exam #1 Flashcards
(118 cards)
1
Q
plasma membrane: structure and function
A
structure: phospholipid bilayer, selectively permeable (polar head, non polar tail)
function: gives form to cell, controls passage of materials into and out of cell, and participates in intracellular communication
2
Q
cytoplasm: structure and function
A
structure: fluid, jellylike substance between the plasma membrane and the nucleus in which organelles are suspended
function: matrix substance in which chemical reactions occur
consists of cytosol and organelles
3
Q
nucleus: structure and function
A
structure: large body within a cell, double layer membrane
function: contains DNA and directs the cell’s activities
4
Q
extracellular matrix/fluid
A
the fluid outside of cells including the blood plasma and the interstitial fluid within the tissues
“ECM/ECF”
contains water, carbohydrates, and proteins
5
Q
passes through the cell membrane via simple diffusion
A
-gases (CO2, N2, O2) —> all permeable
-small uncharged polar molecules (ethanol, H2O, urea) —> ethanol permeable, H2O and urea slightly permeable
6
Q
passes through the cell membrane via carrier-mediated transport
A
-large uncharged polar molecules (glucose, fructose)
-ions (K+, Mg2+, Ca2+, Cl-, HCO3-, HPO4 2-)
-charged polar molecules (amino acids, ATP, glucose 6-phosphate, proteins, nucleic acids)
-ALL impermeable
7
Q
concentration differences (gradients) lead to what net movement?
A
the “downhill” net diffusion of a solute from a region of higher concentration to a region of lower concentration
this diffusional driving force is proportional to the concentration gradient
8
Q
simple diffusion
A
non-carrier mediated “downhill” movement of some molecules across a cell membrane
9
Q
the degree to which a substance will diffuse across a lipid bilayer depends on?
A
the selective permeability of that membrane
10
Q
osmosis
A
-net diffusion of water across a membrane from regions of higher [H2O] to lower [H2O]
-simple diffusion
-in order to occur: (1) membrane must be selectively permeable to water (2) concentration gradient for total solute must exist across the membrane (3) solute must be osmotically active/membrane nearly impermeable to solutes
11
Q
dynamic equilibrium
A
concentrations are equal of both water and solute
no net movement
12
Q
osmotic pressure
A
the physical force needed to counteract osmosis
increased solute concentrations increase the osmotic pressure
13
Q
molality (m)
A
1m soln = (1 mol solute) / (1 kg solvent)
14
Q
osmolality (Osm)
A
the total molality of the solution = the sum of the molalities of all solutes present
(same for osmolarity)
multiply by m or M by number of ions to get Osm or OsM
15
Q
tonicity
A
total concentration of solutes
differences in tonicity lead to osmotic movements of water
16
Q
isotonic
A
no movement of water
same tonicity
equal tension
17
Q
hypotonic
A
water moves in —-> cell expands
medium has lower tonicity than inside the cell
lower tension
18
Q
hypertonic
A
water moves out —> cell shrivels up
medium has higher tonicity than inside the cell
higher tension
19
Q
pumps
A
-membrane transport protein
-ATPases
-active transport
-largest and slowest
20
Q
carriers
A
-membrane transport protein
-transporters
-passive and active transport
-faster than pumps, slower than channels
21
Q
channels
A
-membrane transport proteins
-passive transport
-fastest
22
Q
uniporter
A
moves one molecule downhill
(energetically no different than channels)
23
Q
symporter
A
moves one molecule downhill and one uphill in the same direction
(aka contransporter)
24
Q
antiporter
A
moves one molecule uphill and one downhill in opposing directions
25
passive transport
-facilitated diffusion
-direction of transport is energetically downhill
-all channels and uniporters
26
active transport
-direction of transport is energetically uphill (ATPases is energy source)
-primary active transport: all pumps
-secondary active transport: symporters and antiporters
27
the sodium pump
-Na+/K+ ATPase pump creates and maintains the primary ionic gradients across the plasma membrane
-for each ATP burned, the pump moves in 3 Na+ ions out and 2 K+ ions in
-both are being moved uphill, against their concentration gradients
-electrogenic: moving positive charge 1+ outside the cell
28
sodium/glucose cotransporter
-symporter
-secondary active transporter that couples the uphill movement of ions or molecules to the downhill movement of Na+ (or K+ in other examples)
29
molecules that are too large to enter or exit the cell via carrier-mediated transport and transport by?
