UNIT 2 - ANS Flashcards
1
Q
What is homeostasis?
A
A steady state condition that requires energy to maintain the system
2
Q
What are the four functions a control system must perform?
A
- SENSE the vital parameter
- COMPARE the input signal with a set point
- MULTIPLY the error signal by a proportionality factor
- ADJUST the vital parameter by activating an effector system
3
Q
What is negative feedback?
A
Reverses a disturbance in some factors and leads to stability
4
Q
What is positive feedback?
A
A change in some factors produces an enhanced change in the same direction
5
Q
What is cell signaling?
A
The intracellular response to extracellular signals that allows cells to communicate
6
Q
What is signal transduction?
A
The conversion of information into a chemical change, a universal property of living cells
7
Q
What are the three main methods of intercellular communication?
A
- Endocrine
- Paracrine
- Autocrine
8
Q
What is specificity in signal transduction?
A
Cell specific receptors and bonds
9
Q
What is amplification in signal transduction?
A
An enzyme cascade where one enzyme activates multiple others
10
Q
What is integration in signal transduction?
A
The ability to receive multiple signals and produce an appropriate response
11
Q
What is desensitization in signal transduction?
A
When a signal is present continuously, resulting in reduced receptor sensitivity
12
Q
What are the six processes in a signal transduction sequence?
A
- Recognition
- Transduction
- Transmission
- Modulation
- Response
- Termination
13
Q
What are the four categories of receptor-based signal transducers?
A
- Transmembrane G protein-coupled receptors (GPCRs)
- Transmembrane gated ion channels
- Transmembrane enzyme linked receptors
- Soluble nuclear receptors
14
Q
What are the four categories of chemical signaling molecules?
A
- Small hydrophilic molecules
- Lipophilic molecules
- Peptides and proteins
- Others (nucleotides, gases, endocannabinoids)
15
Q
What is the primary neurotransmitter of the peripheral efferent neural pathways?
A
Acetylcholine (ACh)
16
Q
What are the two types of synapses?
A
- Electrical
- Chemical
17
Q
What distinguishes ionotropic receptors from metabotropic receptors?
A
Ionotropic receptors are ion channels, while metabotropic receptors activate enzymes and trigger cascades
18
Q
What neurotransmitter is synthesized from tryptophan?
A
Serotonin
19
Q
What is the role of dopamine in the brain?
A
It is involved in reward, motivation, and motor control
20
Q
What is excitotoxicity?
A
Neuronal injury initiated by excessive glutamate receptor activity
21
Q
True or False: GABA is the primary excitatory neurotransmitter in the brain.
A
False
22
Q
Fill in the blank: The end product of catecholamine metabolism is _______.
A
Vanillylmandelic acid (VMA)
23
Q
What is the rate-limiting step in catecholamine biosynthesis?
A
Tyrosine hydroxylase
24
Q
What neurotransmitter receptors are primarily metabotropic G protein-coupled receptors?
A
Biogenic amine neurotransmitter receptors
25
What is the function of calmodulin (CaM) in signaling events?
It modulates downstream signaling events mediated by calcium
26
What are biogenic amine neurotransmitters removed from the synaptic cleft by?
Reuptake into the presynaptic terminal, reuptake into non-neuronal cells & glands, or diffuse into circulation to be metabolized
## Footnote
Examples include norepinephrine (NE), epinephrine (EPI), and dopamine.
27
What type of receptors do biogenic amine neurotransmitters primarily use?
Metabotropic G protein-coupled receptors, with the exception of the ionotropic 5-HT3 serotonin receptor.
28
List the adrenergic receptor subtypes and their associated pathways.
* α1 – Gq → PLC
* α2 – Gi → inhibits AC → reduces cAMP
* β – Gs → activated AC → increases cAMP
29
Where are the largest dopaminergic neurons located?
In the brain’s substantia nigra.
30
What roles do serotonergic neurons play?
* Sleep & wakefulness
* Emotions
* Cognition
* Cardiovascular, respiratory, & intestinal activities
31
True or False: Derangement of serotonergic pathways can contribute to anxiety and depression.
True
32
What is the target receptor for Zofran?
The ionotropic 5-HT3 serotonin receptor.
33
What role does histamine play in the body?
* Arousal & attention
* Memory, learning, & mood
34
Fill in the blank: Nonconventional neurotransmitters cannot be stored in vesicles and must be synthesized and released on _______.
demand
35
What are the main purinergic neurotransmitters?
* ATP
* ADP
* Adenosine
36
What enzyme converts ATP to adenosine in the synaptic cleft?
