Physiology Lecture 14 - Mechano/thermo sensation + taste

Piezo1 and Piezo2

these are mechano transduction channels, and have more than 30 transmembrane domains

Merkel Cells

these are touch receptors that are slow adapting, located in superficial skin, and are for fine differences in touch. An example of what these are used for are for reading braile

Meissner's Corpuscles

these are touch receptors taht are rapidly adapting, in hairless areas, make up 40% of the hand, and give a "tickling" sensation

Pacinian corpuscles

these are touch receptors that are rapidly adapting, located in deepr tissue, and have large receptive fields. An example of the type of touch these sense is going to be the heavy vibration of a drill, or texture sensing

Ruffini endings

these type of touch receptors are slow adapting, in deep skin, have large receptive fields, and detect deep, sustained pressure and stretching. An example of these would be feeling a massage

Ruffini endings

which type of touch receptors are abundant in the periodontal ligament?

Hair follicle receptors

these type of touch receptors are rapid adapting, only in hairy skin, and sense light movement of the hair on skin. An example would be rubbing cotton on arm hair

Muscle spindles

groups of specialized dintrafusal muscle fibers surrounded by a capsule of connective tissue

Head, heart

there ar especialized proprioceptors in the _________ and the __________

around, stretched, ion channels

Sensory afferents are coiled ___________ the central part of the intrafusal spindle of muscle, when the muscle is ______________, the tension on the intrafusal fibers activates mechanically gated _______ ____________________, which leads to an action potential

Proprioceptors

sensory receptors that sense the internal forces acting on the body (ex. muscle spindles)

periodontal ligaments

these are a set of ligaments that connect the tooth to the alveolar bone of the socket. These ligaments suspend each tooth in its socket and give the tooth some limited movement within the socket

thermosensation

this is the ability to detect temperature

4

How many types of temperature receptors to we have?

Combinatorial code

even though we only have 4 types of temperature receptors, the receptors will combine signals from all 4 receptors, which gives us a sense of overall temperature. This concept is called ______________________ ________________

TRP channels

a large family of cationic channels that can respond to a multitude of stimuli and chemicals. This cahnnel family has been implicatd in mechanosensing, thermosensing, and nocisensing functions in neurons

False

True or false: smell and taste don't really have any effect on one another, and if you lose your sense of smell, then things taste exactly the same as they did before

Taste buds

these are sensory organs for gustatory (taste) sensation, which are clutered of 50-100 different cells, they are located in the papillae

Epithelial cells

taste receptors are modified ______________ _________

Taste pore

these allow microvilli of the receptor cells to have access to the surface of the tongue

Differention of support cells

dying receptor cells in the tongue can be replaced with the ___________________________ _____ _______________ _________

ATP

Taste receptors release this as a neurotransmitter to specialized nerve endings on cranial nerve fibers instead of firing an action potential

liquid

In the signaling of taste, tastants dissolve in ___________ come into contact witht he surface or receptors

taste receptors

After tastants have been dissolved, they bind to the __________ _______________

depolarizes, Ca2+, entry, releases

when tastants bind to the receptor, the membrane _______________ triggering the opening of voltage gated _____(what ion?) channels, allowing the _______ of that ion, which then ____________ the neurotransmitter (usually serotonin or ATP)

Salty, Sour, Sweet, Bitter, Umami

What are the 5 tastes that we know of so far?

Fat

this is a recently identified possible taste that isn't formally called a taste at this point, but could be

Closing of K+ channel

What causes the depolarization in a sweet taste receptor?

True

True or False: the identity, concentration, and valence (whether it is good or bad) value of tastants is conveyed to brain by the action potentials provided by the taste buds

Labeled lines

Though it has not been thoroughly investigated yet, neurons likely tune to specific tastants, which is an example of this phenomenon when processing

ATP

What is the main neurotransmitter released from taste buds to communicate with gustatory nerves?

Seratonin, GABA

these are two other neurotransmitters besides ATP that can possibly communicate with gustatory nerves

False

True or false: each taste bud only responds to one taste, and does not respond to any others

Facial (CN VII)

this cranial nerve, along with lingual branch of glossopharyngeal, sense for taste buds in the anterior 2/3 of the tongue

Glossopharyngeal (CN IX)

this cranial nerve, along with superior larygeal branch of vagus nerve sense for the taste buds in the posterior one third of the tongue, and on the palate

Vagus (CN X)

this cranial nerve senses the taste buds of the epiglottis and esophagus

Nucelus of the solitary tract

this contains interneurons synapse of the vagus nerve connecting taste with the GI system in a "gustatorial-GI reflex arc" essentially your ability to throw up if you taste something gross

Nucleus of the solitary tract

where do the sensory neurons in the cranial nerve ganglia project to?

Medulla

where is the nucles of the solitary tract located?

thalamus and hypothalamus

After the nucleus of the solitary tract, the axons project to the ventral posterior complex of which organ, and which other organ?

Insula

After the signal is projected to the thalamus or hypothalamus, the taste sensation is projected to the gustatory cortex in which part of the frontal lobe?

Cultural and psychological influences

These influence can impact valence response (whether something tastes bad or not), because at low concentrations the aversive tastes to bitter or sour flavors can be overcome.

False

true or false: Tast is the only thing that affects flavor, so vision, hunger or thirst level, mouth feel, intensity, or smell does not affect it

Pons

medulla

Pain and temp from all 3 branches of the trigeminal nerve enter the CNS at the ____ and descend to the ____ and cervical regions

A long axon where pain and temp fibers synapse on 2nd order neurons

What is the spinal nucleus?

trigeminal

The spinal nucleus is part of the ____ nerve

AP

• ATP is released as a NT to specialized nerve endings on cranial nerve fibers

Taste receptors do not fire __

direct entry of Na+ ions through channles that lead to a depolarization (becomes more negative)

How is salt taste detected?

H + ions enter cell through channels and blocks the outward flow of K+ that leads to a depolarization (more +)

How is sour taste detected?

glucose binds to a receptor which leads to a GPCR cascade that causes K+ channels to close and depolarization takes place (more +)

How do we detect sweet taste?