Chp 14/15 Flashcards
Visceral efferent neurons in the autonomic nervous system innervate
visceral effectors smooth muscles cardiac muscles exocrine glands endocrine glands
autonomic nervous system is primarily involved in
maintaining homeostasis of internal environment
Structurally, each nervous system division consists of
nerves, nerve plexuses, and autonomic ganglia
Each motor command is carried over what kind of circuit
two cell circuit
Most effector organs and tissues receive impulses from
both ANS divisions, a dual or parallel innervation
The two divisions often serve as antagonists to each other in adjusting and maintaining internal homeostasis
sympathetic and parasympathetic
Parasympathetic system dominates in
in sleep and other relaxed or resting states
Sympathetic dominates during
skeletal muscle activities and various emergency situations (fright, panic, rage, aggression)
There is a constant interplay between the two divisions
parasympathetic and sympathetic
one motor neuron to skeletal muscle effectors
somatic
two motor neurons to visceral effectors
autonomic
Where is there a middle man in the autonomic or somatic CNS? What is its name?
autonomic
sympathetic chain ganglion or cranial nerve X (vagus)
Autonomic visceral reflex arch sends information
along the afferent pathway–> dorsal root ganglion –> central nervous system –> preganglionic axon–> autonomic ganglion–> ganglionic neuron–> visceral effector
Where is the sympathetic chain ganglion found
on the autonomic visceral reflex arch
Sympathetic nervous system fiber length
short preganglionic fibers and long postganglionic fibers
Parasympathetic fiber length
long preganglionic fibers and short postganglionic fibers
rest sex and digest nerve is
the vagus nerve
Our neuron transmiter for fight or flight is called
adrenaline noreiphenephrine
epinephrene
Parasympathetic control is
short lived, highly localized control
Sympathetic control is
long lasting, diffuse effect
Neurotransmitter released in the preganglionic parasympathetic and sympathetic nervous system
acetylcholine
Neurotransmitter released in the postganglionic parasympathetic and sympathetic nervous system
parasympathetic- acetylcholine
sympathetic- norepinephrine
Parasympathetic receptors
nicotine- excititory
muscarinic- excitatory or inhibitory
Sympathetic receptors
alpha- excitatory
beta- excitatory or inhibitory
Nicotinic receptor does what
turns on the parasympathetic nervous system
muscarinic receptor does what
turns on or off the parasympathetic nervous system
alpha receptor does what
turns on the sympathetic nervous system
beta does what
turns on or off the sympathetic nervous system
What would a beta blocker do?
blocking that receptor for the sympathetic nervous system. the activity of flight or fight. Hypertension. lower you blood pressure
what fiber releases acetylcholine
cholinergic fibers
what fiber releases norepinephrine
adrenergic fibers
depending on the receptor type neurotransmitter effects can be
excitatory or inhibitory
Norepinephrine is eaten up by
catechol-o-methyltransferase (COMT) and Monoamine oxidase (MAO)
Do cholinergic fibers or adrenergic fibers cause longer lasting effects and why?
adrenergic fibers tend to cause longer lived effects due to the slower degradation of norepinephrine by COMT and MOA
What causes PTSD
Slower degredation of norepinephrine from adrenergic fiber
In what case would an MAO inhibitor be prescribed?
I want norepinephrine to stay…. to help with depression. aka lethargy
adrenergic receptors respond to
norepinephrine and epinephrine
If your ANS isn’t functioning during youth it is normally because of
injury to it
In old age ANS efficiency decreases resulting in
orthostatic hypotension, constipation, and dry eyes.
orthostatic hypotension is
the inability of your body to respond to postural changes in blood pressure
Orthostatic hypotension happens to
old people and pregnant women
Raynauds Disease
causes sudden severe vasoconstriction in the fingers toes and occasionally the ears and nose. Causes skin color changes.
Referred pain
happens because there aren’t nerve receptors for every part of our organs. The visceral afferents run in the same nerves with somatic afferents
Photoreceptors are found in the
retina
What are the two kinds of photoreceptors that we have
rods and cones
Rods are for and cones are for
dim light
color
cones are activated by
light
When you are activating the photoreceptors which nerve is being activated
optic
the only place in our eye where we have no photoreceptors (rods or cones) “blind spot”
optic disc
Area in our eye with the most cones
the depression (fovea centralis) in the maculae lutea
What type of neurons do we have in the retina
bipolar neurons
what kind of neuron has a cell body in the middle and axons on both sides
bipolar neuron
why are there chambers inside all if the eye cavities
because of the fluid of the eye to keep the shape of the eye
what is a cataract
calcium deposits on the lens making it harder to see because our vision is more cloudy.
