Midterms: Pain and Thermal Sensation

Question 1

What are nociceptors, and what stimuli can activate pain sensation?

Answer 1

Nociceptors are pain receptors. They can be stimulated by mechanical, thermal, and chemical stimuli.

Question 2

Describe the types of nociceptors based on stimulus and location.

Answer 2

Types based on stimulus include high threshold mechanociceptors, chemical nociceptors, silent nociceptors, mechano-thermal nociceptors, and polymodal nociceptors. Based on location, they can be found in the skin, joints, and viscera.

Question 2

What chemicals stimulate nociceptors, and what are their effects?

Answer 2

Chemicals include bradykinin, substance P, histamine, nerve growth factor, potassium ions, serotonin, acetylcholine, and ATP. They induce pain, inflammation, and hypersensitivity.

Question 2

Explain the concept of double pain sensation and its significance.

Answer 2

Double pain sensation involves initial fast pain followed by slow pain. It helps alert the body to potential harm and ensures sustained awareness of injury.

Question 2

What are A Delta and C fibers, and what types of pain do they transmit?

Answer 2

A Delta fibers transmit fast pain, while C fibers transmit slow pain, both associated with tissue damage.

Question 2

How do pain receptors respond to stimuli, and what are the consequences of prolonged stimulation?

Answer 2

Pain receptors adapt minimally and may exhibit temporal summation, hyperalgesia, hypoalgesia, and allodynia. Prolonged stimulation increases pain fiber excitation.

Question 2

How do nociceptors respond to chemical stimuli, and what are some examples of these stimuli?

Answer 2

Nociceptors respond to chemical stimuli such as bradykinin, substance P, histamine, and prostaglandins, inducing pain and inflammation.

Question 2

What neurotransmitter is involved in fast pain transmission, and where is it secreted?

Answer 2

Glutamate is the neurotransmitter for fast pain transmission, secreted in the spinal cord at A Delta nerve fiber endings.

Question 2

Describe the pathways for pain sensation transmission in the spinal cord.

Answer 2

Pain sensations travel via the anterolateral system, including the neospinothalamic tract for fast pain and paleospinothalamic tract for slow pain.

Question 2

What are the characteristics of fast pain versus slow pain?

Answer 2

Fast pain is sharp, pricking, and acute, felt within 0.1 seconds after stimulation, while slow pain is burning, aching, and chronic, felt after 1 second or more.

Question 2

What are the CNS centers involved in pain sensation processing?

Answer 2

CNS centers include the reticular areas of the brainstem, the ventrobasal complex of the thalamus, and the somatosensory cortex.

Question 2

What are interneurons and transmission cells in pain processing?

Answer 2

Interneurons modulate pain signals, while transmission cells integrate nociceptive information. They include low-threshold, high-threshold, thermosensitive, and wide-dynamic range cells.

Question 2

Explain the concept of lateral inhibition in pain processing.

Answer 2

Lateral inhibition enhances contrast in sensory signals by inhibiting adjacent neurons. It improves the clarity of pain perception.

Question 2

Describe the types of pain fibers and their roles in pain sensation.

Answer 2

A Delta fibers transmit fast pain, while C fibers transmit slow pain. They terminate on relay neurons in the spinal cord, contributing to the perception of pain.

Question 2

What role do nociceptors play in the transmission of pain signals?

Answer 2

Nociceptors are free nerve endings that detect noxious stimuli and transmit pain signals to the spinal cord for further processing.

Question 2

What are the primary nerve fibers and secondary fibers involved in the anterior spinothalamic pathway?

Answer 2

Primary nerve fibers are C fibers, while secondary fibers are A Delta fibers.

Question 2

How does the rate of tissue damage correlate with pain sensation intensity?

Answer 2

Pain intensity correlates with the rate of tissue damage. Faster damage rates result in more intense pain sensations.

Question 2

Explain the process of temporal summation in pain processing.

Answer 2

Temporal summation involves the progressive increase in pain fiber excitation as a pain stimulus continues, leading to heightened pain sensation.

