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79 Cards in this Set
- Front
- Back
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What does the CNS consist of?
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Brain and spinal cord
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What does the PNS consist of?
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Somatic and Autonomic nervous system
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What is the Enteric nervous system?
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"brain of the gut"
An extension of the ANS within the walls of the GI tract |
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Somatic vs. Autonomic in terms of neuron systems
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Somatic
-one neuron between CNS and target organ Autonomic -a ganglion existed between CNS and the target organs thus it is a 2-neuron system |
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Somatic vs. Autonomic in terms of effectors (target organs)
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Somatic
-voluntary: skeletal muscles Autonomic: -involuntary: smooth, cardiac, gland cells |
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Somatic vs. Autonomic in terms of afferents
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Somatic
-from skin (touch, temp, vibration, pain) and from muscle, tendoms, cartilages, and bone -they're called proprioceptors and nociceptors with precise localization Autonomic -Afferents are from involuntary organs -They're called mechanoreceptors, chemoreceptors, nociceptors (localized) |
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Somatic vs. Autonomic in terms of the exit of the spinal cord
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Somatic:
-ventral horn Autonomic: -interomediolateral column of the spinal cord and from the brain stem (preganglionic) -postgang is outside of CNS |
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Somatic vs. Autonomic in terms of axon myelination
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Somatic
-myelinated axons Autonomic: -Unmyelinated varicosities |
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Somatic vs. Autonomic in terms of number of affected cells
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Somatic:
-1 axon to 1 cell (myocyte) Autonomic: -1 axon to many cells |
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Somatic vs. Autonomic in terms of stimulation (excitatory vs. inhibitory)
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Somatic:
-stimulation is excitatory only -paralysis occurs in absence of nerve stimulation Autonomic: -can be both inhibitory and excitatory -effectors can be spontaneously active |
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Somatic vs. Autonomic in terms of neurotransmitter
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Somatic
-Acetylcholine Autonomic: -ACh and Norepinephrine (NE) -and peptides, purines, NO...etc. |
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Somatic vs. Autonomic in terms of receptors
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Somatic
-Cholinergic (subtype nicotinic) Autonomic -Cholinergic: nicotinic and muscarinic -Adrenergic: alpha and beta |
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Somatic vs. Autonomic in term of signal pathway and speed
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Somatic
-Sodium ion channels, very fast Autonomic -G proteins, 2nd messengers, slower transmission |
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Sympathetic vs. Parasympathetic in terms of preganglionic nerves origination
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Symp:
-Preganglionic nerves (myelinated) come from Thoracolumbar spinal cord (T1-L2/3) -ganglia include paravertebral chain and prevertebral chain (celiac, superior mesenteric, and infereior mesenteric) Parasymp: -Preganglionic nerves originate in the cranial and sacral regions of the CNS -Cranial outflow is CNIII, VII, IX, X -Sacral outflow is S2, 3, 4 |
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Sympathetic vs. Parasympathetic in terms of terminal location
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Symp:
-after the paravertebral chain, they spread to different varicosities in target organs -after the prevertebral chain, usually close to the target organs Parasymp: -terminal ganglia are close to or imbedded within the target organs -thus pregang nerves (myelinated) are long and postgang nerves (myelinated) are short |
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Sympathetic vs. Parasympathetic in terms of neurotransimtters released
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Symp:
-ACh released from all pregang (even in adrenal medulla) -NE released from most postgang -The exception is skin and skeletal: ACh (eccrine sweat glands) and ACh in arterioles of skeletal muscles Parasymp: -ACh released from all pregang -ACh released from all postgang |
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Describe the nerve fibers going for adrenal medulla
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Pregang innervation originates from thoracic spinal cord, passes through the sympathetic trunk WITHOUT synpasing, terminates on adrenal medullary chromaffin cells.
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What do the chromaffin cells contain?
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Epi and Norepi
Epi are more potent than NE, thus magnifies the effects of sympathetic nerve stimulation while also reaching targets with sparse or even no innervation |
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What is the neuroendocrine reflex and its significance?
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Secretion of epinephrine by the adrenal medulla
It imparts an important endocrine component to generalized sympathetic nervous system discharge |
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Fun fact: sympathetic and parasymp work together to have dual innervation in many organs, and they're often reciprocal (not anatgonistic)
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Example:
To slow the HR, medulla oblongata increases the firing rate of the vagus nerve to the heart while at the same time decreasing the firing rate of the sympathetic nerves to the heart Moral of the story, both divisions operate cooperatively and simultaneously. |
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Define the following reflexes:
Micturition Defecation Erection Ejaculation and how are they controlled? |
Micturition: emptying of the urinary bladder
Defecation: emptying of the lower colon and rectum Erection: self explanatory Ejaculation: same Control from the spinal cord at the lower lumbar and sacral level, also, control from higher centers of the CNS can facilitate or inhibit those rellexes |
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What are some reflexes controlled by the brainstem
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-Regulation of BP (medulla)
-Respiration (medulla and pons) -Salivary secretion (medulla and lower pons) -Vomiting (medulla) -Swallowing, coughing, sneezing (medulla) -Pupillary and lens accommodation (midbrain) |
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What is the hypothalamus?
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The "head ganglion" of ANS
The interface between higher centers (cortex and limbic system) and the brainstem and spinal cord |
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What is the function of hypothalamus?
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Regulates ANS, endocrine, and somatic systems
To maintain steady state (homeostasis), act upon emotional needs, and protect the body against perceived dangers |
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Fun fact: There's no BBB in the hypothalamus
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This allows the hypothalamus to sample contents of the blood from the hypothalamic blood vessels from moment to moment to allow it to initiate processes to correct any imbalance
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What is the limbic system?
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It's a subcortical group of structures which convey emotional states to specific hypothalamic nuclei
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What is the pathway for a fright response (from the limbic system)?
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Anterior cingulate cortex
Amygdala Hypothalamus |
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What is the pathway for a fight response (from the limbic system)?
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Prefrontal cortex
Amygdala Hypothalamus |
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How do the majority of the neurons communicate with other neurons and cells?
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Neurotransmitter (chemical messenger)
Traverses the synaptic cleft and activates receptors on target cells with great specificity |
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What are 3 ways for the removal of the transmitter from the synapse?
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Diffusion
Enzymatic degradation Reuptake (back into the axon that released it) |
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What are the amines neurotransmitters?
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Acetylcholine (ACh)
Catecholamines: EPI and NE, Dopamin, Serotonin (5-HT), histamine Amino acides Peptides Purines NO |
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Define the following:
Mimetic Lytics Adrengergic Cholinergic |
Mimetic - agents that mimic the effects of nerve stimulation
Lytic - anatogonists, the agents that block the effects of nerve stimulation Adrenergic - an agent that can act similar to epi and NE (symp) Cholinergic - an agent that acts similar to ACh (parasymp) |
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ACh vs. NE: in terms of where they're found
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ACh - ALL preganglionic in ANS (symp, parasymp, pregang of adrenal medulla); ALL postgang parasymp, and a few of postgagn symp, and also for skeletal muscle NMJ
NE - ALL postgang symp except: sweat glands, and skeletal muscle arterioles |
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What does acetylcholinesterase do?
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Breakdown of ACh in the synaptic cleft
1.) acetate diffuses away, choline reuptake |
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What are the two types of ACh receptors? and where are they found? and what are their signaling pathway?
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Nicotinic and muscarinic
Nicotinic is found in NMJ and in all symp and parasymp ganglia Muscarinic is found in the postgang target organs |
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What are the two types of ACh receptors? and what are their signaling pathway?
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Nicotinic and Muscarinic
Nicotinic - sodium ion channels (rapid) Muscarinic - G proteins (slow) |
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What are the subtypes of nicontinic receptors and where are they located?
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N_m: located in skeletal muscle fibers
N_n: located in autonomic gang (and adrenal medulla) with alpha and beta subunits |
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What are the subtypes of muscarinic receptors and where are they located?
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M1 through M5
In ANS, both M2 and M3 are located in cardiac, smooth, and gland cells. M2 are inhibitory where as M3 are excitatory |
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Fun fact: sympathetic and parasymp work together to have dual innervation in many organs, and they're often reciprocal (not anatgonistic)
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Example:
To slow the HR, medulla oblongata increases the firing rate of the vagus nerve to the heart while at the same time decreasing the firing rate of the sympathetic nerves to the heart Moral of the story, both divisions operate cooperatively and simultaneously. |
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Define the following reflexes:
Micturition Defecation Erection Ejaculation and how are they controlled? |
Micturition: emptying of the urinary bladder
Defecation: emptying of the lower colon and rectum Erection: self explanatory Ejaculation: same Control from the spinal cord at the lower lumbar and sacral level, also, control from higher centers of the CNS can facilitate or inhibit those rellexes |
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What are some reflexes controlled by the brainstem
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-Regulation of BP (medulla)
-Respiration (medulla and pons) -Salivary secretion (medulla and lower pons) -Vomiting (medulla) -Swallowing, coughing, sneezing (medulla) -Pupillary and lens accommodation (midbrain) |
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What is the hypothalamus?