-vesicles ---> vesicular fusion
-endocytosis moves molecules into the cell
-exocytosis moves molecules out of the cell
30
charge gradient across cell membrane
-unequal distribution of charge creates a membrane potential
-typical cell at rest has a membrane potential (Vr) of -60 mV to -80 mV (inbalance caused by K+ channels)
-inside of the cell negative relative to the outside being 0mV
-neurons, muscle cells, and cardiac cells are electrically-excitable cells
31
chemical driving force: K+, Na+, Cl-, and Ca2+
outward: K+
inward: Na+, Cl-, and Ca2+
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value of the membrane potential (Vm) is dependent on
-all ionic concentration gradients across the membrane
-the permeabilities of all ions across the membrane
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Vr is nearly equal to Ek due to
-the presence of leaky K+ channels that are always open
-not quite equal because there are also leaky Na+ channels
34
Ex
-Ex = 61 / z log10 [Xo] / [Xi]
-Nernst equilibrium potential for X ions: the voltage that the membrane would assume if it were only permeable to X ions ---> reach electrochemical equilibrium
-"balance point" between two diffusional driving forces acting on ion X
-when Vm = Ex, there is no longer any net movement of ion X across the membrane
35
electrical driving force: K+, Na+, Cl-, Ca2+
outward: Cl-
inward: K+, Na+, Ca2+
36
Ex values for K+, Na+, Cl- and Ca2+
K+ = -87
Na+ = +64
Cl- = -89
Ca2+ = +129
-close to Vm: K+ and Cl-
-extremely positive: Na+ and Ca2+
37
how cells communicate via cell signaling
-chemical signals are released from one cell into the ECF and sensed by a target cell
-local (autocrine and paracrine), neurotransmission, and endocrine
-target cells respond to these chemical signals via receptor proteins
38
receptor protein types
-channel linked receptors: ligand-gated ion channels (nervous system)
-enzyme linked receptors
-G-protein coupled receptors (nervous system)
-intracellular receptors
39
nervous system: divisions, structure, cell types
-2 divisions: CNS and PNS
-structure: 7 major parts of CNS and 3 broad regions of the brain
-2 cell types: glia and neurons (in both CNS and PNS)
40
anatomy of a neuron
-dendrites: responsible for receiving and interpreting incoming info from other neurons
-cell body: contains the nucleus
-axon hillock: originof the axon, axon potentials initiated here
-axon: conducts action potentials
-nerve terminal: outflow of information
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CNS consists of
PNS consists of
CNS: brain and spinal cord
PNS: all nervous tissue outside of CNS
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afferent neurons
-sensory neurons
-bring info in
-PNS to CNS
-long axons
43
efferent neurons
-motor neurons
-bring info out
-CNS to PNS
-long axons
-two types: somatic and autonomic motor neurons
44
interneurons
-located entirely in the CNS
-associative/integrative functions of the nervous system
-short axons
45
nuclei v.s ganglia
-nuclei: clusters of cell bodies in the CNS
-ganglia: clusters of cell bodies in the PNS
46
tracts v.s nerves
-both are fibers
-tract: bundle of axons in the CNS
-nerve: bundle of axons in the PNS
47
projection neurons
-long axons ---> send info long distance
-similar to sensory and motor
-largely in CNS
48
somatic and autonomic motor neurons
somatic: control skeletal muscle
autonomic: control everything else such as smooth muscle, cardiac muscle, and glands
49
classification of neurons
-functional: afferent, efferent, inter, and projection
-morphological (pseudo, bi, multi)
-neurotransmitter released
50
morphological classes of neurons: pseudo, bi, multi
-pseudounipolar: 1 process coming out of cell body, sensory neuron
-bipolar: 2 processes coming out of cell body
-multipolar: multiple processes coming out of cell body, interneuron, somatic neuron, and autonomic neuron (most abundant)
51
neuroglia / glial cells
-supporting cells that aid the functions of neurons
-3 main types: astrocytes, oligodendrocytes, and Schwann cells
52
astrocytes
-CNS
-most abundant type of glial cell
-help regulate the external environment via end-feet on capillaries and neurons
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oligodendrocytes
-CNS
-insulate central axons
-create multiple internodes of myelin sheath ("white matter") by wrapping plasma membrane around the axon
