Nervous System Flashcards
collect info from other neurons
dendrites
contains the nucleus and most cell organelles
cell body
integrates info collected by dendrites and initiates nerve impulses at the beginning of the axon
axon hillock
conducts action potential away from the cell body
axon
nerve cells that are excitable = generate and transmit electrical signals, more specifically action potentials
neurons
modulate neuron activity (provide support)
glia
at the tip of the axon that carries Ap away from presynaptic cell to postsynaptic cell
axon terminals
originating cell body
presynaptic cell
receiving target cell
postsynaptic cell
cluster of nerve cells
ganglion (ganglia)
ganglia may be enlarged and fused at the anterior end to form a –
brain
cnidarians have simple networks of neurons called – that achieves little or no integration of information
nerve nets
in bilaterally symmetric animals, the ganglia are often –
paired
The increase in brain size in humans is mostly due to an increase in the –
cerebral cortex
the human brain is also highly – and more of it is devoted to associative functions
convoluted
In – body size and brain size are correlated, but higher primates fall above this regression line
vertebrates
In humans, the – is the largest brain area and is made even larger by convolutions
cerebral cortex
The anterior end of neural tube develops into –
hindbrain, midbrain, and forebrain
most “primitive” part of the brain that controls breathing and circulation and helps regulate behavior patterns
hindbrain
processes visual and auditory info (eg reflexive response to noise)
midbrain
most complex and developed portion of the brain
forebrain
the posterior end of neural tube develops into
spinal cord
the hindbrain becomes
medulla, pons, and cerebellum
controls physiological functions such as breathing
medulla and pons
coordinates muscle activity and maintaining balance
cerebellum
Brainstem is composed of
midbrain, medulla, and pons
all info traveling between the spinal cord and higher brain areas must pass through the –
brainstem
consists of the diencephalon and telencephalon
forebrain
Forebrain – = thalamus and hypothalamus
diencephalon
two cerebral hemispheres (also called cerebrum) that process sensory perception, learning, memory and conscious behavior
telencephalon
T or F: CNS is encased in bone
True
T or F: PNS is encased in bone
False
lobe for visual
Occipital
lobe for complex sensory processing (visual and auditory)
Temporal
lobe for representation of the body and movement in space
Parietal
lobe for motor cortex and involved in planning
Frontal
The cortex is folded into ridge – and valleys – giving it bigger surface area
gyri, sulci
The two hemispheres are – with respect to all functions
not symmetrical
divides the frontal and parietal lobes
central sulcus
located in front of the central sulcus and controls muscles in specific body areas
primary motor cortex
parts of the body with fine motor control (face and hands) have – representation
disproportionate
inability to identify objects
agnosias
If the left brain hemisphere is damaged, there is often some form of – which is a deficit in the ability to use or understand words
aphasia
In frontal lobe, just in front of primary motor cortex essential for speech but if damaged can still read and understand language
Broca’s area
in temporal lobe, damage results in inability to speak sensibly (written or spoken language is not understood) but can still produce speech
Wernicke’s area
near Wernicke’s area; essential for integrating spoken and written language
Angular gyrus
the inability to recognize faces even though you can identify people based on hearing or touching
prosopagnosia
the left and right hemispheres are connected by white matter called
corpus callosum
In the PNS, bundles of axons are called
nerves
In the CNS, bundles of axons are called
tracts
There are a – of neuron forms
variety
The – of all neurons can generate and conduct action potentials
plasma membranes
The axon terminals comes extremely close to the membrane of the target cell forming a –
synapse
evolution of nervous systems: network of neurons –>
ganglia –> brain-spinal cord
sensory relay station
thalamus
a vital part of the endocrine system which regulates physiological functions and drives
hypothalamus
bundles of axons are surrounded by – tissue
connective
some axons in a nerve may be carrying info to the CNS while others in the same nerve are carrying info from the CNS to –
the body’s organs
