Neuro - ANS Flashcards by Alyssa Santos

A system that is totally involuntary and without conscious awareness. It came from the visceral motor division of the peripheral nervous system. It controls glands, cardiac muscles and smooth muscles but NOT skeletal muscles. It targets the organs of the thorax, abdominal cavity, blood vessels, sweat glands and muscles in the skin.

Autonomic Nervous System

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ANS motor neurons that conduct impulses from the spinal cord or brain stem to the effectors. (3)

Cardiac muscle tissue, smooth muscle tissue of blood vessel and organs, and glandular epithelial tissue.

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Two divisions of the ANS

Sympathetic and Parasympathetic division.

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ANS effectors have ______- they are innervated by both the sympathetic and parasympathetic fibres.

Dual innervation

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Division of the ANS that covers the thoracic and lumbar spine. It has dendrites and cell bodies in the grey matter of the thoracic and upper lumbar segments of the spinal cord. It is also known as the thoracolumbar division as the nerve fibres comprising this division arise off the cord between T1-L1. It has 2 kinds of neurons-preganglionic and postganglionic neurons. All in all, it functions as an emergency system. (fright, flight, fight system)

Sympathetic Nervous System or SNS or Thoracolumbar division.

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SNS neurons that leave the spinal cord and terminate collateral ganglia.

Preganglionic Neuron

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SNS neurons that leaves the collateral ganglia and terminates in smooth muscle, cardiac muscle or glands.

Postganglionic Neuron

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Division of the ANS that promotes homeostasis when the body is at rest. It has dendrites and cell bodies located in the grey matter of the brain stem and the sacral segment of the spinal cord. It is also known as the craniosacral division as the nerve fibres comprising this division arise in the brain stem and off the cord. Preganglionic neurons travel long distances and terminate on postganglionic neurons near organs and glands. It functions mainly as a vegetative system.

Parasympathetic Nervous System or PaSNS or Craniosacral Division.

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PaSNS cranial nerves. (4)

Oculomotor
Facial and Glossopharyngeal
Vagus (x nerve)

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PaSNS cranial nerve that innervates smooth muscle within the eye itself and causes pupil constriction.

Oculomotor Nerves

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PaSNS cranial nerves that innervate the salivary glands.

Facial and Glossopharygeal Nerves.

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PaSNS cranial nerve that carries about 75% of PaSNS output. It innervates most thoracic and abdominal glands.

Vagus (X nerve)

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PaSNS output in the sacral area (Pelvic splanchnic nerves) operates.. (3)

Bladder, reproductive organs, & large intestine/rectum.

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PaSNS nerves in the sacral area.

Pelvic sphlanchnic nerves.

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↑ HR and strength of contraction
↑ BP, release of epinephrine, & sweat secretions
Dilate blood vessels in skeletal muscles, pupils, & respiratory passages
↓ peristalsis, digestive secretion, salivation
Inhibit defecation and bladder function

Sympathetic Control

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↓ HR, strength of contraction, & BP
↑ peristalsis, salivation, & digestive secretions
Stimulate contraction of bladder
Constricts the pupils & respiratory gases

Parasympathetic Control

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To supply (an organ or other body part) with nerves.

Innervate

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Bring to an end.

Terminate

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Sympathetic ganglia which lie between the para-vertebral ganglia and the organ of supply. They are also called the prevertebral ganglia, receive input from the splanchnic nerves and innervate organs of the abdominal and pelvic region. These include the celiac ganglia, superior mesenteric ganglia, and inferior mesenteric ganglia.

Collateral ganglia

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3 organs that only have sympathetic innervation.

Blood vessels, sweat glands, & adrenal medulla

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Sympathetic stimulation causes ____ of smooth muscle in the vessel wall resulting in increased vascular changes.

Contraction

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Vasodilation occurs in the CVS by SNS causes..

↑ blood flow to skeletal muscle and organs

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Vasoconstriction occurs at the cutaneous membrane by SNS causes..

