Sensation

Question 1

What is sensation?

Answer 1

Our senses translate physical energy into something we can use
They gather information from the outside world and produce an internal state

Question 2

CONVERSION- name the four stages

Answer 2

1- accessory structures (modify physical stimuli)

2-transduction (energy picked up by receptors and converted into neural energy)

3-sensory nerves send transduced neural energy to the brain (thalamus and then to different parts of the Cortex)

4-sensation-message-brain (sensation is produced when the message reaches the brain)

Question 3

Measurement and threshold

noise
What is it called when cells randomly do or don’t fire?
What do they increase or decrease?

Answer 3

1-exhibition(random firing)
Inhibition (do not fire)
2-random exhibition/firing that either increases or decreases the sensed intensity of a stimulus

Question 4

Implications of random exhibition or inhibition?

Answer 4

1- lack of consistency (repeated presentations of the same physcial level of intensity do not always produce the same internal sensation)
2-if a signal is doubled it doesnt always produce a doubling of sensation
3-absolute threshold-physical intensity at which a person can detect the stimulus 50% of the time

Question 5

Who proposed the difference threshold?
what is it?
what is fraction?

Answer 5

1-Weber law
2-smallest amount of change in a stimuli before change is detected
3-threshold increases in proportion to the standard (change in intensity/intensity of standard)

Question 6

Hearing:
what is frequency?
amplitude?
complexity?

Answer 6

1- pitch (hertz) humans 20-2000hz
dogs-8000hz
2- volume (decibels)
3- nature of sound

Question 7

Inside ear:
1 what does every sound begin as?
2 when the tuning fork vibrates, what happens?
3: what happens when the sound reaches the listener?
4 where does the outer ear funnel changes to?

Answer 7

1) every sound begins as a vibration
2) when the fork vibrates it causes the air to expand and a series of pressure waves move away from the tuning fork
3) it enters the outer ear, which consists of external ear and auditory canal
4) Outer ear funnels changes to middle ear

Question 8

what does the stirrup vibrate against?

Answer 8

it vibrates against the oval window
> pressure changes cause the ear drum to vibrate, in turn 3 bones(attached to small membrane) in middle vibrate
(Hammer, anvil and stirrup)

Question 9

What does the oval window seperate?

Answer 9

Seperates middle and inner ear

Question 10

Cochlea:
What is its structure?
what is it attached to?
what is the membrane lined with?
what happens when the cochlea vibrates?

Answer 10

1) fluid filled tube thats coiled
2) its attached to the auditory nerve
3) lined with hair like receptors called cilia
4) when the oval window vibrates it causes the fluid in the cochlea to move in waves and causes the cilia to move. Neurons then fire>auditory nerve>interpreted as sound

Question 11

Hearing pitch:
whats the theory called?
Depending on the pitch what happens to the basilar membrane?
is there any support?
problem?

Answer 11

1- place theory
2- vibrates more
3- basilar membrane vibrates more depending on pitch (apex near oval window)
4-comes from artifically stimulating particular areas of the membrane> produces different sensations
eldery who cant hear pitch have damage to the membrane
5-below 10,000hz no specific place vibrates more than another

Question 12

Frequency theory:
The higher the frequency, the faster?
problem?
frequency and volley theory:

Answer 12

1-faster the vibrations
2-rate that hair cells are stimulated not which hair cells
3- above 10,000hz cells cannot fire any faster-refraction period
4: alternation of firing of hair cells sending a frequency of signal to the brain

Question 13

Vision:
what is light part of?
what is light measured in?
how big is the sprecturm?

Answer 13

1) light is part of the electromagnetic sprectrum
2) almost wave like-measured in nanometers
1nm-1 billionth
3-400-780nm
light encounters cornea first and pupil varies in size

Question 14

Photo-receptors:
what do they contain?
what do photopigments break down into?
primary colours?

Answer 14

1) photo pigment
2) rods: dim light, no colour info, fovea, RHODOPSIN
cones: bright light, IODOPSIN
3) primary colours- can produce any colour of the specturm
red, blue and yellow>subtractive
red, blue and green> addictive

Question 15

Trichromatic theory:
how can colours of the sprecturm be made?
primary colours–>pigments

Answer 15

1) Can be made of either a unique wavelength of light or combination
2) pigments: subtractive:dark grey
light: addictive:white

coincide with three types of cones on the retina:
short wavelengths:blue
med>green
long>red
colour mixtures will cause more than one type of iodopsin to be bleached

Question 16

support for trichromatic theory:

Answer 16

dichromatic blindness: only two types of iodopsin either blue or green
need red and green to distinguish red from green> cant make this distinction. However they can see yellow

monochromatic blindness:one type of iodopsin
monochrome
no colour variation

Question 17

Photoreceptors to sensation:

Answer 17

cones and rods- conveyed to ganglion cells via biopolar cells-optic nerve-brain

Question 18

Touch tactile sense:
how many receptors?
name the receptors?

Answer 18

1) 3
2) temp, pressure and pain
temp: relative
pressure: relative, changes are felt but get used to it
pain: pathways with neurotransmitters, endorphines and acupuncture

Question 19

smell
name the chemical secreted in the body which produce physiological responses?

olfaction?

Answer 19

1) pheromones>androstenone

olfaction: high adaption, ability to detect odour drops to about 30%
8% lose sense of smell and lose interest in sex

Question 20

taste:

what are the sensors?

Answer 20

1: taste bud

bitter, salty, sweet and sour