Question 2

Describe the role of glutamate in pain transmission.

Answer 2

Glutamate is the primary neurotransmitter for fast pain transmission, secreted at A Delta nerve fiber endings in the spinal cord.

Question 2

What is the significance of wide-dynamic range T-cells in pain processing?

Answer 2

Wide-dynamic range T-cells integrate inputs from various pain fibers and contribute to the localization and discrimination of pain modalities

Question 3

What are the key CNS centers involved in pain processing, and how do they contribute to pain perception?

Answer 3

Key CNS centers include the reticular formation, periaqueductal gray matter, thalamus, and somatosensory cortex. They contribute to pain perception by modulating sensory discrimination, affective responses, and autonomic reactions to pain.

Question 3

Describe the characteristics of the archispinothalamic tract and its role in pain sensation.

Answer 3

The archispinothalamic tract, similar to the paleospinothalamic tract, is multisynaptic and diffusely transmits pain sensations. It contributes to the sensation of diffuse and difficult-to-localize chronic pain.

Question 3

refers to reduced pain sensitivity during stressful events, such as predator attacks. It involves the release of norepinephrine and endogenous cannabinoids, which act on receptors in the brainstem and amygdala to dampen pain perception.

Answer 3

Stress-induced analgesia What are the three types of sensory receptors involved in thermal sensation?

Question 3

How does the anterior spinothalamic pathway contribute to the emotional component of pain?

Answer 3

The anterior spinothalamic pathway, characterized by C fibers, connects to brain centers involved in emotional processing, such as the limbic system, influencing the affective component of pain.

Question 3

bind to specific receptors in the nervous system, inhibiting pain transmission. They exert analgesic effects by inhibiting the release of neurotransmitters involved in pain signaling and modulating emotional responses to pain.

Answer 3

Endogenous opioids, such as enkephalins and endorphins,

Question 3

What temperature range activates cold receptors?

Answer 3

Cold receptors are activated by temperatures below 15 degrees Celsius.

Question 3

What is the gateway control theory, and how does it explain pain perception?

Answer 3

The gateway control theory suggests that the severity of pain sensation is determined by the balance of excitatory and inhibitory inputs to neurons in the spinal cord. Increased activity of non-painful sensory fibers can inhibit pain transmission, reducing the sensation of pain.

Question 3

What are the three types of sensory receptors involved in thermal sensation?

Answer 3

Cold receptors (Krause-end bulbs), warmth receptors (Ruffini’s endings), and pain receptors.

Question 3

Which type of nerve fibers innervate cold receptors?

Answer 3

Cold receptors are innervated by A-delta myelinated nerve fibers.

Question 3

At what temperature do warmth receptors respond?

Answer 3

Warmth receptors respond to temperatures above 30 degrees Celsius.

Question 3

What is the primary neurotransmitter released by type C nerve fibers in thermal sensation?

Answer 3

Glutamate is the primary neurotransmitter released by type C nerve fibers.

Question 4

What are the main classifications of pain sensation?

Answer 4

Physiologic or acute pain, pathologic or chronic pain, fast pain, and slow pain.

Question 5

How do thermal receptors adapt to temperature changes?

Answer 5

Thermal receptors adapt by altering their metabolic rates in response to temperature changes.

Question 6

What is spatial summation in thermal sensation?

Answer 6

Spatial summation occurs when multiple thermal receptors are activated, particularly in large areas of the skin.

Question 6

How does cortical control influence sensory sensitivity?

Answer 6

Cortical control modulates the intensity of sensory input by decreasing lateral spread of sensory signals and increasing signal sharpness.

Question 7

What is the function of the thalamus in somatic sensation?

Answer 7

The thalamus discriminates crude tactile sensation and plays a role in discriminating pain and thermal sensation.

Question 7

What are dermatomes, and how are they clinically useful?

Answer 7

Dermatomes are segmental fields of skin innervated by specific spinal nerves, clinically useful for assessing spinal cord injury levels and completeness.