Exam 5 lecture 1

exteroceptors

sense stimuli external to the body

interoceptors

sense stimuli int the internal organs

sensory receptor

structure specialized to detect a stimulus

Sense organ

a structure that combines nervous tissue with other tissues that enhance its response to a certain type of stimulus.

Sensory adaptation

if a stimulus is prolonged, neuron firing frequency is lowered down, and you become less aware of a stimulus

thermoreceptors

detect heat or cold

mechanoreceptors

detect physical deformation of plasma membrane or tissue

photoreceptors

detect light

chemoreceptors

Detects chemicals,

odor, taste, and body fluid comp

nociceptors

detect tissue injury and damage

Types of mechanoreceptors

tactile (vibration touch/ pressure)

stretch (proprioceptors)

Tension/pressure change in organs (baroreceptors)

baroreceptors

type of mechanoreceptors

tension/ pressure changes in walls of blood vessels, digestive organs, bladder, and lungs

proprioceptors

type of mechanoreceptors,

detect stretches

Tactile receptors

type of mechanoreceptors,

Vibration/touch/pressure

General senses distribution in body

receptors all over the body

Special senses distribution in body

Limited to the head

5 special senses

smell taste, balance, hearing and vision.

have specialized structures fro detection

General senses

everything that isn’t smell taste, balance, hearing and vision.

touch, pain, and temperature

What detects touch?

What are general sense stimuli detected and signaled by?

pseudounipolar neurons

What are special sense stimuli detected and signaled by?

Specialized receptors cells receive signal and the stimulus causes Neuro transmitter release

Transmitts impulse into neurons

Exception to special sense stimuli detection and signaling rule

smell is received by receptive endings of olfactory neurons

Merkel disc

Tactile disk

general sensory receptor in skin

sense steady pressure and texture

Releases serotonin upon skin compression

Pacinian corpuscle

lamellar corpuscle

general sensory receptor in skin

senses to vibration

bulbous corpuscle

Ruffini corpuscle

general sensory receptor in skin

senses heavy and continuous touch/pressure

stretch of skin

Hair receptor

light touch - sense hair movement

end bulb

krause bulb

general sensory receptor in skin

unknown, possibly temperature and touch

Tactile corpuscle

Meissner’s corpuscle

general sensory receptor in skin

(capsule of schwann cells)

responds to flutter and stroking movements

(massage)

Free nerve endings

general sensory receptor in skin

Pain(nociceptors)

heat (warm-R)

cold (cold-R)

What does the merkel disc consist of?

merkel cell + nerve ending

Some of general sensory receptors have a capsules. What are they made of ?

• fibroblasts

• collagen fibers

• ground substance

• glial receptors

Meissner (tactile) corpuscle

type of surrounding capsule

contain modified Schwann cells, arranged as horizontal lamellae

Pacinian Corpuscle

type of surrounding capsule, has collagen fibers

Pain

uncomfortable conscious perception of tissue injury or noxious stimulation

Nociceptive pain

Pain from tissue injury that causes injury inflation

somatic or visceral

Visceral pain

Nociceptive pain

Types of visceral pain

Mucosal injury example

peptic ulcer

type of visceral pain, under nociceptive

What kind of pain is a petic ulcer injury

mucosal injury

visceral, under nociceptive

Obstruction or capsular distension example

kidney stone

visceral pain, nociceptive

What kind of pain are kidney stones

Obstruction or capsular, visceral pain, nociceptive

Somatic pain

under nociceptive pain

Deep somatic pain

what does osteoarthritis count as

Deep, somatic pain, under nociceptive

superficial pain

Somatic pain, nociceptive

What is skin pain classified as?

Superficial somatic pain, nociceptive

Neuropathic pain

Injury to the nervous system, lesion or disease

Tingling senstations

Types of nociceptive pain

somatic and visceral

What kind of pain is peripheral neuropathy

neuropathic

When does peripheral neuropathy happen?

when the peripheral nerves are damaged

What kind of pain is a stroke

messener's corpuscle

When does a stroke happen

What kind of pain is Multiple sclerosis

Neuropathic pain

When does multiple sclerosis happen

when the immune system attacks myelin nerve sheathing in brain and spinal cord

What kind of pain is spinal cord injury

Neuropathic

What causes a spinal cord injury

trauma

Nociplastic pain

pain in which neither nociceptors are activated or neuropathy happens. Findings suggest altered nociceptor function

Fibromyalgia pain type

Nociplastic

When does fibromyalgia happen?

