The Brain and Special Senses Flashcards
What are the 5 special senses?
Vision Hearing Taste Smell Balance
Where are receptors located for the special senses?
Within special sense organs.
What are the general senses?
Temperature Pain Vibration Touch Pressure Proprioception (body position)
Info relayed from the CNS is sent to the what sensory fibres?
Afferent
Paired olfactory organs are located where?
Nasal cavity (either side of septum). Inferior to cribriform plate of ethmoid bone.
What components make up the olfactory organs?
- Epithelium
- Supporting cells
- Receptor cells
- Glands (secrete mucus)
- Cilia
Describe the smelling mechanism.
- Air swirls within nasal cavity.
- Reaches olfactory organs, lipid/water-soluble chemicals dissolve, diffuse into mucus and stimulate receptors.
- Dissolved chemicals interact with receptors (odorant binding proteins) on cilia surface.
- Binding of odorants changes permeability of receptor membrane -> AP.
- AP relayed to olfactory bulb via axons penetrating cribriform plate.
- Info to CNS, smell interpreted.
Axons leaving the olfactory bulb travel to which parts of the brain?
Olfactory cortex of cerebrum
Hypothalamus
Limbic system
The olfactory cortex is located within which lobe?
Temporal
Where are the gustatory receptors found?
Superior surface of tongue
Pharynx
Larynx
Why are gustatory receptors not found on surface of tongue?
To protect them from mechanical damage, chewing and extreme tastes.
What are the three types of papillae? Rank them from smallest to largest, stating the number of buds.
- Filiform (no buds)
- Fungiform (5 buds)
- Circumvallate (100 buds)
What components make up a taste bud?
- Sensory receptors (gustatory cells)
- Supporting cells
- Microvilli that project into fluids through taste pores.
What are the 5 taste sensations?
- Sweet
- Sour
- Salty
- Umami
- Bitterness
Where are the receptors located that relay info on hydration status?
Pharynx
Describe the taste mechanism.
- Chemicals dissolved by saliva, move down taste pores.
- Chemicals meet microvilli (which extend from receptor cells).
- Stimulates change in membrane potential of receptor -> AP in sensory neurone.
- AP sent to CNS by one of three cranial nerves.
What three cranial nerves send an AP to the CNS in gustation?
Facial (VII)
Glossopharyngeal (IX)
Vagus (X)
The gustatory cortex is located in what lobe?
Temporal
Light is refracted at what parts of the eye?
Cornea and lens.
Define refraction.
The alteration of light when it travels from medium to another.