11.6 nervous system Flashcards
dendrites
receive info and transfer to cell body
glial cells
nervous tissue support cells. can divide
oligodendrocytes
produce myelin in CNS
*glial
Schwann cells
produce myelin in PNS
*glial
myelin sheathes
act as insulators and are separated by nodes of ranvier. instead of travelling down , it jumps (saltatory conduction).
white and grey matter
myelin is white, neurons are grey
microglia
(phagocytes of the CNS),
*glial
ependymal
(use cilia to
circulate CSF),
*glial
satellite cells
(support ganglia – groups of cell bodies in PNS),
*glial
astrocytes
(physical support to neurons of CNS; maintain mineral and nutrient balance)
*glial
sensory (afferent) neruons
receive initial stimulus like neurons in eye
motor (efferent) neurons
stimulate effectors, target cells that elicit some response (Ex: neurons
may stimulate the muscles)
association (interneuron)
located in spinal cord & brain- receive impulses from sensory and
send impulses to motor neurons. They are integrators, as they evaluate impulses for
appropriate response. ~99% of nerves are interneurons. Some reflex arcs do not require an
interneuron
how to generate action potential
- resting. -70mV
- stimulus opens gated ion channels. let Na+ in depolarizing it. if at -50mV will cause all volt gates down axon to open **all or nothing
- repolarization. gated channels let out k+, restoring polarization. na+ is IN here and k+ is out
- hyper polarization. too much k+ released (-80)
- refractory. neuron won’t respond now. ** Stops AP from going backwards!
refractory period absolute
na+ channels are inactive. no response to stimulation
relative refractory period
abnormally large stimuli can generate AP
electrical transmission across synapse
travels along membranes of cap junctions. this is bidirectional, fast
chemical transmission across synapse
unidirectional
- ca+ gates open. depolarization allows ca2+ to enter cell via voltage dependent calcium channel
- synaptic vessels release NT. release into cleft.
- NT binds with post synaptic receptors. diffusion and binding
- postsynaptic membrane is excited or inhibited
- NT goes away
postsynaptic membrane when its excited
Na+ gates open, membrane is depolarized
excitatory postsynaptic potential
(EPSP), if threshold potential is succeeded, action potential is generated
postsynaptic membrane when its inhibited
K+ gates open, membrane becomes hyperpolarized
inhibitory postsynaptic
potential (IPSP)… it becomes more difficult to generate action potential
acetylcholine
muscle contraction. used for Peripheral NS
Glutamate
- AA NT
in invertebrates at muscular junctions - most common in vert in CNS
gamma aminobutyric acid
- AA NT
inhibitory among brain neurons
glycine
- AA NT
- inhibitory NT among synapses of the CNS outside the brain
epinephrine, norepinephrine, dopamine and serotonin
- AA derived
- secreted between neurons of CNS
- epi and norepi act in Sympathetic NS
neuropeptide NT
endorphins and stuff
gases NT
Nitrous oxide. not stored. involved in relaxation of smooth muscle
acetylcholinesterase
- hydrolyzes acetylcholine and is on the post synaptic cleft. terminates singal
there are ___ branches of the autonomic and somatic NS
efferent and afferent
afferent branch
sensory
efferent branch
motor
somatic NS
sensory components from eyes and motor components to skeletal muscles
autonomic NS
conveys sensory impulses from blood vessels and organs and motor components transmits TO organs
CNS structure
- interneurons, brain and spinal chord
- B and S have three layers of coating called meninges.; outer later is dura after (thick with blood), arachnoid matter (web) then Pia mater directly covering the stuff
- between arachnoid and Pia matter is CSF produced by choroid plexus in the CNS
brain components
outer grey matter (Cell bodies) and inner white matter (axons). has forebrain, midbrain and hindbrain
forebrain
contains cerebellum (cerebral cortex), olfactory bulb, thalamus, hypothalamus, basal ganglia and hippocampus
cerebral cortex
in cerebellum processes sensory input / important for perception, memory, voluntary
movement, and learning)],
olfactory bulb
smell
thalamus
(relay for sensory information
between spinal cord and cerebral cortex),
hypothalamus
hypothalamus- visceral function (water balance,
blood pressure, temperature regulation, hunger, thirst, sex, circadian rhythms [coordinated by
suprachiasmatic nucleus]),
basal ganglia
centers for planning/learning movement sequences,
hippocampus
memory consolidation and spatial navigation
Midbrain
– relay center for visual/ auditory impulses; motor control
Hindbrain
posterior part of brain;
cerebellum
(maintenance of balance, hand-eye
coordination, timing of rapid movements, motor skills – note that the cerebellum doesn’t
initiate movement, but helps coordinate it),
pons
hindbrain. (relay center to allow communication b/w
cortex and cerebellum),
medulla oblongata
hindbrain. (breathing, heart rate, gastrointestinal activity)
brainstem
consists of midbrain + medulla oblongata + pons. Connects the cerebrum
with the spinal cord. The reticular formation (a network of neurons within the
brainstem) regulates sleep and arousal.
