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41 Cards in this Set
- Front
- Back
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-Relay signals of external stimuli (e.g., sight, sound) to the brain and spinal cord.
-Send signals from the brain and spinal cord to the I body (e.g., muscle, glands).
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Sensory Neurons
Motor Neurons |
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Divisions NS = ___ and ___ CNS = ___ and ___ PNS = ____ and ____; ____ emerging from or entering the CNS |
CNS and PNS
Brain and SC
Somatic and Autonomic; nerve |
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____ nervous system regulates conscious movements via efferent nerves exiting from the CNS to skeletal muscles. |
Somatic |
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The ____ nervous system regulates functions of internal organs, autonomously, i.e., independent of conscious effort, and is subdivided into the _____, ______ and _____ nervous systems. |
Autonomic parasympathetic nervous system (PSNS) sympathetic nervous system (SNS) enteric nervous system (ENS) |
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The ______ operates largely during relaxation (rest and digest), while the _____ operates largely during stressful conditions (fight or flight). |
parasympathetic nervous system (PSNS) sympathetic nervous system (SNS) |
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This is found within the walls of GI tract. It receives nerve impulses from the PSNS and SNS and influence from chemical mediators (e.g., serotonin, substance P) released by other types of neurons within the GI tract. |
enteric nervous system (ENS) |
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The enteric nervous system (ENS) controls ___, ____, and ___. Myenteric plexus and submucosal plexus are 2 networks of ____ and ____. |
motility, secretion and blood flow nerve cells and blood vessels |
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ANS can be classified anatomically, according to _____ and physiologically, according to ____. |
-origin of preganglionic fibers from the brainstem or spinal cord -the identity of the transmitter released from nerve terminal. |
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Anatomical classification of ANS:
PSNS -
SNS –
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-Cranial (brain and spinal cord) and sacral outflow.
-Thoracic and lumbar outflow.
(CTLS) |
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Physiologic classification of ANS:
Cholinergic –
Adrenergic – |
-Acetylcholine (ACh) is released from nerve terminal.
-Norepinephrine (or noradrenaline; NE) or epinephrine (or adrenaline; E) is released from nerve terminal. |
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The cell bodies of the _____ fibers of the sympathetic and parasympathetic nerves originate in the brain and spinal cord. Anatomy of PNS 1/6 |
preganglionic |
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Nerve impulses arising from the preganglionic fibers release this neurotransmitter at the synaptic cleft to activate these cells.
Anatomy of PNS 2/6
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Acetylcholine (ACh)
(All preganglionic nerves release ACh)
postganglionic
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The postganglionic cells subsequently send nerve impulses along their fibers to nerve terminals thereby causing the release of another transmitter (ACh, NE or dopamine) to the ______. Anatomy of PNS 3/6 |
effector organs/tissues. |
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All preganglionic nerves release ACh. Most postganglionic parasympathetic nerve terminals release ____. All postganglionic sympathetic nerve terminals release ___, or in a few cases _____, Anatomy of PNS 4/6 |
-Acetylcholine (ACh) -NE or DA |
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This is part of the SNS and is comprised of modified postganglionic cells.
Anatomy of PNS 5/6
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Adrenal medulla |
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The adrenal medulla releases ____ (85%) and ____ (15%) into the circulation. Anatomy of PNS 6/6 |
Epinephrine Norepinephrine |
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This is synthesized from acetyl CoA and choline within the cholinergic nerve terminals and is transported into and stored in vesicles.
An AP arriving at nerve terminal causes ______, fusion of the vesicular and cell membranes, and release of ACh by (exocytosis). |
ACh
Ca++ influx |
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ACh released at the cholinergic nerve terminals can bind and activate ____ ( ___ or ___) at effector organs to elicit a response, or be degraded by this enzyme.
There is negligible circulating ACh.
ACh release is blocked by this toxin. Injecting this toxin into a skeletal muscle prevents muscle contraction. |
cholinoceptors (aka cholinergic R) (nicotinic or muscarinic R)
acetylcholinesterase
botulinum (NB - sp.)
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Exception! BV are minimally inverted by parasympathetic NS -> PSNS has little control over BV caliber. However, injecting ACh intravenously can cause _____. What's the mech? |
Vasodilation ACh.MAChR on endothelial cells lining arterioles -> release nitric oxide (NO) -> diffuses to smooth muscle cells of arterioles -> dilation. |
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-Nicotinic receptors present in skeletal muscle at the postsynaptic side of the neuromuscular junction of somatic nerves are called?
-Nicotinic receptors present in autonomic ganglia (parasympathetic/sympathetic) are called? |
-neuromuscular nicotinic receptors (NM)
-ganglionic nicotinic receptors (NN) |
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These receptors are present in autonomic ganglia (parasympathetic/sympathetic). These receptors are present in effector organs of postganglionic parasympathetic nerves. |
-Nicotinic -Muscarinic |
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Nicotinic receptor agonists? |
Nicotine (an alkaloid), ACh (Both NM and NN) NB - blockers of NM and NN (e.g. tubocurarine and hexamethonium) are specific for NM or NN, respectively. |
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Muscarinic receptor agonists? |
Muscarine (an alkaloid) ACh, methacholine (synthetic drug) (likely more to come) |
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Two main types of adrenergic receptors (adrenoceptors) at effector organs/tissues? |
alpha (α1 or α2)-adrenoceptors beta (β1, β2 or β3)-adrenoceptors. |
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Epinephrine, the transmitter released by the adrenal medulla can bind to and activate which subtypes of adrenoceptors? |
all five: α1, α2, β1, β2 or β3 (~equal Ka) E for all |
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Norepinephrine, the transmitter released by the adrenergic nerve terminal, can readily activate four/five subtypes of adrenoceptors. |
α1, α2, β1 or β3 (~equal Ka)
NOT β2
NE for not B2 |
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Synthetic agonists of adrenoceptors
Phenylephrine binds?
Isoproterenol binds?
Salbutamol binds?
PIS 1 12 2 |
Phenylephrine: α1
Isoproterenol: β1 = β2 (~equal Ka)
Salbutamol: β2 |
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SNS - fight or flight reactions. SNS flight or flight reactions are mediated via released ____ and ___ from the _____ganglionic nerve terminals and/or _____, as well as by the presence of _______ at certain target tissues. |
NE and E postganglionic and/or adrenal medulla selective adrenoceptors (α1, α2, β1, β2 or β3) |
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PSNS - rest and digest activities. The firing of PSNS nerves releases ____ at autonomic _____ nerve terminals. |
ACh cholinergic |
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The influence of the PSNS depends on the presence of ____ nerves (release of ___) and presence of _______ receptors. |
PSNS ACh cholinergic (aka cholinoceptors) (nicotinic or muscarinic) |
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PSNS - rest and digest activities. Stimulate PNS: -> pupil _____ -> broncho______ -> _____ GI and urinary activities -> _____ heart rate.
Missing SNS CC? |
-> pupil constriction -> bronchoconstriction -> increased GI and urinary activities -> decreased heart rate.
(SNS are opposite) |
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General rules for adrenoceptor effects α1-Adrenoceptors -> ? |
contraction (e.g. BV) |
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General rules for adrenoceptor effects
α2-Adrenoceptors -> ? |
decrease sympathetic nerve activity and release of norepinephrine |
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General rules for adrenoceptor effects β1-Adrenoceptors -> ? |
increase heart rate and contractility |
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General rules for adrenoceptor effects β2-Adrenoceptors -> ? |
relaxation (e.g., vasodilation in lungs and bronchodilation), metabolic functions |
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General rules for adrenoceptor effects β3-Adrenoceptors -> ? |
lipolysis |
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Activities of the SNS and PSNS - name the R or fxn! (1/2) |
Try to see the trend in this... *PSNS is not innervating BV!!* |
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Activities of the SNS and PSNS - name the R or fxn! (2/2) |
This too... |
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Radial Muscle Innervation? Receptor? Effect of contraction/relaxation? |
SNS α1 Contraction -> mydriasis (dilation) |
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Circular Muscle Innervation? Receptor? Effect of contraction/relaxation? |
PSNS M Contraction -> miosis (constriction) |
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Ciliary muscle Innervation? Receptor? Effect of contraction/relaxation? |
The ciliary muscle is circular! Contract → reduce tension in the ligaments → lens becomes rounder → accommodation for a near object. |
