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Flashcards in Phys Test 4 Deck (36):
1

Autonomic NS control centers

1 Spinal cord
2 Brain stem
3 Hypothalamus
- subconscious sensory signal

2

Efferent signals

-transmitted through sympathetic and parasympathetic
-Most organs controlled by one or the other

3

Sympathetic NS

-Preganglionic- Short fiber
-Postganglionic- Long fiber
-Fight or flight

4

difference between sympathetic nerves from skeletal motor nerves

-each sympathetic pathway from the cord to the stimulated tissue is composed of two neurons, (Pregaglionic and ostgaglionic)

5

Sympathetic NS originate

-In spinal cord from T1-L2

6

Preganglionic transmission options from sympathetic chains

1. Synapse directly with postganglionic fibers
2. Follow preganglionic pathway to one of
two peripheral ganglia where they synapse
with postganglionic fibers
3. Pass through the sympathetic chains then
through the splanchnic nerves to the two
adrenal medullae

7

Sympathetic fibers & the skeletal nerves

-Some postganglionic fibers that originate
in the sympathetic chains pass back into
the spinal cord at all levels of the cord
-They then extend to all parts of the body
via the skeletal nerves

8

Adrenal Medullae

-Receive sympathetic preganglionic
innervation
-Fibers pass through sympathetic ganglionic
chains on to adrenal medulla without
synapse via splanchnic nerves
-Preganglionic fibers synapse with special
cells within the adrenal medulla that
secrete epinephrine and norepinephrine
into the blood
-Cells are postganglionic neurons with
simple nerve fibers that secrete the
hormones

9

Parasympathetic NS

Preganglionic
-Pass all of the way to the effector organ Postganglionic
-With the synapse at the effector organ the postganglionic fibers are very short, located in wall of organ
-Rest and digest

10

PSN system originates from

-Cranial nerves: 3, 7, 9, &; 10
-Second and third sacral nerves (some from 1 and 4)
-75% of PSNs are in the vagus nerve (Cranial nerve 10)

11

Synapses

-Junction point between neurons and/or between
neurons and effector organs
-Release neurotransmitter
that interacts with receptors
on postsynaptic membrane
-Result of transmitter release depends on type of
transmitter released and
purpose of receptor (Excitatory; Inhibitory)

12

Synapse Structure

-Mitochondria: produce ATP for transmitter production
-Transmitter Vesicles: store
transmitter substance (2,000
to 10,000 molecules)
-Synaptic Cleft: space between presynaptic terminal & Postsynaptic membrane (200
to 300 angstroms)
-Receptor Proteins
-Presynaptic terminal contains large number of voltage-gate calcium channels

13

Transmitter

-Action Potential activates Ca++ channels in presynaptic terminal
-Causes Ca++ to rush into terminal end and stimulate release of transmitter into synaptic cleft
-Amount of transmitter released is based on the amount of Ca++ that enters presynaptic terminal

14

Transmitter Action Components

-Receptor proteins on postsynaptic neuron have
1. Binding Comonent- Protrudes from surface into cleft
2. Ionophore component- Passes through membrane to interior of postsynaptic neuron

15

Ionophore types

-Ion channel- Controls passage of specific ions (SHORT TERM EFFECT)
-Second messenger activator- activates one or more substances inside postsynaptic neuron; interact with other cellular components to increase or decrease specific functions (LONG TERM EFFECTS)

16

Ionophore ion channels

-Cation channel- mainly Na, movement of Na into postsynaptic neuron tends to be excitatory (depolarization)
-Anion channel- mainly Cl, too small to pass hydrated Na or other cations, movement of Cl into postsynaptic neuron tends to be inhibitory (hyperpolarization)

17

Ionophore second messengers

-most common are G-proteins
-Alpha, Beta, and Gamma attached to receptor protein that protrudes into interior of neuron
-alpha- activator component= released when receptor protein activated
-allow prolonged changes at the postsynaptic neuron even though receptors are no longer stimulated by transmitter

18

actions stimulated by Alpha component of Ionophore

-OPEN specific ion channel through postsynaptic membrane (channel can remain open for long periods of time)
-ACTIVATION of cyclic adenosine monophosphate (cAMP)
-ACTIVATION of one or more intracellular enzymes
-ACTIVATION of gene transcription which creates change in metabolic machinery and cellular structure.

19

Acetylcholine released by

-all ANS preganglionic fibers
-most parasympathetic postganglionic fibers

20

Norepinephrine released by

-most sympathetic postganglionic fibers
-Postganglionic fibers to sweat glands and piloerector muscles release acetylcholine
-Postganglionic fibers to some blood vessels release acetylcholine

21

Fibers that release acetylcholine are called

Cholinergic fibers

22

Fibers that release norepinephrine

adrenergic fibers

23

Acetylcholine called

Parasympathetic transmitter

24

Norepinephrine called

sympathetic transmitter

25

Acetylcholine production

-Production requires choline acetyltransferase to combine acetyl-CoA + Choline

26

Acetylcholine removal

-Removal catalyzed by acetylcholinesterase which the choline is transported back into terminal nerve ending to be used for more acetylcholine

27

Norepinephrine production

Tyrosine-> Dopa
Dopa->Dopamine
Dopamine->Norepinephrine
-in adrenal medulla, 80% of norepinephrine is converted to epinephrine

28

Norepinephrine removal (3)

-50-80% moved back into terminal nerve ending by active transport
-most of the rest diffuses away from the nerve endings into surrounding tissue
-small amount destroyed by monoamine oxidase or catechol-O-methyl transferase
(So norepinephrine can pretty much be removed from everywhere.

29

Norepinephrine active time

-normally remains active for several seconds
-norepinephrine and epinephrine released by the adrenal medulla into blood remains active for 10 to 30 seconds which is deactivated by ctechol-O-methyl transferase mainly in the liver

30

Cholinergic receptors types

-Muscarinic
-Nicotinic

31

Muscarinic receptors

-Cholinergic receptor type
-activated by muscarine and acetylcholine
-receptor on effector organs innervated by parasympathetic postganglionic fibers

32

Nicotinic receptors

-Cholinergic receptor type
-activated by nicotine and acetylcholine
-receptor on postganglionic fibers of all autonomic fibers
-receptor on neuromuscular junction of skeletal muscles

33

Adrenergic receptor types

-Alpha (Alpha 1 and Alpha 2)
-Beta (Beta 1, Beta 2, and Beta 3)
-Both can produce excitatory AND inhibitory responses based on the EFFECTOR ORGAN

34

Adrenergic (Norepinephrine) effect and secreted by

-secreted by adrenal medullae
-main affect on alpha receptors
-much smaller effect on beta receptors

35

Andrenergic (Epinephrine) effect and secreted by

-Secreted by adrenal medullae
-Excites both Alpha and Beta equally

36

Adrenergic Receptors (look at flashcards

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