____ - works with the medulla for balance, posture, and breathing regulation.

______ - Helps control eye movement, relays auditory and visual

system signals.

Medulla - Arterial Baroreceptor Reflex

Carotid arteries signal via ____nerve to _______ nerve (CN IX).

While aortic baroreceptors signal via _____ nerve (CN X)

Medulla - Arterial Baroreceptor Reflex

A decrease in pressure will reduce signals sent to the VMC

The VMC sends signals via the autonomic nervous system to the

circulation to either?

(choose all that apply)

What are Decussations?

nerves relaying pain signals cross over at ______

_____ - areas of brain with crossings of only axons

(eg, corpus collosum)

The cerebellum receives signals about posture from the spinal cord, also known as ________.

The cerebellum receives motor information from the cerebral cortex, info about balance from vestibular organs of _______.

Damage to what area of the brain would cause the following?

hypotonia, ataxia (unsteady ‘drunken’ gait), and intention tremor, etc

Thalamus and hypothalamus

(the diencephalon)

_____ - processes sensory info going to cerebral cortex, processes motor info coming from cerebral cortex

(on way to brain stem and spinal cord)

Thalamus and hypothalamus

(the diencephalon)

most sensory systems synapse with the thalamic nuclei, which

send signals to appropriate cerebral cortex area.

What area of the brain does NOT synapse at the thalamus?

Basal ganglia, hippocampus, amygdala

______ - composed of the caudate nucleus, putamen, globus pallidus, substantia nigra, subthalamic nuclei.

______ - receives input from ALL lobes of cerebral cortex, send projections -> via thalamus -> to frontal cortex to regulate movement

Basal ganglia, hippocampus, amygdala

In general, ______ (from the substantia nigra) inhibits excessive caudate nucleus and putamen signaling to cortex.

Basal ganglia, hippocampus, amygdala

In general, GABA produced by _______ inhibits over-activity of many structures of the basal ganglia.

_______ - is the excitatory neurotransmitter released by the

basal ganglia nuclei.

(Note: structures reduced by signal from globus palladus)

Basal ganglia, hippocampus, amygdala

The following are part of what system?

Hippocampus is for memory.

Amygdala is for emotions.

Diseases of basal ganglia lead to

hyperkinetic and hypokinetic

disorders.

Early sign - jerky trajectory of hand when reaching to touch a spot.

Later sign - hyperkinetic choreiform movements.

(rapid, involuntary ‘dancing’ movements, appear until incapacitate patient)

_______ - iatrogenic disease due to long-term use of

neuroleptic drugs such as phenothiazides or haloperidol.

Note: Drugs work by blocking dopaminergic transmission, and results in hypersensitivity of D3 dopaminergic receptors, causing imbalance in putamen and caudate nucleus response to

dopamine from substantia nigra.

Diseases of basal ganglia lead to hyperkinetic and hypokinetic disorders.

_______ - has both hypokinetic and hyperkinetic features.

Note: One of the most common neurodegenerative diseases, sporadically

occurring in many middle-aged and elderly individuals.

Note: ~60,000 new diagnoses each year.

Note: Symptoms appear when 60-80% of substantia nigra dopamine-producing neurons degenerate.

Note: lack of facial expression, lack of normal ‘fidgety’ actions and gestures.

Virtually all info coming to or from cerebral cortex processed through relay nuclei of thalamus. Contains different types of neurons, such as?

______ – with long axons to synapse at other relay nuclei or in cerebral cortex

_____ – form neuronal ‘bridges’ from lower to upper neurons; may bridge relay nuclei

SENSORY INFORMATION

_______ - level of stimulus

necessary to be aware of particular sensation

Process that conveys information regarding the body

surface and its interaction with the environment.

(Somatosensation)

____ - discriminative touch.

____ - temperature.

____ - painful, mainly chemical, but also mechanical and thermal.

Somatosensation must be distinguished from proprioception.

________ - information regarding body movement and position.

(Note: muscle and joint receptors and the vestibular system)

Somatosensory receptors: the first-order sensory afferent neurons.

1) Free nerve endings

- receptors; nociceptors, hairy (aka: ______ ) skin mechanoreceptors, thermoreceptors.

- Found at hair roots (detects motion)

and with nociceptors (pain receptors).

- Nociceptors are _____, hair root are ________.

2) Enclosed nerve ending receptors & free ending touch receptors [hairless (glabrous) skin].

- _______(sense vibration, rapid adapting).

- Ruffini (sense stretch of skin, slow adapt)

- _______(sense texture, sliding; flutter and stroking; rapid adapt)

- _____receptors are bare nerve endings, most sensitive, sense shape

and texture (shallow in skin), slowly adapt.

- All mechanoreceptors

3) specialized cell endings receptors.

