NURS 1750 Lecture Notes - Lecture 7: Mitosis, Distorted Vision, Eyelid
28 Jun 2018
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Anatomy and Physiology
Chapter Seventeen: Special Senses (Pgs. 576 - 618)
Sensory Modalities
General Senses:
- Somatic: four modalities of somatic
- Tactile: Touch, pressure, vibration, itch and tickle.
- Thermal: coldness and warmth
- Proprioceptive: position of body parts and muscles
- Pain: fast and slow
Special Senses:
- Smell, taste, vision, hearing and equilibrium.
Sensory Receptors - Location
-Exteroreceptors: located at or near external surface of body- monitor external
environment.
- hearing, vision, smell, taste, touch, pressure, vibration and pain
-Interoreceptors: monitor the body’s internal environment.
-Proprioceptors: provide information about body position, muscle length and tension and
the position and movement of joints.
Sensation
→ For sensation to occur, four events need to happen:
1. Stimulus
2. Transduction
3. Generation
4. Integration
General Senses
→ Sensory receptors dependent on the type of stimuli
-Mechanoreceptor: mechanical stimuli- touch, pressure, vibration, proprioception,
hearing, equilibrium, stretch of blood vessels and organs
-Thermoreceptors: temperature
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-Nociceptors: painful stimuli-physical or chemical
- Nociceptors, the receptors for pain, are free nerve endings found in every tissue
of the body except the brain
-Photoreceptors: light on retina
-Chemoreceptors: chemicals in mouth (taste) nose (smell) and body fluids
Somatic Sensations - Pain Types
- Fast pain (acute, sharp or pricking) perceived in 0.1 second
- Slow pain (chronic, burning, aching or throbbing) is perceived a second or more after the
stimulus.
- Superficial somatic pain: arising from skin receptors.
- Deep somatic pain: skeletal muscles, joints, tendons and fascia.
- Visceral pain- pain sensors in visceral organs- presents in or just deep to the skin that
overlies the stimulated organ.
What is the Difference?
Pain Tolerance Pain Threshold
- Greatest intensity of painful
stimulation that a person is able to
tolerate.
- Individuals vary in their pain tolerance.
- Smallest intensity of a painful stimulus
at which a person perceives pain.
- All individuals have the same pain
threshold.
Somatic Sensations - Referred Pain
→ Referred pain is when pain is felt in another area. (ie. a urinary tract infection often
associated with low back pain)
-
Proprioception: recognizing position of body parts.
- Proprioceptors: in muscles and tendons.
Special Senses
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Order of Senses
- First order neuron –sensory impulse from the sensory
receptor to the central nervous system.
- Second order neuron – carries the information from the
central nervous system to the thalamus.
- Third order neuron – sensory information from the
thalamus to the cerebral cortex
decussates from one side to the other side of the CNS
(in pyramids) along 2nd order neuron.
Olfaction: Sense of smell
- Smell & taste are chemical senses called
chemoreceptors
- Nose: 10 -100 million receptors for smell (olfaction)
- Olfactory Epithelium: inferior surface of the cribriform
plate (ethmoid bone) and extends along the superior nasal concha
Olfactory Epithelium
- Receptor Cells:
- First-order neuron- olfactory pathway.
- Bipolar neuron.
- Knob-shaped dendrite.
- Axon-through cribriform plate- ends in the olfactory bulb
- Supporting Cells:
- Columnar epithelial cells lining mucous membrane.
- Physical support, nourishment, and electrical insulation.
- Detoxify chemicals
- Basal Cells:
- Stem cells- undergo mitosis.
- Produce new olfactory receptor cells- live for month -replaced
- Olfactory glands (Bowman’s glands) produce mucus that is used
to dissolve odor molecules so that transduction conversion into
electrical impulses) may occur
- Bowman’s Glands:
- Olfactory glands (Bowman’s glands) produce mucus -dissolve
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Document Summary
Proprioceptive: position of body parts and muscles. Exteroreceptors: located at or near external surface of body- monitor external environment. hearing, vision, smell, taste, touch, pressure, vibration and pain. Proprioceptors: provide information about body position, muscle length and tension and the position and movement of joints. For sensation to occur, four events need to happen: stimulus, transduction, generation. Sensory receptors dependent on the type of stimuli. Mechanoreceptor: mechanical stimuli- touch, pressure, vibration, proprioception, hearing, equilibrium, stretch of blood vessels and organs. Nociceptors, the receptors for pain, are free nerve endings found in every tissue of the body except the brain. Chemoreceptors: chemicals in mouth (taste) nose (smell) and body fluids. Fast pain (acute, sharp or pricking) perceived in 0. 1 second. Slow pain (chronic, burning, aching or throbbing) is perceived a second or more after the stimulus. Superficial somatic pain: arising from skin receptors. Deep somatic pain: skeletal muscles, joints, tendons and fascia.
