light changes the __ of the __ receptor, located on the intracellular disk membranes 2) activating its __ __ 3) __, the __ messenger is then degraded 4) deactivating plasma membrane __ channels, __ the rod cell
conformation; rhodopsin
G protein
cGMP; secondary
Na; hyperpolarizing
86
Dark current leads to a ?
graded response
87
Under light conditions: __ is enzymatically degraded by a phophodiesterase, closing __ __ channels, minimizing the __ current and leads to __ , graded by the __ of the light stiumuls
cGMP
cGMP-gated Na+ channels
dark
hyperpolarization
intensity
88
Glutamate is normally __ on postsynaptic _- cells (__-__)
inhibitory
bipolar
non-spiking
89
With more light, there is less __ released on __ cells, which increases the __ __ release by the __ cells and leads to an __ in the __ cell (__)
glutamate; bipolar
excitatory neurotransmitter
bipolar
EPSP; ganglion; spiking
90
Compare neural transmission with endocrine
neural: fast, addressed signals, neurotransmitters
endocrine: slow, broadcast signaling, hormones
91
What are the three types of hormones?
steroid
peptide and protein
amine
92
Steroid hormones are __ bound and include __ and __
carrier
LDL, HDL
93
Describe steroid hormones
synthesized on demand, NOT stored
secreted by diffusion
receptors are mainly intracellular, but can be extracellular
94
What are six steroid hormones?
aldosterone, cortisol, testosterone, estradiol, pregnenolone, and cholesterol
95
What are two examples of peptide and protein hormones?
Gonadotropin-releasing hormone (GnRH)
insulin
96
Describe peptide and protein hormones.
stored in vesicles and secreted on demand
receptors are extracellular, typically GPCRs
97
Insulin is stored in?
vesicles
98
Describe amine hormones
stored in vesicles and secreted on demand
99
What are the two main classes of amine hormones?
hydrophilic catecholamines and lipophilic iodothyronines
100
Describe hydrophilic catecholamines
use extracellular receptors
101
Describe lipophilic iodothyronines
use intracellular receptors
102
What are three examples of catecholamines
dopamine, norepinephrine, and epinephrine
103
What are two examples of thyroid hormones?
Thyroxine (T3) and Triiodothyronine (T3)
104
What are three examples of endocrine systems?
vertebrate pituitary gland, mammalian nutrient metabolism, and vertebrate salt and water balance
105
What are hormones responsible for?
any and all metabolic changes in target cells, including up-regulation and down-regulation of enzymes, and transcription of DNA
106
What kinds of receptors can hormones bind to?
G protein-coupled
intracellular, or enzyme-linked membrane receptors
107
Steroid hormones act as __ __ once bound to an intracellular receptor molecule
transcription factors
108
T/F: hormones cannot activate second-messenger systems via G proteins
False
109
Hormones may have a __ __ effect, due to many cells having __ receptors
whole-organism
many
e.g. insulin
110
Vasopressin (ADH) and oxytocin are produced in __ and released into the blood flow __
hypothalamus
anterior pituitary
111
What two hormones does the posterior pituitary release?
antidiuretic hormone (ADH) aka vasopressin
Oxytocin
112
Both __ and __ are peptide hormones that are synthesized in the hypothalamus and stored in the __ pituitary
ADH, oxytocin
posterior
113
What is ADH responsible for?
water retention in the kidneys, vasoconstriction
114
What is oxytocin responsible for?
contraction of the uterus during birth, lactation, love
115
The anterior pituitary gland exhibits neurosecretory control of __ cells as it responds to neurohormones released by the __
endocrine; hypothalamus
116
What is the hypothalamo-hypophysial portal system?
dedicated vascular pathway that connects the hypothalamus and anterior pituitary
117
What two major groups of hormones act on are produced in the anterior pituitary gland?
non-endocrine and endocrine
118
What do non-endocrine tissues influence?
growth and metabolism of bone and muscle
119
Most hormones of the anterior pituitary are classified as __ hormones
tropic
120
Define tropic hormones
those that stimulate release of other hormones
121
What is an example of a hormone that impacts a non-endocrine tissue?
growth hormone
122
What is an example of a hormone that impacts other endocrine glands?
ACTH
123
What is the function of ACTH?
stimulates the production of cortisol (a stress hormone) from the adrenal cortex
124
What are the two major types of neurohormones released in the hypothalamus?
releasing hormones, release inhibiting hormones
125
Releasing hormones and releasing inhibiting hormones stimulate release of __ pituitary hormones
ANTERIOR
126
RHs and RIHs enter the __ vessels, where they control secretory cells of the __
portal; adenohypophysis
127
What are the seven hormones produced in the hypothalamus and released in the anterior pituitary glands?
