Term
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Definition
| Skeletal muscles are controlled by the motor side of the somatic nervous system. Movement of skeletal muscles occurs in response to commands that are usually under conscious control (exceptions are certain postural and spinal reflexes) |
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Term
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Definition
| is represented by a highly complex network of neurons found in the walls of the gut. |
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Term
| The autonomic nervous system controls the following effectors: |
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Definition
-cardiac muscle
-smooth muscle
-glandular epithelium |
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Term
| In the somatic nervous system... |
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Definition
| a motor neuron in the spinal cord sends an axon through a peripheral nerve and make a direct synapse with skeletal muscle fibers. |
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Term
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Definition
| The axons of the first neurons are called pregalionic axons, and neurons themselves are called preganglionic neurons. |
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Term
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Definition
| The axons of the second-order neuron are called post ganglionic axons. The neurons themselves are called postganglionic neurons, even though their cell bodies are within the ganglia |
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Term
| Spinal cord Autonomic ganglia |
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Definition
| The first motor neurons of the sympathetic and parasympathetic branches of the autonomic nervous system are in the spinal cord, as in the case of the somatic nervous system. However, the efferent pathways of the sympathetic and parasympathetic autonomic nervous system involve groups of second-oder neurons that are located in autonomic ganglia outside of the CNS. The axons of the first motor neurons synapse with these second-order neurons, which in turn send their axons to the visceral effectors, i.e. cardiac muscle, smooth muscle or glandular epithelium. |
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Term
| There are three general goups of ganglia in the parasympathetic and sympathetic branches of the autonomic nervous . |
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Definition
-Paravertebral ganglia
-Collateral ganglia
-Terminal ganglia/Intramural ganglia |
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Term
| Paravertebral ganglia sympathetic trunk |
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Definition
| The paravertebral ganglia are arranged like a string of beads along either side of the vertebral column. The beads are the ganglia, and the whole string is the sympathetic trunk |
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Term
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Definition
| The second group also associated with sympathetic division. Ganglia in this group are called collateral ganglia. |
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Term
| Terminal ganglia (intramural ganglia) |
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Definition
| The third group associated with parasympathetic division. They belong to the parasympathetic division, and are located wither very close to the organ be innervated or are actually within the walls of the organ itself. In the gut, neurons in these ganglia input into the enteric branch of the autonomic nervous system. |
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Term
| Myelinated preganglionic axons of the sympathetic |
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Definition
| exit with somatic efferents through ventral roots of spinal cord segements T1-T12 and L1-L2. |
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Term
| White rami Paravertebral ganglion |
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Definition
| Once outside the vertebral column, white rami branch away from spinal nerve and connect with a paravertebral ganglion. The white rami are white because their fibers are myelinated. |
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Term
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Definition
| Once they have entered the parabertebral ganglion, the preganglionic fibers may: Form synapses with second-oder neurons in the paravertebral ganglion. The fibers of these second-order neurons are unmyelinated. These postganglionic fibers (=axons) emerge from the paravertebral ganglia in the gray rami and join the spinal nerve again. They innervate many organs, including the iris of the eye, the salibary glands, lungs, heart. |
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Term
| once they entered the paravertebral ganglion, the preganglionic fibers may: alternatively |
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Definition
| the preganglionic fibers may pass straight through the paravetabral ganglion without synapsing ( they are still called preganglionic because they haven’t synapsed yet). There after, these preganglionic fibers may do one of many things. |
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Term
| Preganglionic fibers that do not synapse in paravertebral ganglion. |
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Definition
| The preganglionic fibers may emerge from the paravertebral ganglion and pass up or down the sympathetic trunk before forming synapses with second-order neurons in other paravertebral ganglia. The unmyelinated axons of the postganglionic, second-order neurons rejoin the spinal nerves via the gray rami |
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Term
| Slanchinic nerves Colateral ganglia |
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Definition
| Instead of passig up and down the sympathetic trunk, the preganglionic fibers may emerge from the paravertebral ganglion in nerves called the splanic nerves, and form their first synapses with second-order neurons in the collateral ganglia. |
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Term
| Collateral ganglia include |
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Definition
celia ganglion
the superior mesenteric ganglion
the inferior mesenteric ganglion. |
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Term
| From second-oder neurons in the the collateral ganglia... |
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Definition