Vitreous humor is in the
is in the posterior chamber
what muscle does the trochlear nerve innervate
the superior oblique muscle
what muscle does the abducens innervate
the lateral rectus
every other muscle around the eye (except for two) is cranial nerve
III oculomotor
what nerve handles your rods and cones
your optic nerve
what controls pupil size
iris
Lens stays in place by
the ciliary body
what contracts our eye every time we focus
the ciliary body
If the lens is bulging outward (convex) is for
near vision
If the lens is concave is for
far distance
myopia
near sightedness
hyperopia
far sightedness
presbyopia
far sightedness from old age considered normal
What are the three main colors that we pick up
red, green and blue
photopigments are found in
rods and cones
Photopigments in rods are sensitive to
dim light
photopigments in cones are sensitive to
bright light and colors
Pathway that light takes
Light first goes through the lens, anterior chamber, posterior chamber, hits the rods and cones on the retina, open up sodium channels, hyperpolarize, send that transmission through the optic nerve, cross over to the occipital, then lastly tapes into memory in the frontal lobe so you know its an A.
lacrimal means
tears
where does the lacrimal gland sit and where do the tears come out
superior lateral, medial
color blindness issue with
rod
The three ossicle bones move on
axis cotratempranine nerve
Stapes movement displaces
paralympth
where in the brain is sound processed
the temporal lobe
the pathway in which sound travels
The sound waves travel from the outer ear and in through the auditory canal, causing the eardrum, or tympanic membrane, to vibrate. This, in turn, causes the three small bones, known as the ossicles, or the hammer, the anvil and the stirrup, in the middle ear to move. The boney ossicles are connected to the cochlea, and that’s going to cause something to happen in the cochlea that’s going to cause a signal to go via the auditory nerve to the brain.
auditory ossicles
the three tiniest bones in the body form the coupling between the vibration of the eardrum and the forces exerted on the oval window of the inner ear. Formally named the malleus, incus, and stapes, they are commonly referred to in English as the hammer, anvil, and stirrup.
The auditory ossicles move on
and axis that allow them to pivitol axis
The chorda tympani is a
branch of the facial nerve that originates from the taste buds in the front of the tongue, runs through the middle ear, and carries taste messages to the brain.
The stapes moves
in a piston like action, hitting the boney labrynth, displacing the parilympth in the boney structure
Perilymph
(also known as Cotunnius’ liquid, and liquor cotunnii) is an extracellular fluid located within the cochlea (part of the inner ear) in two of its three compartments: the scala tympani and scala vestibuli.
light refraction
- light will bend when it passes from one medium (air) into another (lens) e.g. pencil in glass of water
convex lens
- (thicker at center, tapered at edge) causes light to bend so that it comes together at a focal point
real image
image at focal point of convex lens —> inverted & reversed
what focuses light on the retina
cornea and lens
constant (unchanging) refraction
cornea
can change refraction and focal length; ciliary muscles change convexity of the lens
lens
emmetropic eye
normal, healthy eye
far point of vision
distance beyond which lens will not change its shape (about 20 feet) (flattest point of the lens)
Less than 6 feet, several adjustments are made:
accommodation of lens - lens shape becomes more convex, light rays bend more sharply, shorter focal length for the closer object (ciliary muscles for lens)
near point of vision
- shortest distance for focusing (maximum convexity of lens); about 8-10 inches; gets worse with age
presbyopia
poor close vision in elderly; inelasticity of the lens
accommodation of pupils
constriction of pupils; better focus, less divergent rays (constrictor muscles of iris)
convergence of eyes
eyes rotate medially to keep image on center of the retina (medial rectus muscles of eyeballs)
Vision Problems Related to Refraction
myopia
hyperopia
astigmatism
myopia
(“nearsighted”) - distant objects are blurred; distant objects are focused in front of the retina, rather than directly on it
eyeball too long; lens too strong
concave lens can correct light before eye
myopia
hyperopia
(“farsightedness”) - close objects are blurred; close objects are focused beyond the retina, rather than directly on it
eyeball too short; poor refraction of a lens
convex lens can correct light before eye
hyperopia
astigmatism
- blurry images at all distances; unequal curves on lens and/or cornea, creating discontinuous image on the retina
outer segment of eye
contain membrane-bound discs with pigments that absorb and react to light
rods
pigment discs stacked like pennies all the way to the base, membranes are DISTINCT from the plasma membrane
rods (6 facts)
- sensitive to dim light (night vision)
- respond to ALL wavelengths (colors)
- only “grey” information to the brain
- 100 rods per ganglion cell to brain
- widely spread throughout the retina
- not good for visual acuity
cones
pigment discs taper off toward the base, membranes are CONTINUOUS with the plasma membrane
Cones (6 facts)
- require bright light for stimulation
- different cones have different pigments specific for certain wavelengths (colors)
- can convey color information to brain
- 1-3 cones per ganglion cell to brain
- primarily concentrated in fovea (center)
- essential for visual acuity
opsin involved in biochemistry of visual pigments
transmembrane protein in the membrane of pigmented discs of rods and cones
retinal
light absorbing molecule that changes shape when struck by a photon of light
vitamin A
precursor to retinal (eat your carrots!!!!!!)
