BIOL203 Lec 21: Intro to special senses

What is the term for a structure specialized to detect a stimulus?

Sensory receptor

What is the term for a structure that combines nervous tissue with other tissues?

A sense organ

Exteroceptors sense stimuli (internal/external) to the body

Interceptors detect stimuli in the (internal/external) organs

Which are also called visceroceptors?

External

Internal

Interceptors are also called visceroceptors

When a physical stimulus, such as touch, taste, or color, acts on a sensory receptor cell specifically designed to respond to that stimulus, the energy of the stimulus is transduced into an _____________ response, also called a _________ potential, which is a type of (local/action) potential.

electrical

receptor

local

T/F The brain can distinguish stimuli intensities based on which neurons are firing, how many, and how fast

T

What is the term describing the idea that if a stimulus is prolonged, there is a decreased neuron firing frequency, making you less aware of the stimulus

Sensory adaptation

What sensation do thermoreceptors detect?

Hot/cold

What sensation do mechanoreceptors detect? What does this include?

Physical deformation of cells and tissue

Includes vibration, pressure, stress, tension, touch

What sensation do chemoreceptors detect? What does this include?

Chemicals

Includes odors, tastes, body fluid composition

What sensation do photoreceptors detect?

Light

What sensation do nociceptors detect?

Tissue injury or damage

___________ are a type of mechanoreceptor that sense the position and movements of the body or its parts. They occur in muscles, tendons, and joint capsules

Proprioceptors

What is the proprioceptor organ that senses muscle stretch?

Muscle spindle

What is the proprioceptor organ that senses tension in a join?

Tendon organ

_________ senses are limited to the head

_________ senses located all over the body

Special

General

T/F - The special senses don't need any specialized structures for detection, they just use the same structures as the rest of the body

F

Are touch, pain, and temperature each special senses or general senses?

All general senses

Name the 5 special senses

smell, taste, sight, hearing, equilibrium

For the general senses, ______ neurons fire (action/local) potentials

unipolar

action

For the special senses, specialized receptor cells (not neurons) trigger _________ release which then generate a local potential to the cranial nerve

neurotransmitter

What is the single exception sense for the rule that specialized receptor cells detect the stimulus?

What cell is the receptor cell then?

Smell

Bipolar neuron is the sensory cell

Name the 7 general sensory receptors in the skin

"My Pink Rabbit Kinda Hates Messy Floors"

M → Meissner's tactile corpuscle

P → Pacinian lamellar corpuscle

R → Ruffini bulbous corpuscle

K → Krause end bulb

H → Hair receptor

M → Merkel tactile disc

F → Free nerve endings

What do the free nerve endings sense?

pain and temperature

What do the Meissner's tactile corpuscle respond to?

Flutter and stroking movements

What does the Krause end bulb detect?

Not sure...? But we know it plays a role in the mucosa in the mouth

What does the hair receptor detect?

Light touch

What does the Ruffini bulbous corpuscle detect?

Heavy touch, skin stretch

What does the Pacinian lamellar corpuscle detect?

Vibration

What does the Merkel tactile disc sense? What does it release?

Steady pressure and texture

Releases serotonin

What is the term describing the uncomfortable conscious perception of tissue injury or noxious stimulation?

Pain

T/F Pain is subjective, highly variable, and influenced by mental state

T

What kind of pain stems from tissue injury (like cuts, burs, chemical irritation, inflammation)

Nociceptive pain

What are the 2 types of nociceptive pain?

visceral and somatic

Give 2 examples of visceral pain

Mucosal injury - peptic ulcer

Obstruction - kidney stone

Osteoarthritis is an example of ______ somatic pain

A burn is an example of _______ somatic pain

deep

superficial

T/F Nociceptive pain is neural pain

F - it is non neural

__________ pain is caused by a lesion or disease of the somatosensory nervous system

Neuropathic

Peripheral neuropathy is an example of neuropathic pain that happens when?

When peripheral nerves are damaged (ex: diabetes)

A stroke is an example of neuropathic pain that happens when?

When blood flow to the brain is stopped

Multiple sclerosis is an example of neuropathic pain that happens when?

When the immune system attacks myelin nerve sheathing

Spinal cord injury is an example of neuropathic pain that happens when?