TSH, ACTH, MSH, GH, LH, FSH, and prolactin
128
T/F: the hormones released in the anterior pituitary gland are separated by a subpopulation of cells
true - each area of cells secrete a specific hormone
129
The adrenal cortex is controlled by the __/__
hypothalamus/ pituitary
130
What is the most common mechanism of hormonal modulation?
negative feedback
131
Define negative feedback
a hormone inhibits its own secretion by acting on the axis it is part of
132
Define synergism
one hormone amplifying the effects of another
133
What is an example of synergism?
vasopressin increases the effects of CRH on the secretion of ACTH
134
Define permissiveness
mechanism in which one hormone is required for the other to work
135
What is an example of permissiveness?
cortisol permits epinephrine to cause vasoconstriction
136
Define antagonism
one hormone opposing the action of another
137
What are four examples of how hormonal modulation is accomplished?
negative feedback, synergism, permissiveness, and antagonism
138
Insulin acts to __ blood glucose
decrease
139
Glucagon and epinephrine are insulin __
antagonists
140
Glucagon and __ are synergistic to each other
epinephrine
141
What are the two main hormones in mammalian nutrient metabolism
insulin and glucagon
142
Insulin is secreted by the beta cells of the __, and it __ blood glucose, causing cells to take __ glucose, fatty acids, and proteins. Opposes __, storage of __
pancreas
lowers
in
glucagon
nutrients
143
Insulin is stimulated by high __ __ levels, high __ meal, GI hormones and __ activity (rest and digest)
blood glucose
protein
parasympathetic
144
Insulin promotes the formation of __, __, and __
glycogen, triglycerides, proteins
145
Glucagon is secreted by the __ cells of the pancreas, and __ blood glucose levels, opposing action of __. Mobilization of ___
alpha, raises, insulin
nutrients
146
High carbohydrate meal triggers insulin __ and glucagon __
increase; decrease
147
Vasopressin causes __ to be incorporated into the __ membrane of duct epithelial cells for __ retention
aquaporins; apical; water
148
What are the three fluid compartments of the body?
intracellular body fluid
interstitial fluid
blood plasma
149
What system is involved in vertebrate salt and water balance?
Renin-angiotensin-aldosterione system
150
Renin-angiotensin-aldosterone system conserves water along with __
ADH
151
Low blood pressure stimulates __ secretion by the kidney; which catalyzes the production of __, which triggers __ secretion by the adrenal cortex
renin
angiotensin
aldosterone
152
__ increases absorption of Na+ in the kidney, water follows by __
Aldosterone
osmosis
153
Angiotensinogen secretes __ and produces __. Angiotensin I produces __, which has four functions
renin; angiotensin I
angiotensin II
154
What is the function of angiotensin II?
aldosterone secretion, stimulates vasopressin secretion, promotes thirst, and stimulates constriction of systemic arterioles
155
Angiotensiogen stimulates hormones which adjusts __ __ pressure
arterial blood
156
__ __ __ acts to excrete water from the body
atrial natriuretic peptide (ANP)
157
Stretch receptors in specialized muscle cells in the atrium of heart sense __ blood pressure and secrete __
high
ANP
158
ANP inhibits _- reabsorption by kidneys, acting as a diuretic
Na
159
What is a diuretic
someting that promotes the production of dilute urine
160
AND opposes the actions of the __ and __ systems
ADH, RAA
161
Muscle is a tissue built of specialized __ cells also called?
contractile
muscle cells; muscle fibers; myocytes; myofibers
162
What are the two main categories of muscle?
striated muscle tissue and smooth muscle tissue
163
Describe striated muscle tissue
appearance of alternating light and dark bands, which are collections of contractile proteins (sarcomeres). Makes up the skeletal muscle (most) and cardiac muscle
164
Describe smooth muscle tissue
uses contractile proteins that are not organized into sarcomeres, so there's no striated appearance. Smooth muscle lines the blood vessels, gut, respiratory tract
165
Skeletal muscle hierarchy: __ muscle consists of multiple bundles of muscle __. __ are long, multinucleate, cylindrical cells, organized in parallel. Each myofiber consists of many parallel __. Each myofibril is composed of repeated __.
skeletal
fibers; myofibers
myofibrils
sarcomeres
166
What is the fundamental unit of contraction?
sarcomere
167
What is the composition of sarcomere?
actin and myosin filaments
168
Skeletal muscle fibers are subdivded into repeated long __ sarcomeres with a _ __ at each end
sarcomeres
z-disk
169
Actin is the __ filament, while myosin is __
thin; thick
170
Where is actin found?
attached at the midpoint to z-disks and project to either side
171
Where is myosin found?
at the center of each sarcomere and attach to actin at each end
172
Titin filaments make up __ of total muscle mass. and they function as __ __, allowing the muscle to __
10%
elastic bands
relax
173
Each actin filament is composed of: 1) two twisted, bended polymer chains of globular __ molecules with a _ binding domain 2) two strands of __ molecules that lie from end to end in the grooves formed by the actin chains. 3) __ molecules attached at intervals to tropomyosin strands
actin; myosin
tropomyosin
troponin
174
__ and __ act to control whether myosin __ can interact with __ filaments
tropomyosin; troponin
cross-bridges
actin (thin)
175
Each myosin molecule has a globular head with an __ binding domain, a __ pocket, and a flexible __ with two light chains of __
actin
nucleotide
neck
myosin
176
What is the sliding filament theory?