11-cis isomer of retinal
non-activated form of retinal, prior to absorption of photon energy; has a “kinked” double bond
all trans isomer of retinal
activated form of retinal, after struck by photon of light; double bond straightens out
rhodopsin excitation of rods
visual pigment in rods; in membranes of pigmented discs of outer segment
HYPERPOLARIZATION of rod and excitation of rod
a. Na+ channels (open in dark) are closed
b. rod is hyperpolarized (increased negativity)
c. Ca++ channels in synapse close
d. less neurotransmitter released by the rod
photopsins involved in excitation of cones
3 distinct pigments in cones are sensitive to 3 different parts of visible spectrum
what kinds of cones are there
blue green and red cones
blue cones
maximum sensitivity at 455 nm
green cones
maximum sensitivity at 530 nm
red cones
- maximum sensitivity at 625 nm
different colors cause
differential activation of each of the three different cones
color blindness is
inherit gene for one of the photon proteins that is deficient (mainly male), most common are red and green mutations
Light and Dark Adaptation of
Rhodopsin
light adaptation very dark → very bright
a. rhodopsin in rods is quickly bleached out
b. sensitivity to shallow light disappears
c. rods are inhibited by other retinal cells
d. cones are activated to take over (5 mins.)
e. consensual pupil reflex - constriction
dark adaptation - very bright → very dark
a. cones are gradually cease to be stimulated
b. “bleached out” rods can produce rhodopsin
c. rods eventually take over in the dim light
d. pupillary dilation - pupils increase size
nyctalopia
(night blindness) - deficiency in function of rods during dim-light situations
vitamin A deficiency is general cause
The Visual Pathway: Photoreceptors to Occipital Cortex
Retina Axon Path Thalamus Axon Path Cerebral Cortex
Retina visual path to cerebral cortex
RETINA photoreceptors (rods & cones) -> bipolar cells -> ganglion cells (axons = optic nerve) ->
AXON PATH optic nerves (from each eye retina) optic chiasma (medial fibers cross over) optic tracts (opposite visual field)
THALAMUS lateral geniculate body of thalamus ->
AXON PATH optic radiation (fibers to cortex)
CEREBRAL CORTEX occipital lobe - primary visual cortex
other brain areas that receive visual information
superior colliculi - for control of extrinsic eye muscles
- pretectal nuclei - mediate pupillary light reflexes
- suprachiasmatic nucleus of hypothalamus - circadian rhythm
vibration of medium
- sound travels in compression waves through a particular medium
a. solid fastest ————-> liquid —————-> gas slowest
sound as a wave
the series of high pressure and low pressure areas are called
“compressions” and “rarefactions”, respectively
sine wave
graphic representation of areas of compression and
rarefaction of a sound wave
wavelength
the distance between 2 areas of compression for a
given sound wave
Frequency
the number of waves that pass a given point in one
second (1/s = 1 Hertz)
different types of frequency
i. short wavelength/high frequency - high pitched tones
ii. long wavelength/low frequency - low pitched tones
iii. human frequency range - 20Hz - 20,000 Hz (2-3 Hz distinction)
amplitude
intensity of energy in a given wave of sound; signified by height of sine wave
amplitude loudness
subjective interpretation of the intensity of a sound
amplitude decibel
logarithmic scale to measure the intensity of sound waves
Transmission of Sound to the Inner Ear
air --> external auditory canal --> tympanic membrane (ear drum) --> ossicles (malleus, incus, stapes.) --> oval window of cochlea --> vibration of cochlear fluid --> basilar membrane of cochlea
Resonance of Basilar Membrane
- vibration of oval window -> perilymph vibration
- for 20 - 20,000 Hz only, vibration of vestibular membrane
- vestibular membrane vibration -> endolymph vibration
- endolymph vibration -> vibration of basilar membrane
- basilar membrane “fibers” of different length, thickness, and tension like strings of a piano
resonance -
different fibers of basilar membrane have different “natural frequencies”
SPECIFIC parts of basilar membrane vibrate only at
SPECIFIC frequency (pitch)
Excitation of Hairs Cells of Organ of Corti
1. cochlear hair cells
- rest on the basilar membrane, contain “stereocilia” which project into the “tectorial membrane” just above
Excitation of Hairs Cells of Organ of Corti pathway
a. basilar m. vibration -> hair cell vibration
b. hair cell vibration -> opening/closing channels
c. depolarization/hyperpolar -> cochlear nerve
d. cochlear nerve impulses -> to brain
Anatomical Pathway to the Brain
