NPB101: Neurophysiology Part 3

The Peripheral Nervous System (PNS)

PNS is made up of ____

neurons

T/F: PNS neurons live inside

False, they dont formally live inside the brain and spinal cord

PNS is made up of ____ neurons & ____ neurons.

afferent neurons & efferent neurons

Afferent neurons

carry sensory information

Afferent neurons carry ___ information from ____ tissues

sensory, peripheral

Afferent bring info from

• Gi tract

• surface of skin

• visceral organ

Info processed by brain or spinal cord

Efferent neurons

carry information to control (motor)

Efferent neurons carry ____ to control ____ tissues

information, peripheral

Efferent neurons ___ transmit signals that ____ the activity of muscles and glands

axons, control

Being consciously perceived means

coming to the surface of the skin or they’re going to a very specialized organ that’s designed for detecting stimuli

Three subdivisions of Peripheral Afferents that carry info towards the CNS

• General Somatic Sensory Afferents

• Special Sensory Afferent

• Visceral Sensory Afferent

Innervating

supply (the body/skin) with nerves

General Somatic Sensory Afferent

Touch sensitive neurons that are innervating the skin

somatic (body)

General Somatic Sensory Afferent are ___ sensitive neurons & also ___ sensitive

pain, temperature

The General Somatic Sensory Afferent is pain and temperature sensitive because

Both pain & temperature are innervating the skin because the skin is a multi use organ

Special Sensory Afferent

Neurons that are innervating specific organs that detect stimuli

• ex: eye detect light waves

• skin: protection

• ear: soundwaves

• tongue: special sensory afferent

These are all specialized organs

General Somatic Sensory Afferent touch receptor

Dorsal Root Ganglia

has a cell body of a neuron with an axon that has a terminus that has AP propagating

What are these structures called on the neuron

Dendrites

Dendrites

receives information coming into the neuron

What can form on a dendrite?

The synaptic connection between two neurons where a neuron comes in and forms a synapse with a target neuron is that can form on a dendrite

What is this blue thing in the touch receptor?

This is a modified dendrite

What can travel through this modified dendrite?

AP can travel through the modified dendrite

T/F: AP cannot travel through dendrites

True BUT with the exception of a modified dendrite

What is this modified dendrite process called

This is called the afferent process as you know afferent does sensory

Where are the actual dendrites?

So in the General Somatic Neuron they are all built with the ___ process

afferent

The afferent process can be __list__ sensitive

touch, pain, temperature

Interneuron

• sends info to the brain

• This is set in the Gray Matter of our spinal cord

Special Senses are found in the ____ structures that are only designed to pick up a ____

specific, stimulus

Olfactory and taste buds are parts of what afferent?

olfactory and tastebuds are part of the special sensory afferents

Visceral Sensory Afferents

innervate our internal organs

Visceral Sensory Afferents go along the same pathway as our ____ ____ afferents

general somatic

Visceral input ___ to the ____ and turn ___ an involuntary autonomic response

talks, brainstem, on

Visceral Sensory Afferent carry ____ stimuli applied to ____ organs

sensory, internal

Do we consciously perceive these stimuli (sensory stimuli applied to internal organs)?

No, we dont feel blood vessels stretching and our stomach acids working, so no

Peripheral Motor Efferent Neurons

These neurons carry “demand” info from spinal cord to target organs

Peripheral Motor Efferent Neurons has two subdivisions

• Somatic Efferent Neurons

• Autonomic Efferent Neurons

Somatic Efferent Neurons do (voluntary/involuntary) ____ control of your ___ muscle

voluntary, skeletal

Autonomic Efferent Neurons do (voluntary/involuntary) ____ control to your ___

involuntary, organs (lungs, heart)

Lower Motor Neuron

controlled by upper motor neurons (brain)

Example of Lower Motor Neuron (Somatic Efferents)

wiggling fingers, so plan to wiggle our finger in our brain —> talks to lower motor neuron and send signals to muscle

T/F: Somatic motor neurons are controlled by both voluntary & involuntary inputs

True, Somatic Motor Neurons are controlled by voluntary input and also controlled by involuntary input

T/F: The Autonomic NS controls the visceral organs

True the Autonomic NS does control the Visceral Organs

Autonomic NS in term of the efferent pathway (motor) is broken up into how many distinctive parts

a. 2

b. 5

c. 6

d. 3

2

What are the two distinctive parts of the Autonomic Efferent?

• Parasympathetic (PNS)

• Sympathetic (SNS)

T/F: The heart received input from only PNS

False, the heart receives input from both PNS & SNS

When you receive input from both branches what is this called?

Dual input

T/F: The effects of the PNS are opposite (ANTAGONISTIC) of the SNS

True, example: in SNS heart beats faster and beats stronger & in PNS the heart beats slower

Why are branches antagonistic?

PNS & SNS are antagonistic (opposite of eachother) because it gives FINE CONTROL & allows super quick control of organs

Speed up heart rate by ___ the rate ____ activity while simultaneously ____ the rate of ______

increasing, sympathetic, decreasing, parasympathetic

Dual input example

Speed up heart rate by increasing the rate of PNS activity while simultaneously decreasing the rate of SNS. This creates fine control

T/F: Dual input does not have exceptions

False dual input does have exceptions

Dual input exceptions

• Salivary Glands: both inputs are stimulatory

• Blood vessels: primarily SNS

• Sweat Glands: primarily SNS

T/F: SNS quiets things/shuts things down

False, SNS actually activates things while PNS shuts things down

T/F: SNS does “Rest & Digest”

False, PNS actually does Rest & Digest while SNS does Fight or Flight

Rest & Digest

when your body is relaxed after eating a meal & your body is trying to incorporate those calories to build of glycogen & fat stores —>PNS

Fight or Flight

in these really stressful situations your PNS ⬇ while your SNS ⬆, SNS talks to organs saying beat faster to do fight or flight

T/F: when you are in Rest & Digest you need your heart beating faster and pushing out blood

False, when you are in Rest & Digest you need that blood flow to go to digestion as you are in a relaxed state

Neurons talking to a target process

we use neurotransmitters: norepinephrine & acetylcholine

T/F: Acetylcholine is associated with PNS

True, acetylcholine is associated with PNS while norepinephrine is associated with SNS

Acetylcholine has two parts

{Nicotinic & Muscarinic } Ach-R a.k.a Cholinergic receptors

Muscarinic

in Visceral organs that bind to acetylcholine and generate internal intracellular signal (second messengers) primary receptor

Norepinephrine bind to receptors

{a₁, a₂, B₁, B₂} adrenergic receptors which have different subtypes

T/F: Adrenergic receptors do second messengers

True

Adrenergic stimulation

cAMP

T/F: If the target does not have any receptors it cannot get a particular response

True, no target no response

T/F: Cholinergic receptors bind to acetylcholine

True Cholinergic receptors bind to acetylcholine (Ach) as it mediates our PNS responses

T/F: Adrenergic receptors bind to norepinephrine

True, Adrenergic binds to norepinephrine or epinephrine which is the neurotransmitter mediating the sympathetic response

Adrenaline

that is epinephrine