Touch, taste, smell Flashcards
What information does the somatosensory system provide ?
The somatosensory system provides information about touch, pressure, temperature, and pain, both on the surface of the skin and inside the body.
What are the 3 interacting somatosensory systems ?
The exteroceptive system (cutaneous/skin senses), The interoceptive system (organic senses), The proprioceptive (kinesthesia) system
The exteroceptive system (cutaneous/skin senses)
Responds to external stimuli applied to the skin
The interoceptive system (organic senses)
Provides information about conditions within the body and is responsible for efficient regulation of its internal milieu
The proprioceptive (kinesthesia) system
Monitors information about the position of the body, posture and movement.
3 layers of skin :
- Epidermis
- Dermis
- Hypodermis
______ skin is ‘hairless’ skin (e.g., palms of hands and feet). It is where we are the most sensitive.
Glabrous
Meissner’s corpuscles
Detect very light touch and localized edge contours (brail-like stimuli). They cause pressure sensitive ion channels to open when touched. They are encapsulated.
Where are Meissneir’s corpuscles ?
Only on glabrous skin
Are Meissneir’s corpuscles encapsulated?
Yes
Merkel disks
Not encapsulated. They are sensitive to simple touch (local skin indentations).
Pacinian corpuscle
Encapsulated and also sensitive to vibrations (light touch).
Ruffini corpuscles are sensitive to …
Stretch and the kinesthetic sense of finger position and movement.
2 categories of thermal receptors
those that respond to warmth and those that respond to coolness
Temperature information is poorly _____ and _____ than touch
Poorly localized and slower
True or false : the axons that carry temperature to the CNS are unmyelinated or thinly myelinated.
True
Some of the receptor proteins that are sensitive to temperature can also be activated by certain _____
Ligands
capsaicin molecules activate ____ receptors
Heat
Temperature channels are temperature gated ___ channels.
Ion
Axons from skin, muscles, and internal organs enter the CNS via _____nerves.
Spinal
Poorly localized information (e.g., crude touch, temperature, and pain) crosses over the midline in the ____ ____, just after the first synaptic connection.
Spinal cord
After the spinal cord, poorly localized information ascends to the ______ through the _______ tract.
Thalamus through the spinothalamic tract.
Highly localized information (e.g., fine touch) ascends ______ through the _____ column of the spinal cord.
Ipsilaterally through the dorsal column of the spinal cord.
The first synapse in the highly localized information pathway is in the _____.
Medulla
From the medulla, the highly localized nformation crosses over to the contralateral side as it ascends to the _______.
Thalamus
Both high and poorly localized info. pathways get bundled together in the _____ before synapsing in the thalamus.
Midbrain
When different sites of primary _______ cortex are electrically stimulated, patients report sensations in specific parts of their bodies (pain, temperature).
Somatosensory
The relationship between cortical stimulations and body sensations is reflected in a ______ map of the body surface.
Somatotopic
Tactile _____ is damage in the somatosensory cortex.
Agnosia
Patients with tactile agnosia have trouble identifying objects by ____ alone.
Touch
Chronic pain is in the _____ lobe
Parietal
Phantom limb sensation is due to confusion in the __ ___
Somatosensory cortices
6 tastes
- Sweetness (sugar molecules)
- Umami (glutamate or glutamine molecules)
- Bitterness (variety of molecules)
- Saltiness (positive ions like sodium)
- Sourness (pH level, concentration of free hydrogen ions)
- Fat (fatty acids)
These tastes are activated by metabotropic receptors
Sweetness, umami, bitterness, fat (also fatty acid transporters)
Taste linked to highly permeabe to sodium ion channel
Saltiness
Taste linked to ion channel that is highly permeable to free protons
Sourness
MSG (monosodium glutamate) is an _____ that activates both salt and umami receptors.
Amino acid
When a taste molecule binds to a taste receptor protein, it produces a change in ____ _____
Membrane potential
Taste buds contain 20 to 150 ____ receptor cells, some for each type of taste (sugar, umami, bitter, salt, sour, or fat).
Taste
True or false : taste receptor cells do not have traditional action potentials. They release neurotransmitter in a graded fashion.
True
Taste receptor cells are replaced about every ___days, because they are directly exposed to a rather hostile environment of our mouth.
10
True or false : The papilla is not where taste receptors are.
True
___ and ____ taste receptor cells are instinctively rewarding
Sugar and umami
The primary _____ cortex is in the ____ lobe of the cerebral cortex.
Gustatory, insula
Odorant molecules are _____ substances (stay in the air)
Volatile
Most of odorant molecules are ____ soluble and of organic origin (come from life
Lipid
The receptor proteins that transduce odorants into a change in membrane potential are ______ g protein-coupled receptors.
Metabotropic
Humans express ~___ different types of odorant receptors.
400
The tissue of the nasal sinus that sits underneath the skull (the cribriform plate) and contains olfactory receptors cells.
Olfactory epithelium
Each olfactory cell expresses ___ type(s) of olfactory receptor protein.
1
Olfactory receptor cells synapse in ____ in the olfactory bulb, which in turn sends axons into the brain.
Glomurelli
Each _____ processes information from 1 type of olfactory receptor cell (1 smell)
Glomerulus
Olfactory information does not relay in the thalamus. It goes directly to primary olfactory cortex in the _____ lobe and the _____.
Temporal lobe and the amygdala.
4 roles of pheromones
- attract or repel other members of the same species
- signal attractiveness and sexual receptivity
- mark a path to follow (as seen in ants)
- signal danger (in urine)
Pheromones are non ____
Volatile
___ to ____ pheromone signaling is especially powerful.
Female to male
If the ______ system is functional in a male mouse, they will only attempt to mate with female mice that are in heat.
Vomeronasal
Lee-Boot Effect
When female mice are housed together (without any male urine present), their estrous cycles slow down and eventually stop.
Whitten Effect
Pheromones in the urine of male mice can trigger synchronous estrus cycles in groups of female mice.
Vandenbergh Effect
Earlier onset of puberty seen in female animals that are housed with males.
Bruce Effect
The tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male.
