2)Pain Physiology Objectives and Concepts

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What is the name of the mechanism that inhibits pain impulses before they reach the upper levels of the brain?

Presynaptic inhibition

Enkephalin and endorphin system

Corticofugal pathway

Gate-control mechanism of pain inhibition (correct)

What is the role of GABAergic interneurons in the Gate-Control Mechanism of pain?

They increase the pain fibers' depolarization

They decrease the calcium entering the presynaptic cell

They increase the neurotransmitter release at the presynaptic terminal

They activate the enkephalinergic neurons in the dorsal horn (correct)

What is the effect of the GABAergic interneurons on the pain fibers in the Gate-Control Mechanism of pain?

They have no effect on the pain fibers' depolarization

They increase the calcium entering the presynaptic cell

They decrease the pain fibers' depolarization (correct)

They increase the pain fibers' depolarization

What is the effect of the decreased calcium entering the presynaptic cell in the Gate-Control Mechanism of pain?

It decreases the neurotransmitter release Signup and view all the answers

What is the effect of the decreased neurotransmitter release on the postsynaptic neuron (the 2nd order neuron of the pain) in the Gate-Control Mechanism of pain?

It decreases the postsynaptic neuron activation Signup and view all the answers

What is the purpose of the compensatory mechanism initiated by the stimulation of neurons in the periventricular and periaqueductal areas of the brainstem and hypothalamus?

To prevent the subject from dying due to pain shock Signup and view all the answers

Which type of nerve fibers transmit fast pain?

Myelinated A-delta fibers Signup and view all the answers

What is the main function of pain?

To provide a protective mechanism Signup and view all the answers

Which type of pain is transmitted by unmyelinated C fibers?

Slow pain Signup and view all the answers

What is the characteristic of slow pain?

It can create an unbearable feeling when prolonged Signup and view all the answers

Which type of pain is felt as burning, pinprick, knife wounded, electric shock, etc.?

Fast pain Signup and view all the answers

What type of stimuli can trigger fast pain?

Chemical, thermal, mechanical, or polymodal stimuli Signup and view all the answers

What is the main function of the facial nerve?

Motor function of the face Signup and view all the answers

What is the characteristic quality of neuropathic pain?

Burning, tingling, and electric shock-like Signup and view all the answers

What is the main symptom seen in trigeminal neuralgia?

Excruciating, episodic pain Signup and view all the answers

What is the main cause of thalamic pain syndrome?

Lesion in the thalamus Signup and view all the answers

Which of the following best describes the progression of the condition mentioned in the text?

It starts with a burning sensation, hyperalgesia, and allodynia. Signup and view all the answers

What is the mechanism behind phantom pain or phantom feeling?

It is caused by the sensory coding of previous pain sensation in the sensory cortex due to neural plasticity. Signup and view all the answers

What is the characteristic result of syringomyelia, according to the text?

It results in the weakening of the muscles in the hands and bilateral loss of pain and temperature sensation. Signup and view all the answers

Which of the following is the initial symptom of syringomyelia mentioned in the text?

Bilateral loss of pain and temperature sensation and paralysis Signup and view all the answers

What is the cause of the condition known as herpes zoster or shingles, according to the text?

It is caused by the reactivation of the chickenpox virus in the nerves. Signup and view all the answers

How does the chickenpox virus reach the spinal ganglia in the case of herpes zoster?

It is taken by the peripheral nerves and carried to the spinal ganglia by retrograde transport Signup and view all the answers

What physiological method of pain relief involves activating touch or proprioceptive pathways?

Acupuncture applications Signup and view all the answers

Which system is responsible for transmitting somatic sensations related to fine touch and vibration to the upper brain areas?

Dorsal column-medial lemniscal system Signup and view all the answers

What type of pain senses are carried by the lateral spinothalamic pathway?

Thermal senses Signup and view all the answers

In what part of the body does chronic pain fibers following acute pain pathways ultimately relay to?

Brainstem (reticular formation) Signup and view all the answers

What physiological response can lead to unconsciousness during severe pain or emotional shock?

Excess release of endorphins Signup and view all the answers

Which method of pain relief is thought to be dependent on lateral inhibition through inhibitory interneurons?