When the body experiences trauma

T/F Nociplastic pain is the mechanistic basis for chronic pain because it is a combination of tissue damage and nerve damage

F - nociplastic pain is the mechanistic basis for chronic pain, but is is NEITHER due to tissue damage or nerve damage

Which type of pain is characterized by widespread pain, fatigue, sleep, memory, and mood problems

Nociplastic pain

Name 2 examples of nociplastic pain

Fibromyalgia

Irritable bowel syndrome

Many symptoms of irritable bowel syndrome are related to _____________ of the nerves within the GI tract

hypersensitivity

Name the 7 molecules of the pain producing molecules in the inflammatory response in the PNS

- Histamine

- Bradykinin

- Serotonin

- Prostaglandin

- H+

- CGRP

- Substance P

What molecule is associated with the muscle pains from generating ATP under anaerobic conditions?

H+

What molecule is released by nociceptors at the sight of tissue injury?

Substance P

CGRP

What is the main efferent molecule that inhibits pain?

Opiates

What are the main afferent molecules that inhibit pain?

Substance P

Glutamate

Each tongue papilla is made of (one/multiple) taste bud(s)

Each taste bud is made of (one/multiple) taste pore(s)

Each taste bud is made of (one/multiple) taste cells

Each taste cell can taste (one/multiple) taste(s)

Multiple

One

Multiple

One

Name the 5 tastes

sweet, salty, sour, bitter, umami

How do the taste cells come in contact with the stimuli?

Molecules dissolve in the saliva to flood the taste pore

Are taste cells neurons?

No

Can taste cells have microvilli on them?

Yes

What is the term for the cells between taste cells that provide them nutrients and support?

Supporting cells

What is the term for the stem cells below the taste cells that replace them weekly?

Basal cells

How are sensory neurons made aware about flavors?

Neurotransmitter release

Which 3 tastes activate the g protein?

sweet, bitter, umami

Which taste is produced by the metal ions Na+ and K+?

Salty

Which taste is associated with acids?

Sour

Which taste is associated with carbohydrates?

Sweet

Which taste is associated with spoiled foods and alkaloids such as nicotine and caffeine?

Bitter

Which taste is associated with a meaty taste produced by amino acids such as aspartic acid and glutamic acid

Umami

Salt and sour channels are associated with depolarized __ channels

Na+

The chemical stimuli in food is called what?

Tastants

Which part of the brain is associated with the emotions and memory with taste

Amygdala

Which part of the brain is associated with the autonomic function of taste, like salvation, gagging, and vomiting

Hypothalamus

Name the 5 steps of the gustatory projection pathway starting at the tongue

1. Taste buds

2. Cranial nerves

3. Medulla

4. Midbrain

5. Gustatory cortex

_________ is the response to airborne chemicals called odorants

Olfaction

Odorants are detected by receptor cells in a patch of ________ in the olfactory _______ in the roof of the nasal cavity

epithelium

muscosa

What are the 3 cranial nerves associated with taste

1. Vagus nerve X

2. Glossopharyngeal nerve IX

3. Facial nerve VII

Are olfactory sensory cells neurons?

Yes, they are bipolar

What is the cranial nerve for smell?

Olfactory nerve I

T/F both taste cells and olfactory cells have supporting cells and basal cells

T

What are the different structures in the PNS of the olfactory projection pathway? What is this called?

Receptor cells and olfactory nerve fascicles

What is the structure in the CNS of the olfactory projection pathway? What is this called?

glomerulus

Olfactory tract and bulb

What are the 3 parts of the primary olfactory cortex, which receives input directly from the olfactory bulb? It creates conscious perception of odor.

Piriform cortex

Amygdala

Entorhinal cortex

What are the 2 parts of the secondary olfactory cortex, which helps to integrate odor, taste, and vision to identify and discriminate among odors.

Insula

Orbitofrontal cortex

Which region of the brain stores olfactory memory?

hippocampus

Which region of the body triggers autonomic olfactory responses, such as appetite, salivation, and gastric contraction?

brainstem

The olfactory cortex can send fibers back to the olfactory bulbs where they can synapse into the ________ __________ cells which are interneurons

GABAergic, granule

What can granule cells do?

inhibit the mitral and tufted cells (which normally relay olfactory information from the bulb to the brain)

What is the goal of the cortical feedback modulation of the olfactory bulb circuit?

olfactory discrimination

Give an example of cortical feedback modulation

Smell changes under different situations

Food may smell more appetizing when you are hungry than when you just ate or when you are ill