Download Outcome 1 Week 3 notes Taste

Unit 2 Psychology
Area of Study 1: What influences a person’s perception of
the world?
Sensation and perception
Key knowledge: Dot point 2
“Taste and vision as two examples of human sensory systems, including the roles of sensory
receptors and receptive fields, transmission of sensory information to the brain, and
representation of sensory information in the cerebral cortex.”
TASTE
Taste: the sensory experience of food or drink that is put into the mouth and perceived as
flavour.
Taste is also referred to as gustation.
There are five primary tastes: sweet, sour, bitter, salty and umami (savoury).
Umami was recently added to the list of tastes. The word umami is Japanese for “delicious
savoury taste.”
Umami is produced by glutamate and several amino acids associated with meats and high
protein foods.
Taste has evolved as a survival mechanism. It assists us in distinguishing between foods that
are helpful and harmful. Many poisons taste bitter or sour (tastes that we generally reject).
Sweet and savoury/salty foods are pleasing to the palate and eating these allow us to meet
our nutritional requirements.
The cells on the surface of the tongue are specialised to respond to the primary tastes,
however, other factors such as smell, texture, appearance and temperature also factor into
our taste experience.
Taste sensation and perception
The sensory receptorcells for taste are called gustatory receptors and are located in the
taste buds.
Taste buds: tiny structures located on the tongue’s surface.
1
Taste buds are the tiny bumps (papillae) that cover the surface of the tongue. There are
approximately 10,000 taste buds on the tongue.
Taste buds have a lifespan of about 10 days and are constantly being replaced due to factors
such as heat, infection and toxins that damage and destroy them.
Taste buds contain receptor cells known gustatory receptors.
Gustatory cells: the receptor cells for taste located on the surface of taste buds.
There are approximately 100 gustatory receptors per taste bud. Each gustatory receptor has
a gustatory hair that reaches the outside environment through an opening called a taste
pore.
When food or drink are consumed, the soluble chemical molecules are dissolved by saliva
and come into contact with the taste buds.
The chemical molecules enter the taste pores on the taste buds and are absorbed by the
gustatory receptor cells.
Taste sensation is detected when the chemical molecules dissolved by saliva come into
contact with the taste buds.
TASTE PERCEPTION PROCESS
1. Reception: the soluble chemical molecules in food and drink are dissolved by saliva
and are absorbed by the taste buds.
2. Transduction: gustatory receptor cells convert the chemical stimuli into
electrochemical energy that can be sent to and interpreted by the brain.
3. Transmission: Neural impulses (electrochemical energy) travel from the taste buds
to the medulla in the brain stem via the cranial nerves. The medulla relays the taste
information to the Thalamus, which sends the information to the Primary Gustatory
Cortex.
4. Selection: two areas of the Primary Gustatory Cortex, the anterior insula and the
frontal operculum filter and analyse the taste stimuli (type of taste and intensity of
the sensation).
5. Organisation: taste information is transmitted from the Primary Gustatory Cortex to
the limbic system (hippocampus, hypothalamus and amygdala) that allow us to
organise and begin interpreting the taste. Memories (hippocampus) and emotions
(amygdala) are an important component of taste perception.
6. Interpretation: The Somatosensory Cortex, as well as the other brain areas
mentioned all work together to form an understanding of the taste, such as the type
of taste and whether it is weak or strong.
2
TASTE SENSITIVITY
Taste sensitivity: the intensity with which we perceive the sensation of a taste and flavours.
People with a high sensitivity are able to distinguish flavours mixed together. People with
low sensitivity, tastes are not as strong and find it difficult to distinguish individual flavours.
Absolute threshold: the minimum amount of stimulus energy an individual requires to be
conscious of a sensation.
The number of taste buds a person has will influence the absolute threshold.
*Student Activity Manual:
- Activity 8.6 (pages 191-192)
- Activity 8.7 Part A (page 193)
3