Nervous System Physiology Part 6 Flashcards
How many separate sensory areas are located in the anterior parietal lobe? What are they called?
There are two separate sensory areas:
* Somatosensory area I
* Somatosensory area II
What is the reason for the division into somatosensory area I and area II?
There is a distinct and separate spatial orientation of the different parts of the body in each of these two areas.
Which somatosensory area is more extensive and of much more importance for somatosensory perception? What term often refers to this area?
Somatosensory area I. In popular usage, the term “somatosensory cortex” almost always means area I.
What side of the body does each lateral side of the somatosensory cortex primarily receive sensory information from?
Almost exclusively from the opposite side of the body.
List the characteristics of somatosensory area I regarding the sensory projection system.
- Specific
- Specific, point to point
- Cause to specific sense and nerve impulses
List the characteristics of somatosensory area II regarding the sensory projection system.
Non-specific
* Common pathway, dispersion
* Maintain and change the excitability
What is the somatosensory cortex responsible for?
It is responsible for processing sensory input from various parts of the body.
Which body parts are represented by the largest areas in the somatosensory corte
The lips (greatest), face, and thumb.
How is the size of a body part’s representation in the somatosensory cortex determined?
By the number of specialized sensory receptors in that body part.
Which body areas are represented by relatively small regions in the somatosensory cortex
The trunk and lower parts of the body.
the somatosensory cortex, where is the head represented?
In the most lateral portion of somatosensory area I.
In the somatosensory cortex, where is the lower body represented?
Medially
What causes pain in the body?
Pain occurs when tissues are being damaged.
Why does the body react to pain stimuli?
To remove the pain stimulus
What is the pain ascending pathway?
It involves primary afferents with nociceptor endings synapsing on ascending neurons after entering the CNS.
Which neurotransmitters are involved in the pain ascending pathway?
Glutamate and the neuropeptide substance P.
How is pain suppressed by the descending pathway from the brain?
Descending inputs from the brainstem stimulate interneurons to release endogenous opiate neurotransmitters.
What effect do endogenous opiate neurotransmitters have?
They inhibit neurotransmitter release from afferent pain fibers and inhibit ascending neurons.
How does morphine affect pain pathways?
Morphine inhibits pain similarly to endogenous opiates by acting on opiate receptors.
What are the types of pain?
Fast and slow pain, deep pain, visceral pain, referred pain, and inflammatory pain.
What are the subtypes of inflammatory pain?
Hyperalgesia, allodynia, and pain from cytokine and growth factor release
What are the two major types of pain?
- Fast pain
- Slow pain
How quickly is fast pain felt after a painful stimulus is applied?
About 0.1 second.
How quickly does slow pain begin after a painful stimulus?
Begins only after 1 second or more and then increases slowly over many seconds and sometimes even minutes.
List the characteristics of fast pain (onset, duration, nature, afferent fibers, neurotransmitter, significance, localization).
- Onset: During application of the stimulus
- Duration: Short duration
- Nature: Pricking
- Afferent: A-delta fibers
- Neurotransmitter: Glutamate
- Significance: Determine site & severity; Initiate withdrawal reflexes.
- Localization: Well-localized
List the characteristics of slow pain (onset, duration, nature, afferent fibers, neurotransmitter, significance, localization).
- Onset: Shortly after application if tissue damage occurs
- Duration: Longer duration
- Nature: Burning
- Afferent: C-fibers
- Neurotransmitter: Substance-P
- Significance: Associated with arousal, autonomic & emotional reactions
- Localization: Poorly-localized
What may happen when incoming nociceptive afferents activate interneurons? What is this phenomenon called?
It may lead to the phenomenon of referred pain, in which the sensation of pain is experienced at a site other than the injured or diseased tissue.
What is believed to cause referred pain?
Convergence of visceral and somatic afferent neurons onto ascending pathways produces the phenomenon of referred pain.
What is referred pain
Pain perceived at a location other than the site of the painful stimulus, often from visceral organs to specific body surface areas.
Which body surface areas are associated with referred pain from the heart?
Chest and left arm
Which organ’s pain is often referred to the lower back?
Kidney
What is the function of the retina?
It transduces light waves into visual information.
What are photoreceptors in the retina?
Specialized cells (rods and cones) that detect light and initiate visual processing.
Besides photoreceptors, what other cells help process visual information in the retina?
Bipolar cells, ganglion cells, horizontal cells, and amacrine cells.
Which part of the eye contains the photoreceptors?
The retina