↓ blood flow, blood; renal blood flow is shunted to the heart and intestinal blood flow shunted to skeletal muscles.

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Increases SNS stimulation increases stimulation to the sweat glands thus increases..

sweat production.

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A high spinal cord transection (above T1) essential eliminates the sympathetic response and the patient has difficulty in ____ their body.

cooling

A condition in which the nerves inside the spinal column become damaged

Spinal cord transection

Organ in which increased SNS stimulates the release of the hormones E and NE.

Adrenal Medulla

Several varieties of molecules with axon terminals of neurons that are released into the synaptic cleft in response to a nerve impulse and affect the membrane potential of the postsynaptic neurons.

Neurotransmitters and receptors

3 possible effects of synapses

1. Stimulated or inhibited by other NT, drugs, or toxins. 2. Removed from synaptic cleft. 3. Binding to the receptor site.

NT that is released by the PNS and CNS neurons.

Ach or Acetylcholine

NT that is released by post-ganglionic sympathetic nerves.

Epinephrine and Norepinephrine.

2 major types of neurons, receptors and NT present in the ANS.

Cholinergic and Adrenergic

Cholinergic NT

Ach or acetylcholine

3 Cholinergic neurons (that secretes Ach)

1. All the sympathetic and parasympathetic preganglionic neurons. 2. Sympathetic postganglionic neurons to sweat glands. 3. All parasympathetic postganglionic neuron.

2 Cholinergic receptors.

1. Nicotinic receptors | 2. Muscarinic receptors

Cholinergic receptors that is present in the plasma membrane of dendrites and cell bodies and motor end plates at neuromuscular joints.

Nicotinic receptors

Cholinergic receptors that is present in the plasma membrane of smooth muscles, cardiac muscle and glands including sweat glands.

Muscularinic receptors

Ach binds to both nicotinic and muscarinic. True or False.

True.

What part of the neuron is Ach released

Synaptic cleft

What enzyme continuously inactivates Ach

Acetylcholinesterase (Ach-ase)

Adrenergic NT

NE, E (aka adrenaline and noradrenaline)

Adrenergic Neurons

all mostly postganglionic neurons

Adrenergic Receptors

1. Binds NE and E | 2. Two types of receptors a and b which are further divided in α1, α2, β1, β2, β3.

The activity of NE and E at a synapse is terminated either when.. (2)

1. The presynaptic neuron take up the NT (reuptake occurs) or 2. The NT are inactivated by catechol-O-mathyltransferase (COMT) or monoamine oxidase (MAO).

Adrenergic receptor of NE&E. - Found mostly in the heart but can also be found in the kidneys and adipose tissue. - ↑ HR and force of contraction - ↑ Conduction thro AV node - ↑ fat breakdown stimulates renin release by the kidneys

β1

Adrenergic receptor of NE&E. - Found mostly in the lungs and other sympathetic target organs. Abundant in blood vessels serving the heart, liver and skeletal muscles. - Mostly inhibitory; vasodilation of deep coronary arteries; vasodilation of blood vessels of skeletal muscles; bronchodilation of bronchi and bronchioles; relax uterus and urinary bladder smooth muscles. - ↓ GI muscle tone/activity/secretion - ↑ HR and force of contraction

β2

Adrenergic receptor of NE&E. - Found in the adipose tissue. - Stimulate fat breakdown by fat cells.

β3

Adrenergic receptor of NE&E. - Found in blood vessels. Most importantly in blood vessels serving the skin, mucosae, abdominal viscera, kidneys and salivary glands, also, virtually all sympathetic target organs except the heart. - Vasoconstriction in deep coronary vessel, most blood vessels in the viscera, blood vessels in the skin. - ↑ peripheral resistance & blood vessels. - Close sphincter of bladder - Dilates pupils in the eyes.