when patients have increased sensitivity to pain

Irritable bowel syndrome pain type

Nociplastic

What Is IBS

abdominal discomfort caused due to altered bowel movements

related to hypersensitivity of nerves

Endogenous molecules that produce pain in PNS and CNS

Release Into Nerve endings:

histamine

bradykinin

serotonin

prostaglandin

protons

Released by the nerves:

Substance P

Calcitonin gene related peptides (CGRP)

Endogenous molecules that produce pain in PNS and CNS released by nerves

Substance P

Calcitonin gene related peptides (CGRP)

Endogenous molecules that produce pain in PNS and CNS released Into Nerve endings:

histamine

bradykinin

serotonin

prostaglandin

protons

Axon reflex

causes pain in PNS and CNS

substance P and Calcitonin gene related peptides (CGRP) are released by nociceptors at the site of injury and promote

histamine

bradykinin

serotonin

prostaglandin

protons

release

Nociceptive modulation

OPOID RELEASE TO STOP PAIN

IN CNS

Primary afferent neurons move signal from pain stimulus to spinal cord in substancia gelatinosa

Substance P and glutamate are released into second order neurons

The second order pathway connects with the descending efferent pathway which releases opiates into primary afferent neurons

These opiates are then received by the primary afferent neurons, which inhibits the release of substance P and Glutamate

Enkephalins

Opiate that inhibits the 2nd order pain neuron in CNS adaptive modiulation

4 different types of papillae

Circumvallate

fungiform

filiform (doesn’t have receptors)

foliate

What papillae doesn’t have receptors?

filiform

Papilla structure

Inside of papillae there are taste buds, consisting of

Taste buds

In papillae, groups of taste cells, and each one has receptors for only one type of taste

Taste bud structure

Tastants

Chemical stimuli that cause taste

Salt and sour activation of gustatory receptors

On hairs

Ion channels cause a depolarized membrane which release neurotransmitters to stimulate sensory neurons.

Sweet, bitter, and umami activation of gustatory receptors

On hairs,

Different tastes involve different receptor mechanisms, but typically with G proteins

which release neurotransmitters to stimulate sensory neurons.

Salt activation of gustatory receptors

Produced by metal Ions (Na+ K+)

Sour activation of gustatory receptors

associated with acids

sweet activation of gustatory receptors

associated with carbohydrates

bitter activation of gustatory receptors

associated with spoiled foods and alkaloids

like nicotine and caffeine

umami activation of gustatory receptors

produced by aas like aspartic and glutamic acids

Taste pores

contains taste hairs

CN VII

facial nerve

anterior 2/3 of tongue

CN IX

Glossopharyngeal nerve

posterior 1/3 of tongue

CN X

Vagus nerve

covers pharynx, palate and epiglottis

Process of nerve impulses from gustatory receptors to different parts of the brain

Taste buds wire to CN VII, IX, and X.

This information travels to the medulla, in which it travels to the NTS (nucleus of the solitary tract

This then wires to the hypothalamus (which controls autonomic reflexes with taste) like salivating, gagging and vomiting. Also processed by amygdala which controls the emotion and memory of a taste

Then goes to the cortex, in which the gustatory cortex, which processes taste is activated,

as well as the orbitofrontal cortex, which integrates taste smell and sight signals

orbitofrontal cortex

integrates taste smell and sight signals ,

in the cortex, last step of gustatory implementation

gustatory cortex

processes taste

in the cortex, last step of gustatory implementation

Solitary tract

3rd step of gustatory implementation

series of sensory nuclei that form a vertical column of grey matter in the brainstem

Do taste receptor cells generate Action potentials upon stimulation?

No, they generate receptor portentials

Do plasma membranes of microvilli contain receptor sites that bind selectively with chemicals in saliva?

yes

Structure of olfactory system

Odorants

detected by receptor cells in the roof of the epithelium of the nasal cavity

Olfactory dendrites

surfaces contain receptor proteins, detect and send singnals to olfactory receptor cells

olfactory receptor cells

Neurons, receive information from olfactory dendrites, and send to olfactory nerve fibers

What is unique about olfactory receptor cells

They are replaceable, but not all are replaced with age, leading to a loss of smell

Olfactory nerve fibers

in fascicles, receive information from olfactory receptor cell

Olfactory fascilces

consists of Olfactory nerve fibers receive information from olfactory receptor cell

as a whole all fascicles make up the olfactory nerve

CN I

Olfactory nerve, made of fascicles

Olfactory epithelium

Consists of basal, olfactory receptor, and supporting cells

Olfactory mucosa

Contains olfactory dendrites, detect smells