54
Schwann cells
-PNS
-insulate peripheral axons
-create one internode of myelin sheath ("white matter") by wrapping the entire cell around the axon
55
four distinct regions of a neuron
1. dendrites: synaptic potentials and integration (receiving info)
2. soma: same as dendrites
3. axon: action potential conduction
4. nerve terminal: synaptic transmission (transmitting info)
56
depolarization, hyperpolarization, and repolarization
-depolarization: Vm becomes positive relative to Vr (caused by movement of Na+ and Ca2+)
-hyperpolarization: Vm becomes negative relative to Vr (caused by movement of K+ out and Cl- in)
-repolarization: Vm moves back toward Vr
(Vr = -70 mV)
57
ion channels
-always passive transporters = down the gradient
-electrical excitability is mediated by changes in permeability through ion channels=changes in Vm
-transmembrane proteins that conduct ions
-specific and gated (regulated permeability)
-3 types: voltage-gated (Na+, K+, Ca2+, Cl-), ligand-gated, and mechanically gated
58
voltage gated ion channels
channel that carries each individual ion down its concentration gradient (change the membrane potential)
59
ligand-gated ion channels
-bind to a chemical that controls the channel
-receptor is a channel itself
-NT activates/opens the channel
-gated by a chemical NT
-faster because more direct
60
mechanically gated ion channels
respond to changes in physical stress on the membrane
61
action potential
-propagated electrical "wave" running the length of an axon
-stereotypical (waveform always looks the same)
-all-or-none event
-threshold ~ -55 mV : ~15 mV depolarized from rest, stimulated by electrical events in the stoma
-shape and duration of waveform reflects changes in membrane permeability to Na+ and K+ (opening and closing of voltage-gated channels for Na+ and K+)
-slow K+ channels to close causes undershoot
62
ion channels of the action potential
1. "fast" Na channel
-exists in 3 distinct states: (1) closed at Vr, (2) open when depolarized, (3) inactivated
-voltage gated (2 gates): (1) main gate opens first, (2) inactivation gate plugs the channel (ball and chain)
2. "slow" K channel
-exists in 2 distinct states: (1) closed at Vr, (2) open when depolarized
-voltage gated (1 gate): main gain
63
action potential sequence of events
1. initial depolarizing stimulus must reach threshold
2. Na channels open (fast) --> depolarizing effect
3. K channels open (slow) --> repolarizing effect
4. Na channels inactivate (fast) --> repolarizing effect
5. both Na and K channels close (K slower)
64
absolute and relative refractory period
absolute refraction period:
-due to inactivated Na+ channels
-resistant to another action potential that follows
-ensures unidirectionality of nerve impulse
-places limits on AP frequency
relative refractory period:
-due to continued outward diffusion of K+
-can experience AP, but membrane has to be depolarized
65
cable properties of the axon
characteristic of synaptic and receptor potentials in dendrites and soma
66
conduction of the AP: increase conduction velocity
-increase axonal diameter
-myelinate the axonal membrane (provides insulation)
67
neurotransmission: presynaptic to postsynaptic neuron
presynaptic (terminal boutons):
1. action potentials conducted by axon
2. opens voltage-gated Ca2+ channels
3. release of excitatory neurotransmitter
postsynaptic:
4. opens chemically ligand-gated channels (dendrites and soma)
5. inward diffusion of Na+ causes depolarization (EPSP)
6. localized, decremental conduction of EPSP
7. opens voltage-gated Na+ and then K+ channels (axon initial segment)
8. conduction of action potential (axon)
68
events in the presynaptic cell
1. action potentials reach axon terminals
2. voltage-gated Ca2+ channels open in response to depolarization
3. Ca2+ binds to sensor protein in cytoplasm
4. Ca2+ protein complex stimulates fusion and exocytosis of neurotransmitter via synaptic vesicles
69
acetylcholine (Ach)
NT that enables learning, memory, and muscle contraction
70
glutamate (Glu)
-major excitatory NT of CNS
-GPCR
-interacts with receptors that cause depolarization
71
GABA
-major inhibitory NT of the CNS
-LGIC
-interacts with receptors that cause hyperpolarization
72
biogenic amines
-catecholamines (tyrosine derived): dopamine, norepinephrine, and epinephrine