α1

Adrenergic receptor of NE&E. - Found in the membrane of adrenergic axon terminals; pancreas, blood platelets. - inhibits NE release from adrenergic terminals; inhibits insulin secretion by pancreas, promotes blood clotting - Vasoconstriction of deep coronary vessel

α2

All the adrenergic receptors are found in the post synaptic neuron except what receptor..

α2, it is located in the right side of the pre-synaptic neuron.

Any neuron that releases Ach

Cholinergic

Any neuron that releases NE&E

Adrenergic

The only NT released by the PaSNS

Ach

In the PaSNS chain; the 1st neuron is myelinated while the 2nd neuron is not. True or false

True

In the PaSNS chain, the first receptor on the 2nd neuron is the muscarinic receptor while the 2nd one near the target organ is the nicotinic receptor. True or False

False; the other way around

In the SNS the 1st neuron release what NT

Ach

In the SNS what kind of receptors are in the 2nd neuron

Nicotinic Receptors

The spinal cord is composed of 5 divisions

``` Cervical (8) Thoracic (12) Lumbar (5) Sacral (5) Coccygeal (1) ```

Two connections of spinal nerves

1. Posterior (dorsal) root | 2. Anterior (ventral) root

Connection of spinal nerves that only contains sensory fibres which conducts impulses from the periphery to the spinal cord. It has a swelling called the dorsal root ganglia which contains the cell bodies of unipolar sensory neurons.

Posterior (dorsal) root

A swelling of the posterior (dorsal) root which contains the cell bodies of unipolar sensory neurons.

Dorsal root ganglia

Connection of spinal nerves that contains axons of motor neurons which conduct from the CNS to effectors (ie., muscles, glands, cells)

Anterior (ventral) root

Posterior and anterior roots unite to form a spinal nerve at the __________.

intervertebral foramen

Because the posterior root contains sensory axons and the anterior root contains motor axons; a spinal nerve is a _______.

mixed nerve

Spinal nerve covering consists of (3)

Endonerium Perineurium (Fascicles) Epinerium

Covers the axon of a myelinated or unmyelinated neuron.

Endonerium

Groups of endonerium wrapped axons forming a bundle of axons.

Fasciles

A bundle of axons is covered by a ____

Perineurium

Covers the entire spinal nerve.

Epineurium

Except for the thoracic nerves, the anterior portion or ventral rami of spinal nerves tend to be braided together to form a network called ______ on the right and on the left sides of the body.

Plexuses; a network of spinal nerves

4 Nerve Plexuses

1. Cervical plexus (C1-C5) 2. Brachial plexus (C4-T1) 3. Lumbar plexus (L1-L4) 4. Sacral plexus (L4-S4)

Plexus that serves the skin and muscle of the head, neck, superior shoulder and diaphragm.

Cervical plexus (C1-C5)

The nerve that serves the diaphragm.

Phrenic nerve (C3-C5)

Plexus that serves the shoulders and upper limbs.

Brachial plexus (C4-T1)

Plexus that serves the anterior and lateral abdominal wall, external genitalia and parts of the lower limb.

Lumbar plexus

The femoral nerve is formed from ___-____.

L2-L4

Plexus that serves the buttocks, perineum and lower limbs.

Sacral plexus

The THICKEST AND LONGEST NERVE IN THE BODY that is formed from L4-S3; extends the length of the thigh and sends branches into hamstring muscles and the adductor magnus.

Sciatic nerve

Each spinal nerve except C1 receives sensory input from a specific area of the skin called _____. It is a mapping of the regions of the skin innervated by each spinal nerve.

dermatome

Dermatome overlap considerably, therefore if a sensory nerve root is cut sensation is not totally lost from that dermatome; _______ have to be severed or anaesthesized in order to have a total loss of sensation.

3 successive dermatomes

Spinal nerve damage can be assessed with _____ on dermatomes.

pinprick

A one-way system comprised of an ascending tract and a descending tract. - Myelinated. They are only CNS and one way, up or down! Nerves carry both ways.

Spinal tracts

All nerve fibres in a tract have a similar ___, _____, and ____.

origin, destination and function.

Many nerve fibres have their origin or destination in the ____,

