Pain, Orgasm, and Enteric Sensations Flashcards
Or: "the bad, the good, and the ugly"
What pathway does pain take to reach the brain?
The anterolateral pathway
Describe the concept of reffered pain
When pain is sensed anywhere other than the origin of the pain
Caused by the skin and visceral organs acting on the same anterolateral pathway (DIFFERENT DRGs)
Describe the Gate control theory of pain
Inhibitory interneuron – Projection neuron – anterolateral pathway to brain
(inhibitory interneuron inhibits projection neuron)
C fibres: inhibit inhibits inhibitory interneuron and excites projection neuron
Aalpha/Abeta fibres: Excite inhibitory interneuron and projection neuron
Brain’s “central influence” can stimulate inhibitory interneuron
Why do Adelta fibres react faster than C fibres?
They are myelinated
Why does a small infection of shingles cause a wide band of pain in a patient?
It infects a single dermatome
Somatosensation is ___lateral
Ipsilateral
eg damage to left side of dorsal column leads to loss of touch sensation in left side
True/False? reflexes do not recruit brain activity
True
Why do people rub their wounds?
Touch stimulates inhibitory interneurons in the spinal cord via activation of Aalpha and Abeta fibres
What types of mechanoreceptor are most prevalent in the clitoris? What other cells are there?
FA I and FA II
Also free nerve endings
*Krause-Finger’s corpuscles (receptor for cold)
Describe the distribution of mechanoreceptors in the penis
SA are very prevalent in the tip of the penis, and FA are more seen along the shaft
What is a possible role of SA receptors on the penis? Why do we think this?
Possible intromission guide
Removal in sensory afferents in animals results in loss of proper mounting orientation
What is the Pudendal nerve and what is its function?
Carries sensory & motor signals from genitals and anus
(receives signals from dorsal penile nerve/clitoral nerve)
Buildup of sensory signals believed to take place in spine, and stimulates hypogastric nerve when threshold is reached
Do most afferents leaving the gut respons more to mechanical or chemical stimuli?
Both
Mechanoreceptors of contraction and distension is carried out by __________
Receptors in series
Low threshold enteric afferents carry sensations of ______ whereas high threshold afferents carry _____
Both types can be sensitized by ________
Fullness/gas
Pain
Chemical irritation