-serotonin (tryptophan derived)
73
serotonin
-many GPCRs, effects can be stimulatory or inhibitory
-one LGIC: Na+/K+ channel, stimulatory
74
dopamine
-all GPCR
-effects can be stimulatory or inhibitory
75
norepinephrine and epinephrine
-all GPCRs: alpha and beta receptors
-effects can be stimulatory or inhibitory
76
electrical response of post-synaptic cell: EPSP v.s IPSP
-EPSP = excitatory = depolarization of the receiving cell
-IPSP = inhibitory = hyperpolarization of the receiving cell
-response of post-synaptic cell depends on the type and subtype of NT present in the dendrites and soma
77
overview of synaptic transmission
1. release of NTs from the pre-synaptic nerve terminal
2. interaction of NTs with post-synaptic cell membrane
3. removal of NTs from synaptic cleft
78
G-protein coupled receptors
-intergral membrane protein, NOT channels
-NT binds to receptor to open and pass current
-G-protein becomes activated and causes changes in voltage
79
nicotinic acetylcholine receptor
-always generates EPSP in post-synaptic cell
-LGIC
-depolarizes potential up to 0mV
1. channel closed until NT(acetylcholine) binds to it
2. open channel permits diffusion of specific ions (more Na+ in and less K+ out)
80
muscarinic acetylcholine receptor
-always generates and IPSP in post-synaptic cell
-heart cell
-GPCR
-hyperpolarization
1. ACh binds to receptor
2. G-protein subunit dissociates
3. G-protein binds to K+ channel, causing it to open (K+ out of cell)
81
inotropic and metabotropic receptors
inotropic: LGIC
metabotropic: GPCR
82
clearance of NT from cleft
-passive mechanisms (all synapses): happens very slowly via simple diffusion that is always occurring
-active mechanisms (synapse dependent): reuptake (secondary active transporters take NTs back into cell) OR digestion (enzymes) while it's on the cleft
83
7 major parts of the CNS
spinal cord
medulla oblongata
pons
cerebellum
midbrain
diencephalon
cerebrum
84
3 broad regions of the brain
forebrain (cerebrum and diencephalon)
midbrain
hindbrain (cerebellum, pons, and medulla)
85
brain stem consists of
midbrain, pons, and medulla oblongata
86
forebrain
-cerebrum: cerebral cortex, basal ganglia, hippocampus, and amygdala
-diencephalon: thalamus and hypothalamus
87
cavities filled with cerebrospinal fluid (CSF)
ventricles (brain) and central canal (spinal cord)
88
gray matter
cerebral cortex (outer layer gray matter) and nuclei
89
white matter
tracts
(myelination)
90
cerebrum
-cerebral hemispheres: L and R
-corpus callous: how L and R side communicate
-higher brain functions
90
cerebrum
-cerebral hemispheres: L and R
-corpus callous: how L and R side communicate
-higher brain functions
-structure: cerbral cortex
----gyrus (peak) and sulcus (valley)
----four lobes: frontal, parietal, occipital, and temporal
-structure: subcortical regions
----basal ganglia, hippocampus, and amygdala
91
lateral sulcus
dividing line between temporal love on bottom and frontal/paritel lobes on top
92
central sulcus
diving line between frontal love and parietal lobe
93
longitudinal fissure
dividing line between L and R cerebral hemisphere
94
the cerebral hemispheres
-L and R hemispheres divided by the longitudinal fissure and connected by the corpus callosum
-cerebral laterization
-decussation of fibers: contralateral (cross-over) and ipsilateral (stay on same side)
95
precentral gyrus and postcentral gyrus
precentral: primary motor cortex involved with the control of voluntary muscles (contains motor map of right side of body controlled by left side)
postcentral: somatosensory cortex for cutaneous and proprioceptive senses
96
lobes: parietal, frontal, temporal, occipital
parietal: sensory info bottom-up processing
frontal: top-down processing
temporal: auditory processing, learning, memory
occipital: visual processing, contains visual map
97
L hemisphere v.s R hemisphere
left: analytics, math, language skills
right: spatial orientation, locate, recognize
98
cerebral cortex: major neurons
-cellular/functional layering
-projection neurons: pyramidal cells (major) and glutamatergic (excitatory)
-local interneurons (short axons): located in all cell-layers, GABA-ergic (inhibitory)
99
subcortical regions: basal ganglia, hippocampus, and amygdala
basal ganglia: control of voluntary movement
hippocampus: learning and memory
