Unit 4 Flashcards
(78 cards)
1
Q
CNS
A
- brain
- spinal cord
2
Q
PNS
A
- voluntary
- involuntary
3
Q
Involuntary
A
- sympathetic
- parasympathetic
2 efferent neurons
- preganglionic
- postganglionic
4
Q
voluntary
A
skeletal muscle
1 efferent neuron
5
Q
autonomic
A
- cardiac
- smooth
- glands
6
Q
sensory neuron
A
to
7
Q
somatic motor neuron
autonomic motor neuron
A
from
8
Q
efferent division
A
from the CNS
9
Q
afferent division
A
to the CNS
10
Q
Autonomic Nervous System (ANS)
A
efferent system that governs fx w/o conscious effort
CNS to periphery
11
Q
Branches of the ANS
A
- sympathetic nervous system (SNS)
- parasympathetic nervous system (PNS)
12
Q
SNS
A
fight or flight
- increase HR, BP
- blood volume shifts to skeletal muscles
- bronchodilation
- increase blood glucose (liver)
13
Q
PNS
A
rest and digest
- increase GI motility
- increase visceral blood flow
- decrease HR
14
Q
Anatomy of ANS
A
2 neuron system
- Preganglionic and Postganglionic
- Pairs of neurons linked together
- Action potentials driven through sodium channels across synapses
- Chemical communication at ganglia and junction with target organ
15
Q
sympathetic neurons
A
-Preganglionic neurons located in the thoracic and lumbar region
-Synapse in 2 cord-like chains of ganglia that run parallel
on each side of the spinal cord
-Long postganglionic neurons
16
Q
Parasympathetic
A
Preganglionic neurons arise from cranial/sacral regions of spinal cord and synapse in ganglia near or on the effector organ (short postganglionics)
17
Q
neurotransmitters
A
mediate signals // cell/targets
neurotransmitters received by down-stream cell and produce a response
18
Q
ANS: 2 kinds of neurotransmitters
A
- Cholinergic
- Adrenergic
19
Q
Acetylcholine
A
released by both PNS and SNS presynaptic neurons
-cholinergic
20
Q
These receptor (at the ganglia) are called ________ (b/c they bind other chemicals as well…namely nicotine)
A
Nicotinic
21
Q
nicotinic receptors
A
actually sodium channels, so when they open they stimulate an action potential to travel down the postganglionic neuron
22
Q
Drugs that target nicotinic receptors essentially…
A
turn on ALL of the ANS
23
Q
parasympathetic fibers release Acetylcholine (Ach) at the postganglionic target
A
called Cholinergic Neurons
24
Q
Cholinergic Neurons
The receptors on targets are called
A
muscarinic receptors
25
Action of Ach is terminated quickly by:
acetylcholine esterase (enzyme)
26
Parasympathetic NS dominated by:
activity of muscarinic receptors interacting w/ Ach
27
Ach
very versatile neurotransmitter
- acts at all ganglia (bind nicotinic receptors)
- motor neurons release Ach
- Ach binds nicotinic receptors on skeletal muscle
- binds muscarinic receptors in PNS
28
Cholinesterases
get rid of Ach very quickly
| when Ach is released from the receptors it is rapidly destroyed
29
pathway of Ach
1. Ach is released
2. Ach binds w/ its receptor
3. action of Ach is terminated by AchE
4. if AchE is inhibited. Ach is not broken down as quickly and produces a more dramatic effect
30
adrenergic receptors
Alpha
| Beta
31
Alpha
| smooth muscles in blood vessles
alpha 1 - post-synaptic and primarily found in the vasculature
alpha 2 - autoreceptors and found on the nerve terminal and in the brain
32
Beta
beta 1 - found in the heart (and in the kidney)
beta 2 - found in the lungs, also influence metabolic rate
33
Nor-epinephrine (NE)
released by sympathetic postganglionic neurons and generate response
34
NE will bind to ______ receptors
adrenergic
35
most NE gets pumped back into post-ganglionic neurons
re-uptake mechanism
| takes longer to get rid of NE from synapse
36
receptors for Ach
- muscarinic
| - nicotinic
37
receptors for Norepinephrine
- Alpha (1 and 2)
- Beta 1
- Beta 2
38
sympathetic nervous system
innervates most of the vascular smooth muscle
| BP and peripheral resistance controlled by SNS
39
stimulation
vasoconstriction
40
not stimulated
vasodilation
41
cholinergic receptors
- muscarinic receptors are located at the parasympathetic postganglionic fibers (target organ)
- nicotinic receptors are found at the motor end plate (neuromuscular junction), in all autonomic ganglia and in adrenal medulla
42
Responses to PNS stimulation
Heart - decreases HR (SA node and AV node) - effects limited to the atria
Eye - contracts the sphincter of the iris and constricts the pupil, contracts ciliary muscle - accommodation for near vision
GI - increases secretions and peristalsis
Genitourinary - muscle in bladder wall contracts, sphincter relaxes
43
Where are Adrenergic receptors and what do they do when stimulated?