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The "head ganglion" of ANS
The interface between higher centers (cortex and limbic system) and the brainstem and spinal cord |
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What is the function of hypothalamus?
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Regulates ANS, endocrine, and somatic systems
To maintain steady state (homeostasis), act upon emotional needs, and protect the body against perceived dangers |
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Fun fact: There's no BBB in the hypothalamus
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This allows the hypothalamus to sample contents of the blood from the hypothalamic blood vessels from moment to moment to allow it to initiate processes to correct any imbalance
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What is the limbic system?
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It's a subcortical group of structures which convey emotional states to specific hypothalamic nuclei
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What is the pathway for a fright response (from the limbic system)?
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Anterior cingulate cortex
Amygdala Hypothalamus |
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What is the pathway for a fight response (from the limbic system)?
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Prefrontal cortex
Amygdala Hypothalamus |
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Describe the cholinergic transmission (synthesis to receptors)
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Synthesis from choline and acetate
Storage in vesicles Release by exocytosis Enzymatic removal by AChE, major removal mechanism) Uptake of choline (acetate diffuses away) Resynthesis of choline and acetate Receptors (muscarinic and nicotinic) |
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Describe the adrenergic transmission (synthesis to receptors)
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Synthesis by intraneuronal enzymes
Storage in vesicles Release by exocytosis Removal by uptake (both intra and extraneuronal) Enzymatic destruction by MAO (monoamine oxidase, intraneuronal and extra) and COMT (extraneuronal) Receptors are alpha 1 and 2, and beta 1, 2, 3 |
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What are the two synthetic analogs of catecholamines and which receptors do they have the most affect on (alpha and beta)
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Phenylephrine (PE) and isoproterenol (ISO)
PE works on alpha and no effect on beta ISO works on beta and no effect on alpha |
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What are the ways for drug to increase availability of transmitter in synapses, thus thereby enhancing or prolonging its action?
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-protein synthesis
-inhibit uptake -stimulate release -inhibit enzyme that inactivate the transmitter -inhibit autoreceptors |
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What are the ways for drug to decrease availability of transmitter in synapses, thus thereby enhancing or prolonging its action?
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-inhibit synthetic enzyme
-block exocytosis (blocking release) -stimulate autoreceptors (blocking release) |
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Fun fact: the chronic use of potent psychopharmaceuticals can lead to dire consequences
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as receptors are down-regulated (by overuse of agonists), or upregulated (by overuse of blockers)
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Define desensitization and supersensitivity
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Desensitization: repeated or prolonged exposure to an agonist
(i.e. nose sprays, insulin resistance leads to type-2 diabetes) Supersensitivity: denervation, injury (horner's: pupil dilation by low concentration of EPI in blood) and chronic exposure to receptor blockers (tardive dyskinesia: chronic use of antipsychotic drugs which block dopamine receptors) |
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Fun fact: Sympathetic nerve from cervical and upper thoracic chain ganglia innervate all myocardial tissue (atria and ventricles, SA and AV). In this case, beta-1 receptors up HR, force of contraction, and velocity of conduction (by both EPI, the hormone, and NE, the transmitter
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Parasympathetic innervation is by the VAGUS nerve. The neurons only innervate the SA and AV nodes and the atria (not the ventricles)
Muscarinic receptors decrease HR, conduction velocity, and force of contraction Bottomline: the vagus nerve has more of an effect on the SA node than the sympathetic nerves |
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Fun fact:
Alpha-1 adrenergic receptors on the SM of blood vessels mediate vasoconstriction Beta-2 adrenergic recetpors on SM on blood vessel (skeletal and coronary arterioles) vasodilate in response to EPI in blood |
Thus, all blood vessels with a SM layer have at least some sympathetic innervation but NO PARESYMPATHETIC innervation, except in erectile tissue blood vessels
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The baroreceptor reflex, what is it and describe the afferent and efferent limb
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It serves as moment-to-moment regular of BP to maintain a steady state
Afferent is the in the carotid and aortic sinuses which detect pressure (9th and 10th cranial nerves) Efferent includes the sympathetics innervating the heart, all arterioles, and small veins (not in the CNS) and parasymp motor of the vagus innervating the nodal tissues and atrial muscle of the heart |
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Where is the center of the baroreceptor reflex? and what is its function?
