Autonomics Flashcards by Adam Purviance

The functional unit of the autonomic nervous system is a ___-____ ___ pathway

two-neuron motor

ex: heart rate, sphincter tone, digestion

How well did you know this?

Not at all

Perfectly

What is the reflex, regulatory role of the ANS?

homeostasis

How well did you know this?

Not at all

Perfectly

This is the site of integration and control for many autonomic functions. It is also the origin of the neuroendocrine, hypothalamic-pituitary axis

hypothalamus

How well did you know this?

Not at all

Perfectly

This nervous system is anatomically confined to the GI tract but it is intimately related to both sympathetic and parasympathetic divisions of the ANS.

enteric

How well did you know this?

Not at all

Perfectly

Besides homeostasis, what else is the hypothalamus involved in?

emotional behavior and motivational drives

How well did you know this?

Not at all

Perfectly

Temperature regulation is a complex process affected by both ____ and ____ ____ changes

hypothalamic; skin temperature

How well did you know this?

Not at all

Perfectly

The ____ effects of changes in hypothalamic temperature include alterations in blood flow, sweat production, shivering, metabolism and posture

direct

How well did you know this?

Not at all

Perfectly

Changes in skin temperature produce reflex effects which modulate the hypothalamic “set point”. What occurs at this set point?

point at which sweating or shivering will begin

How well did you know this?

Not at all

Perfectly

A direct effect of osmolarity exists in the organum vasculosum of the lamina terminals and subfornical organ which lack what?

blood-brain barrier

note: osmoreceptors in this area are extremely sensitive to osmolarity

How well did you know this?

Not at all

Perfectly

Reflexy, mouth dryness stimulates thirst via the ______

hypothalamus

How well did you know this?

Not at all

Perfectly

Input from sense organs and the neocortex influence a variety of specific hypothalamic and limbic areas to produce complex reflex changes such as?

fear, rage, grief, fight or flight

How well did you know this?

Not at all

Perfectly

In regards to sexual behavior, a direct effect of circulating ____ and _____ in the anterior ventral area of the hypothalamus has been shown to stimulate aggressive-receptive behavior in non-human species

estrogens; androgens

How well did you know this?

Not at all

Perfectly

True or false? All reflex effects are stimulated by the hypothalamus.

false; reflex effects are stimulated via all sensory systems although not all reflexes are mediated via the hypothalamus

How well did you know this?

Not at all

Perfectly

The hypothalamus has direct influence over the _____ to control release of many hormones

pituitary

How well did you know this?

Not at all

Perfectly

The hypothalamus sends excitatory and inhibitory signals to the pons and medulla which can control or override normal autonomic homeostatic mechanisms. ____ ____ signals can then modify control via either the hypothalamus or by influences on nuclei in the medulla or pons

peripheral “feedback”

How well did you know this?

Not at all

Perfectly

micturition

a pontine micturition center coordinates emptying of the bladder which is otherwise an autonomic reflex.

How well did you know this?

Not at all

Perfectly

The medulla is the site of ____ ____ ____ of the circulation.

final global integration

note: it contains several integrating centers that may interact with one another. They all receive information from peripheral receptors and cause reflex adjustments in heart rate and ultimately, blood pressure

How well did you know this?

Not at all

Perfectly

In regards to the medulla, a ____ area controls vasoconstriction

vasomotor

How well did you know this?

Not at all

Perfectly

In regards to the medulla, _____ and _____ areas are critical in control of heart rate and contractility

cardioinhibitory; cardioacceleratory

How well did you know this?

Not at all

Perfectly

Other ANS functions integrated in the medulla include:

respiration, gagging, swallowing, coughing, sneezing, and vomiting

How well did you know this?

Not at all

Perfectly

The parasympathetic outflow tracts are characterized by _____ preganglionic neurons and ____ postganglionic neurons

long; short

How well did you know this?

Not at all

Perfectly

Where are most of the synapses in the parasympathetic system located?

on or in the target organ

How well did you know this?

Not at all

Perfectly

Parasympathetic preganglionic nerves originate in 4 regions. Where does CN III project?

projects to ciliary ganglia and is responsible for lens accommodation and pupillary contraction

How well did you know this?

Not at all

Perfectly

Parasympathetic preganglionic nerves originate in 4 regions. Where does CN VII project?

projects to lacrimal and salivary glands via pterygopalatine and submandibular ganglia

How well did you know this?