Alpha
peripheral blood vessels
contraction of constriction...mostly vasoconstriction
44
Where are Adrenergic receptors and what do they do when stimulated?
Beta 1
Heart
increase HR and contractility
45
Where are Adrenergic receptors and what do they do when stimulated?
Beta 2
smooth muscle
relaxes smooth muscle...bronchodilation, decrease secretion in bronchioles
increase metabolic rate
46
Responses to SNS stimulation
Heart - increase HR, contractility, cardiac output
Eye - innervates the radial muscles of iris (alpha receptors) dilating the pupil
GI - SNS diverts attention away from the GI tract decreasing secretions and motility
GU- relax bladder wall and contracts the sphincter
47
General Rules of Innervation
- many organs are innervated by both SNS and PNS
- most of the time the 2 systems have opposing effects
- important organs that receive innervation from both SNS and PNS - eye, heart, bronchial smooth muscle, GI, GU
- resting state, most dually innervated organs are controlled by PNS
48
drug design
we could effect neuronal conduction - stop conduction along axons
49
drug design
Ganglionic agonists (NICOTINIC):
will fire off ALL the ganglia and all the targets will get SNS and PNS stimulation at the same time. Also neuromuscular junction stimulation
50
drug design
Ganglionic (NICOTINIC) antagonists:
block PNS and SNS as well as neuromuscular junction
51
Nicotinic agonists
Will turn on all of the ANS – not clinically desirable
Toxicity: skeletal muscle contraction
REMEMBER: nicotinic receptors are the only receptor found in the voluntary nervous system
52
Nicotinic antagonists
| trimethaphan
- Blocks the entire autonomic nervous system by blocking ganglionic transmission
- Used in hypertensive emergencies but with many side effects.
Decreases sympathetic tone
Rarely used due to side effects
But will block skeletal muscle contraction
53
Muscarinic agonists
located at the targets for the PNS
Turn on the receptors and produce a parasympathetic like response. “rest and digest”
inhibit the breakdown of Ach = Ach will be present in higher levels at the synapsis
54
Muscarinic agonist
| pilocarpine, bethanechol
turns on muscarinic receptors at targets
Uses:
- Glaucoma: constricts pupil, increase drainage
- GI retention: post GI surgery
- Urinary retention: spinal cord problems
- Supraventricular tachycardia: SA node is setting the rate too fast. Pacing takes place in the atrium, SA node receives input fro the PNS.
- Atropine (muscarinic antagonist) poisoning: competition
55
Muscarinic antagonist
| atropine, scopalamine
Blocks muscarinic receptors at targets – interferes with actions of PNS
Uses:
-Dilates eyes
- Problem w/ getting air into airways due to PNS constriction.
- Motion sickness: scopolamine. Can be delivered across the skin (patches & skin). Has nothing to do with ANS. Problem is in the brain, scopolamine blocks receptors in the brain.
Parkinson’s Disease: block the Ach to balance the dopamine deficiency
GI tract hyperactivity: interfere with peristalsis (usually preparations of atropine + opiate)
Insecticides that are Ach-esterase inhibitors (muscarinc agonists) can be blocked by atropine (also nerve gases)- think competition again.