| unmyelinated post ganglionic axons distribute themselves to many organs. In the case of the celia ganglia, these organs include the stomach, spleen, liver, kidney and small intestine |
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Term
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Definition
| is one apparent exception to the general rule of two neurons in the efferent pathways of the symptheti and parasympthetic branches of the autonomic nervous system, some preganglionic axons from first neurons in the sympathetic nerves synapse directly on cells in the adrenal medulla. |
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Term
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Definition
| Secrete their neurotransmitters into the bloodstream. These neurotransmitters, more correctly called hormones, are norepinephrine and its close relative epinephrine (= adrenalin). |
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Term
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Definition
The parasympathetic division of the autonomic nervous system has its first neurons in two widely-sepatated locations of the central nervous system:
the head (cranial) end
the tail (sacral) end. |
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Term
| The cranial group of parasympathetic neurons is found |
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Definition
| in certain cranial nerve nuclei of the midbrain, pons and medulla |
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Term
| The sacral group of the parasympathetic neurons is found |
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Definition
| in the gray matter of the spinal cord segments S2-S4 |
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Term
| Cranial end of the parasympathetic division |
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Definition
| Parasympathetic preganglionic fibers exit cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal) and X (the vagys). |
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Term
| Parasympathetic: Cranial Nerve III (oculomotor) |
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Definition
ganglion:
- ciliary organ
- iris |
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Term
| Parasympathetic: Cranial Nerve VII (facial) |
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Definition
ganglion: pterygopalatine organs
-lacrimal (tear) glands and nasopharyngeal mucosa
-subamandibular organ
-salivary |
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Term
| Parasympathetic: Cranial X (the vagus) |
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Definition
| Ganglion: has its second neurons in the walls of organs (intramural ganglia) organs - lungs, heart, liver, stomach, small intestine, ascending colon |
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Term
| Sacral end of the parasympathetic division |
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Definition
| Collectively, the sacral parasympathetic outflow as preganglionic fibers from the ventral roots of S2-S4. These fibers constitute the pelvic splanchnic nerves. They synapse with second, postnglionic neurons in the walls of the urinary bladder, rectum, genital organs. These synapses are called intramural synapses. |
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Term
| Acetylcholine binds to two types of cell surface receptor: |
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Definition
-nicotinic receptors
-muscarinic receptors |
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Term
| Norepinephrine binds to two types of cell surface receptors: |
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Definition
-alpha-adrendergic receptors
-beta-adrenergic receptors |
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Term
| Distribution of neurotransmitter receptors |
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Definition
| -The membranes of sympathetic and parasympathetic postganglionic neurons have nicotinic acetylcholine receptors. -alpha and beta-adrenergic receptors are found on the membranes of cells that respond to norepinephrine. -Muscarinic acetylcholine receptors are found on the cells that respond to acetylcholine released from autonomic nerve endings. |
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Term
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Definition
| The cells of the adrenal medulla are modified postganglionic sympathetic neurons. When stimulated by preganglionic neurons they release catecholamines epinephrine (80%) and norepinephrine (20%) into the blood (epinephrine is another word for adrenalin). From the adrenal medulla, these catecholamines are swept by the bloodstream to many tissues and organs, so that sympathetic stimulation of the adrenal can have widespread action throughout the body. |
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Term
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Definition
| One receptor for acetylcholine is found in the postsynaptic membrane of both sympathetic and parasympatheic postganglionic neurons, and is called a nicotinic receptor. The motor endplate of the neuromuscular junction also has nicotinic receptors. nicotinic acetylcholine receptors are also found in the brain, where they are responsible for the effects of nicotine and nicotine addiction from cigarette smoking. The nicotinic receptor is an example of a ligand-gated ion channel. |
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Term
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Definition
| The second receptor for acetylcholine is found in the postsynaptic membrane of synapses formed by the second neurons of the parasympathetic division with visceral effectors. This receptor is called the muscarinic (so called because the toadstool toxin called muscarine acts as an agonist) |
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Term
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Definition
| Bind both epinephrine and norepinephrine. Alpha receptors are found in the walls of blood vessels |
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Term
| Beta-adrenergic receptors |
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Definition
| bind norepinephrine and epinephrine. Certain blood vessels have Beta receptors as well as alpha receptors in their walls. Beta-adrenergic receptors mediate the increase in force and rate of contraction of the heart when the sympathetic system is stimulated. |
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Term
| Sympathetic is involved in the fight-orflight response: |
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Definition
1) Pupils dilate
2) Heart rate and force of contraction increase
3) Blood vessels in skin and viscera contract.