The cerebrum is about 3-4 mm and officially has – layers but is essentially a – sheet
6, 2D
verbal and logic
LEFT
visual and spatial
RIGHT
behavior/movement
FRONT
sensory input/perception
BACK
more complex
OUTSIDE
more essential
INSIDE
right body
LEFT
left body
RIGHT
divides the frontal and parietal lobes
central sulcus
located in the front of the central sulcus that controls muscles in specific body areas
primary motor cortex
parts of the body with fine motor control, such as face and hands, have
disproportionate representation
just behind the central sulcus that receives touch and pressure info from the thalamus
primary somatosensory motor cortex (parietal lobe)
areas with high densities of mechanoreceptors have
disproportionate representation
Normal language ability depends on the flow of info among areas of the – cerebrum
left
Damage to the – causes contralateral neglect syndrome where a person is unable to recognize stimuli from the left side of the body
right parietal lobe
If the – is cut, knowledge or experience of the right hemisphere can no longer be expressed in language
corpus callosum
– allow the AP to pass directly between two neurons
electrical synapses
In vertebrates, most synapses are –
chemical
chemical AP can travel up at speeds up to
100 m/sec
grow around axon and insulate axon with myelin (not in brain or spinal cord)
Schwann cells
- induce tight junctions between endothelial cells
- establish lining of capillaries
- establish blood brain barrier
Astrocytes
myelin sheaths in brain and spinal cord
oligodendrocytes
act as macrophages and mediators of inflammatory responses
microglia
– is an autoimmune disease that affect myelin
Multiple sclerosis
– typically prevents antibodies form entering the brain and spinal cord
blood-brain barrier
The sodium-potassium pump requires energy to move – and establish concentration gradients
Na + out and K+ in
The inside of the cell is usually – relative to the outside because “leak channels” allow some ions (K+) to diffuse out
negative
the electrical charge difference across the membrane which is measured in millivolts between the inside and outside of a neuron
membrane potential
the steady state membrane potential of a neuron
resting potential (-60mV)
Under resting conditions:
K permeability is high (many open K channels)
Na permeability is low (Na channels are closed)
Cl permeability is also low
membrane potential becomes more positive
depolarization
membrane potential becomes more negative
hyperpolarization
An – is a sudden, rapid reversal in the voltage across a portion of the plasma membrane
action potential
For – positively charged ions flow into the cell making the inside of the cell more positive than the outside
1 or 2 milliseconds
open and close in response to the membrane’s potential
voltage-gated channels
open and close in response to the presence or absence of a specific chemical/NT which can bind directly to the channel protein
chemically-gated channels
only K+ channel open
resting potential
voltage-gated Na+ channel open
depolarized: Na+ ions enter the cell traveling down its concentration gradient
chemically gated K+ channel open
hyperpolarized
The membrane potential at any given time depends on
how many and which channels are open
the resting potential is – because the resting membrane is permeable mainly to K+
negative
Until a – is reached when large numbers of these channels simultaneously open and a very rapid AP “spike” is produced
threshold
A new AP cannot be generated again at the part of the membrane until the voltage-gated Na – itself for the next AP
resets
there is a short – during which theses voltage-gated Na channels cannot open
refractory period
begins slowly through already open K channels
repolarization: more K ions leave the cell traveling down its concentration gradient
T or F: AP are conducted down axons without reduction in signal
True
An AP is – because it spreads to adjacent membrane regions
self-generating
– enables saltatory conduction
myelin
The – are regularly spaced gaps in the myelin along an axon
nodes of Ranvier
Saltatory Conduction: AP are generated at the – and the positive current flows down the inside of the axon
nodes
AP appear to jump from node to node, a form of propagation called
saltatory conduction
Myelin is oil-like and reduces the “capacitance” of the axon membrane, with fewer ions needed to depolarize
change in membrane potential is faster and requires less energy
are chemical synapses between motor neurons and skeletal muscles
neuromuscular junctions
