Somatic Sensations: II. Pain, Headache, and Thermal Sensations

Question 1

fast pain

Answer 1

Fast pain is also described by many alternative names, such as sharp pain, pricking pain, acute pain, and electric pain. This type of pain is felt when a needle is stuck intothe skin, when the skin is cut with a knife, or when the skin is acutely burned. It is also felt when the skin is subjected to electric shock. Fast-sharp pain is not felt in most deep tissues of the body

Question 2

slow pain

Answer 2

Slow pain also goes by many names, such as slow burning pain, aching pain, throbbing pain, nauseous pain, and chronic pain. This type of pain is usually associated with tissue destruction. It can lead to prolonged, almost unbearable suffering. Slow pain can occur both in the skin and in almost any deep tissue or organ.

Question 3

pain receptors are

Answer 3

free nerve ending which are superficially present in the skin and in some deep tissues as well like atrial wall, joint surfaces periosteum falx and tentorium of the cranial vault

Question 4

why deep tissue transmit slow pain

Answer 4

they are sparsely populated with free nerve endings so they transmit slow chronic aching type of pain

Question 5

what type of stimuli excite pain receptors (both type)

Answer 5

Pain can be
elicited by multiple types of stimuli, which are classified
as mechanical, thermal, and chemical pain stimuli. In
general, fast pain is elicited by the mechanical and thermal
types of stimuli, whereas slow pain can be elicited by all
three types.

Question 6

Some of the chemicals that excite the chemical type of

pain are

Answer 6

bradykinin, serotonin, histamine, potassium ions,
acids, acetylcholine, and proteolytic enzymes. In addition,
prostaglandins and substance P enhance the sensitivity of
pain endings but do not directly excite them.

Question 7

hyperalgasia

Answer 7

pain receptors
adapt very little and sometimes not at all. In fact, under
some conditions, excitation of pain fibers becomes progressively greater, especially for slow-aching-nauseous
pain, as the pain stimulus continues. This increase in sensitivity of the pain receptors is called hyperalgesia

Question 8

the pain is corellated to

Answer 8

the rate at which the damage is occurring and also the intensity of the pain is directly related to the damage occurring in the tissue

Question 9

what is extracted from damaged tissues or seen an increase in when tissues are being damaged

Answer 9

you can extract brandykinin which is a substance that causes most amount of pain
also an increase in potassium ions or proteolytic enzymes that attack the nerve endings

Question 10

what other 2 factors can be a cause of pain in muscles

Answer 10

muscle ischemia which is due to the accumulation of lactic acid due to anaerobic respiration and also could be due to release of bradykinin and proteolytic enzymes in the damaged tissues.
muscle spasm which directly induce mechanosensitive receptors and indirectly compress blood vessels causing muscle ischemia and increasing metabollic rate which furthur upsets the situation

Question 11

fast pain and slow pain pathway to spinal cord

Answer 11

The fast-sharp pain signals are elicited by either mechanical or thermal pain stimuli. They are transmitted in the
peripheral nerves to the spinal cord by small type Aδ
fibers at velocities between 6 and 30 m/sec. Conversely,
the slow-chronic type of pain is elicited mostly by chemical types of pain stimuli but sometimes by persisting
mechanical or thermal stimuli. This slow-chronic pain is
transmitted to the spinal cord by type C fibers at velocities
between 0.5 and 2 m/sec.

Question 12

Neospinothalamic Tract for Fast Pain.

Answer 12

The fast type
Aδ pain fibers transmit mainly mechanical and acute thermal pain. They terminate mainly in lamina I (lamina marginalis) of the dorsal horns, and there they excite second-order neurons of the neospinothalamic tract. These second-order neurons give rise to
long fibers that cross immediately to the opposite side of the cord through the anterior commissure and then turn upward, passing to the brain in the anterolateral columns.

Question 13

Termination of the Neospinothalamic Tract in the

Brain Stem and Thalamus.

Answer 13

few fibers of the neospinothalamic tract terminate in the reticular areas of the
brain stem, but most pass all the way to the thalamus without interruption, terminating in the ventrobasal complex along with the dorsal column–medial lemniscal tract for tactile sensations A few fibers also terminate in the posterior nuclear group of the thalamus.

Question 14

type of nerutransmitter released for fast pain fibers

Answer 14

glutamate

Question 15

Paleospinothalamic Pathway for Transmitting SlowChronic Pain

Answer 15

In this pathway, the peripheral fibers terminate in the spinal cord almost entirely in laminae II and III of the
dorsal horns, which together are called the substantia
gelatinosa, as shown by the lateral most dorsal root type
C fiber. nerve signals then pass through addditional short fibers within the dorsal horn and then lastly through long fibers and are transmitted to the other side of the cord through anterior commisure and then upward to the brain through anterolateral pathway

Question 16

neurotransmitter released from type C fibers

Answer 16

substance P which sends slow signals to cns and also glutamate which sends fast signals
thats why you have double pain sensation one by glutamate which is fast pain and other is the lagging signal send by slow pain send by type c through substance p

