Chapter 5B Flashcards
Eyelids
- act as shutters to protect eye from environmental insults
- helps disperse tears
Lacrimal gland
Produces tears
Pupil
- opening which allows lint into the eye
- size adjusted by iris muscle networks
- composed of two sets of smooth muscles
Eyelashes
- trap fine airborn debris before it can fall into the eye
Cornea
- transparent
- light rays pass into the inferior of the eye
- lacks blood vessels
Lens
- separates two fluid filled cavities
- lacks blood vessels
Aqueous humor
- clear, watery fluid
- carries nutrients for the cornea and lens
Where is aqueous humor produced
Within the ciliary body
Glaucoma
- if aqueous humor is not drained from a blockage in the anterior cavity
- causes pressure to rise and can lead to blindness if not cured
Iris
- thin, pigmented, smooth muscle within the aqueous humor
- responsible for eye color
Astigmatism
- curvature of cornea is uneven so light rays are unequally refracted
Ciliary body
- adjust lens; known as lens accommodation
Consists of: - ciliary muscles
- suspensory ligaments
Optic disc
Blind spot
- no image because there are no rods and cones
Macula
- high concentration of cones (high acuity)
- overlying ganglion and bipolar cells
Macular degeneration
- leading of blindness
- loss of photoreceptors in macular lutea
- “ doughnut vision”
Fovea central is
- only cones
- area of sharpest vision
Retina
- nervous tissue layer
- contains photoreceptors
- highly pigmented to prevent reflection or scattering of light
Vitreous humor
- larger cavity
- jellyfish like substance
- maintains spherical shape
Choroid
- contains blood vessels that nourish the retina
- highly pigmented to prevent reflection/ scattering of light
Sclera
- outermost layer
- layer of connective tissue
- white part of the eye
Accommodation
- ability to adjust the strength of the lens, which is dependent on shape
- regulated by the ciliary muscle
Lens flattened
- ciliary muscle relaxed
- suspend story ligaments tout
- far vision
- sympathetic simulation
Round lens
- ciliary muscle contracts
- near Visio.
- parasympathetic stimulation
Presbyopia
- old cells use soerical shape
- affects people 45-50
- require reading classes
Emmetropia
- normal eye
Hyperopia
- far sightedness
- corrected by cones lens
Myopia
- near sightedness
- corrected by a concave lens
Cataracts
- lens fibres become opaque therefore light rays cannot pass through
- surgically removed
Phototransduction
- process of converting light stimuli into electrical signals
- photoreceptors hyperpolarize on light absorption
Visual field
- field of view that can be seen without moving the head
Photopigments
- undergo chemical operation when activated by light
2 components - opsin (part of the disc membrane)
- retinene ( vitamin a, within opsin, light absorbing part)
Rhodopsin
- rod pigment
- absorbs all visible light wavelengths
Rods
More sensitive; low light; shades of grey
- low acuity
- night vision
- much convergence in retinal pathway
- more numerous in periphery
Cones
- detect color
- low sensitivity
- high acuity
- day vision
- little convergence in retinal pathway
- concentrated in fovea and macular lutea
Dark adaptation
- gradually distinguish objects due to the regeneration of rod photopigments
Light adaptation
- as cone photopigments rapidly breakdown by light exposure, light sensitivity decreases
Night blindness
- deficiency of vitamin A
- photopigments of both rods and cones are reduced; but still enough cones to see
- reversible
Color blindness
- genetically controlled
- more common males
- lack of cone type
External ear
- pinna
- external auditory meatus
- tympanic membrane
Pinna
- skin covered flap of cartilage, collects sound waves and channels them down into the external ear
- relatively immobile
- shape helps people distinguish weather sound is coming from directly in front or behind
Tympanic membrane
- vibrates
- must have equal pressure on either side of the tympanic membrane
Eustachian (auditory) tube
- connects the middle ear to pharynx
- can be pulled open by yawning, chewing, and swallowing
- permits air pressure within the middle ear to equalibrate with atmospheric pressure
Cochlea
- hearing portion of the inner ear
- coiled tubular system lying deep within the temporal bone
Pitch discrimination
- ability to distinguish between various frequency’s of certain sound
- capacity depends on shape of the basilar membrane
- narrow end (near oval window) vibrates best with high frequency pitches
- wide end vibrates maximally with low frequency tones
Intensity discrimination
- depends on the amplitude of vibration
Loud sound = more vibration
Primary auditory cortex
- precieves discrete sounds
Higher order auditory cortex
- integrated sounds into a coherent, meaningful pattern
Conductive deafness
- sound waves are not adequately conducted through the external and middle portions of the ear to set the fluids of the inner ear in motion
