What is meant by sensory adaptation?
Sensory adaptation is when sensory receptor cells (afferent neutrons) are able to ignore maintained or repeated stimuli.
State some sensory receptor cells that demonstrate little sensory adaptation.
Pain receptors and the mechanoreceptors that control balance.
Think of a benefit of sensory adaptation
Allows your body to ignore unchanging stimuli (like clothes) that is usually unimportant and helps you react to new stimuli such as someone punching your arm.
Why should pain receptors not show large sensory adaptation?
Because pain receptors let you know what is wrong with something in your body. Such as that punch to the arm.
Action potentials arriving at the visual cortex of the brain will be interpreted as ______________
Action potentials that arrive at the olfactory bulb will be interpreted as ________________
What is a sensory system
A set of organs and tissues for detecting a stimulus
What is a sensory organ?
A sensory organ is one that converts a stimulus into an electrical signal
Name some common examples of sensory organs.
Ears 👂🏻, eyes 👀, nose 👃🏻
What is sensory transduction?
The transformation of environmental stimuli or information into neural signals
What are receptor proteins?
A protein that has the ability to open or close an ion channel in response to a particulate type of stimulus.
A change in membrane potential of a sensory receptor cell due to a particular stimulus is known as a ________ ________
Name all the types of sensory cell membrane receptor proteins. Hint: I MET Mr Cameron Pollock
Mechanoreceptor 🔧, electroreceptor⚡️, thermoreceptor🔥, chemoreceptor💊, photoreceptor ☀️.
Receptor potentials are graded membrane potentials or action potentials?
Graded membrane potentials
State one difference between action potentials (AP) and graded membrane potentials (GMP).
APs can travel long distances whereas GMPs travel short distances.
State two ways in which receptor potentials (graded membrane potentials) can generate action potentials.
1. The receptor potential triggers action potentials in sensory receptor cell itself. 2. Receptor potential can cause pre-synaptic neutron to release neurotransmitters that cause post-synaptic neurone to generate action potentials.
Which sensory receptors are iononotropic and which are metabotropic? Hint: I MET Mr Cameron Pollock
Ionotropic: mechanoreceptor, thermoreceptor and electroreceptor. Metabotropic: chemoreceptor and photoreceptor
Photo and chemoreceptors activate what in response to its stimulus?
Photo and chemoreceptors activate a G-protein signalling cascade that opens ion channels on the receptor cell.
What is an odorant?
A molecule in the environment that binds to and activates an olfactory receptor protein on the cilia of olfactory receptor neutrons (ORN)
Why is it hard to smell when you have a cold? 🤧
You get a runny nose when you get a cold and that extra mucous creates a thicker layer of mucous around the Olfactory receptor neurons (ORN). Odorant molecules will find it harder to diffuse through the thicker layer of mucous and so few odorant molecules will bind to the receptor proteins (chemoreceptors) on the ORN.
What is the function of the mucous film part of the olfactory epithelium.
It’s gives protection to the epithelial tissue lining the nasal cavity
Can ORNs regenerate themselves and if so why?
Yes - the epithelial lining is constantly shed so ORNs have to regenerate.
Explain how an action potential is generated in ORNs
1. Odorant molecules diffuse across mucous film and binds with receptor proteins on ORNs activating a G-protein. 2. The G-protein then activates an enzyme that increases the number of a second messengar (cAMP in vertebrates) in the receptor cell's cytoplasm. 3. cAMP then opens a ion channel allowing Na+ into the cell causing depolarisation of that part of the cell, generating the action potential. In short: Odorant molecule - receptor protein - G-protein - enzyme - second messenger - Influx of Na+ causing depolarisation - Action potential generated in ORN.
Each ORN expresses how many receptor protein types?
Just one type
State the trend in odorant molecules and perceived smell.
The greater the concentration of odarent molecules the greater the frequency of action potentials and this the greater the intensity of the smell.
What is a pheromone?
A type of chemical signal molecule that is used to communicate with individuals of the same species.
Tastebuds are ____________
The sense of taste is called _________
State the name of each type of sensory receptor cell membrane protein below: