Pain, Sleep & Spinal Cord: Key Concepts

Pain Transmission & Receptors

• C fibers transmit slow and burning pain.
• Free nerve endings are responsible for fast pain transmission.
• Substance P sensitizes nociceptors and contributes to inflammatory pain.
• Tissue hypoxia can cause intense visceral pain.
• The thalamus sends pain signals primarily to the somatosensory cortex.
• Parietal pain is well-localized and transmitted via somatic fibers, unlike visceral pain.

Sleep Regulation

• REM sleep is defined by high brain activity and rapid eye movements.
• The hypothalamus is heavily involved in regulating the sleep-wake cycle.
• Melatonin, primarily produced at night, is key in sleep regulation.
• Delta waves are most predominant during deep sleep (stages 3-4 of non-REM).

Spinal Cord & Brain Function

• The spinal cord has gray matter in the center and white matter in the periphery.
• Alpha waves are associated with a relaxed state of wakefulness.
• The gate control theory explains pain reduction through tactile stimulation.
• The lateral spinothalamic tract carries rapid pain signals to the brain.
• The cerebellum adjusts motor function by modulating coordination and precision of the movements.
• The reticular formation regulates muscle tone and posture.
• The tectospinal tract is involved in reflexive head and eye movements to visual stimuli.
• Lesions in the corticospinal tract result in paralysis and loss of voluntary motor control.
• The deep nuclei of the cerebellum transmit output signals.
• The left hemisphere is typically more related to language.
• The direct pathway of the basal ganglia facilitates movement by diminishing thalamus inhibition.

Reflexes

• The withdrawal reflex is a polysynaptic reflex.
• Reciprocal inhibition involves inhibiting antagonist muscles when agonists contract.
• Alpha motor neurons carry motor signals from the spinal cord to muscles.
• The withdrawal reflex is triggered by withdrawing from a painful stimulus.
• The spinal cord's main role in motor control is to generate reflexes and automatic movements.

Neurotransmitters & Synapses

• Calcium ions are essential for neurotransmitter release at synapses.
• Glutamate is the primary excitatory neurotransmitter in pain transmission.
• Axodendritic synapses are the most common in the central nervous system.
• Dopamine plays a key role in the function of the basal ganglia.

Motor Control & Movement

• Basal ganglia are involved in modulating voluntary movements and muscle tone control.
• Rhythmic movements like walking occur when central pattern generator circuits are active.
• The supplementary motor area coordinates postural and bilateral movements.

Memory & Learning

• Working memory is needed for solving immediate problems; it disappears quickly.
• The hippocampus is essential for synaptic plasticity and long-term learning.
• The area of Broca is crucial for language production.
• Declarative memory is most affected in Alzheimer's disease.
• The cerebellum receives both sensory and motor information to adjust movements.
• Reflex learning is NOT a type of learning related to the cerebral cortex.
• Caudal vermis controls axial movements and posture.
• The frontal lobe relates most to decision-making and abstract thought.
• Basal ganglia participate when forming implicit or procedural memory.

Cerebellum Structure & Damage

• The dentate nucleus serves as the primary output center of the cerebellum.
• The cerebellum primarily works to coordinate and adjust movements in motor control
• The prefrontal cortex relates to planning and executing complex tasks.
• Lesions to the cerebellum typically result in hypotonia and ataxia.

Hormones

• Corticotrophs secrete ACTH.
• Gonadotropic cells secrete follicle-stimulating hormone.
• Steroid hormones include cortisol.
• Thyroid hormones (T3 and T4) are lipo-soluble.
• The zona fasciculata of the adrenal cortex secretes glucocorticoids like cortisol.
• The pineal gland secretes melatonin. -Hypothalamic releasing and inhibiting hormones are amines.
• The zona glomerulosa of the adrenal cortex secretes mineralocorticoids, such as aldosterone.
• Chromaffin cells in the adrenal medulla secrete noradrenaline.
• Thyrotrophic cells secrete thyroid-stimulating hormone.
• Alpha cells secrete glucagon.
• Prolactin promotes milk release and secretion by the mammary glands.
• Follicle-stimulating hormone starts oocyte development

The Senses

• The retina's structure receives light & converts it to receptor potentials & nerve impulses
• The outer ear includes the auricle, the external auditory canal, and the eardrum.
• The spiral organ of Corti rests upon the basilar membrane
• Olfactory receptors come from basal cells
• The eye focuses images using the lens.
• The cochlea contains liquids, ducts, and membranes that transmit vibrations to the spiral organ (organ of Corti)
• Cranial nerves that innervate taste: facial, glossopharyngeal and vagus

Miscellaneous

• The amygdala is fundamental in the emotional modulation of memories.
• The corpus callosum connects the cerebral hemispheres, allowing communication.
• Mineralocorticoids increase blood levels of Na+ and water while decreasing blood levels of K+.
• Dynamic equilibrium maintains the body's position (mainly the head) with movements.