4) dilation of bronchioles to allow faster movements of air into and out of the lungs
5) Blood vessels in skeletal muscles dilate
6) Liver glycogen is converted to glucose
7) Epinephrine and norepinephrine are secreted by the adrenal medulla 8) “Non-essential” activities are inhibited (e.g. activity of the gastrointestinal tract, such as digestive secretion and movement.) |
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Term
| Action of sympathetic and parasympathetic stimulation: pupil of eye |
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Definition
Symp - dialated
Para - constricted |
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Term
| Action of sympathetic and parasympathetic stimulation: glands (lacrimal, salivary) |
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Definition
sympathetic - no action or slight stimulation
parasympathetic - strong stimulation sweat
symp - strong stimulation (cholinergic)
para - no action Gastric symp - inhibition parasy - stimulation |
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Term
| Action of sympathetic and parasympathetic stimulation: stomach |
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Definition
symp - dcreased motility
para - increased motility |
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Term
| Action of sympathetic and parasympathetic stimulation: Heart |
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Definition
Symp - increased rate and force of contraction
Para - decreased rate (strong stimulation causes “vagal arrest”) |
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Term
| Action of sympathetic and parasympathetic stimulation: Lungs (smooth muscle in the bronchi and bronchioles) |
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Definition
symp - dilated
para - constricted |
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Term
| Action of sympathetic and parasympathetic stimulation: arterioles (skin, viscera) |
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Definition
symp - constricted
para - not innervated |
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Term
| Action of sympathetic and parasympathetic stimulation: veins and muscular venules |
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Definition
symp - constricted
para - not innervated |
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Term
| Action of sympathetic and parasympathetic stimulation: basal metabolism |
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Definition
symp - increased
para - not innervated |
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Term
| Action of sympathetic and parasympathetic stimulation: penis |
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Definition
Sym - ejaculation
Para - erection (also of clitoris in female) |
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Term
| Action of sympathetic and parasympathetic stimulation: liver |
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Definition
symp - glycogen --> glucose
para - moderate glycogen |
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Term
| Action of sympathetic and parasympathetic stimulation: intestine |
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Definition
Symp - decreased mobility, tone
Para - strongly increased mobility, tone |
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Term
| The autonomic reflex involves |
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Definition
1) a receptor
2) a sensory afferent neuron
3) one or more interneurons
4) a preganglionic motor neuron
5) a postganglionic motor neuron in an autonomic ganglion
6) an effector (smooth muscle, cardiac muscle, glandular) |
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Term
| The difference between somatic and autonomic reflexes |
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Definition
| The only real difference is the presence of two motor neurons in the efferent motor pathway, the second on being housed in a sympthetic or parasympathetic autonomic ganglion |
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Term
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Definition
1) A fall of blood pressure causes special stretch receptors (baroceptors) in the aortic arch and carotid artery to become less strech and to reduce their firing rate. this reduses the frequency of action potentials passing up the sensory axons neurons in the medulla.
2) this increases the firing rate of a group of neurons in the medulla
3) The neurons in the medulla signal to sympatheric motor neurons, which (via postganglionic neurons) cause the heart to increase its rate and force of contraction.
4) The sympathetic motor neurons also cause smooth muscle contraction in the blood vessels, narrowing them (=vasoconstriction). |
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Term
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Definition
-cardiac
-respiratory
-vasomotor
-swallowing
-vomiting |
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Term
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Definition
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Term
| Autonomic system: Cerebral cortex |
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Definition
| Control of the sympathetic and parasympathetic branches of the autonomic nervous system by the cerebral cortex seems to occur primarily during emotional stress (fear, anxiety, etc) |
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Term
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Definition
| the cerebral cortex operates through the limbic system. Note, however, that some components of the limbic system are actually cerebral cortex (e.g. the cingulate gyrus,) |
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Term
| Autonomic System: Hypothalamus |
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Definition
| The hypothalamus is the major output pathway of the limbic system, and the hypothalamus controls and integrates the autonomic nervous system. |
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Term
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Definition
| The hypothalamus in turn can stimulate centers in the pons and medulla. For example, the cardiac and vasometor centers in the medulla can increase heart rate, force of heart contraction, and ma rise the blood pressure. The micturition center in the pons regulates micturition. respiratory centers are found in the pons and medulla. |
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