Ectonucleotidase.
37
What are the two major pathways that initiate apoptosis?
* The intrinsic (mitochondrial) pathway
* The extrinsic (cell receptor-initiated) pathway
38
What is the function of Nitric Oxide (NO) in cell signaling?
Acts as a universal intracellular messenger, involved in autocrine & paracrine signaling.
39
What is the role of receptor guanylyl cyclases?
Turn GTP to cGMP.
40
What do receptor tyrosine kinases (RTKs) primarily bind to?
* Insulin
* Growth factors
41
What is the JAK-STAT system associated with?
Tyrosine kinase-associated receptors.
42
What are the two families of intracellular (nuclear) receptors?
* Steroid hormones
* Prostaglandins, vitamin D, thyroid hormones, & retinoic acid
43
What is the difference between necrosis and apoptosis?
Necrosis is uncontrolled cell death with inflammation; apoptosis is programmed cell death without inflammation.
44
What type of signaling do β1-adrenoreceptors primarily mediate in cardiac myocytes?
Chronotropic, inotropic, dromotropic, & lusitropic effects.
45
What is the role of phosphodiesterases (PDE) in cyclic nucleotide signaling?
Terminate cyclic nucleotide signals.
46
What is the significance of cyclic nucleotide phosphodiesterase 3 (PDE3)?
It metabolizes cAMP to 5'-AMP.
47
What is the primary function of the autonomic nervous system (ANS)?
Ensure the physiological integrity of cells, tissues, & organs.
48
What are the three major divisions of the autonomic nervous system?
* Sympathetic nervous system (SNS)
* Parasympathetic nervous system (PNS)
* Enteric nervous system (ENS)
49
What type of receptors are primarily involved in signal transduction through GPCRs?
G-protein-coupled receptors.
50
What are the five second messengers you should know?
* cAMP
* cGMP
* IP3
* DAG
* Calcium ion (Ca++)
51
True or False: SNS stimulation of most arterial vessels causes vasodilation.
False
52
What is the effect of α2 receptors in the CNS?
Stimulation leads to sedation, MAC reduction, bradycardia, & vasodilation.
53
What does stimulation of postsynaptic alpha-2 receptors lead to?
Acute vasocontraction & hypertension.
54
What is the effect of increased cAMP in the heart?
It ↑ intracellular Ca++ & the force of contraction, but also ↑ the rate of relaxation by accelerating the return of Ca++ to the SR
55
What happens to vascular smooth muscle when cAMP levels increase?
Increased cAMP inhibits light chain kinase, causing vasodilation and decreased systemic vascular resistance (SVR)
56
In which situations are PDE inhibitors helpful?
Beta-blocker-induced myocardial depression, acute heart failure unresponsive to IV catecholamines, anytime increased inotropy & reduced afterload are desirable
57
What is the prototype nonselective PDE inhibitor?
Theophylline
58
What is the primary neurotransmitter of the sympathetic nervous system?
Norepinephrine (NE)
59
What is the rate-limiting step in catecholamine synthesis?
Tyrosine hydroxylase activity
60
How can cells generate tyrosine if the supply is low?
Cells can generate tyrosine from phenylalanine
61
What enzyme converts L-DOPA to dopamine?
Aromatic L-amino acid decarboxylase
62
What is the role of dopamine in the synthesis of norepinephrine?
Dopamine is converted into NE by the enzyme dopamine-β-hydroxylase
63
How is norepinephrine released from presynaptic nerve terminals?
An action potential depolarizes the nerve terminal, opening voltage-gated Ca++ channels, leading to exocytosis of NE
64
What mechanism primarily removes catecholamines from the synaptic cleft?
Reuptake into the presynaptic nerve (~80%)
65
Which drugs block norepinephrine reuptake?
Tricyclic antidepressants & cocaine
66
What are the two main enzymes involved in catecholamine metabolism?
Monoamine oxidase (MAO) & Catechol-O-methyltransferase (COMT)
67
What is vanillylmandelic acid (VMA) in relation to catecholamines?
It is the end-product of catecholamine metabolism eliminated through urine
68
What is the primary neurotransmitter in the parasympathetic nervous system?
Acetylcholine (ACh)
69
What are the three types of receptors that acetylcholine stimulates?
* Nicotinic type N (NN)
* Nicotinic type M (MN)
* Muscarinic (M1-5)
70
What is the rate-limiting factor for acetylcholine synthesis?
Availability of substrates, choline & acetyl-CoA
71
What enzyme is responsible for the synthesis of acetylcholine?
