1.5 what is sensation?
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What is sensation?
Conscious awareness of a stimulus
What's the linage of how sensation becomes realized?
Stimulus is picked up by the receptor > receptor sends info down the nerve > nerve sends it up to brain, where it will be interpreted (realized)
2 types of sensations
Types of sensation ) general: 2 subtypes
Types of sensation ) what are special sensations?
- Specific environmental stimuli that is picked up by specialized organs
- *ears, nose, ears
Types of sensation ) what are general sensations?
- These are sensations that you feel in body or internally within the organs
- *somatic or visceral
Subtypes of somatic sensations (5)
- *position in space
Subtypes of visceral sensations (2)
*gas feeling in stomach or stomachs/ heart attack
Subtypes of special sensations
*these are picked up by specialized organs
What are 4 requirements for sensation
-Translation and cortical processing
Requirements of sensation) Stimulus
It can be from inside or outside
- *inside: lack of heart leading to heart attack
- *outside: touching something hot
Requirements of sensation) receptor
Protein in the membrane of a nerve or special cells that detects and converts stimulus to AP or GP
Requirements of sensation) what does detecting and converting stimulus lead to?
Converting = Transduction
Requirements of sensation) AP conduction
AP that was conducted travels up the sensory nerves to spinal cord and then brain
Requirements of sensation) translation and cortical processing
Occurs in the brain so we can realized the sensation
Perceptual processing at the cortical level involves... (5)
-detecting the stimulus
-detecting how intense the stimulus is
-identify the site or pattern of the stimulus
-recognition of a pattern
-distinguish features and qualities
Perceptual processing at the cortical level involves) detecting the stimulus
- Perceptual detection
- *what is it? Pen or pencil?
Perceptual processing at the cortical level involves) detecting how intense the stimulus is
- Magnitude estimation
- *train whistle
- **if its low, then it must be far; if its loud, then it must be close
Perceptual processing at the cortical level involves) identify the site or pattern of the stimulus
- Spatial discrimination
- *braille language
Perceptual processing at the cortical level involves) recognition of a pattern
Ex) brain interpreting music as a whole sound instead of single individual music notes
Perceptual processing at the cortical level involves) distinguish features and qualities
- Ex) smooth vs rough
- *Ice cream is smooth, cold, sweet, creamy
- *tomato soup is smooth, hot, bitter, creamy
- **helps us distinguish the little things that make things
What are the 5 types of receptors?
- Responds to Mechanical pressure
- *somebody touches you
Responds to Light stimulation
- Responds to change in temperature
- *touch hot stove or ice cube
Respond to pain transmission
Respond to chemicals
Receptors located in skin
Receptors located in viscera (internal organs)
Receptors located in joints and muscles
2 types of Proprioceptors
- Fire off action potential constantly
- Ex) Will fire APs to let you know that you have your arm extended out
- *lets you maintain knowledge where your limb is in space
- Fires off AP when joint changes position
- *fires AP when you move your outstretched arm to over your head as you are moving
Free nerve endings are...
Pain releases which 2 chemicals
- bradykinin and Potassium
- *nerves will respond to these chemicals then fire off AP that will eventually reach the CNS
What chemical does itch release?>
Not all nerve endings respond to all sensations
Free nerve endings) Temperature
Respond to a change in hot or cold temps
Free nerve endings) extreme temp or pain receptors
- Will respond to burn or frostbite
- *interpreted as pain
free nerve endings that respond to cold and warm, which are there more?
- Nerve endings that detect cold
- *they are also located superior to the nerve endings that detect warm
Where are Merkels disks located
Deep epidermis near dermal papillae
What do Merkel disks respond to (2)
-2 pt discrimination
-light touch pressure
Where are Merkel disks more numerous in?
What are hair follicle receptors
- Responds to movements of the hair follicles
- *ex) insect crawling will activate these
Encapsulated nerve endings ) meissners corpuscles : function (2)
-2 pt discrimination
-low frequency vibration
Encapsulated nerve endings ) meissners corpuscles : where can these be found more?