- Example shown is found in ear.

-All _______.

_______: slow adapting receptors

responding for the duration of a stimulus.

______: rapidly adapt to a

constant stimulus – turn off.

(only sensitive to CHANGE in stimulus, NOT duration)

Discriminative touch receptors.

1) _____ receptor – steady pressure, texture.

2) ____corpuscle – flutter, stroking

3) Pacinian corpuscle – vibration

4) ______ corpuscle - stretch

- Have specialized secondary structures to

pick up specific mechanical stimuli

- e.g. onion-like connective tissue

Location of the receptors.

(Superficial vs Deep)

_______: Pacinian corpuscle, Ruffini corpuscle.

______: nociceptors, thermoreceptors, Merkel and Meissner corpuscle.

Acuity: the ability to precisely localize a stimulus.

- The lips have the _____ acuity (2-point discrimination threshold~1 mm).

- The calf has the _____ (threshold ~48 mm).

Note: 2-point discrimination is tested when nerve damage is suspected, as well as when monitoring nerve regeneration.

Temperature receptors of skin, 2 types.

1) ____receptors - Sense temps lower than body temperature.

2) ____receptors - Activated above body temperature to about 45 C (113 F).

(Note: Pain receptors (nociceptors) activated above 45 C)

________ – unresponsive to mechanical stimulation, but become ‘awakened’ in response to tissue inflammation after injury.

(Note: have reduced threshold, can cause hyperalgesia)

______ - secreted by primary sensory neurons at peripheral injury sites, also mediate

inflammatory response (neurogenic inflammation).

Sensory information processing involves 3 fundamental steps.

1) _______– involving a sensory receptor sensitive to a particular type of energy or chemical,

which converts stimuli into action potentials that travel -> toward the CNS.

2) ________– the neural pathway that nerve signals take to get to a terminal point in the CNS;

modulation of the signal may occur during transmission.

3) ________– via the primary and association sensory cortex, where the action potentials are

-> interpreted into a sensation.

Sensation – the type of sensory signal leading to a perception

Nociception is the _______ (being sent to brain).

Pain (processed and interpreted in brain) is the ________.

Somatosensory pathway.

- Starts with activation of peripheral ______ (primary) afferent, ending in -> cerebral cortex.

- Primary afferent, a pseudounipolar neuron with cell body in the _____ or _____(peripheral) ganglion.

- Primary afferent axon synapses with a ______afferent neuron in spinal cord or brain stem nucleus.

- The secondary afferent synapse with tertiary afferent neurons in _______ or thalamus

- Axons cross over to the opposite side ______ level of thalamus

- All somatosensory pathways include _________– when stimulated, thalamic nuclei

send axons to cerebral cortex (usually terminatin in parietal lobe).

Neospinothalamic pathway

carries sharp prickling pain and cool/cold, via type______ primary afferent

Medial lemniscal pathway

Transmits body discriminative touch and proprioception, via ____ primary afferent

______ - ‘slow pain’ slow to perceive but persists (intense) – make up ~70% all nociceptive fibers.

Gate-control theory of pain.

Stimulation of touch _____ can decrease pain perception due to convergence of inputs

onto spinal cord neurons

(Note: this is why rubbing skin in area of injury helps relieve pain)

Efferent analgesic system: inhibits afferent pain signals.

Mechanisms:

- pain afferents stimulate neurons in_____ (PAG) in the ____(PAG surrounds cerebral aqueduct).

- Stimulation of PAG in rats allowed surgery on rats with no anesthetic, with animals

not exhibiting ____!

- Neurons from PAG project to ________ (clusters of serotonin-producing neurons).

Activated raphe neurons project to _____interneurons in dorsal horn throughout spinal

cord (and also to thalamus and frontal lobes), where they inhibit or block transmission of

_________ (blocks pain before relayed to brain)

ANALGESIC NT

Projections of Raphe nuclei releases _______on inhibitory neurons, where it causes the release of ______.

Enkephalin causes presynaptic & postsynaptic inhibition of incoming ___ and __ pain fibers, where they synapse in the _____ horns.

ANALGESIC NEUROTRANSMITTERS

(Enkephalin summary)

-Reduces strength of nociceptive message from primary sensory nerve.

&

-Hyperpolarizes secondary sensory nerve, thus reducing probability of generating action potential for further transmission of pain signal.

(NOTE: this pathway is involved in pain inhibition response during acutely stressful events, and pain relief from taking opioid meds)

Endogenous opioids.

Three classes of opioid receptors, includes Mu, delta, kappa – all widely distributed in brain.

Q1) Interacts with the opioid peptides:

beta-endorphin (___receptors)

enkephalins (___receptor)

dynorphins (___receptor)

Sources of Pain, and their pathways.

