BIO PSYC - SENSORY SYSTEM

Question 1

What is the role of sensory systems?

Answer 1

• to perceive environmental stimuli through specialised mechanisms
• sensory systems consist of receptors in specialized cells and organs that perceive changes in the internal and external environment

-Law of specific nerve energy: Whatever excites a particular nerve establishes a special kind of energy unique to that nerve

Question 2

Explain sensory pathways?

Answer 2

• stimulus as a physical energy - sensory receptor acts as a transducer

Transducer = a system or device that converts one form of energy to another form of energy

stimulus> threshold - action potentials to CNS

Integration in CNS - Cerebral cortex or acted on subconsciously

Question 3

What is the typical sensory pathway?

Answer 3

Peripheral Nervous system
- stimulus picked up by receptors
- afferent neuron
CNS
- spinal cord or brainstem
- second order neuron
- thalamus
- third order neuron
- cortex

Question 4

Name the functions/ stimulus of each receptor:
Mechanoreceptors
Thermoreceptors
Photoreceptors
Chemoreceptors
Nociceptors
Osmoreceptors
Baroreceptors
Exteroceptors
Interoceptors
proprioreceptors

Answer 4

Mechanoreceptors - respond to touch, pressure, vibration, stretch and itch

Thermoreceptors - sensitive to changes in temperature

Photoreceptors - respond to light energy

Chemoreceptors - respond to chemicals

Nociceptors - sensitive to pain causing stimuli

Osmoreceptors - detect change sin concentration of solutes, osmatic activity

Baroreceptors - detect changes in fluid pressure

Exteroceptors - sensitive to stimuli arising from outside the body. located near the surface.

Interoceptors - recieve stimuli from internal viscera. monitor a variety of stimuli

proprioreceptors - monitor degree of stretch located in musculoskeletal organs

Question 5

What are the 3 types of receptor structure?

Answer 5

a) Simple receptors
- neurons with free nerve endings

b) complex neural receptors
- have nerve endings enclosed in connective tissue capsules

c) most special senses receptors
- cells that release neurotransmitter onto sensory neurons, initiating an action potential

Question 6

What is the purpose of the eye?

Answer 6

• Focus light to create an image on the retina

Question 7

Describe the visual pathway:

Answer 7

• input from left visual field is projected on the right hemiretina of each eye
• info from the right hemisphere-retina of each eye travels to the lateral geniculate nucleus of the thalamus on the right side.
• half of the optic fibres cross at the optic chiasm

Question 8

What are the pathways from eye to the brain?

Answer 8

Cortical route:
- retina - LGN - visual cortex

Subcortical routes
- retina - hypothalamus

• retina - superior colliculus

Question 9

What and where pathways in audition?

Answer 9

What pathway: sensitive to pattern of sound in the anterior temporal cortex

Where pathway: sensitive to sound location in the posterior temporal cortex and the parietal cortex

Question 10

Gustatory Pathway from Taste Buds:

Answer 10

Taste information reaches the cerebral cortex
Primarily through the facial (VII) and glossopharyngeal (IX) nerves
Some taste information through the vagus nerve (X)
Sensory neurons synapse in the medulla

Question 11

What is somatosensory?

Answer 11

Pain: experience evoked by harmful stimulus

From pain receptors impulses are carried out slowly

Pain axons release two neurotransmitters in the spinal cord
- glutamate and substance P

From medulla to cerebral cortex, both touch and pain are represented on the contralateral side