Not at all

Perfectly

Parasympathetic preganglionic nerves originate in 4 regions. Where does CN IX project?

projects to the otic ganglion and parotid salivary gland

The dorsal motor nucleus of the vagus is the origin of CN X which innervates viscera where?

throughout thorax and upper abdomen

The pelvic nerves originating from S2,3,4 innervate the lower abdominal and pelvic viscera and contribute to the regulation of what?

micturition (bladder control), defecation, sexual functions

In regards to sympathetic outflow, signals from cells in the hypothalamus and brainstem descend the spinal cord in cells of the ____ _____ ____

intermediolateral cell column (IML)

Axons in the IML synapse with sympathetic preganglionic neurons in the thoracolumbar region. The sympathetic preganglionic fibers project in 3 ways. Describe.

1. may synapse in adjoining chain ganglion (paravertebral projection) 2. may extend up or down before synapsing (paravertebral projection) 3. may pass outside the chain to their synapse (prevertebral projections)

Sympathetic preganglionic neurons originate where in the spinal cord?

between T1-L3

Describe the length, myelination status, and fiber type of sympathetic preganglionic neurons.

small, myelinated, B fibers

Ordinarily, sympathetic preganglionic fibers have conduction velocities of ___-___ m/sec

3-15

These are ganglia within the sympathetic chain which lie parallel to the spinal cord.

paravertebral ganglia

These ganglia lie outside the sympathetic chain and include the celiac, superior, and inferior mesenteric ganglia in the abdomen

prevertebral ganglia

Adrenal medullae behave like two giant sympathetic ganglia. Preganglionic fibers project directly to the adrenal gland where they synapse on ____ cells which release Epi and NE into the blood

chromaffin cells

Describe the length, myelination status, and fiber type of sympathetic postganglionic neurons

long, unmyelinated, C fibers

What is the postganglionic to pregnaglionic neurons ratio in the enteric nervous system?

10^5 : 1 note: one autonomic fiber can influence thousands of enteric fibers

Physiologically the autonomic nerves are crucial for the coordinated function of the enteric control of what?

muscular and secretory activity

In regards to autonomic transmitter-receptor interaction, the magnitude of response is directly related to what 2 things?

1. number of receptors available | 2. transmitter concentration

____ is the cholinergic transmitter

Ach

Ach is released by axon endings of all preganglionic neurons in the ANS. This is _____ transmission and includes the parasympathetic and sympathetic fibers

synaptic

Ach is released by axon endings of somatic motor neurons to ____ _____

skeletal muscle

Ach is released by axon endings of parasympathetic postganglionic neurons. This is _____ _____ transmission

neuroeffector junction

Ach is released by axon endings of sympathetic postganglionic neurons to eccrine type sweat glands. These are referred to as _____-____ fibers

sympathetic-cholinergic

What is the principle adrenergic transmitter?

NE is released by what?

most sympathetic postganglionic neurons at the neuroeffector junction; adrenal medulla

In regards to nonadrenergic/noncholinergic, this is the first substance proven to play a role in the ANS. It is released by some interneurons in autonomic ganglia and is released by some postganglionic parasympathetic neurons in the gut

VIP (vasoactive intestinal peptide)

Where are nicotinic receptors found?

1. cell bodies of all postganglionic neurons 2. motor end plates of skeletal muscle 3. effector organs

Where are alpha and beta adrenergic receptors found?

on effector organs and on postganglionic axon terminals

Nicotinic receptors are cholinergic receptors stimulated by nicotine. How does this receptor work?

a pore forms when 5 subunit complex responds to nicotine

There are two types of cholinergic - Nicotinic receptors, Nm (N1) and Ng (N2). Where are they found?

N1: neuromuscular junction; N2: autonomic ganglia and in the adrenal medulla

What competes for the N1 receptor?

curare competes with Ach

What competes for the N2 receptor?

Hexamethonium

Muscuarinic receptors are cholinergic receptors stimulated by muscarine. How do these receptors work?

operate through G-proteins and second messengers

Where are muscarinic receptors found?

only on visceral organs

What competes for muscarinic receptors?

atropine

In regards to muscarinic receptors where are M1, M2, and M3 found?

M1: glands M2: heart and smooth muscle M3: smooth muscle and secretory glands

Adrenergic receptors are stimulated by NE and Epi. They are sub-classed on the basis of _____ _____

selective antagonists (blockers)

Alpha adrenergic receptors. What are they stimulated by? What competes for them? Where are the two types?

1. stimulated by Epi, NE, and PE 2. Phentoalmine competes and blocks effects of receptor stimulation 3. Alpha 1 (post junctional); Alpha 2 (pre or post junctional)

Beta adrenergic receptors. What are they stimulated by? What competes for them? What are the 3 types?

