NPB101: Neurophysiology Part 4

Detecting Stimuli

DISCLAIMER: Receptor is used here in this Part 4 in regards to a sensory system is that it cangrab onto the stimulus whether its light waves, sound waves, chemicals, becaus ethey are the cell types that can do transduction

In PREVIOUS parts its used as: bind to a neurotransmitter and they are little proteins that are on the cell & bind to specific chemical

Receptors

NS

transduces and filters things out

Transduction

converting a stimuli into an electrical signal

T/F: even if you don’t have a receptor you can still detect stimulus and transduce the stimulus

False, you need a receptor to detect stimulus and transduce the stimulus

When the neuron has a ____ receptor, it detects the receptor and ___ the ____ potential

special, changes, membrane

T/F: it has to be a neuron that has a special receptor to detect the receptor and have membrane potential

False, it can also be a sensory cell not a neuron

Membrane potential change (Receptor Potential)

when stimulus is detected it changes the membrane potential and when we have a change in the membrane potential that change is from rest & is called a graded potential well specifically a receptor potential

Receptor Potential

if its a neuron it can cause a neuron to fire an AP

Majority of our sensory systems

when we get a receptor potential most of them cause the cell to depolarize & fire off an AP w/exception of our eyes & brain to hyperpolarize

T/F: Our Sensory Systems can only depolarize

False, our sensory systems can depolarize & hyperpolarize

Which of the following statements about detecting stimuli and/or sensory systems is TRUE?

A. Sensory receptors cells always depolarize in response to stimuli

B. Stimuli are always consciously perceived before a

response is elicited

C. In receptor neurons, strong stimuli causes large APs,

while small stimuli induce small APs

D. Sensory receptors must convert the“form” of a stimulus

into a change in membrane potential.

E. ALL of the above are TRUE statements.

A: no it also hyperpolarizes

B: No you cant feel all the stimuli inside your body

C: No because AP are stereotyped & an AP will set off as long as it passes threshold

D. it has to transduce so YES

Components of Sensory Systems

1. Receptor Cells

2. Pathways

3. Nervous Tissue

Receptor Cells

“capture” / detect the stimulus & some can be neurons or cells

Pathways (Afferent)

Carry the info to a central processor (spinal cord or even brainstem)

Nervous Tissue

filter (thalamus filters) & process the sensory input (exception: taste & olfactory) (can be processes in different spots)

Receptor neuron

receive the stimulus

T/F: In some instances the neuron will fire AP (depolarize)

False, the neuron will fire AP in MOST instances which is our main focus

Explain what is occurring here

receptor potential occurring on the axon and spreads to the axon hillock that creates and AP and then it regenerates

Neuron

carrying the info and fire the AP

Receptor Cell

Receptor cell receive stimulus and the cell changes membrane potential like depolarizing and it affects the release of neurotransmitter

What is the neuron doing here

the neuron is firing the AP

Stimuli that are transduced by Non-receptor cells

• Pancreatic B-cells

• GI endocrine

The B-cell is in the ____ & produces ____

pancreas, insulin

What is happening here

The beta cell is sitting in the pancreas & blood flows to it and the pancreas will grab glucose out of the bloodstream & the beta cell detects the glucose coming into it & changes the amount of insulin it secretes