EXAMPLE: physical blockages, rupture of the eardrum, middle ear infections, fluid accumulation, restriction of ossicular movements
TREATMENT: hearing aids
Sensorineural deafness
- sound waves are transmitted to the inner ear, but are not transmitted into nerve signals; caused by defects in the organ of corti or the auditory nerves
Neural presycusis deafness
- degenerative, age related
- occurs when the hair cells “wear out”
- partical hearing loss
Vestibular apparatus function
- equilibrium and coordination of head with movements of the eye and postural movements
Semicircular canals
- detect rotation or angular acceleration/deacceleration of the head
Otolith organs
Utrical and saccual
- provide information about the position of the head relative to gravity (static) and changes in the rate of linear motion
- movement of kinocilium and stereocilia results in changes in hair cell potential
- tiny calcium carbonate crystals
- gelatinous
Receptors for taste and smell
Chemoreceptors
salty
Na –> depolarizes cells
sour
H
shut down k channels because H blocks channels
accelerate na entery
bitter
- Kaloids
G protein, gustducin + second messenger
Example: caffiene
umami
Glutamate (MSG); high fatty acids
meaty or savory taste
- popular is asian dishes
cranial nerves involved in taste
CN7
CN9
CN10
CN11
CN12 –> muscles
olfactory pathway
- olfactory buld (uses g protein: golf and second messenger: cAMP)
- glomenuli
- mitral cells
- goes to cortex or lymbic system (emotional connection)
vomeronnasal organ
- detects pharamones
- travels to the lymbic system
3 types of olfactory cells
- oldfactory receptor cells
- supporting cells
- basal cells
olfactory receptor cells
- affrent neurons
- axons for the olfactory nerve
- contains cilia which contains the binging cells for odorants
supporting cells
secrete mucous
basal cells
- precoursors for olfactory receptor cells
- replaced every 2 months
effrent division
CNS –> receptors
- prensent in the grey mattter of the spinal cord and medulla oblongota
- uses only epinephrine/norepinephrine and acetylcholine
autonomic division
- sympathetic
- parasymapthetic
sympathetic
- flight or flight response
- provides thoracolmbar branch
sympathetic preganglionic neurons
- paravertebral position
- short
- secretes ACh in ganglion
acetylcholine receptors
- cholinergic nictinic
- cholinergic muscranic
sympathetic postganglionic neurons
- long
- secretes: norepinephrine/ epinephrine
norepinephrine and epinephrine receptors
adrengic receptors
types of adregenic receptors
- alpha
(1,2) - beta
(1,2,3)
Alpha 1 receptors
(NE>E)
- most tissues
- uses calcium second messenger
Example: salivary glands, in males ejaculation/ in females ciltoral excitation, urinary bladder
Alpha 2 receptors
(NE>E)
- uses cAMP as second messsenger
- inhibitory effect
Example: smooth musscles of the GI tract (relax), decreases insulin
beta 1 receptors
(NE=E)
- excitatory
Example: increases heart rate
beta 2 receptors
(E>NE)
- uses cAMP second messenger
- inhibitory
Example: flattening of lens (far vision), smooth muscles of the respitory tract, blood vessles, liver
Beta 3
(NE>E)
- uses cAMP second messenger
- excitatory response
Example: adipose tissue (brown fat)
parasympathic division
- rest and digest
- provides: craniosacral branch
parasympathic preganglionic neurons
- long
- futher from organ/ on or near target
- secretes ACh
parasympathic postganglionic neurons
- short
- secretes ACh –> cholingic muscranic
polio
- caused by a virus
- fecal- oral root of entry
- dirty food / water
Symptoms: motor neuron, destroys cells body, cells dealth, paralysis - effects war torn countries
Treatment: vaccines
Amyotropic lateral sclerosis (ALS) / Lou-Gehrig’s disease
- mitochondrial disease (less energy)
- abdominal accumulation of neurofiliament
- axonal transport reduced
- glutamate
- no cure
Somatic
- sketletal muscles
- forms neuromuscular junction
0 myelinated potential
nuromuscular junction is
vunerable
black widow spider venom effect on the neurmuscular junction
- causes explosive relase of ACh which continually depolarizes the neuromuscular junction
Botulism toxin effect on the neurmuscular junction
- produces by chostridum botulinum (bacteria)
- blocks the release of ACh
- results isn paralysis ( no muscle tone)
Curare effect on the neuromuscular junction
- block action of ACh at receptor sites
- used on arrow heads for aminal paralysis
organophosphates effect on the neuromuscular junction
- prevents inactivation of ACh
- nerve gases
myasthenia gravis effect on the neuromuscular junction
- inactivates ACh receptors sites
- autoimune diesease
- dropping fo eyelids, difficulty chewing, and difficulty walking
acetylcholinesterase
- after action potential
- removes ACh by breaking it down into choline (used) and acetic acid (waste)