1) _____Pain (classification)

A) cutaneous, superficial or peripheral pain.

&

B) deep pain.

CUTANEOUS, SUPERFICIAL, OR PERIPHERAL PAIN

- Pain from skin and muscles or peripheral nerves themselves

This pain has two components – (a) initial response, followed by (b) later response.

1. Sharp pricking pain (via A delta fibers) reaches the CNS via ______ tract, which

allows for immediate awareness of a painful sensation and for awareness of exact location.

2. Burning and soreness pain (via C fibers) resulting from tissue damage reaches the CNS via

the ________tract

( integrated with limbic areas, allowing for emotional processing of pain, activating descending pain suppression pathways).

________tract (which will mediate visceral, emotional and autonomic reactions to pain)

DEEP PAIN.

- joint receptors tendons and fascia (i.e., deep structures), producing dull, aching or burning pain.

- Deep pain is accompanied by a definite ______response associated with sweating and nausea,

changes in blood pressure and heart rate.

- Somatic deep pain reaches the CNS mainly via the ______ and _____tract (as is visceral pain).

VICERAL PAIN

In visceral organs, nociceptors respond to mechanical stimulation such as pressure, tissue damage, and chemical stimulation (mostly via silent nociceptors).

- Most visceral afferents does not give rise to _____sensation – if do, is poorly localized.

- Visceral pain is ____, less precisely graded and typically accompanied by slowing of the

heart, lowered blood pressure, cold sweats and nausea (strong autonomic response).

- It conveys also hunger, thirst, electrolyte balance, irregularity in the ______and

circulatory systems.

VICERAL PAIN

These signals reach the CNS bilaterally by the following three channels:

1) _____ nerves innervating the body wall and diaphragm

2) ______ nerves (via splanchnic afferents – mostly in deep viscera)

3) ________ nerves (via vagal afferents)

VISCERAL PAIN

NOTE: Visceral pain caused by chemical means (e.g. GI lesions), tumors, and thrombosis of artery will frequently not be localized to the site of cause, but to a distant site (referred pain)

NEUROPATHIC PAIN

A sharp, shooting and devastating pain

A persistent pain that arises from functional changes occurring in the CNS secondary to

peripheral nerve injury.

- Once the nerve is damaged, the damaged nerve elicits sustained activation of ______ and/or nociceptive afferents.

- Neuropathic pain is due to ______activation of the nociceptive system without specifically stimulating the nociceptors.

REFERRED PAIN

A painful sensation at site other than the injury (localized to a distant site).

One possible explanation.

- axons carry pain information from the viscera enter into the spinal cord by the same route as

the ______ pain sensation axons

- Within spinal cord the sensory information converges on the same __________.

- Convergence gives rise to the phenomenon of ________.

(NOTE: pain associated with angina pectoris, or myocardial infarction is referred to the left chest, left shoulder, and upper left arm)

CLINICAL ABNORMALITIES OF PAIN & OTHER SOMATIC SENSATIONS

Hyperalgesia

- Excessively excitable pain nervous pathway, possible causes

1) Excessive sensitivity of pain receptors themselves (primary hyperalgesia)

2) Facilitation of sensory transmission (secondary hyperalgesia)

The following is an example of?

Q1) extreme sensitivity of sunburned skin (due to excessive histamine, prostaglandin production at burn)

The following is an example of?

Q2) lesions in the spinal cord or thalamus, such as Herpes Zoster/shingles (goes 1⁄2 around the body).

(Note: herpersvirus infects dorsal root ganglion, causing severe pain in the dermatomal segment subserved by the ganglion)

(Note: skin eruption occurs, causing ‘shingles’)

Perception of pain

Ascending pathway to cerebral cortex -> Becomes conscious sensation once reaches

-> ____CNS (pain or itch)

THALAMUS & CORTEX ENABLES PERCEIVING, DESCRIBING, AND LOCALIZING PAIN

- Parts of the thalamus, brainstem and reticular formation identify ______, and diffuse

pain – independent of cerebral cortex. However, identifying location of pain is vague.

- The _______ is required to precisely localize and fully perceive pain sensations.

- The reticular formation and _______ control the emotional and affective response to pain.

- Because the cortex, thalamus and brainstem are interconnected with the _______ and

autonomic nervous system, the perception of pain is associated with an _______response.

what forms the nucleus pulposus?

The anterior neuropore closes during week 4 (day 25) and becomes the _________

Note: Failure of the anterior neuropore to close results in upper neural tube defects (NTDs; e.g., anencephaly).

The posterior neuropore closes during week 4 (day 27). Failure of the posterior neuropore to close results in _____

The rostral part of the neural tube becomes the _____

The caudal part of the neural tube becomes the ____