1. stimulated by Epi, NE, and ISO 2. propranolol competes and blocks effects of receptor stimulation 3. Beta 1 (heart and kidney), Beta 2 (elsewhere), Beta 3 (fat cells)

When does up regulation of adrenergic receptors occur?

when there is increased receptor number which leads to increased responsiveness of the tissue

When does down regulation of adrenergic receptors occur?

when there is decreased receptor number making the tissue less response to stimulation

What is the cholinergic mechanism?

1. Ach is released from nerve ending 2. APs induce influx of Ca2+ - trigger release of Ach from synaptic vesicles 3. Ach activates muscarinic receptors on effector organ

After muscarinic receptors on the effector organ have been activated, Ach is degraded by what enzyme? What are the two products?

acetylcholinesterase; acetate; choline

Some choline is take up directly by the nerve ending and acetate passes into capillaries and reappears in the nerve ending as ____

Acetyl-CoA

The enzyme ____ ____ catalyzes the production of Ach

choline acetyltransferase

What is the rate limiting step of the cholinergic mechanism?

reuptake of choline

In regards to adrenergic transmitters, ____ is released from adrenergic postganglionic neurons

In regards to adrenergic transmitters, ____ is the major hormone of the adrenal medulla

Epi

In regards to adrenergic transmitters, ____ is released from small, intensely fluorescent cells to produce an IPSP in autonomic ganglia.

Dopamine note: plays role in regulation of renal blood flow but is the dominant transmitter within the CNS

In regards to adrenergic transmitters, ____ is co-released form postganglionic vasoconstrictor neurons and contributes to vascular constriction

ATP

In regards to adrenergic mechanisms, biosynthesis of ____ occurs within adrenergic nerves and the adrenal medulla

catecholamines

Adrenergic nerves have two storage pools for NE and Epi. The cytoplasmic pool regulates ___ ____ activity

tyrosine hydroxylase

As NE and Epi accumulate, tyrosine hydroxylase is ____

inhibited

In the cytoplasmic pool, Catecholamines can be degraded by ____ ____

monoamine oxidase (MAO) note: this contributes to stability of the pool

In the cytoplasmic pool pre junctional alpha2 receptors contribute to the concentration of ____ by inhibiting its release

Adrenergic nerves have two storage pools for NE and Epi. The intragranular pool is in equilibrium with the cytoplasmic pool. It is released when what happens?

AP in nerve allows Ca2+ movement in nerve terminal note: ATP, NPY, and dopamine are also released

In regards to storage of NE and Epi, ____ selectively stimulates Epi synthesis by inducing the N-methyltransferase

cortisol

What causes release of NE by postganglionic neurons?

AP -> Ca2+ influx -> exocytosis of granules

At released from preganglionic neurons acts on N2 receptors of chromaffin cells, causing depolarization. What does this induce?

Ca2+ influx -> exocytosis of granules

In regards to adrenal medulla hormones causing release, Epi and NE are released into the blood at a ratio of __:__

4:1

The parasympathetic system generally conserves and restores energy and is therefore, _____

anabolic

Effects of parasympathetics can be characterized generally by DEM BBLUES

defecation emesis miosis ``` bradycardia bronchoconstriction lacrimation urination erection salivation ```

The sympathetic system generally burns energy and provides adjustments in dealing with physiological stress and is therefore, ____

catabolic

The erection is controlled by the parasympathetic system, but ejaculation is controlled by the sympathetic system. True or false?

true

Production of thick saliva and sweating are effects caused by ____ system stimulation

sympathetic

Alpha1 excitatory responses of Epi, NE, and PE are what?

vasoconstriciton, secretion of thick saliva, sphincter contraction, and ejaculation second messengers involved: IP3 and DAG or Ca2+

Alpha2 inhibitory responses of Epi, NE, and PE are what?

decreased motility and secretory activity in the GI tract

stimulation of alpha2 receptors ____ adenylate cyclase cAMP production

inhibits

Beta1 excitatory responses due to ISO, Epi, or NE are what?

positive chronotropic and inotropic effects on the myocardium, as well as renin release

Beta2 inhibitory responses due to ISO, Epi, or NE include what?

relaxation of smooth muscle

Beta3 metabolic response due to ISO, Epi, or NE is ____

lipolysis

Stimulation of Beta receptors ____ adenylate cyclase. Beta1 makes more ____ available for contraction/cardiac acceleration; Beta2 increased uptake of Ca2+ into the SR results in smooth muscle _____

activates; Ca2+; relaxation

Autonomic nerves are tonically active at rest. True or false?

true - this allows for fine adjustments up and down