the neurotransmitter of neuromuscular junctions is
acetylchloline
The arrival of – causes the release of a neurotransmitter
AP
the ability to sense stimuli arising within the body regarding position, motion, and equilibrium
proprioception
Membrane receptor proteins of sensory cells generally cause ion channels to open or close, causing a change in membrane potential called
receptor potential
the receptor protein itself is part of the ion channel and by changing its conformation, opens and closes the channel pore
ionotropic sensory detection
the receptor protein is linked to a G protein that activates a cascade of intracellular events that eventually open or close ion channels
metabotropic sensory detection
ion channels or directly affect ion channels
ionotropic receptor proteins
examples of ionotropic receptor proteins
mechanoreceptors, thermoreceptors, electrosensors
affect ion channels through G proteins and second messengers
metabotropic receptor proteins
examples of metabotropic receptor proteins
chemoreceptors, photoreceptors
different senses connect to different targets
labeled lines
responsible for taste and smell
also monitor internal environment such as CO2 blood levels
chemoreceptors
sense of smell
olfaction
sense of taste
gustation
olfactory sensors are embedded in – at the top of the nasal cavity (vertebrates)
epithelial tissue
axons extend to the – in the brain, dendrites end in olfactory hairs on the –
olfactory bulb, nasal epithelium
a molecule that enters the nasal cavity and binds to an olfactory receptor protein on the cilia of olfactory receptor neurons (ORNs)
odorant
olfactory receptor proteins are specific for particular –
odorants
In the olfactory bulb, axons from ORNs with the same receptor types cluster together to form – which integrate info from olfactory receptors
glomeruli
an accessory structure that traps odorant molecules, converting 3D diffusion to 2D diffusion
mucus
a paired tubular structure embedded in the nasal epithelium with chemoreceptors in the walls (found in amphibians, reptiles, and many mammals)
Vomeronasal organ
chemical signals used to communicate among individuals of the same species
pheromones
Taste buds are replaced every – but the associated neurons live on
few days
Gustation chemoreceptors don’t fire action potentials instead they release transmitter modulates the firing rate of action potentials in –
2nd order sensory neurons
flavor is due to a combination between – and –
taste and smell
Na+ channels for salty
Modulation of K+ channels by H+ for sour
ionotropic transduction
one or two sweet receptors and many bitter receptors via G proteins and 2nd messenger cascades
metabotropic transduction
are found in muscles, tendons, and ligaments
stretch receptors
auditory systems use – to sense sound waves
hair cells
sensory cells that respond to physical (mechanical) forces
mechanoreceptors
adapt slowly and provide continuous info about anything touching the skin; most important tactile receptor found in hairy and nonhairy skin
Merkel’s discs
deeper in skin, adapt slowly and provide info about vibrating stimuli of low frequencies
Ruffini’s corpuscles
deeper in skin, adapt rapidly and provide info about vibrating stimuli of high frequencies
Pacinian’s corpuscle
pain, itch, temperature
free nerve endings
(nonhairy) very sensitive but adapt rapidly and provide info about chanhges in things touching skin (roll)
Meissener’s corpuscles
diminishing response to repeated stimulation which enables animals to ignore background conditions but remain sensitive to changing or new stimuli
adaptation
mechanoreceptors in muscle cells (stretch receptors)
muscle spindles
the – in tendons and ligaments provides info about the force generated by contracting muscles and prevents muscle tearing
Golgi tendon organ
the bending of – or hair cells one way or the other depolarizes or hyper polarizes the cell, causing the postsynaptic fiber to increase or reduce its firing rate
stereocilia
tells fish about movement with respect to water, about pressure waves, and neighboring fish
lateral line system
The lateral line system (at its hair cells) evolved into - systems
vestibular auditory and electrosensory
We have 3 pairs of semicircular canals that signal – in 3 orthogonal planes: roll, pitch, yaw
rotational acceleration
move and bend stereocilia
ampullae
We have vestibular organs for – and –
gravity and linear acceleration
In the base of each semicircular canal duct is a – with a cluster of hair cell stereocilia
cupula
