chapter 17: hearing, smell, taste pt 2

pathway of nerve impulse

1. Cochlear branch of vestibulocochlear nerve VIII

2. medulla

3. midbrain

4. thalamus

5. primary auditory area in temporal lobe

hearing in bony labyrinth by:

cochlea

hearing in membraneous labyrinth by:

Cochlear duct

hearing for hair cells and support structure:

organ of Corti that sits on basilar membrane

with hearing hairs embedded in:

Tectoral membrane

Static Equilibrium with bony labyrinth:

vestibule

Dynamic equilibrium with bony labyrinth and membraneous labyrinth:

semi circular ducts

Static equilibrium with hair cells and support structure

Macula

Dynamic equilibrium with hair cells and support structure:

cristae ampullaris

static equlibrium with membraneous labyrinth

saccule and utricle

Static equilibrium with hairs embedded in

the Olith membrane

Dynamic equilibrium with hairs embedded in:

cupla

how are sounds distinguished?

to determine pitch which is the variation of frequency

each section of basilar membrane where organ of corti is

its tuned for a specific pitch

high frequency sounds

displace the basilar membrane near the base

medium frequency sounds

displace the basilar membrane near the middle

low frequency sounds displace the basilar membrane near the apex

apex

long, floppy fibers

what are the two types of equilibrium?

1. Static Equilibrium

2. Dynamic equilibrium

Static equilibrium

refers to control of the position of the head with respect with respect to gravity and linear acceleration

hairs are embedded in otolith membrane

head tilts and otoliths move, gel bends hairs

generates nerve impulses

saccule and utricle contain a region of hair cells

Macula

in utricle

macula is horizontal

in saccule

macula is vertical

Dynamic Equilibrium

refers to control of the position of the head during rotational movements

hairs cells and supporting cells are found in the ampulla

hairs are embedded into capula

vestibular nuclei

major integrative center for balance

cerebellum

coordinates muscle activity to maintain your posture , balance and head position

with smell, when olfactory hairs on the dendrities respond to chemical stimulus via a receptor protein by:

1. olfactory hairs, they extend from dendrite of olfactory receptor and are embedded in mucus layer

2. mucus dissolves odor molecules in incoming air

3. dissolved odor binds to a recptor protein

4. opens up Na+ channels leading to a generation of an action potential

which sensation is the only one that reaches the cerebral cortext WITHOUT a synapse in the thalamus?

Sense of smell

Olfactory adaptation

occurs rapidly

only smell scents a short time and then no longer smell odor even though it is still there because ion channels close after a few minutes

olfactory receptors have a lifespan of:

about 60 days and are replaced by mitosis of basal cells

receptors in Gustation:

are found in taste buds located on the tongue

taste receptors are modified epithelial cells

what are the 5 basic taste sensations?

1. sweet

2. sour

3. salty

4. bitter

5. umami

sweet detects

sugars

sour detects

H+

salty detects

Na+

bitter detects

basic pH like baking soda

umami detects

amino acids

one taste receptor detects

only one taste

each taste bud

can detect all taste

taste cells are replaced every:

10 days by mitosis of basal cells

how does taste information travel

1. facial nerve

2. glossopharyngeal

3. vagus

4. to medulla

5. to thalamus

where is the primary taste cortex located?

in the 5th cerebral lobe known as the Insula