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Medulla oblongata
There's a set point in BP: a rise in BP will decrease symp and increase vagus (lowering HR and resistance) A drop in BP will then increase the symp and decrease the vagaus parasymp, increasing HR and peripheral resistance |
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What does the splanchnic bed refers to and how can it be controlled?
And fun facts about it |
It is the BV of the abdominal and pelvic visceral organs
vasoconstrict by symp when other organs need blood in constant regulation by baroreceptor reflex and higher centers Contains nearly half the circulating blood volume at rest |
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How are the skeletal muscle blood vessels controlled?
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The muscle at rest has constricted BV: most of its nerves are noradrenergic vasoconstricturs, acting on alpha_1 adrenergic receptors
The muscles that are active have local metabolites that are the primary dilators |
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How are the kidney vessels controlled? and fun facts about it
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The symp nervous system regulate the renal blood flow (more intrinsic) and it participates in the serection of renin
The symp are vasoconstrictor, acting at alpha 1 adrenergic receptor During exercise, kidney vessels vasoconstrict, lowering urine formation rate. But due to control within the nephron, urine formation never cease Intrinsic mechanisms in the kidney are more important regulators of renin than the sympathetic nerves |
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About the renal vessels (part of the splanchnic bed)
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Afferent arteriole is wider than efferent, promoting the ultrafiltration in glomerulus
Vasoconstriction reduces filtration = secretion of renin (a sympathetic discharge) Stimulates Na and water absorption, raises BP Constriction occurs at EFFERENT arteriole (to allow for adequate glomerular hydrostaic pressure) |
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How is the skin controlled?
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Symp constricting skin BV via alpha-1 adrenergic receptors
Dilation is passive by decreasing the symp activity Emotion can also regulate skin BV via the limbic system During hot, symp shunt blood to the surface by decrease symp firing to dissipating heat During cold, symp increase firing to constrict BV to surface |
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Fun fact about control of skin: the hypothalamus controls skin blood vessels during regulation of body temperature
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A heat retention center and heat dissipation center reside in separate nuclei in the hypothalamus
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Hot sweat vs. Cold sweat
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Hot sweat stimulated by cholinergic neurons in the symp chain gang, with the receptor being muscarinic cholinergic
Cold sweat simulated by EPI and the receptors are alpha1 adrenergic receptors During cold sweat, EPI is released during fight/flight and trigger vasoconstriction and sweating |
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ANS control of lung
Fun facts about symp and parasymp |
Symp from thoracic chain ganglia dilate bronchioles via beta-2 receptors (increasing airflow)
Parasymp from the vagus contract bronchiolar SM via muscarinic receptors (restricts airflow in the lungs) |
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ANS control of the eyes
Fun facts about symp and parasymp |
Symp from the two superior cervical ganglia, innervate the pupillary radial muscle, all blood vessels within and outside the eye, and muller's muscle (superior tarsal muscle in the eyelids)
parasymp from the 3rd cranial nerve (this is part of COPS), innervates the pupillary sphincter muscle and the ciliaris muscle of the ciliary body Also for parasymp, CN VII also innervates the lacrimal glands |
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What are mydriasis and miosis
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Mydriasis: pupillary dilation when light is dim
Miosis: pupillary constriction when the light is bright Both act by contraction of SM |
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Describe lens accommodation by the ciliaris m.