Choline acetyltransferase
72
How is acetylcholine released from the presynaptic nerve terminals?
An action potential causes voltage-gated Ca++ channels to open, leading to exocytosis
73
What role does acetylcholinesterase (AChE) play in neurotransmission?
It hydrolyzes ACh after it unbinds from receptors
74
What are the two complementary pathways of the autonomic nervous system?
* Sympathetic nervous system (SNS)
* Parasympathetic nervous system (PaNS)
75
What is the main exception in the efferent architecture of the ANS?
The adrenal medulla has no postganglionic neuron; chromaffin cells secrete EPI & NE into circulation
76
What is a ganglion in the context of the autonomic nervous system?
A peripheral collection of nerve cell bodies where preganglionic & postganglionic neurons synapse
77
What is the stellate ganglion and its significance?
It is a confluence of the inferior cervical ganglion & T1 ganglion, providing SNS innervation to the ipsilateral head, neck, & upper extremity
78
What syndrome results from blockade of the stellate ganglion?
Horner’s syndrome
79
Fill in the blank: The sympathetic preganglionic neurons arise from _______.
T1-L2
80
What are the two key areas of the adrenal gland?
Medulla and Cortex
## Footnote
Medulla secretes catecholamines; Cortex secretes glucocorticoids, mineralocorticoids, and androgens.
81
What type of fibers travel directly to the adrenal medulla?
Preganglionic sympathetic B fibers
## Footnote
These fibers arise from T5-T9 and there are no postganglionic sympathetic fibers in this pathway.
82
What neurotransmitter do preganglionic sympathetic B fibers release onto chromaffin cells?
ACh (Acetylcholine)
## Footnote
This stimulates NN ACh receptors on chromaffin cells.
83
What is the typical secretion ratio of EPI to NE at rest from the adrenal medulla?
80% EPI and 20% NE
## Footnote
EPI is secreted at 0.2 mcg/kg/min and NE at 0.05 mcg/kg/min.
84
What is pheochromocytoma?
A catecholamine-secreting tumor, mostly NE
## Footnote
It usually originates in the chromaffin tissue of the adrenal gland.
85
What are common symptoms of pheochromocytoma?
HA, diaphoresis, tachycardia
## Footnote
HA stands for headache.
86
What must be done before beta blocking in pheochromocytoma treatment?
Alpha block
## Footnote
This is crucial to prevent complications.
87
What are the consequences of removing a pheochromocytoma?
Hypotension and hypoglycemia
88
What factors influence the distribution of K+ across cell membranes?
SNS activity and insulin
## Footnote
Medications like digoxin, ACEi, ARBs, and BB can increase extracellular K+.
89
What is the short-term effect of sympathetic stimulation on serum K+ levels?
Initial rise in serum [K+]
## Footnote
This effect is very short-lived.
90
What is the long-term effect of EPI binding to Beta-2 receptors on skeletal muscle?
Decrease in serum [K+]
## Footnote
This is due to the activation of the Na+/K+ pump, shifting K+ into the cells.
91
List some situations that promote transcellular K+ shifts.
* Acidosis (Efflux)
* Destruction of cell membrane (Efflux)
* Succinylcholine (Efflux)
* Hyperosmolarity (Efflux)
* Alkalosis (Influx)
* Methylxanthines (Theophylline) (Influx)
* Beta-2 agonists (Influx)
* Insulin (Influx)
92
What is the role of the ANS in maintaining physiological parameters?
It uses reflexes and feedback loops.
93
What are the components of biological feedback loops?
* Sensor (Detector)
* Afferent pathways
* Control center
* Efferent pathway
* Effector organ or tissue
94
Which tissues does the ANS influence?
All tissues except skeletal muscle.
95
What are some key points of integration between the ANS and endocrine system?
* Renin-Angiotensin-Aldosterone System (RAAS)
* Vasopressin
* Glucocorticoids
* Insulin
96
What are the two types of mechanisms that maintain blood pressure?
* Neuronal (Short term)
* Hormonal (Long term)
97
What does the baroreceptor reflex primarily help maintain?
Arterial blood pressure
## Footnote
It operates as a negative feedback loop.
98
What happens to HR and contractility when blood pressure increases?
Decreased HR and contractility
99
What is a typical adaptation time for baroreceptor setpoint changes?
1-3 days
100
What are the names of the surgeries that can affect the baroreceptor reflex?
* Carotid Endartectomy
* Mediastinoscopy
101
Name two drugs that impair the baroreceptor reflex.