Question 17

Projection of the Paleospinothalamic Pathway (Slow-Chronic Pain Signals) into the Brain Stem and Thalamus

Answer 17

The slow-chronic paleospinothalamic pathway terminates widely in the brain stem very less terminate in thalamus
1) the
reticular nuclei of the medulla, pons, and mesencephalon;
(2) the tectal area of the mesencephalon deep to the
superior and inferior colliculi; or (3) the periaqueductal
gray region surrounding the aqueduct of Sylvius. These
lower regions of the brain appear to be important for
feeling the suffering types of pain,

Question 18

slow type of pain terminates in what areas and it has what effect on body

Answer 18

reticular area of the brain stem and the interlaminar nuclei of the thalamus cause overall arousal and spread excitability in the whole cns thats why you cant sleep when in chronic pain

Question 19

anaglesia system

Answer 19

This variation results partly from a capability
of the brain itself to suppress input of pain signals to the
nervous system by activating a pain control system, called
an analgesia system

Question 20

The analgesia system, consists

of three major components:

Answer 20

(1) The periaqueductal gray
and periventricular areas of the mesencephalon and
upper pons surround the aqueduct of Sylvius and portions of the third and fourth ventricles. Neurons from
these areas send signals to (2) the raphe magnus nucleus,
a thin midline nucleus located in the lower pons and upper medulla, and the nucleus reticularis paragigantocellularis, located laterally in the medulla. From these
nuclei, second-order signals are transmitted down the
dorsolateral columns in the spinal cord to (3) a pain inhibitory complex located in the dorsal horns of the spinal
cord. At this point, the analgesia signals can block the pain
before it is relayed to the brain.

Question 21

enkephalin

Answer 21

is the substance released by nerve endings in mostly periventricular periaqueductal gray area which transmits signs to gray horns of spinal cord to produce enkephalin locally which blocks transmission of type c and fast pain fibers

Question 22

referred pain

Answer 22

Often a person feels pain in a part of the body that is fairly
remote from the tissue causing the pain. This phenomenon is called referred pain

Question 23

why referred pain takes place

Answer 23

In the figure, branches of visceral pain fibers are shown to
synapse in the spinal cord on the same second-order
neurons (1 and 2) that receive pain signals from the skin.

Question 24

causes of true visceral pain are

Answer 24

ischemia
chemical stimula 
muscle spasm of hollow viscera 
overdistention of hollow viscus 
insensitive viscera

Question 25

Ischemia

Answer 25

Ischemia causes visceral pain in the same way
that it does in other tissues, presumably because of the
formation of acidic metabolic end products or tissuedegenerative products such as bradykinin, proteolytic
enzymes, or others that stimulate pain nerve endings.

Question 26

chemical stimuli

Answer 26

. On occasion, damaging substances
leak from the gastrointestinal tract into the peritoneal
cavity. For instance, proteolytic acidic gastric juice may leak
through a ruptured gastric or duodenal ulcer. This juice
causes widespread digestion of the visceral peritoneum,
thus stimulating broad areas of pain fibers. The pain is
usually excruciatingly severe.

Question 27

Spasm of a Hollow Viscus.

Answer 27

spasm of a portion of the
gut, the gallbladder, a bile duct, a ureter, or any other
hollow viscus can cause pain, possibly by mechanical stimulation of the pain nerve endings. Another possibility is
that the spasm may cause diminished blood flow to the
muscle, combined with the muscle’s increased metabolic
need for nutrients, thus causing severe pain

Question 28

cramps

Answer 28

cramps, with the pain increasing to a high degree of severity and then subsiding. This process continues intermittently, once every few minutes. The intermittent cycles
result from periods of contraction of smooth muscle. For instance, each time a peristaltic wave travels along an overly excitable spastic gut, a cramp occurs. The cramping type of pain frequently occurs in persons with appendicitis, gastroenteritis, constipation, menstruation, parturition, gallbladder disease, or ureteral obstruction.

Question 29

Overdistention of a Hollow Viscus.

Answer 29

Overdistention of a Hollow Viscus. Extreme overfilling of a hollow viscus also can result in pain, presumably
because of overstretch of the tissues themselves. Overdistention can also collapse the blood vessels that encircle
the viscus or that pass into its wall, thus perhaps promoting
ischemic pain

Question 30

Insensitive Viscera.

Answer 30

A few visceral areas are almost
completely insensitive to pain of any type. These areas include the parenchyma of the liver and the alveoli of the lungs. Yet the liver capsule is extremely sensitive to both direct trauma and stretch, and the bile ducts are also sensitive to pain. In the lungs, even though the alveoli are insensitive, both the bronchi and the parietal pleura are very sensitive to pain.