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For far vision, the ciliaris muscle is relaxed, lens flatten, lower refractive power
For near vision, the ciliaris muscle contracts (by parasymp innervation), lens gives a rounder shape, more refractive power |
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Describe Horner's syndrome
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Partial or total sympathetic denervation of the eye, usually due to damage to the superior cervical ganglion or its nerve trunk in the neck, resulting in the following:
1.) miosis (narrow pupil) 2.) ptosis (lid lag) 3.) flushed facial skin (vasodiliation) 4.) failure to sweat 5.) No effect on parasymp functions: lens accommodation, salivary, aqueous humor, lacrimation are intact (remember Horners only affect symp) 5.) supersensitivity to EPI in blood |
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ANS control of GI
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Salivary: parasymp by CN VII and CN IX secretes watery fluid and enzymes (muscarinic); symp by the superior cervical gang secretes mucous glands (alpha-1 adrenergic) and innervating the blood vessels
Walls and glands of GI tract: parasymp innervates everything in GI to stimulate motility and secretion via SM cells, gland cells, and neurons of the intrinsic plexuses (muscarinic); whereas symp will do the exact opposite (alpha-1 receptors) Sphincters: see walls and glands above, similar actions |
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ANS control of defecation and micturition
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Defecation:
-Somatic relax sphincter, permitting parasymp reflex -Parasymp then contract rectal and sigmoid colon walls, relaxes sphincter and wham! Micturition: when bladder wall detects stretch, it sends signal back to the reflex center to have a desire to empty bladder; symp is inhibitory by contracting the trigone sphincter and relaxing the detrusor muscle; parasymp then do the exact opposite to pee |
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Describe how the sympathetic nervous system would affect the following:
Liver (glycogenolysis and gluconeogensis) Lipolysis Insulin release Renin release |
Liver: Epi affecting beta-2 and alpha 1, raising blood glucose by breaking down glycogen (glycogenolysis), and generating glucose from AA's (gluconeogensis). Therefore, EPI mobilizes glucose as energy reserves
Lipolysis - using adipose tissue to mobilize energy Insulin release - inhibit the release Renin release - stimulates the release |
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Fun fact: during F/F, posterior hypothalamic nuclei stimulate the sympathetics causing changes in:
Cardio Lung Skin Eyes Metabolism GI GU Describe the changes |
Cardio: increase BP, HR, force of contraction, and conduction velocity, vasoconstricting in skin and splanchnic organs
Lung: bronchioles dilation Skin: cold sweat and piloerection Eyes: dilated pupils and flat lens, open eyelids Metabolism: mobilzation of glucose and free FA's GI and GU: down motility and secretion and urine formation |
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Describe the hypothalamic-pituitary-adrenal axis
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Turns on during stress (along with F/F)
Corticortropic-releasing hormone (CRH) stimulate release of ACTH (from ant. pituitary) ACTH stimulate the secretion of CORTISOL The major significance of cortisol is that it can support adaptation to stress: short-term: rise in BP by gluconeogensis, and mobilization of free FA's by lipolysis long-term (not a good thing): connective tissue breakdown, suppression of immune response, interferes with wound healing |
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Fun fact: parasympathetic response is specific, not generalized, meaning the simultaneous discharge of all of the craniosacral parasympathetic nerves at once is pretty fucking dangerous
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Here's why:
First, what cranial nerves are we talking about: III, VII, IX, X III: contraction of ciliary muscle (near vision) VII: lacrimation, salivation IX: copious secretion from parotid (saliva) X: AV node slows and stops wall with decrease contraction, bronchiolar constriction (labored breathing), diarrhea with increased motility in walls Sacral: urination, defecation, vasodilation in erectile tissue Skin: sweating |
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Fun fact about prolong ACh stiumulation by inhibiting acetylcholinesterase: Since ACh stimulate muscarinic receptors with greater potency than nicotinic
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Oftentime, atropine, a muscarinic block is used to prevent fatal heart stoppage
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When ACh inhibitors activate both sympathetic and parasympathetic divisions, which divisions has more influence on more organs?
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Parasymp: HR, GI and GU motility and secreation, lens accommodation, aqueous humor secretion and lacrimation
Symp: force of contraction, conduction velocity, blood vessels (total peripheral resistance), distribution of blood flow, mobilization of stores of carbs, fat, and protein Pupillary reflexes are 50:50 by both |
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What kind of influences do the following receptors have on the effector organ:
Alpha-1 Alpha-2 Beta-1 Beta-2 Beta-2 M2 muscarinic cholinergic receptors M3 muscarinic cholinergic |
Alpha-1: excitatory, contraction of smooth muscle, contraction of sphincter in GI and bladder, contraction of ducts and glands in reproductive tract, secretion of sweat
Alpha-2: inhibitory, opposite of alpha-1 Beta-1: excitatory, stimulate all heart functions, lipolysis (mobilizing fat), release of renin Beta-2: inhibitory, relaxes SM and relaxes lung bronchioles (increasing air flow to lungs), response best to EPI and not NE Beta-3: promote lipolysis M2: inhibitory actions on the heart and relaxation of sphincher in the GU M3: excitation; release motility, promote glandular secretion |
