Lecture 4 - Sensation Flashcards
1
Q
What are the 5/ Debated 6 sense
A
- Sight
- Smell
- Touch
- Hearing
- Taste
- Proprioception - Internal, not external sense
- where our body is in space
- where our skeletal/ muscular systems are in relation to yourself
- invisible sense
IT’S ONLY BECAUSE OF OUR RECEPTORS THAT WE CAN !EXPERIENCE! PHYSICAL STIMULI
2
Q
Outline smell in humans •What is it •What is the sensory organ •Where are the receptor organs •Where is it processed
A
- As humans, our talents lie elsewhere, we are not very good at this
- we dont have many olfactory receptors
- and these transmit to a relatively small olfactory bulb
- Dogs olfactory bulb is 30 times as developed as humans - Sensory Organ is the Nasal Cavity
- Receptors are in the nostrils/ nasal cavity
- Specialised cells in this that pick up information from the air and transmit it via neurons - Processing is done by the olfactory bulb
- sits above the nose
3
Q
Outline what can go wrong with smell
A
You can become Anosmic - Cant smell very well
- rare, 1 in 100
e.g. cant distinguish the smells of:
•Chocolate, •Baby powder, •Cinammon etc
- if you are not good at this, you might be anosmic
4
Q
Outline taste in humans •What is it •What is the sensory organ •Where are the receptor organs •Where is it processed
A
- Taste includes: Sweet, Sour, Bitter, Salty, and debatably umami (marmite for instance)
- we are not great at this - Sensory organ is the mouth
- uses the nose a bit - Receptors
- most are in mouth/ tongue - Processed in two places:
A) Brain Stem - Checks if toxic
- if something is toxic, it makes sense to get rid of it very quickly. If we have food poisoning, go through brain stem to check, and if so it makes us involuntarily be sick
B) Primary Gustatory Cortex - Experience taste
- Brain stem is not a conscious nor experiential region of the brain, so to experience taste, you have to go to the primary gustatory cortex
- this is in the cortex - suggesting evolutionarily, it was a rather late development - not as important as checking if it was toxic or not
5
Q
Outline what can go wrong with taste
A
Can be Ageusiac - can’t taste very well
6
Q
Outline touch in humans •What is it •What is the sensory organ •Where are the receptor organs •Where is it processed
A
- We are much more concious of touch compared to other senses
- perhaps because there is a lot more cultural meaning behind it
- E.g. different words for different types of touch: Stroking, hit, corressing etc - we dont have this much discriminatory language for other sense
- might be more psychological than other sense, because it involves actions of a person (self/other) - Not one single sensory organ
- Receptor organs
- All over the body - Somatotropically distributed
•Babies have lots of receptors in their lips to increase chances of eating, but this ability sticks around, which is why we still have lots of receptors in lips when we are older. Lots in hands too.
- But there is a trade off between coverage and efficiency. The more coverage in one area, the less there is elsewhere, less coverage = less efficiency
- better at distinguishing touch on finger tips, compared to upper arm
- Receptors aren’t sensitive to chemicals like smell/ taste, but sensitive to pressure: which then gets translated into the standard chemical/ electrical pressure
7
Q
Outline Hearing in humans •What is it •What is the sensory organ •Where are the receptor organs •Where is it processed
A
- Hearing is important, as most of us rely on sound for language, communication interaction
- but your experience of sound is just pressure waves hitting your ears
- If a tree fell and no one was around, would it make a sound, no it would just make pressure waves
- System interprets physical stimuli into experience of sound - sound waves are just pulses of pressure
•As people get older, more variation in abilities, but general hearing is lower. Most at 20-24 can hear up to 1600 Khz - Sensory organ is the ears
- Receptors - quite mechanical
A) Pressure waves come in, push ear drum (timpani)
B) Drum vibrates - but very small, need to amplify vibrations
C) Hammer, Anvil & Stirrup amplify the vibrations - not massively as is still small. But big enough to distinguish variations in vibrations
D) Stirrup pushes on Oval Window
E) Then kind of stops being mechanical, and more chemical - Moves into Cochlea where hair cells convert it into an electrical signal
- Processing - Primary Auditory Cortex (Contralateral)
- Complicated process to get to this stage
8
Q
What are sound waves measured in?
A
Hz = hertz = cycles per second
- how quickly the waves come in
1khz = 1,000 cycles per second 1mHz = 1,000,000 Cycles per second
9
Q
Outline levels of hearing
A
At the highest level, we can’t experience the waves as sound, but a bat for instance hears stuff well above us
- Medial Ultrasound: 1-20 Million hz
- Bat Clicks: 25-80 thousand Hz
- Humans hear at: 1,200 Hz lol
- bats can hear this, but they live in a world completely beyond our fathom - Whales can hear deeper - so we are roughly in the middle of the range of animals above surface
10
Q
What is the cochlea?
A
The tube like organ in the inside of the ear - that transfers mechanical movement into chemical/ electrical signals
- it’s rolled up to increase surface area in small place
Inside of the cochlea is cochlea fluid, and on the walls of the cochlea, in the fluid are Specialised Hair cells
- Previously: Taste cells have been responsive to chemicals, and touch receptors responsive to pressure
- this time, the hair cells are responsive to movement - and turn it into neuronala ctivity
- Degree of fluid moving -> degree of hair cell bending -> degree of signal
11
Q
Outline the steps of processing sound
**
A
in the cortex
- Pressure waves coming in
- Cochlear
- Auditory nerve fiber
- Bilateral Cochlear Nucleus
- Superior Olivary nucleus
- Inferior colliculus
- Medial geniculate nucleus
- Auditory cortex (right or left)
12
Q
Outline sight in humans •What is it •What is the sensory organ •Where are the receptor organs •Where is it processed
A
- Sight is the queen of senses
= the process of turning photons/ light particles into vision
- But you don’t have to be fully sighted to function, harder but doable, with help can live normal life ass possible - Sensory Organ - eyes
- Receptor Cells = On the Retina - rods & cones
- Light goes through the iris, the lens and the vitreous body to hit the specialised receptors at the back of the eye
- One end of the cell takes the physical stimuli, and convers it into something that can travel down the pathways - i.e. chemical/ electrical
- the other end of the cell then transmits this signal/ excitation.
Step by step: 1. Light comes in, 2. Hits retina, 3. Goes to the back of the retina where there are rods & Cones, 4. moves back through bipolar cells, 5. Then back through ganglian cells, 6. then to optic nerve - Processing - visual pathways
- processing routes end in cortex as per usual
- you experience sight in the HINDBRAIN - Optic Nerve, 2. Optic Chasm, 3. Optic Tract, 4. Lateral Geniculate Nucleus, 5. Optic Radiation, 6. Primary visual cortex - one in each hemisphere of occipital lobe
13
Q
What are light waves
A
Light waves are electromagnetic pulses
- on the electromagnetic spectrum - most of which we cannot see.
- we can only see, experience and react to the Visible light section
- gamma rays for instance are the same physical substance, but we cannot see them. As well as radio waves but these are so far away from our abilities
IT’S ONLY BECAUSE OF OUR RECEPTORS THAT WE CAN !EXPERIENCE! PHYSICAL STIMULI
14
Q
Outline Rods & cones
A
Rods: work well in dim light
Cones: detect colours, function well in bright light
15
Q
Outline Cortical Blindness as something that can go wrong with vision
- what is it
A
- Discovered: 1990s in the first case
• You have no experience of vision whatsoever, no sight or vision at all
•Due to the pathways between eyes and cortex being lost - perhaps due to stroke - resulting in NO VISION IN EITHER LOBES
Because of occipital damage
