W7 Sensory Systems and Chemical Sense

Question 1

What are the 3 common Steps in coversation of sensory processing across systems

Answer 1

1- Requires a physical stimulus.
2- Must transform the stimulus into nerve impulse = sensory receptors in the peripheral nervous system.
3- Evoke a response to the signal in the form of perception of sensation = Central Nervous System.

Question 2

Sensory Receptors

Answer 2

Cells not just proteins.
Engery from the environment =[sensory transduction]=> Electrochemical signls in sensory receptors (graded and action potentials)

Question 3

Sensory receptros proteins

Answer 3

Many sensory receptor cells prossess ion channels and G-protein coupled receptors that are common to many bodily functions

Question 4

Proprioception

Answer 4

Detect if you are contracting or not your muscle.

Question 5

5 Traditional Senses

Answer 5

Hearing
Vision
Small
Balance
Taste

Question 6

Hearing

Answer 6

Mehanical stimulus, Mechanoreceptor. Located in the inner ear, cochlea

Question 7

Balance

Answer 7

Mechanical stimulus, Mechanoreceptor. Located in the inner ear.

Question 8

Vision

Answer 8

Light Stimulus. Photoreceptors. Located in Retina.

Question 9

Touch

Answer 9

Mechanical Stimulus. Mechanoreceptor. Located in Skin.

Question 10

Temperature

Answer 10

Thermal Stimulus. Thermoreceptor. Located: Skin

Question 11

Pain

Answer 11

Mechanical thermal, checimal stimulus. Nociceptor. Located: skin, internal organs

Question 12

Proprioception

Answer 12

Mehanical Stimulus. Mechanoreceptor. Located in Muscle tendons, jionts.

Question 13

Olfaction

Answer 13

Chemical Stimulus, Chemoreceptor, Nassal vaity (location)

Question 14

Tsate

Answer 14

Chemical Stimulus. Chemoreceptor. Located: tongue, pharynx, palate epiglottitis.

Question 15

What happens with senses?

Answer 15

Stimulus => Sensory receptor is activitated => Membrane permeability is altered in the sensory cell => receptor potential develops in the sensory cell = [neurotransmitter released onto afferent neuron terminal]=> action potential is generatedin afferent neuron terminal => propagates to CNS => information intergrated by CNS.

Question 16

Graded Receptors potential

Answer 16

Increase in size in response to increases in stimulus amplitude.

Question 17

Action potentials Receptors

Answer 17

are always the same size but have threshold for activation

Question 18

Olactory receptors (direct neuronal activation)

Answer 18

Large enough receptor potentials cause depolarisation in cell soma, trigger action potential to travel down to olfactory blub. Ion influx causes membrane depolaraisation and graded receptor potential develops in a cilium.

Question 19

Synapse and Receptors: Taste

Answer 19

Ion influc causes membrane depolarisation and graded recepor potential develops. Initates synaptic vesicle fusion wiht membrane and neurotransmitter release. Neurotransmitter binds to postsynaptic receptors, generating an EPSP in dendrite of the afferent neuron. Large enough EPSP generate action potentials.

Question 20

Sensory receptors can convery what 4 types of information

Answer 20

Modality, location, intensity, timing

Question 21

Stimulus modality is coded by what?

Answer 21

Labelled line code. Receptor is selective for one type of stimulus energy.

Axons of the receptor/associated afferent neuron acts as a modality specific line of communication.

Question 22

Labbeled line code is what ?

Answer 22

Faulty in syneasthesia. Research in 2018 found genes that are likely to be responsible
‘the name Kate taste like chocolate’

Question 23

Stimulus location - receptors

Answer 23

Spatial arrangement of activated receptors within a sense organ gives information about the stimulus.

Determined by the stimulus energy and anatomy of the sneory organ/receptor

Somatic system: receptive field is region of skin innervated by the terminals of the receptor neuron.

Visual system: receptive field of photoreceptor is the region of the visual field prokected onto that receptor.

Question 24

Stimulus intensity - receptors

Answer 24

Intensity is the total amount of stimulus energy deliered to the receptor.

