ELM15: Sensory systems 2 Flashcards
What is the basic structure of the olfactory system in mammals?
- Neurons have ends that project to glomeruli in olfactory bulb
- Go to mitral cells
- Go to olfactory centres
What is basic structure of olfactory system in insects|?
- Olfactory neurons have ends that project to glomeruli in antennal lobe
- Go to projection neurons
- Information goes to mushroom body and lateral horn
What is the structure of the human olfactory system
Olfactory epithelium at top of nose with olfactory receptor neurons
Neurons have cilia with receptors
Each receptor activated by a different odorant
What is the lay out of the olfactory receptor neurons and the glomerulus in humans?
Neurons converge into one glomerulus
What type of receptor are human olfactory receptors?
GPCRs
What is the process of olfactory receptors becoming activated?
- Odorant binds
- Alpha subunit on G protein swaps GDP for GTP
- Adenylate cyclase activated
- Breaks down ATP to cAMP
- cAMP released
- Cyclic nucleotide gated channels open
- Influx of calcium and sodium onto olfactory receptor neuron
- Depolarisation and AP firing
What is the combinatorial code of odorants?
Each odorant binds to several receptors and activates many neurons
Each neuron is activated by many odorants
What are the 5 basic tastes?
Bitter sweet umami salty sour
Where are taste receptors?
On the end of taste buds on the tongue
How do taste receptors pass on information?
Are stimulated and release neurotransmitters
Stimulates gustatory nerves
What are the three different types of structures containing taste receptors?
Circumvallate
Foliate
Fungiform
What are the three different types of taste receptor molecular structure?
GPCRs
TRP
Epithelial Na channel
What are pheromones?
Non volatile chemical cues in environment
Stimulate the vomeronasal organ in nasal cavity
What is the normal human hearing range?
20-20000 Hz
How do we hear lower frequency waves?
Low pitch
How do we hear low intensity?
Quieter
What makes up the auditory system?
External middle and inner ear
What makes up the vestibular system?
Semicircular canals
Otolith organs
What is the structure of the cochlea?
Spiral
Fluid filled
How does the cochlea help us hear?
- Fluid in cochlea is activated and transmits motor information
- Moving fluid moves basilar membrane
- Basilar membrane moves relative position of hair cells
- Sound converted into electrical signal
How does potassium enter hair cells?
Stereocillium arranged like a staircase connected by tip links
Movement pulls open potassium ion channels
What does opening of potassium ion channels do to hair cells (Mechanotransduction)
- Potassium enters
- Depolarisation
- Calcium enters and glutamate released
- Information transduced into signal
- Glutamate activates terminals on spiral ganglia neurons
How do we know what direction a sound is coming from?
Compare how long it takes for a sound to each each ear
What is the function of the vestibular system?
Detect balance and movement
What do the utricle and saccule do in the vestibular system?
Detect head acceleration and position
What do the semicircular canals do in the vestibular system?
Detect head rotation and balance
How is steady pressure detected?
Merkel cells
Ruffini endings
How is vibration detected?
Meissners
Pacinian corpuscles