amygdala: emotion and memory, part of the limbic system
100
diencephalon: thalamus
-"relay center" for ascending somatosensory info
-integration of motor info between basal ganglia, cerebellum, and cerebral cortex
101
diencephalon: hypothalamus
-regulation of "essential" behaviors: body temp, growth, eating and drinking, reproduction, body clock
-numerous neural centers (nuclei)
-emotional components via medulla and limbic system
-regulation of pituitary gland and the ANS
-extensive connections with CNS
102
midbrain
-role in motor control: linkages between cerebellum, basal ganglia, and cortex
-components of visual and auditory systems
-major pathway for control of eye movements
-dopaminergic projection pathways: nigostriatal system (motor control --> Parkinson's) and mesolimbic system (addiction/reward behaviors --> schizophrenia)
103
cerebellum
-"little brain"
-coordination of movement, motor learning, eye and head movement, control of balance
-involvement in language and other higher cognitive functions
-major input center for receiving info from spinal cord, cerebral cortex, inner ear
-three regions: cerebellar cortex (three layers, five neuron types --> 4 interneurons and purkinje cells), internal white matter, and three deep nuclei
104
purkinje cells
mediate motor functions of the cerebellum by producing IPSPs in their post-synaptic neurons
105
pons
-ventral pontine nuclei relay motor and somatosensory info from the cerebral cortex to the cerebellum
-dorsal nuclei are involved in respiration, sleep, and taste
106
medulla oblongata
-decussation of many tracts occurs at the medulla
-"vital center" nuclei: cardiovascular regulation
-early relay nuclei for taste, hearing, balance, control of neck and facial muscles
107
spinal cord
-central gray matter: two dorsal horns and two ventral horns
-surrounding white matter: funiculi
-ascending and descending tracts
108
ascending tracts
-sensory info from PNS to CNS
-medial lemniscal tract and lateral spinothalamic tract
-bottom-up control
-crossover occurs at the level of the medulla for medial lemniscal tract
-crossover occurs at many different points across spinal cord before medulla for lateral spinothalamix tract
109
descending tract
-motor output from CNS to PNS
-corticospinal tract and extrapyramidal tract
-top-down control
110
learning and memory
-synaptic plasticity
-short-term memory ("early" LTP): seconds to hours, synaptic changes can be easily reversed (no new protein synthesis)
-long-term memory ("late" LTP): days to years, synaptic changes are more permanent (new protein synthesis)
111
implicit v.s explicit memory
implicit: skills-based memory, how to do something
explicit: claritive facts, somantic, what, where, when
112
inotropic (LGIC) glutamate receptors
-non-NMDA-Rs: no LTP, AMPA, Na+/K+ channel, always generates EPSP, depolarize ~ 0 mV, open just because glutamate binds
-NMDA: LTP, voltage and ligand gated Na+/K+/Ca2+ channel, Ca2+ as second messenger, open because glutamate bound and change in voltage
113
mechanisms of LTP
-normal synaptic transmission (NMDA-R inactive)
--> early LTP (NMDA-R activation and short-term effects)
--> late LTP (NMDA-R activation and new protein synthesis, long term effects)
114
depression
-decreased activity of biogenic amine pathways
-resperine decreased monaminergic signaling in the brain by inhibiting uptake of biogenic amines into presynaptic vesicles, had parkinson-like side effects
115
3 generations of anti-depressant drugs
1. MAOIS: increase movement and concentration of NT; downside: targets all monoamines in the CNS
2. tricyclics: inhibit reuptake mechanism; downside: affects all monoamines in CNS
3. SSRIs: target some monoamines more than others and amine transporter; downside: still effects other circuits in the brain
116
dopaminergic projection: nigrostrital pathway
-underactive
-compromise in Parkinson's disease
-L-DOPA can have schizophrenia-like side effects
-DA nuclei in substantia nigra of midbrain project to putamen of basal ganglia
-important for motor control
117
dopaminergic projection: mesolimbic pathway
-overactivity in Schizophrenia
-D2 (GPCR) antagonists can have Parkinson's-like side effects
-important in reward behavior and emotion
-DA nuclei in ventral segmental are of midbrain project to nucleus accumbent (of basal ganglia) and prefrontal cortex (limbic system)