* VA (Volatile Anesthetics)
* NE (Norepinephrine)
102
What is the Bainbridge reflex?
Prevents blood sludging in veins and atria due to right atrial stretch.
103
What characterizes the Bezold-Jarisch reflex?
Triad of bradycardia, hypotension, and coronary artery dilation.
104
What is the main cause of the vasovagal reflex?
Physiological stress
105
What does the oculocardiac reflex involve?
Afferent CN5 and efferent CN10
## Footnote
Known as the '5 & dime' reflex.
106
What is the CNS ischemic response?
Massive activation of the SNS due to cerebral ischemia.
107
What triad does Cushing’s Reflex consist of?
* Hypertension
* Bradycardia
* Irregular respirations
108
What is the primary neurotransmitter for the ANS?
ACh (Acetylcholine) and NE (Norepinephrine)
109
What are the three alpha selective adrenergic agonists?
* Phenylephrine
* Clonidine
* Dexmedetomidine
110
What is a characteristic of Phenylephrine?
A pure alpha 1 stimulant
## Footnote
Causes venous and arterial vasocontraction.
111
What is the primary effect of Clonidine?
Inhibits NE release causing vasodilation.
112
What is the action of Dexmedetomidine?
Stimulates alpha 2 R leading to inhibition of neuronal firing.
113
What are the effects of beta 2 selective agonists?
Bronchodilation and vasodilation.
114
What is the main effect of Epi at lower doses?
Favors beta stimulation, increasing CO, HR, and inotropy.
115
What happens at high doses of NE?
Favors B1 and alpha effects, causing systemic vasoconstriction.
116
What is the effect of low-dose dopamine?
Stimulates D1R, resulting in vasodilation and increased renal blood flow.
117
What is the significance of dopamine in renal function?
Increases renal blood flow and urine output at low doses.
118
What is comorbidity?
The presence of one or more additional conditions co-occurring with a primary condition.
119
Why must dopamine be administered as an infusion?
Due to its rapid metabolism.
120
What effect does low-dose dopamine infusion (<3 ug/kg/min) have on renal blood flow?
Increases renal blood flow and urine output.
121
Which receptors are stimulated by low-dose dopamine to increase renal blood flow?
D1 receptors.
122
What is the conclusion regarding dopamine's effectiveness in preventing acute kidney injury?
Dopamine does not prevent or reverse acute kidney injury or failure.
123
What complications can low-dose dopamine be associated with?
CV, pulmonary, GI, immune, and endocrine complications.
124
What is the recommendation regarding the administration of dopamine to protect the kidneys?
It should be abandoned due to unlikely benefits and potential detrimental effects.
125
What is isoproterenol derived from?
Dopamine.
126
What are the receptor activities of isoproterenol?
B1 and B2 activity with no alpha activity.
127
What is the main clinical use of isoproterenol?
Historically used to increase heart rate in patients with heart block, but now has limited clinical use.
128
What adverse effects are associated with isoproterenol?
Precipitation of supraventricular and ventricular arrhythmias.
129
What is dobutamine's primary pharmacological activity?
Enhances myocardial contractility and reduces vascular tone.
130
What type of agonist is dobutamine?
Selective B1 agonist with mild B2 effects.
131
What is a potential adverse event associated with dobutamine?
May extend cardiac muscle infarction and increase AV conduction.
132
What is ephedrine's primary action on adrenoreceptors?
Exerts both direct and indirect actions with predominant indirect actions.
133
What mechanism allows ephedrine to provoke the release of norepinephrine?
Endocytosis into adrenergic presynaptic terminals, displacing norepinephrine.
134
What is tachyphylaxis in the context of ephedrine use?
Depletion of presynaptic norepinephrine leading to reduced efficacy with repeated use.
135
What are the two classifications of selective B2 agonists based on their duration of action?
Short acting and long acting.
136
Name three short-acting B2 agonists.
* Albuterol
* Terbutaline
* Levalbuterol
137
What are the side effects of B2 stimulation?
Tremor, anxiety, and restlessness.
138
What is a significant risk associated with long-acting B2-selective agents?
Asthma-related death due to severe asthma exacerbations.
139
What is the prototype for nonselective alpha antagonists?
Phenoxybenzamine.
140
How does phenoxybenzamine affect blood pressure?
Reduces arterial BP but can trigger reflex tachycardia and orthostatic hypotension.
141
What is the best treatment for hypotension induced by phenoxybenzamine?
Vasopressin and fluids.
142
What is phentolamine used for?
