lab exam 3 Flashcards
visual signal transduction (light)
- absorption of light by rhodopsin triggers a change in retinal (from 11-cis to all-trans)
- change in retinal produces a series of reactions that close the sodium channels in rod
- calcium channels in synaptic cleft close
- no neurotransmitter released
- bipolar cell remains depolarised
- neurotransmitter released at synaptic cleft of bipolar cell
- ganglion cell depolarised
- action potential along optic nerve
Rods
- Most numerous
- Operate in dim light
- Do not discriminate color
- Many rods feed single ganglion cell (fuzzy and indistinct images)
- Rod-shaped
Cones
- Less numerous
- Operate in bright light
- Discriminate colors (red, green, blue)
- One cone feeds one ganglion cell (detailed and high resolution vision)
- Cone-shaped
Process of light being absorbed and transferring into a neural signal
- In the dark, all-trans retinal converts back to its 11-cis form
- Sodium moves into rods through ligand-gated calcium channels
- Calcium moves into rod through voltage-gated calcium channels
- Influx of calcium causes the release of neurotransmitter
- Binding of neurotransmitter to bipolar cell causes hyperpolarization
- No neurotransmitter released at synaptic cleft of bipolar cell
- No depolarization of ganglion cell
- No action potential along optic nerve
trace pathway of light from eye to retina
- through the cornea
- through our anterior chamber
- light goes through the pupil
- light passes through the lens
- moves through posterior cavity
- comes down to the retina
3 chambers of cochlea
- scala vestibuli
- scala tympani
- scala media
Structures of ear and brief functions
Pinna - protections, directs sound waves into ear
External auditory canal - produce earwax, transmission of soundwaves
Tympanic membrane - transfers and amplifies sound waves for ossicles
Ossicles (malleus, incus, stapes) - transmit vibrations from tympanic membrane to oval window
Oval window - vibrations at oval window causes movement of fluid in cochlea
Round window - allows fluid in the cochlea to move
Semicircular canals - house equilibrium receptors
Vestivule - house equilibrium receptors
Cochlea - houses organ of corti, receptor for hearing
Pathway of vibrations through the ear
- soundwaves directed into pinna
- through external acoustic meatus
- hits the tympanic membrane
- passes vibrations onto ossicles
- vibration of stapes passes on to oval window
- oval window causes movement of fluid within canals of cochlea
Static Equilibrium
Occurs when the body is motionless or moving in a straight line i.e., jumping up and down or driving on a straight road in a car
receptors for static equilibrium located in vesitbule (utricle and saccule)
Macula of utricle detect linear movement in the horizontal plane
Macula of saccule detects linear movement in the vertical plane
Dynamic equilibrium
Occurs when the body is moving in a rotational or angular direction i.e., spinning around in a circle or swinging on a swing
receptor for dynamic equilibrium located in the semicircular canals
Crista located in each of the three semicircular canals detect rotation in the three planes (transverse, sagittal and coronal)
Tastebuds or Gustatory cells
Microvilli or gustatory hairs that project taste pore
Found on tongue and soft palate
Basal cells replace old tastebuds
Structures of the olfactory system
Olfactory mucosa
- located on roof of nasal cavity
- made up of lamina propria and olfactory epithelium
Lamina propria
-contains glands which secrete mucus
Olfactory epithelium
- made up of olfactory receptors, supporting cells and basal cells
structures of nose and functions
Olfactory receptor cells - receptors for smell
Basal cells - differentiate to replaced old olfactory receptor cells
Supporting cells - provide physical support, nourishment and electrical insulation
Mucus - protects olfactory receptor cells which contain binding site for odourants
Olfactory transduction process
- odourant must be in a gaseous state and dissolved in mucus
- Odourant binds to cilia on olfactory receptor (sits within mucus)
- Binding of odourant causes g-protein mediated production of cAMP
- cAMP binds to ligand-gated sodium channels
- Sodium enters sensory neuron causing depolarisation
- Action potential generated along axon of olfactory nerve
differences between skeletal and smooth muscle contraction
skeletal is voluntary
smooth is involuntary
smooth muscles has row of varicosities
skeletal contraction occurs through binding of calcium to troponin
smooth contraction occurs through the binding of calcium to calmodulin