spinal chord
outer area is white matter/inner gray matter (cell bodies). Sensory info enters through
dorsal horn. All motor info exits through the ventral horn.
amygdala
base of cerebellum. nuclei responsible for emotional memory
two hemispheres of cerebral cortex
hemispheres connected by corpus callosum (thick nerve
bundle). Its cerebral cortex is divided by lobes: frontal, parietal, temporal and occipital
Frontal: cerebral cortex
Conscious thought (attention); initiates voluntary skeletal muscle movement via motor
cortex; contains olfactory bulb for smell. Prefrontal cortex (decision making, planning). Broca’s
area (forming speech).
Partietal: cerebral cortex
Sensory areas. Somatosensation - temp, touch, pressure, pain. Proprioception –
orientation of bodyparts in space. Somatosensory cortex.
- Temporal:cerebral cortex
Process and interprets sounds; Wernicke’s area - understand speech. Also contains
hippocampus (involved in memory formation). Aud. cortx
Occipital: cerebral cortex
Process and interpret visual input; object recogition, visual stimuli, etc. Visual & visual
association cortex.
peripheral nervous system
– consists of somatic and autonomic; both have sensory and motor
branches
- somatic (innervates skeletal muscles)
- autonomic (involuntary and innervates cardiac and smooth muscle)
PNS autonomic system sympathetic:
fight or flight BP and HR, ejaculation, energy generation and surpasses household tasks like digestion etc
- preganglia originate and exit in CNS through spinal chord, presynaptic release acetylcholine and post synaptic release epi and norepi
PNS autonomic system parasympathetic:
lower HR, increase digestion, relaxation, arousal.
- originate in CNS brain and form synapses with effectors. preganglia releases acetylcholine and so does post
receptors for acetylcholine
cholinergenic. nicotinic ‘9skeletal muscle) and muscarinic (effectors in ParaNS)
receptors for epi and norepinephrine are called
adrenergic
reflex arc
rapid, involuntary response to a stimulus involving two or three neurons, but brain DOES NOT integrate the sensory and motor activities… instead synapse in spinal cord*** Example: Knee-
jerk (patellar) reflex
mechanoreceptors
touch
thermoreceptors
(temperature),
nociceptors
(pain),
electromagnetic receptors
light
chemoreceptors
(taste, smell, blood chemistry).
vagus nerve
(extending from the medulla oblongata) innervates parts of the heart, lungs,
stomach, intestines, and liver;
sciatic nerve
serves te lower limbs and pelcis;
abduscens nerve
servies
the somatic muscles surrounding eye;
supraorbital nerve
serves sturctures surrounding eye + scalp
eye structure
- has cornea (focus light), pupil (diameter controlled by iris), lens (controlled by ciliary muscles) and retire with light cells
- eye is surrounded by sclera (connective tissue) beneath the choroid (vascular layer with blood)
cones
high-intensity illumination; sensitive to color
rods
low intensity; important in night vision; no color
- Rod pigment rhodopsin [aka visual purple] is struck by photons from light, causing hyperpolarization transduced into neural AP sent to brain
Photoreceptor cells synapse to
to bipolar cells to ganglion cells to axions of ganglion cells then bundle to optic nerve
blind spot
where optic nerve exits
fovea
densely packed with cones; important for high acuity vision [most dense cxn of
photoreceptors here]
vitrous humor
(jelly-like, between lens and retina, maintains eye shape and optical properties –
makes up most of the eye volume)
aqueous humor
(watery, fills anterior chamber between the lens
and cornea, eye produces it, maintains intraocular pressure and provides nutrients to avascular ocular
tissues)
myopia
nearsightedness
Hyperopia
farsightedness
Astigmatism
irregularly shaped cornea
Cataracts
lens becomes opaque light cannot enter
Glaucoma
– increase in pressure of eye due to blocking of outflow of aqueous humor
ear structure
outer, middle and inner ear; transduces sound energy into impulses
outer ear
auricle/pinna (what we think of as the ear) and auditory canal; direct sound
into external auditory canal
middle ear
amplifies sound; tympanic membrane (eardrum) begins the middle ear and
vibrates at same frequency as incoming sound ossicles (malleus, incus, and stapes)
inner ear
wave moves through the cochlea (vibration of ossicles exert pressure on fluid). As wave moves through pressure alternates, creating motion along the basilar
membrane; this movement is detected by hair cells (not actual hair but specialized
stereocilia) of the organ of Corti => transduced neural signal action potential
semicircular canals
in inner ear. canals responsible for balance (fluid + hair cells
sense orientation + motion)
Only vertebrates have…
Myelinated axons