56
Muscarinic antagonists
side effects
- Photophobia / blurred vision
- Glaucoma can be aggravated
- Tachycardia
- Inhibition of sweating (heat stroke)
- Urinary retention
- Gastric retention
57
Decrease the release or increase the re-uptake mechanism of nor-epi.
Adrenergic antagonists
58
Increase the release of catecholamines (epi and nor-epi)
Adrenergic agonists
Nor-Epi and Epi bind to alpha, beta 1 and beta 2 receptors
59
Alpha 1 agonist
(phenylephrine)
Uses:
- Dilation of the eyes
- Local anesthetic adjunct – vasoconstrict and leaves local anesthetic in area longer / also decreases bleeding from damaged vessels
- Decongestant: constrict vessels carrying fluid to the sinuses and decrease fluid delivery to the
sinuses
- Increase blood pressure due to vasoconstriction, fluid doesn’t leak out of vessels
60
Alpha 1 agonist
(phenylephrine)
side effects:
- Increase BP
- reduction in perfusion = potential for tissue hypoxia and inflammation, more inflammation -> rebound congestion -> more nasal spray etc.
- photophobia
61
Beta agonists (isoproterenol)
Uses:
- CHF to increase HR and contractility
- dilate blood vessels in certain parts of the body…especially skeletal muscle beds (fight or flight mobilize blood to skeletal muscle)
- Treatment of asthma (B2 – bronchodilates) there are B2 selective agents
- Anaphalactic shock: hyperactive immune response with potential for airway collapse and circulatory collapse [epinephrine]
- B2 selective agonist can relax uterine smooth muscle to treat pre-term labor (prevent preterm birth)
62
Beta agonists (isoproterenol)
Side effects:
increase in BP
angina
tachycardia
63
Alpha 1 antagonist (prozasine)
Uses:
Blocks nor-epi binding
- HTN - block alpha 1 constriction
- hypersensitive emergency can cause blood vessel damage rapidly
- Pheochromocytoma: adrenal tumor
- Urinary obstruction with prostate enlargement. (alpha antagonist helps probably through changes in the prostate and the bladder.)
64
Alpha 1 antagonist (prozasine)
Side effects:
- hypotension
- tachycardia: reflex action through activation of SNS
- can induce nasal congestion
- impotence
- fluid retention
65
Beta antagonists
(propranolol)
Uses:
- decrease cardiac output and HR = decrease BP (decrease blood vessel resistance)
- Angina: ischemic heart disease
- Arrythmia: decreases heart rate
- Glaucoma: decreases formation of aqueous humor from the ciliary body
- Hyperthyroidism: not reverse hyperthyroidism, just treats the symptoms of too much thyroid.
- Tremors and anxiety: especially things like stage fright.
- Migraine headaches
66
Beta antagonists
(propranolol)
Side effects:
- May precipitate CHF – decrease contractility
hypotension
- precipitate asthma – block the signals that are keeping the airways open
- rebound hypertension – especially if drug is D/C
67
Pupil - SNS
Contraction of the circular muscle
causes constriction
68
Pupil - PNS
Contraction of the radial muscle
causes dilation
69
Which type of drug is used topically to dilate the pupil during an eye exam?
alpha agonist
70
The neurotransmitter released at the preganglionic sympathetic nerve ending is:
acetylcholine
71
Which of the following kinds of drugs might be used to delay absorption of a local anesthetic?
alpha agonist
72
Drugs that have urinary urgency as a common side effect most specifically contain:
muscarinic agonist
73
A patient has been given medication which stimulates bladder contractions to increase urination. What type of receptors have been stimulated?
muscarinic
74
Where do the efferent pathways of the parasympathetic division originate from as they leave the CNS?
cranial and sacral regions
75
Which receptor when inhibited slows heart rate and decreases force of contraction?
beta 1
76
At times of stress, which of the following occur within the body?
glycogen is broken down and glucose is mobilized
77
The neurotransmitter released at voluntary nerve endings is:
acetylcholine
78
In the peripheral nervous system, which portion(s) send nerve fibers to smooth muscle?
sympathetic, parasympathetic but not voluntary