Determined by stimulus amplitude adn neuronal firing rate.

The Lowest stimulus strenght that can be determined by the response amplitude of the receptor and thus the firing frequency of the afferent neuron.

Question 25

Stimulus timing - receptors

Answer 25

Onset timing is determined by when the stimulus energy is received by the receptor and caused it to fire.

Question 26

Stimulus duration - receptors

Answer 26

detemined by adaptation rates of receptors. Adaptation in response to continuous stimuli, the firing rate of action potentials derease.

Question 27

Tonic Receptors

Answer 27

Slowly adapting receptors, respond to prolonged stimulation.

Question 28

Phasic receptors

Answer 28

Rapidly adapting receptors. Respond at the beginning an dend of a stimulus.

Question 29

Chemical sense

Answer 29

Developed into a more complex system in other animals than in humans.

Question 30

Functions of Chemical Senses

Answer 30

Identify food sources. Avoid noxious substances. Find a mate or mark terrotories.

Question 31

Multiple processes to identify things - chemical sense

Answer 31

Gustarory system (taste) and Olfactory system (small) processed in parallele and then they merg after primary processing, they merge in associatio cortex (CNS)

Question 32

5 Basic tastes

Answer 32

Salty, Sour, Sweet, Bitter, Umami (savory)

Question 33

Salty

Answer 33

Relates to Vital electrolytes. Preference: High salt content. Relevance: Required for many physiological processes

Question 34

Sour

Answer 34

Relates to acidity -H+ Preference: Avoid high Relevance: avoiding rotting food, injury to GI tract.

Question 35

Sweet

Answer 35

Relates to Sugars Preference: High sugar content Relevance: Requried for energy, growth.

Question 36

Bitter

Answer 36

Relates to diverse chemical strucutres. Preference: avoid bitter content Relevance: Avoid toxic substance, poisonous.

Question 37

Umami (savory)

Answer 37

Relates to alino acids (glutamate). Preference: High amino acid preference. Relevance: Protein synthesis, nerotransmission

Question 38

How do we perceive all of the flavors of food?

Answer 38

Different combination of chemical differnt, textures, smells, temperatures

Question 39

Taste organs

Answer 39

Primarily tongue, cheeks, soft palate, pharunx, epiglottis. Lingual papillae (part of the tongue) contain taste buds which are groups of taste cells. 2000-5000 Taste buds ~100 chemoreceptive tast cells per taste bud. Taste pore allows sensory transduction by microvilli.

Question 40

Taste cell vs Tast bud

Answer 40

Taste cellls only respond to one type of stimulus. Taste buds contain taste cells which respond to various stimulus.

Question 41

Olfactory system

Answer 41

Odorants as low as a few parts per trillion can be detected. Human olfactory epithelium = 10 cm2. Dog olfactory epithelium = 170 cm2. Dogs have 100x more receptors/cm2

Question 42

What type of neurons ar'e olfactory receptor cells?

Answer 42

Bipolar chemoreceptive neurons. Odorants must dissolve in the mucus layer to reach olfactory recepotr cells. Transduction machinery is found within the cilia at the end of the dendrite. The primary afferent neuron is the axon (thin, unmyelinated) of the cell. Oflactory receptor cells are regularly replaced.

Question 43

Odorant receprot protiens (ORs)

Answer 43

Humans have ~350 odorant receptor proteins. Olfactory receptor cells only express one odorant receptor. One odorant receptor can recognise multiple odorants. It is the unique combination of odorant receptors that recognise an odorant that allows us to distinguish a specific odor.

Question 44

Traduction occurs via G[olfs]

Answer 44

G-protein coupled receptors. Every Odorant receprot use the same downstream pathway. Adenylyl cyclase cAMP Cyclic nucleotide gated ion channels Depolarizatio Ca2+-gated Cl- channels Further depolarization

Question 45

Receptor potnetial strigger action potentials

Answer 45

Large enoughreceptro potential: threshold for action potential firing reached. Intense stimulus = large receptor potential = inreased action potential firing rate.