cochlear nerve (vestibulocochlear VIII)-> spiral ganglion --> cochlear nuclei (medulla) --> superior olivary nucleus --> lateral lemniscal tract --> inferior colliculus --> medial geniculate body of thalamus --> auditory cortex (superior temporal lobe)
Perceiving Pitch (Frequency)
location of vibration on the basilar membrane
Perceiving Differences in Loudness (Intensity)
amplitude increases, more hair cells of the basilar membrane (with same pitch) are activated
localizing Source of Sound
- superior olivary nucleus - first point where sound from both ears come together
a. relative intensity - the amplitude of sound waves hitting the different ears
b. relative timing - the difference in timing in which a sound reaches both ears
conduction deafness
disruption in sound vibrations to basilar membrane (ext & mid ear)
- blocked auditory canal (wax, fluid)
- perforated tympanic membrane (eardrum)
- otitis media - middle ear infection/inflammation
- otosclerosis - hardening of the earbone joints
sensorineural deafness
disruption anywhere in pathway from hair cells to the auditory cortex
- loss of hair cells (explosion, chronic loud noise)
- damage to vestibulocochlear nerve (VIII)
- damage to nuclei/tracts to the cortex
tinnitus
chronic perception of clicking or ringing
- sudden blow to the tympanic membrane
- gradual deterioration of afferents in cochlear nerve
Menierre’s Syndrome
effects both hearing and balance; results in tinnitus, vertigo, and interspersed nausea and vomiting
- may be too much endolymph beneath basilar membrane
- symptoms can be treated somewhat with drugs
- endolymph may be drained periodically
- hearing loss is progressive
Linear Movement of the vestibular apparatus is
The Maculae of the Vestibule motion is UP/DOWN
Equilibrium and Balance: The Vestibular Apparatus
has linear movement and angular movement
The Angular Movement of the vestibular apparatus involves 5 things
- semicircular canals - three bony “hula-hoop” extensions of vestibule in three different planes
- crista ampullaris - like maculae, contain hair cells that respond to flow of endolymph in canals
a. cupula - like otolith membrane, gelatinous “cap” into which hair cells project - change in angular (rotational) acceleration - movement of the head in non-linear (circular or angular) direction is monitored by three canals
- vestibular nystagmus - movement of eyes to remain fixed on object when on “merry-go-round”
- vertigo - false feeling of gravity or motion
Equilibrium Pathway: Coordinating Inputs in Brain
activated hair cells of crista ampularis ->
(vestibulocochlear nerve) -> vestibular nuclear complex OR cerebellum
vestibular nuclei
also receive input from eyes and somatic proprioceptors; coordinates information to help control motion of eyes, neck, limbs
cerebellum
also receives input from eyes and somatic proprioceptors; coordinates information to help regulate head position, posture, and balance
Problems with Equilibrium
- dizziness, nausea, imbalance, vomiting
- motion sickness - conflict between visual/somatic inputs and action of the vestibular apparatus
a. Bonine, Dramamine, Scopolamine - block inputs from vestibular apparatus to the brain
Risk Factors For Hypertension
age heredity race gender weight diet lifestyle/activity level stress: overstimulates sympathetic division? alcohol tobacco
Preganglionic neurons
cell bodies in the CNS (brain or spinal cord)
transmit Action Potentials from the CNS
preganglionic neurons
in the sympathetic division, the cell body is located
in the lateral gray horns (thoraco-lumbar) of the spinal cord
preganglionic neurons
in the parasympathetic division, the cell body is located in
various nuclei of brain stem or in the lateral gray horns (cranio-sacral)
the postganglionic fiber sends impulses to a
target organ
the effects at the target organ are due to
type of neurotransmitter and specific cell surface receptors on the effector cells
Due to dual innervation The Sympathetic and Parasympathetic Divisions of the ANS innervate
many of the same organs
During dual innervation different effects are due to specific molecular differences in the
neurotransmitters and in the receptor types on the effectors
sympathetic trunk
vertebral chain ganglia (paravertebral ganglia)
a vertical row on either side of the vertebral column
these ganglia are interconnected
thoracic and lumbar origin
each preganglionic neuron synapses with many postganglionic neurons
other sympathetic ganglia are located
in the walls of major abdominal arteries
Nicotinic receptors are found on:
Motor end plates (skeletal muscle)
All postganglionic neurons of both sympathetic and parasympathetic divisions
The hormone-producing cells of the adrenal medulla
The effect of ACh binding to nicotinic receptors is always
excititory