- More numerous in hairless skin
- *soles and palms
Encapsulated nerve endings ) meissners corpuscles : where are they located?
Just below the epidermis
Encapsulated nerve endings ) pacinian corpuscles : respond to (3)
- deep pressure
After receptor cell is stimulated...
Stimulus is transcend by receptor protein and sensory information is relayed to CNS
Faster afferent transmission for ...
- Superficial pain
- **hands or skin
- ***they are myelinated thin
Slower afferent transmission for
- Visceral pain
- **typically are unmyelinated
proprioceptive organs) what does the Golgi tendon organ?
Stretching of Golgi tendon organ causes relaxation of affected muscle and contraction of antagonistic muscle so that the muscle being stretch does not get damaged
proprioceptive organs) what does muscle spindle do?
Stretching of muscle causes contraction of affected muscle and relaxation of antagonistic muscle
How big is the olfactory epithelium?
What does the dendritic end of CN I contain and what do those contain?
It contains olfactory hairs and the hairs contain receptor proteins
What do the basal cells do? (2)
Replace receptors and CN I
With what do the mitral cell bodies interact with?
Synapse with axons from CN I
What is olfactory tract made up off?
Mitral cell axons
What occurs to the odor molecules?
They dissolve in moist mucus of sloughed on the olfactory epithelium
What if the odor molecules do not dissolve?
Then we won't be able to detect it
How does transduction occur in physiology of smell?
Dissolved molecules bind with olfactory receptor which opens NA, CA, CL channels leading to depolarize
Where does the AP of smell travel to?
Olfactory cortex and other limbic areas
What do the inhibitory cells of smell do?
- -they inhibit all but strongest impulses
- *located in bulb
**ignore other scents and only concentrate on the cookie smell you are following
Does the filiform contain taste buds?
No taste buds
What is filiform used for?
Used to provide a rough surface to pick up slippery foods so they won't slip away
What causes black hairy tongue disease?
Overgrowth of filiform Papillae
2 types of gustatory cells
Gustatory cells ) supporting function (3)
-cleans up extra NT that might have leaked out of synapse bw receptor cell and CN
-involved in structural integrity
-nutrition & waste removal
Gustatory cells ) receptor
Does transduction of particular taste
Taste buds cells) what do basal cells do?
- -replaces gustatory cells
- *they only live 7-10 days
What are the 5 basic tastes?
Physiology of taste) first steps (2)
-Molecules of food dissolve in saliva
-saliva goes through the crevices of Papillae and comes in contact with taste buds
What is a taste pore?
- A pore at the entrance of taste buds
- *gustatory hairs stick out here to articulate with saliva
Physiology of taste) transduction
Molecules from the food bind with receptor proteins in gustatory cell membranes and results in depolarization
Physiology of taste) Salty (3)
-food interacts with receptor
-sodium goes in producing depolarization of cell
-depolarization results in a NT being sent from Gustatory cell to synapse in CN
Physiology of taste) Sour (3)
-hydrogen enters the cell
-leads to NA and CA voltage gated channels to open
-depolarization occurs and causes migration of synaptic testicles & exocytosis of NT, which crosses the synapse to bind with CN
Physiology of taste) Bitter, sweet, UNami (3)
-food molecules interact with receptor
-activates G-protein mechanism which increases intracellular calcium levels, which then opens NA voltage channel that leads to depolazation as NA flows in
-also releases NT to CN
Depolarize gustatory cells release NT which..
Depolarize the synapsing sensory nerves
Neural pathways of taste) where do the 3 nerves that innervates the tongue send info to?
Medulla and thalamus
Neural pathways of taste) medulla function (2)
-triggers salivation and gastric juices
-also receives signals from 3 nerves
Neural pathways of taste) where does medulla and thalamus send signals? (2)
-taste cortex primary interpretation and
- -limbic system (emotion)
- *it taste good
- **reminds me of my mom cooking
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