brainstem.

Several of these tracts _______ as they pass up and down the brainstem and spinal cord. Hence the left side of the brain receives sensory info from the right side of the body and send motor commands to that side, and the right side of the body get info and direct the left side of the body.

decussate

(of two or more things) cross or intersect each other to form an X.

decussate.

The origin and destination of a tract are on the opposite side of the body.

Contralateral tract

The origin and destination of a tract are on the same side of the body.

Ipsolateral tract

In ascending tracts, signals usually travel via 3 neurons from their origin (at the receptor) to their destination (in the brain). The axons of these neurons are called _______.

third-order nerve fibres

3 neurons of the ascending tract (ordered)

1. First order neuron 2. Second order neuron 3. Third order neuron

Neurons of the ascending tract that detect the stimulus and takes it to the spinal cord or brain stem.

First order neuron.

Neurons of the ascending tract that takes the sign from the 1st order neuron to the thalamus.

Second order neuron

Neurons of the ascending tract that carries the signal to the sensory division of the cerebral cortex.

Third order neurons.

4 Major ascending tracts.

1. Gracile Fasciculus 2. Cuneate Fasciculus 3. Spinothalamic 4. Spinoreticular tract

Ascending tract that originate below T6 and carries signal from the mid-thotacic region and lower parts of the body. - 1st order neuron travels ipsolaterally and end at the medulla. - Carry signs of visceral pain, vibration and proprioception (ie., nonvisual sense of position and movement of the body) from lower limb to lower trunk.

Gracile fascilucus

Major ascending tract that originate from T6 and upper. It carries the same sensory info as the gracile and join it at T6. Occupies the lateral portion of the dorsal column.

Cuneate fasciculus

Major ascending tract that passes up the anterior lateral columns of the spinal tract. - It carries signs of pain, temp, pressure, light and crude touch. - 1st order neurons end in the dorsal horn of the spinal cord - 2nd order neurons decussate to the opposite side to form spino-thalamic tract - 3rd order neuron goes to the cerebral cortex

Spinothalamic tract

Major ascending tract that carries pain signs resulting from tissue damage to the reticular formation in the medulla and pons.

Spinoreticular tract

Tracts that carry motor signal from the brainstem to the spinal cord.

Descending tract

2 neurons involved in the descending tract

upper and lower neuron

Upper neuron has a soma in the cerebral cortex or brain stem and axons that terminate on the ________in the brainstem or spinal cord.

lower neuron

____ of the lower neurons go directly to muscles or other target organ.

Axons

4 Major Descending Tracts

1. Corticospinal 2. Tectospinal 3. Reticulospinal 4. Vestibulospinal

Major Descending tract that carry motor signals from cerebral cortex for fine coordinated limb movement. The fibres form ridges called pyramids of the ventral surface of the medulla; hence the tract is called pyramidal tract. Most fibers decussate in the lower medulla the rest decussate in the spinal cord.

Corticospinal

Major Descending tract that begins in the midbrain region called tectum; decussate in the midbrain and goes down as far as the neck. Its involved in turning the head in response to sound and light.

Tectospinal

Major Descending tract that originates in the reticular formation of the brainstem control muscles of the upper and lower limbs especially to maintain posture and balance.

Reticulospinal

Major Descending tract that begins in the vestibular nuclei of the brainstem which receives impulse for balance from the inner ear to muscles that fascilitate the limbs; causes limbs to stiffen and straighten; help to keep balance.

Vestibulospinal

The fibres from the corticospinal tract form ridges called __________; hence the tract is called pyramidal tract.

pyramids of the ventral surface of the medulla

The tectospinal tract begins in the midbrain region called ____.

Tectum