Muscarinic receptors occur on all
effector cells stimulated by parasympathetic cholinergic fibers and by those few effectors stimulated by sympathetic cholinergic fibers
The effect of ACh binding at muscarinic receptors:
Can be either inhibitory or excitatory
Depends on the receptor type of the target organ
The two fundamental types of adrenergic receptors
alpha and beta
Effects of NE binding to alpha receptors is generally
excitatory to effectors
Effects of NE binding to beta receptors is generally
inhibitory to effectors
A clinically important exception – NE binding to beta receptors in the heart is
excitatory
Cholinergic receptors
nicotinic and muscarinic
Adrenergic receptors
alpha and beta
Drugs which mimic the action of ACh and NE at their receptors are termed
cholinergic and adrenergic agonists respectively
Drugs which block or inhibit the action of ACh and NE at their receptors are termed
cholinergic and adrenergic antagonists (or “blockers”) respectively
Drugs which enhance the action of ACh and NE at their synapses by delaying enzymatic degradation are termed
anticholinesterases monoamine oxidase inhibitors (MAO-inhibitors)
The cerebral cortex, limbic system, hypothalamus, and the brain stem cooperate to initiate
autonomic motor commands.
emotional input is regulated by
limbic system
overall intergration of the ANS “the boss” are regulated by
hypothalamus
regulation of pupil size, respiration, heart, blood pressure, swallowing are regulated by
reticular formation of the brain stem
urination, defecation, erection and ejaculation reflexes are regulated by
spina cord
Most control from the ans is unconscious and originates from the
hypothalamus
But strong conscious emotional states can trigger
autonomic, usually sympathetic, responses
S(alivation) L(acrimation) U(rination) D(efecation)
Parasympathetic
metabolic “business as usual”
Parasympathetic
rest and digest” – “feed and breed” – basic survival functions
Parasympathetic
any increase in skeletal muscular activity or these activities - increase heart rate, blood flow, breathing
decrease non-survival activities - food digestion, etc.
sympathetic
Slows the heart
Directs normal activities of the digestive and urinary systems
parasympathetic tone
The sympathetic division can override these effects during times of
stress or muscular exertion
Drugs that block parasympathetic stimuli increase
heart rate and interfere with fecal and urinary retention
what cooperation is involved in the complex control of the cardiovascular system
ANS
what cooperation is also seen in control of the external genitalia during sexual activities
ANS
what fibers cause vasodilation and are responsible for erection of the penis and clitoris
para
fibers cause ejaculation of semen in males and reflex peristalsis in the female reproductive tract
sympathetic
Sympathetic stimulation is long-lasting because
norepinephrine (NE):
is inactivated more slowly by MAO and COMT
NE
is an indirectly acting neurotransmitter, triggering a second-messenger system
NE
are released into the blood by the adrenal medulla in certain situations and remain there until inactivated by liver enzymes
NE
Solitary Sympathetic Stimulation
Regulates some effectors not innervated by the parasympathetic division
Therefore, acting more as an on-off switch
These include the adrenal medulla, sweat glands, arrector pili muscles, kidneys, and most blood vessels
what division controls: Thermoregulatory responses to heat
Cutaneous vasodilation and sweating
The sympathetic
what division controls: Release of renin from the kidneys
Increased blood pressure from a complex regulatory response
The sympathetic
what division controls: Metabolic effects (in a complex coordination with the endocrine system)
increases the metabolic rate of body cells
elevates blood glucose levels for use by nervous tissue
shifts cellular metabolism to fats for other tissues
stimulates the reticular activating system (RAS) of the brain, increasing mental alertness
sympathetic
what division has actions serve to support the body during strenuous physical activities and emergencies but may contribute to undesirable side effects in cases of long term stress such as illnesses
sympathetic
what division controls blood pressure, keeping the blood vessels in a continual state of partial constriction (vasomotor tone)
sympatheic
Blood pressure rises or falls with what activity
sympathetic
what is also diverted to or away from different organ systems depending on the level of muscular activity or the presence of emergency or stressful states
blood in the sympathetic state
Alpha-blocker drugs inhibit vasomotor tone and are used to treat hypertension due to what state
sympathetic
