chapter 11- nervous tissue Flashcards
1
Q
how many systems control the body?
A
2- nervous and endocrine system
2
Q
what are the functions of the nervous system?
A
receive sensory input, integrate information, control muscle and glands, maintain mental activities (emotions)
3
Q
what makes up the nervous system ?
A
the brain, spinal cord, CN, spinal nerves, and sensory receptors
4
Q
what do neurons do?
A
transmits electrical impulses
cell body with dendrites and axon
5
Q
sensory neurons
A
sends info towards the spinal cord
6
Q
motor neurons
A
sends info away from spinal cord
7
Q
cranial nerves
A
12 from the brain, but not part of brain and spinal cord
8
Q
spinal nerves
A
31 from spinal cord, but not part of the brain and spinal cord
9
Q
plexus
A
group of nerves- overlap functions
10
Q
neuroglia
A
supportive cells, does not transmit impulses
11
Q
what are the nervous system divisions?
A
central nervous system (CNS)
peripheral nervous system (PNS)
12
Q
central nervous system
A
brain and spinal cord
receives and sends info to the body
“decision maker”
13
Q
peripheral nervous system
A
everything else. detects stimuli, sends into CNS, communicated from CNS to body
14
Q
sensory division
A
afferent
receptors to CNS, external and internal environmental stimuli (temperature, pain, touch, receptor)
15
Q
motor division
A
efferent, CNS to effectors (muscles and glands)
16
Q
somatic NS
A
voluntary division (skeletal muscles)
17
Q
autonomic NS
A
involuntary division (glands, smooth and cardiac muscles)
18
Q
sympathetic NS
A
fight or flight
increased heart rate, blood pressure, respiration rate, eyes wide
19
Q
parasympathetic NS
A
rest and digest
slows heart rate, blood pressure, respiration rate, and eyes pinpoint
20
Q
what are the three points of the neuron?
A
dendrite, cell body, and axon
21
Q
dendrites
A
short extensions, receive info from sensory receptors, neurons, retrograde movement
22
Q
cell body
A
extensive RER= nissl bodies
extensive protein synthesis
23
Q
axon
A
single arise from axon hillock, sends info from cell body to effector
anterograde movement
trigger zone where action potentials are generated
branch to form collateral axons, axoplasm, axolemma
24
Q
what are the neuron types?
A
sensory, motor, and interneuron
25
sensory neurons
afferent neurons conduct action potential towards CNS
26
motor neurons
efferent neurons conduct action potentials away from CNS
27
interneuron
conduct action potentials within CNS from 1 neuron to the next
28
anaxonic neurons
no axon, just dendrites
brain and retina, gradual potential
29
pseudo-unipolar
1 process into 2 branches
peripheral (dendrites) and central
30
bipolar nuerons
2 processes, dendrite and axon
sensory organs (retina, nasal, ear)
31
multipolar
many dendrites and axon
motor neurons of PNS
32
what neuroglia are apart of the CNS?
astrocytes, ependymal cells, microglial cells, oligodrendrocytes
33
astrocytes
blood brain barrier
goes in every direction, attaches close to capillary and anchors
34
ependymal cells
line ventriciles, choroid plexus- makes CSF
35
microglial cells
immune cells, phagocytic
36
oligodendrocytes
forms myelin sheath in CNS
37
which neuroglia are in the PNS?
schwann cells and satellite cells
38
schwann cells
forms myelin sheath in PNS
39
satelite cells
supports/ nutrition
protects from heavy metals (lead, mercury)
40
myelin
speeds up impulse transmission / protects axon
travels from node of ranvier to node of ranvier along axon
in Schwann cell in PNS, oligodendrocytes in CNS
41
what does impairment of myelin do?
slows impulse transmission
42
myelin destroying disease
multiple sclerosis
can't control movements as well
not control skeletal muscle
43
action potentials
electrical signals produced by the nervous system
44
different concentrations of ions
in cytoplasm compared to extracellular fluid
45
extracellular fluid
has higher concentrations of Na+ and Cl- outside of the cell
46
cytoplasm
has a higher concentration of K+
(-) charged molecules, molecules with phosphate
large molecules cannot get through PM easily, more negatively charged
47
what can cause ion channels to open and close?
movement of ions across the PM which changes the charge difference across the PM
48
what causes the PM to become polarized?
the difference in chase across the PM due to uneven amounts of cations and anions across it
49
what is the action potential difference?
-70 mV
50
Na+/K+ pump
pump K+ and Na+ against the concentration gradient
increases K+ inside the cell and Na+ in the ECF
3 Na+ out to 2 K+ in per ATP used
maintains concentration gradient
51
2 changes to RMP
depolarization and hyperpolarization
52
depolarization
inside is more +
-70 mV - -55 mV= generation of action potential
53
excitatory response
increased likelihood of generating AP
caused by Na+, Ca++, entry and changes in ECF K+ concentration
54
hyperpolarization
inside is more (-)
-70 mV - -90 mV = unlikley to generate AP
inhibitory response, caused by K+ exiting the cell and Cl- entering the cell
55
what are leak ion channels?
non gated ion channels
always open, specific to each ion
56
what are examples of gated ion channels?
ligand gated
voltage gated
other gated ion channels
57
what are ligand gated ion channels?
specific molecule to receptor
(ligand= hormone)
58
what are voltage gated ion channels?
voltage change opens gates
59
what are other gated ion channels?
mechanical/ temperature gated channels
60
what is graded in neuron communication?
