Autonomic Hypertension Flashcards
Review of ANS
ANS divided into:
- Sympathetic
- Parasympathetic
Sympathetic divided into:
- Adrenergic agonist (fight)
- Adrenergic antagonist (rest)
Parasympathetic divided into:
- cholinergic agonist
- anticholinergics
What are the neurotransmitters of parasympathetic?
What are the neurotransmitters of sympathetic?
- ACh
- Epinephrine and Norepinephrine
Where does parasympathetic come from in the spinal cord?
Where does sympathetic come from?
- Brain and Lower vertebrae
- Lumbar and Thoracic
What is sympathomimetic?
What drugs are involved with this?
- Promoting the stimulation of sympathetic nerves
- Adrenergic agonists
What is sympatholytic?
What drugs are involved with this?
- Inhibiting the transmission of sympathetic nerve impulses
- Adrenergic antagonists
What are adrenergic drugs used to treat?
- Cardiovascular conditions
- Respiratory conditions
- Common cold
How do most adrenergic drugs exert their effect?
Binding to postsynaptic receptor
What are the subtypes of adrenergic drugs?
What are each of their actions?
Alpha:
1- mainly vascular smooth muscle (vasoconstriction or dilation)
2- presynaptic junctions to influence NE release
Beta:
1- heart, kidney
2- lungs
3-adipose tissue
Is there a clinical use of B3?
No
What are the three catecholamines?
Catecholamines:
- Epinephrine
- Norepinephrine
- Dopamine
What are catecholamines?
- Hormones produced by adrenal glands.
- Usually released in response to physical or emotional stress.
- Released by sympathetic nervous system.
- Sympathomimetic
Catecholamines: Cardiac effects? Vascular effects? CNS effects? Nonvascular Smooth Muscle effects? Metabolic effects?
Cardiac effects: CO=SV*HR
- Positive inotropic effect (↑SV)
- Positive chronotropic effect (↑HR)
Vascular Effects:
- Epinephrine reduced peripheral vascular resistance at low dose, opposite at high dose
- NE elevates BP
CNS Effects:
-large doses can produce anxiety, tremors, HA
Nonvascular smooth muscle effects:
- relax smooth muscle of GI tract
- urinary retention
- dilation of bronchiole smooth muscle
Metabolic effects:
- increases blood glucose and fatty acid levels
- inhibits insulin secretion
- enhance glycogenolysis and gluconeogenesis
Does epinephrine effect all alpha and beta receptors?
Yes
What effect does it have on each receptor?
What is the net effect of all of this?
- B1- increases strength/ rate of cardiac contraction
- B2- relaxes bronchiole smooth muscle, activates glycogenolysis
- B3- activate lipolysis in fat cells
- A1- constricts vascular smooth muscle
- A2- (presynaptically)
Net effect= potent vasoconstrictor and cardiac stimulant
What can epinephrine be used for?
- Anaphylactic shock (epipen)
- Cardiogenic shock (cardiac arrest)
What receptors does norepinephrine act on?
- Acts on A1 receptors to a greater extent than A2 and B1.
- It has little effect on B2
What does norepinephrine mainly do?
Increase BP
What is norepinephrine used to treat?
- Severe hypotension
- Septic shock
What is septic shock?
When an organ is injured or damaged in response to an infection, leading to dangerously low BP
What is the precursor to norepinephrine?
What receptors does it activate?
- Dopamine
- Activates A1 and B1 receptors
What is dopamine used to treat?
- Shock in renal failure
- Cardiac decompensation
What are vasopressor drugs?
Cause vasoconstriction leading to increased BP and MAP
What are some examples of vasopressors?
- Norepinephrine
- Epinephrine
- Dopamine
- Vasopressin
Difference between Direct and Indirect Acting Adrenergic Drugs?
- Direct- directly stimulate alpha or beta receptors
- Indirect- Enhance effects of NE or Epi by inhibiting their reuptake or inhibiting their degredation, or increasing release of NE
What are some examples of direct acting adrenergic drugs?
