Special senses Flashcards
What is taste also called?
Smell?
Gustation
olfaction
The receptors for olfaction and gustation are called what?
chemoreceptors
What must occur to both odorants and tastants to be detected?
Odorants - dissolved in mucus
tastants - dissolved in saliva
Where are the taste buds located?
What do they contain?
Mucosa of mouth and pharynx
most on surface of tongue
contain taste receptor cells and basal cells
What is the mucosa of the mouth and pharynx?
stratified squamous, non-keratinized
Other than cells, what else do tastes buds have?
long microvilli called gustatory hairs
- bathed in saliva and contain dissolved molecules that stimulate taste
Cells in the taste buds are ______ replaced every _ - _ days.
constantly
7-10
How can gustatory hairs be activated?
Molecules in food need to be dissolved in saliva.
What do basal cells do?
Divide to replace worn out gustatory cells.
How many salivary glands do we have?
What do they make?
3
saliva and mucus
What are the five basic qualities of taste?
Bitter, sweet, salty, sour, umami
What is umami elicited by?
glutamate
Why is the taste map a myth?
All tasted modalities can be elicited from all areas containing taste buds.
Chemicals that stimulate gustatory receptors are called ______.
tastants
Describe the gustatory pathway.
Tastants dissolved in saliva
make contact with gustatory hairs which stimulate sensory neurons
Impulses reach thalamus which relays it to gustatory area in the insula - conscious perception of taste; and also to the limbic system - emotional response
Olfaction:
Olfactory receptors are part of the _______ epithelium on the _____ of the nasal cavity
olfactory
roof
What does sniffing do?
draws in more air and intensifies sense of smell
What is the epithelium of the nasal mucosa?
What cells does it contain?
Pseudostratified ciliated columnar epithelium 1 - Olfactory receptors cells 2 - supporting epithelial cells 3 - Basal epithelial cells 4 - Olfactory glands
What do supporting epithelial cells do?
provide support and nourishment
What do basal epithelial cells do?
can form new receptors monthly
What do olfactory glands do?
secrete mucus
How is the function of basal epithelial cells unique to the body?
Regenerates neurons
What is a difference between the receptors of gustation and olfaction?
Receptor in olfaction are actual neurons
receptor in gustation are simple squamous epithelial cells
Olfactory sensory receptors:
- cell bodies located in _______ epithelium
- have an apical ______ that projects to the epithelial surface
- ends in a knob from which olfactory ____ radiate
- –olfactory ____ act as receptive structures for smell by binding to ______
- -Epithelium also covered with _____ which captures and dissolves odour molecules
olfactory - apical - dendrite - ends in knob - olfactory cilia radiate from here cilia mucus
Describe the olfactory pathway.
odorant dissolved in mucus
- binds to and activates olfactory cilia
– axons of olfactory receptors gather in bundles to form the olfactory nerve
— olfactory nerve passes through the ethmoid bone, enters the olfactory bulb and synapses with mitral cells
—- mitral cells transmit impulses along the olfactory tract to:
1 - limbic system - emotion
2 - piriform lobe/olfactory cortex - conscious perception of odour
The olfactory neuron is ______.
bipolar
What is anosmia?
absence of sense of smell
- can be due to injury, zinc deficiency, colds/allergies and polyps
