Lecture 3: General Senses and Special Senses (Olfaction/ Taste) Flashcards
Where are sensory receptors located?
At the peripheral end of a sensory neuron.
Simple Receptors
- free nerve endings
- myelinated or non-myelinated
example: nociceptors (pain receptors)
complex receptors
-sensory endings are enclosed in specialized connective tissue.
ex: Pacinian corpuscle (sense touch)
special sense receptors
- specialized nerve cells or receptor cells that release neurotransmitters onto sensory neurons at a synapse.
the area monitored by a sensory receptors is called a
receptive field
how does the size and density identify sensitivity?
Size and density identify how sensitive you are to stimulus in that region of the body.
thermoreceptors
- sense temperature
- usually free ending in the dermis, skeletal muscles, liver, and hypothalamus
chemoreceptors
-respond to water and lipid soluble substances that are dissolved in body fluids (blood, CSF)
mechanoreceptors
- sensitive to stimuli that distort their plasma membranes (stretching, compression, twisting)
what are the three types of mechanoreceptors?
- Proprioceptors
- Baroreceptors
- Tactile receptors
- Proprioceptors
-monitors position of joints and muscles
-most structurally and functionally complex of general sensory receptors.
- Baroreceptors
-detect pressure change in walls of blood vessels and portions of digestive, respitory, and urinary tracts.
- Tactile receptors
- provide sensation of touch (shape or texture). pressure (degree and frequency of distortion) and vibration
Photoreceptors
- respond to electromagnetic radiation (light)
- only found in human eye
Nociceptors
- pain receptors
with free nerve endings with large receptive fields and broad sensitivity.
What are two types of axons that carry pain information?
Type A fibers
Type C fibers
Type A Nociceptors
-myelinated
- carry sensation of fast or prickling pain (such as cut/injection)
Type C Nociceptors
- unmyelinated
- carry sensation of slow, burning or aching pain (a bump or rug burn)
How are receptors classified?
Based on how they respond.
What are the two types of ways receptors are classified as?
- Tonic
- Phasic
Tonic
-do not adapt
-always active, either increase or decrease action potentials stimuli change
Phasic
- adapt
- inactive unless activated by stimuli
How does phasic work?
Once stimulus reaches a steady state? it turns off.
- this allows body to ignore information that has been evaluated and not found to be a threat to homeostasis (such as wearing clothes)
Olfaction
sense of smell
what happens when you inhale?
- when inhaling through nose, odorant chemicals are carried in the air that you breath.
-structures in nasal cavity including the nasal conchae (turinates) cause the airflow to become turbulent, directing some odorant chemicals to the paired olfactory orans located on the superior surface of the nasal cavity at the cribriform plate of the ethmoid bone.
Olfactory organs are composed of two layers. Which two are they?
- Olfactory Epithelium
- Lamina propria
- Olfactory Epithelium consists of.
- Olfactory receptor cells
- supporting cells
- basal cells
- Lamina Propria consist of
- areolar (connective) tissue
- numerous blood vessels
- nerve fibers
What does the lamina propria contain?
Olfactory glans which are secrete copious amount of mucus.
The mucus dissolves the airborne molecules