- Pseudophedrine
- Phenylephrine
Are indirect acting adrenergic drugs sympatholytic or sympathomimetic?
Sympathomimetic- they mimic the SNS
-Release stored NE, inhibit reuptake, and block degradation
What are some examples of indirect acting adrenergic drugs?
- Cocaine
- Amphetamine
- Ephedrine
What is the effect of these adrenergic drugs such as Amphetamine?
Amphetamine
- Taken up by NE transporters (blocks path) which leaves more NE available to have effect
- inrease alertness, decrease fatigue= used for ADHD, narcolepsy
- AE related to increased BP and HR, and decreased apetite
- Enters CNS, stimulating dopamine receptors= euphoria= abuse potential
What are the effects of cocaine, another indirect adrenergic drug?
- Also inhibits the reuptake of NE
- Significant vasoconstriction= hypertensive crisis, MI, stroke
S24-27
S24-27
What are mixed adrenergic agonists?
Work on both direct and indirect pathways
What are the rehab concerns with sympathomimetics?
- May induce: HTN, cardiac arrhythmias, angina
- Ephedra (weight loss products): cerebral hemorrhage, seizures, and death
Hypertension affects 1 in every _ adults worldwide and is the leading cause of cardiovascular morbitity and mortality. It can be “______”
- 6
- silent
What is the difference between primary hypertension and secondary hypertension?
Primary HTN
-multifactorial, accounts for 90% of cases
Secondary HTN
-produced by underlying disease process
What is the Frank-Sterling Law? What does this mean?
- Says that stroke volume increases as left ventricular volume increases
- Means that preload can be adversely affected by heart disease
What is MAP?
What is Ohm’s law?
- Cardiac output*peripheral resistance
- V=IR
- V= vascular pressure
- I= blood flow
- R= resistance
- If peripheral resistance is increased, so is BP
Drugs can affect variables in these equations to alter BP in what ways?
- Reduced HR→ decreased CO and arterial pressure
- Decrease contractility→ decrease SV→ decrease BP
- Increase vasodilation→ lower peripheral vascular resistance→ decrease BP
- Reduce plasma volume→ decrease SV→ decrease BP
What are factors producing HTN?
- Genetics
- Kidney function
- Potassium and calcium affects vasodilation
- Changes in myocardial tissue and vessels
- Relationship between HTN and hyperinsulinism/ insulin resistance
Renin-angiotensin system + sympathetic nervous system = _____________
potent vasoconstriction
What is renin?
Renal enzyme that promotes the production of angiotensin
What does renin lead to?
- Gets secreted when 1) decreased renal profusion or 2) decreased Na+
- Angiotensinogen→ angiotensin I + ACE → angiotensin II
- Angiotensin II is a VERY powerful vasoconstrictor
Go through the order in depth.
- Low fluid flow or Na+ is sensed
- Renin is secreted
- Kidney releases renin into blood, and liver releases angiotensinogen into blood
- This renin acts on the angiotensinogen to form Angiotensin I
- Angiotensin-converting enzyme (ACE) in pulmonary blood converts Angiotensin I into Angiotensin II
- This then stimulates widespread vasoconstriction
What do PGE2 and PGl2 counteract?
counteract vasoconstriction effect on kidneys
What does taking NSAIDs do to prostoglandin synthesis?
What can this cause?
- Inhibits prostoglandin synthesis
- Can cause renal failure and exacerbate HTN with individuals who have cirrhosis, heart failure, nephrotic syndrome, or HTN
What are 2 other things that control BP?
Baroreceptors:
-mechanoreceptors located in carotid sinus and aortic arch
Chemoreceptors:
-located in carotid body and aortic bodies
Baroreceptors help to do what?
Help blood vessels constrict and dilate as needed
What is the recommended initial therapy for HTN?
Diuretics
How do diuretics work?
Act directly on the nephron to limit water and sodium reabsorption, thus increasing excretion of Na+ and water by kidneys
- Increases amount of urine formed
- Decreases blood volume
- Inexpensive