muscle inches and releases then inches and releases until fully contracted
uses ATP
177
In the absence of __, tropomyosin __ the myosin binding sites on the __ filaments
Ca2+, blocks, actin
178
Fast chemical transmission at the NMJ
AP __ terminal
1) __ channels open
2) __ is released into the __
3) __ binds to __ receptors
4) _- receptors __ the muscle cell
5) The muscular __ propagates to all parts of the muscle, stimulating __
depolarizes
1 Ca
2 ACH; synapse
3 ACh; nicotinic
4 nicotinic; depolarize
5 AP; contraction
179
The __ ( the myocyte cell membrane) forms deep transvers invaginations into the myocyte called __ __
sarcolemma
transverse (T) tubules
180
T/F: The T-tubule system is discontinous with the ECF
false
181
What is the sarcoplasmic reticulum?
network of longitudinal membrane-bound tubules contained entirely within the myocyte, between two T-tubules
182
What joins the T-tubules and the SR?
protein receptor channels
183
At the T-tubule-SR junction, the SR contains a __ channel/receptor called a __ __. The t-tubule contains another receptor (not a channel) called __ __
ryanodine receptor (RyR)
dihydropyridine receptor (DHPR)
184
In skeletal muscle, __ and __ form a complex at the T-tubule-SR-junction. __ is activated by T-tubule depolarization, which stimulates __ to release __ from the __ into the __
RyR; DHPR
DHPR
RyR; Ca
SR; cytoplasm
185
Excitation-Contration coupling: sarcolemma depolarization
1 _ release at the __
2 Opening of __ gated __ channels
3 __ propagates down the ____
1 ACh; NMJ
2 ACh; ion
3 AP; T-tubules
186
Excitation-Contration coupling: Ca efflux from the SR
4 __ reaches the __ receptors, opening the associated __ receptors, and releasing __ from the __
5 __ ions diffuse into the __ and bind to __, enabling __ __
6 Cross bridges go through several cycles of __ while __ is present
4 depolarization; DHPR: RyR;Ca; SR
5 Ca; cytosol; troponin; filament sliding
6 movement; Ca
187
Excitation-Contration coupling: AP termination
7 Meanwhile at the __, __ hydrolizes __ to terminate the __
8 __ ceases at the __ and __ channels close
9 __ actively transport __ back into the __
NMJ; AChE; ACh; AP
Depolarization; T-tubules; RyR
Ca ATPases; Ca; SR
188
What are the three main steps of Excitation-Contration coupling?
Sarcolemma depolarization
Ca efflux from the SR
AP termination
189
Smooth muscle lacks __ and __ but has 5x the amount of __ filaments than striated muscle
sarcomeres; troponin; actin
190
Discuss the organization of actin and myosin filaments in smooth muscle
organized into diagonal bundles around the periphery of the cell; when smooth muscle contracts, the peripheral filaments slide along each other, and the myocytes turn from spindle shaped to globular
191
T/F: The ATPase activity of smooth muscle is faster than that of SO fibers
FALSE: Slower
192
Smooth muscle sometimes has __ __ that function as a single unit of __ muscle
gap junction
smooth
193
How does contraction of smooth muscle occur?
slight depolarization - opens plasma membrane voltage gated Ca channels
194
Ca activates smooth muscle predominately by regulating __ state of __ proteins. Relaxation is accomplished by pumping the __ back out of the cell
phosphorylation; myosin
Ca
195
Smooth muscle cells are innervated by the __, which occurs by diffuse __ release (__ or __)
ANS
neurotransmitter
ACh, catecholamines
196
T/F: Ca enters SMC in a variety of ways
True
197
Smooth muscle: __ binds with __, complex activates the __ __ __ __ (MLCK), which activates __ __ and allows __
Ca; calmodulin
myosin light chain kinase
myosin ATPase
contraction
198
Describe cardiac muscle
uninucleate branched cells that form intercalated discs, which contain gap junctions (electrical synapses) and desmosomes. Specialized pacemaker cells generate endogenous action potentials
199
Action potentials of cardiac muscle are __ lasting, due to __ ion flux across the cell membrane that __ __. this ensures a __ contraction of the muscle cell and coordinated pumping by the heart
long; Ca
prolongs depolarization
prolonged
200
Cardiac cells have limited __ capacity and function mainly __
glycolytic; oxidatively
201
Describe how muscles work in pairs
function in antagonistic pairs, because muscles can only forcibly shorten, they cannot forcibly lengthen
202
Muscle force is directly proportional to __ __ area of __ in a muscle, or __ acting in __
cross-section
sarcomeres
sarcomeres; parallel
203
What are the four different types of muscle contractions?
isometric
isotonic (eccentric or concentric)
204
What is an isometric contraction?
cross-bridges are active, but there is not enough force to generate movement
205
What is an isotonic contraction
cross-bridges are active, there is enough force to generate movement
206
What's the difference between a concentric and eccentric isotonic contraction?
concentric - picks up
eccentric - puts down