As a competitive nonselective alpha-R antagonist.
143
What are the selective alpha1 antagonists mentioned?
* Prazosin
* Terazosin
* Doxazosin
* Tamsulosin
144
What is yohimbine primarily marketed for?
ED, athletic performance, weight loss, HTN, diabetic neuropathy.
145
What is the prototype beta-adrenergic antagonist?
Propranolol.
146
What effects can nonselective beta antagonists produce?
Bronchoconstriction, hypoglycemia, and peripheral vascular constriction.
147
Name a selective beta-adrenergic antagonist.
Metoprolol.
148
What is the primary use of esmolol?
Rapid control of heart rate and blood pressure.
149
What are the three main classes of calcium channel blockers?
* Dihydropyridines
* Benzothiazepines
* Phenylalkylamines
150
What is the primary therapeutic use of calcium channel blockers?
Treatment of HTN, arrhythmias, PVD, cerebral vasospasm, and angina.
151
What is the action of muscarinic antagonists?
Competitive inhibitors of ACh at parasympathetic muscarinic receptors.
152
What are the symptoms of toxicity from muscarinic antagonists?
Excitation, restlessness, sedation, confusion, hallucination, coma.
153
How can muscarinic antagonist toxicity be treated?
Administering physostigmine.
154
What are the main classes of calcium channel blockers (CCBs)?
* Dihydropyridines
* Benzothiazepines
* Phenylalkylamines
## Footnote
Dihydropyridines include drugs like Nicardipine and Clevidipine; Benzothiazepines include Diltiazem; Phenylalkylamines include Verapamil.
155
Which CCB is known for its ability to reduce morbidity and mortality from cerebral vasospasm?
Nimodipine
## Footnote
Nimodipine is specifically indicated for this purpose.
156
What is the impairment on contractility of CCBs from lowest to highest?
* Nicardipine
* Diltiazem
* Nifedipine
* Verapamil
## Footnote
This ranking indicates the relative contractility effects of these CCBs.
157
What are the negative effects of Verapamil and Diltiazem as class 4 antiarrhythmics?
* Negative chronotropic effects
* Negative dromotropic effects
## Footnote
These effects relate to the depression of electrical impulses in the SA and AV nodes.
158
True or False: Verapamil is often used to treat angina due to its greatest myocardial depression.
True
## Footnote
Verapamil is known for its significant myocardial depression effects.
159
Fill in the blank: Direct-acting vasodilators exert an arterial relaxing effect without interfering with _______.
[systemic or local constrictor mechanisms]
## Footnote
This characteristic differentiates them from other vasodilators.
160
What is the mechanism of action for Nitroglycerin (NTG)?
Liberation of nitric oxide
## Footnote
This mechanism leads to its vasodilatory effects.
161
What are the side effects associated with ACE inhibitors?
* Dry cough
* Angioedema
* Profound hypotension
## Footnote
These side effects are due to the inhibition of bradykinin degradation and other mechanisms.
162
What are the primary receptors targeted by inhalational anesthetics?
GABAA receptors
## Footnote
These receptors are involved in the effects of anesthetics on the CNS.
163
What is the effect of vasopressin in vasodilatory states?
It can be administered for those resistant or refractory to catecholamine & fluid therapy
## Footnote
This highlights vasopressin's role in managing specific shock states.
164
What condition is characterized by degradation and dysfunction of diverse CNS structures and includes symptoms like orthostatic hypotension?
Multiple system atrophy (MSA)
## Footnote
MSA was formerly known as Shy-Drager syndrome.
165
What is the primary action of phosphodiesterase inhibitors (PDEi)?
Causing smooth muscle relaxation by reducing PDE breakdown of cAMP and cGMP
## Footnote
This leads to increased levels of these cyclic nucleotides.
166
Fill in the blank: The transplanted heart is severed from ______ influences.
[autonomic]
## Footnote
This results in a heart rate that is determined solely by the intrinsic rate of the SA node.
167
Which CCB is devoid of chronotropic effects and is ideally suited for IV infusion?
Clevidipine
## Footnote
Clevidipine's properties make it suitable for this administration route.
168
What is a potential risk when using nitroprusside (SNP) in myocardial infarction?
Induction of 'coronary steal'
## Footnote
This occurs when blood flow from maximally dilated vessels in ischemic areas is diverted to nonischemic tissue.
169
Which class of drugs is known to prevent platelet aggregation for thrombosis prophylaxis?
PDE3 inhibitors
## Footnote
Examples include Milrinone and Cilostazol.