When shifting fluid pushes on the cupula, it bends the – causes a graded potential
sterocilia
Hair cell depolarizes when bent one way releasing – neurotransmitter
more
Hair cell hyper polarizes when bent the other way releasing – neurotransmitter
less
Hair cells do not fire AP – do
2nd order cells
Outer ear consist or – and –
pinna and auditory canal
Middle ear consists of the – and –
tympanic membrane and middle ear ossicles
serve to collect sound waves
outer ear
serves to amplify sound waves for impedance matching between air fluid of inner ear
middle ear
middle ear ossicles
malleus, incus, and stapes
consists of cochlea
inner ear
transduce sound waves to action potentials in auditory nerve
inner ear
a tapered and coiled chamber composed of three parallel canals separated by the vestibular membrane and the basilar membrane
cochlea
sits on the basilar membrane; transduces pressure waves into action potentials
organ of Corti
High frequency sound vibrates the – of the basilar membrane
base
Low frequency sound vibrates the – of the basilar membrane
apex
Upper and lower canals of the cochlea are joined at –
distal end
flexible membrane at the end of the tympanic canal of the cochlea
round window
responsible for photosensitivity
rhodopsin
photosensitivity depends on the ability of visual pigments to absorb – and undergo a change in –
photons of light, conformation
part of rhodposin that is not photosensitive alone
opsin
nonprotein, light-absorbing functional group cradled at the center of opsin and covalently bound to it
11-cis-retinal
entire rhodopsin molecule sit withing the – of a photoreceptor cell
plasma membrane
eyecups
flatworms
Arthropods have compound eyes consisting of many optical units called – each with its own narrow-angle lens
ommatidia
vertebrate eye consists of 1 optical unit with – lens
wide-angle
tough connective tissue layer that bounds the vertebrate eye
sclera
At the front of the eye, the sclera forms the transparent – through which light passes to enter the eye
cornea
Just inside the cornea is the pigmented – which gives eye color
iris
controls the amount of light that reaches photoreceptor cells at the back of the eye; under neural control
iris
What happens to iris and pupil in bright?
iris constricts and small pupil
What happens to iris and pupil in dark?
iris relaxes and large pupil
the central opening of the iris
pupil
Behind the iris is the crystalline protein – which make fine adjustments in the focus of images falling on the retina
lens
photosensitive layer at the back of the eye
retina
cornea and fluids within the eye – light rays passing through them so they are focused on the retina
bend
lenses become – with age
less elastic
During embryonic development, neural tissue grows out from brain to form the –
retina
photoreceptor cells are always shedding discs from their – ends as their new ones are being generated by the inner segments
distal
pigmented epithelial cells – the shed discs
phagocytose
each outer segments is totally renewed about every –
2 weeks
photoreceptors of the vertebrate retina
rod cells and cone cells
highly light sensitive adn perceive shades of gray in dim light
rod cells
– segment of rod cells contains stack of discs made up of plasma membrane densely packed with rhodopsin
outer
– segment of rod cells contain cell nucleus, mitochondria, and other organelles
inner
Na+ continually enters the outer segment in the –
Dark
Stimulated by light the cell –
hyperpolarizes
a single photon of light results in the
closure of many Na+ channels
function at high light levels and are responsible for high-acuity color vision of day-active
cone cells
highest density of cone cells is in the area of retina that receives light from the center of the visual field, a region called the –
fovea
low sensitivity to light and contribute little to night vision
cone cells
closest layer of neurons in retina to the lights and thus light
ganglion cells
central layer of neurons in retina
biopolar, horizontal, and amacrine cells
the – of the retina fire AP
ganglion cells
patch of photoreceptors that communicate with a ganglion cell forms a
circular receptive field
form synapses with neighboring photoreceptors and bipolar cells
horizontal cells
form local interactions between bipolar cells and ganglion cells
amacrine cells
bundle of axons in nerve carry info about many things simultaneously
nerves
2 unrelated stimuli become linked in same response
associative learning
can consciously recall and describe
declarative memory
memory of how to perform a task
procedural memory