small change in membrane potential in LOCAL area of PM
varies in size, can depolarize or hyperpolarize
if summation of graded potentials= threshold AP
61
action potential
mechanism by which neurons communicate with effectors
travels along PM without losing strength over distance (1-2 ms to occur)
all of none phenomenon
62
what are the 4 phases of action potential ?
depolarization
repolarization
hyper polarization
return to RMP
63
what is a refractory period?
once AP is produced, the area is less sensitive to further stimulation
64
absolute refractory period
once the cycle starts, it must be copleted before another AP starts
spans from AP generation until close to end of repolarization.
cannot generate another AP
65
relative refractory period
follows the absolute refractory period
strong stimulus (> threshold) = production of another AP
66
propagation of AP
once generated AP, passed along PM, propagates in 1 direction down the length of the axon
67
what is continuous conduction?
unmyelinated (PM section by section)
68
what is saltatory conduction?
myelinated (jumps from node of ranvier to next node
69
action potentials
can stimulate AP's in another cell- allows communication between cells
ex. hand on hot stove
70
stimulus of heat
produce AP in sensory nerve fibers
AP propagated along sensory fibers towards CNS
71
sensory neuron AP
produce AP in CNS neurons
CNS AP's causing motor neurons to generate AP's
skeletal muscle AP's
skeletal muscle fiber CONTRACTION
72
synapse
junction between 2 cells where they communicate with each other
info is transferred from neuron to neuron or neuron to effector
presynaptic neuron-> synapse-> postsynaptic neuron
neuromuscular junction, neurogland junction= neuron to muscle or gland
73
what are the different synapse types?
electrical and chemical
74
electrical synapse
not common, gap junctions across cytoplasm from 1 cell to the next
protein channels called connexons- allow act as 1 cell (Na+ flows from 1 cell to the other)
75
what are rapid transmissions ?
Na+ causes generation of Ap in adjacent cell= SYNCHRONOUS activity
occurs in cardiac muscle and smooth muscle
76
chemical synapse
neurotransmitter (chemical messenger= ACh) communicates to effector
presynaptic terminal -> synaptic cleft-> postsynaptic membrane (neuron/muscle/gland)
77
where are action potentials in a chemical synapse?
in the presynaptic terminal-> NT release from terminal
many mitochondria present in presynaptic terminals, also synaptic vesicles
78
what happens during chemical synapse?
action potential-> voltage gated Ca++ channels to open in presynaptic axon terminal -> exocytosis of synaptic vesicle (sensor synaptotagmin) -> NT crosses synaptic cleft, binds to receptors on postsynaptic membrane (depolarizing Na+ or hyper polarizing graded potential K+, Cl-)
79
what are the short term NT effects?
rapid destruction OR removed from synaptic cleft (AChE)
acetylcholine (ACh) is released from receptors
ACh -> acetic acid+ choline (by AChE)
choline (transport back to presynaptic terminal) + acetyl-CoA (choline Acetyltransferase)= ACh reforms
OR diffuses away from synaptic cleft
80
what are NT norepinephrine ?
releases into synaptic cleft, transport back into presynaptic terminal OR monoamine oxidase (MAO) enzyme breakdown
81
what are the 6 classes of neurotransmitters?
acetylcholine
biogenic amines
amino acids
purines
neuropeptides
gases and lipids
82
*acetylcholine
most well understood
stimulates skeletal muscles and ANS
myasthenia gravis
83
what are the two types of biogenic amines?
catecholamines and indoleamines
84
*what do biogenic amines do?
they are in the brain and regulate emotions and biological clock
85
catecholamines
derived from AA tyrosine
dopamine
in motor neurons of ANS
schizophrenia, cocaine (xs dopamine) vs Parkinson's (little dopamine)
86
indoleamines
derived from histamine and tryptophan
histamine and serotonin
Alzheimer's (little serotonin)
LSD, mescaline - bine to receptors and cause hallucinations
87
amino acids neurotransmitters
GABA, glycine, glutamate in CNS
88
purines in neurotransmitters
derived from nucleic acids
adenosine and ATP
89
neuropeptides
substance P and endorphines
short AA chains
90
gases and lipids
nitric oxide nd carbon monoxide
endocannabinoids
91
what are the two types of chemical inhibitory responses?
excitatory and inhibitory
92
excititory chemical synapse response
EPSP (postsynaptic potential)
last few ms's
local graded depolarization
if threshold -> AP
dendrite and neuron cell body
93
inhibitory chemical synapse response
IPSP
local hyper polarization
usually on the cells body and away fro threshold
94
summation
PSP's add together to stimulate an AP (ESPS, IPSP)
spatial and temporal
95
spatial summation
multiple AP's from separate neurons arrive simultaneously at the same postsynaptic neuron
large # stimulated
96
temporal summation
2+ AP's arrive at postsynaptic cell
rapid fire, do not finish
97
what are the two types of neuronal pathways and circuits ?
serial pathway and parallel pathway
98
serial pathway
simple- input travel along 1 pathway to a specific destination
1 neuron stimulates the next and so on
spinal reflex- rapid reflex
automatic response to stimuli
ALL OR NOTHING
99
what uses the serial pathway?
receptors, sensory neurons, CNS integration, motor neurons, effectors
100
parallel pathway
more complex, input travels along several pathways
integrated in different CNS regions
processes a lot of info quickly
triggers unique pathways
same stimulus many responses
important for high level intellect