Question 31

sensations from the abdomen and thorax are transmitted

through two pathways to the central nervous system

Answer 31

the true visceral pathway and the parietal pathway. True visceral pain is transmitted via pain sensory fibers within
the autonomic nerve bundles, and the sensations are referred to surface areas of the body often far from the
painful organ. Conversely, parietal sensations are conducted directly into local spinal nerves from the parietal
peritoneum, pleura, or pericardium, and these sensations are usually localized directly over the painful area

Question 32

Hyperalgesia—Hypersensitivity to Pain what it is and types

Answer 32

A pain nervous pathway sometimes becomes excessively excitable, which gives rise to hyperalgesia. Possible causes of hyperalgesia are (1) excessive sensitivity of the pain receptors, which is called primary hyperalgesia, and (2) facilitation of sensory transmission, which is called secondary hyperalgesia. An example of primary hyperalgesia is the extreme sensitivity of sunburned skin, which results from sensitization of the skin pain endings by local tissue products from the burn—perhaps histamine, prostaglandins, and others. Secondary hyperalgesia frequently results from lesions in the spinal cord or the thalamus.

Question 33

Herpes Zoster (Shingles)

Answer 33

the dorsal root ganglion is infected and then there is pain in the dermatomal segment that is supplied by that root and pain in half of the body
pain is caused by the injected of pain neuronal cell of the dorsal root ganglion and the virus is also transported by the neuronal cytoplasmic flow through the peripheral neural fibers to theri cutenous origins and cause a rash

Question 34

tic doulorex

Answer 34

is a sharp stabbing pain on one side of face with has the sensory distrubution of 5th and 9th cranial nerves
it feels like an electric shock and always by a mechanoreceptor stimulus
eg when a bolus of food touches the tonsils it sets off the pain in mandbilar area supplied by 5th nerve
FIXATION: surgically cutting off the sensory root of the trigeminal nerve seperating it from the motor root so the jaw works fine
(SOMETIMES THERE IS A LESION IN THE SENSORY PART OF THE BRAIN STEM ELICITING THE PAIN)

Question 35

headaches of intracranial origin

Answer 35

tugging on the venous sinuses around the
brain, damaging the tentorium, or stretching the dura at the base of the brain can cause intense pain that is recognized as headache. Also, almost any type of traumatizing, crushing, or stretching stimulus to the blood vessels of the meninges can cause headache. An especially sensitive structure is the middle meningeal artery, and neurosurgeons are careful to anesthetize this arteryspecifically when performing brain operations with use of local anesthesia.

Question 36

Areas of the Head to Which Intracranial Headache Is

Referred.

Answer 36

imulation of pain receptors in the cerebral
vault above the tentorium, including the upper surface of the tentorium itself, initiates pain impulses in the cerebral
portion of the fifth nerve and, therefore, causes referred headache to the front half of the head in the surface areas supplied by this somatosensory portion of the fifth cranial nerve
Conversely, pain impulses from beneath the tentorium enter the central nervous system mainly through the glossopharyngeal, vagal, and second cervical nerves, which also supply the scalp above, behind, and slightly below the ear. Subtentorial pain stimuli cause “occipital headache” referred to the posterior part of the head

Question 37

headache of meningitis

Answer 37

One of the most severe headaches of all is that resulting from meningitis, which causes inflammation of all the meninges, including the sensitive areas of the dura and the sensitive areas around the venous
sinuses. Such intense damage can cause extreme headache pain referred over the entire head.

Question 38

Headache Caused by Low Cerebrospinal Fluid Pressure.

Answer 38

Removing as little as 20 milliliters of fluid from the spinal canal, particularly if the person remains in an upright position, often causes intense intracranial headache. Removing this quantity of fluid removes part of the flotation for the brain that is normally provided by the cerebrospinal fluid. The weight of the brain stretches and otherwise distorts the
various dural surfaces and thereby elicits the pain that causes the headache

Question 39

migraine headache

Answer 39

migraine headache starts with a prodromal sensations like loss of vision, nausea,visual aura
the pain is caushed by reflex vasospasm due to tension that causes ischemia in the blood arteries of the brain and the arteries supplying the breain. exhaustion of smooth muscles in ordered to keep the arteries falcid and inability to maintain normal vascular tone. aslo the bp cause the arteries to dilate and pulsate which stretches the wall of arteries ( temporal artery) that causes the pain
other theories are physiological abnormalities. cortical depression and increase level of k ions in the csf

Question 40

extracranial types of headache are

Answer 40

muscle spasm
irritaion of nasal and accessory nasal
caused by eye disorders

Question 41

muscle spasm

Answer 41

Emotional tension often causes many of the muscles of the head,
especially the muscles attached to the scalp and the neck muscles attached to the occiput, to become spastic, and it
is postulated that this mechanism is one of the common causes of headache. The pain of the spastic head muscles
supposedly is referred to the overlying areas of the head and gives one the same type of headache as do intracranial
lesions.

Question 42

Headache Caused by Irritation of Nasal and Accessory

Nasal Structures

Answer 42

The mucous membranes of the nose and
nasal sinuses are sensitive to pain, but not intensely so.
Nevertheless, infection or other irritative processes in widespread areas of the nasal structures often summate
and cause headache that is referred behind the eyes or, in
the case of frontal sinus infection, to the frontal surfaces of
the forehead and scalp,