NEUROHUMORAL CONTROL STUDY GUIDE Flashcards
1
Q
- Which sympathetic nerve receptor predominantly causes vasoconstriction?
A
alpha 1
2
Q
- Which sympathetic nerve receptor predominantly causes increased contractility?
A
Beta 1
3
Q
- Know the definition of the following terms: chronotropy, inotropy, dromotropy, and lusitropy.
A
- Chronotropy – Heart Rate
- Inotropy – Contractility
- Dromotropy – Conduction Velocity
- Lusitropy – Relaxation
4
Q
- What are some of the major differences between the sympathetic and parasympathetic nervous systems?
A
Sympathetic (Thoraco-lumbar) • Increased HR • Increased chronotropy • Increased dromotropy • Increased arterial & venous resistance • Increased venous capacitance
Parasympathetic (Cranio-sacral) • Decreased HR • Decreased chronotropy • Decreased dromotropy • Decreased arterial & venous resistance • Decreased venous capacitance
5
Q
- Does the sympathetic nervous system primarily stimulate or inhibit the heart?
A
Stimulate
6
Q
- What is the “second messenger” that is involved with sympathetic stimulation of a cardiac muscle cell?
A
- cAMP
* adenylyl cyclase activation allows ATP to change to cAMP (allows greater Ca influx in the sarcolemma)
7
Q
- Which catecholamine does the adrenal gland predominantly release with sympathetic stimulation?
A
epi 80%
norepinephrine 20%
8
Q
- What is the Baroreceptor Reflex? Where are the receptors for this reflex located?
A
- Sensors and buffers changed in BP
* Located in the Carotid SINUS (NOT carotid body) and Aortic Arch
9
Q
- How does the Baroreceptor Reflex help with blood pressure regulation?
A
- Helps reduce daily variation in BP
- Helps with postural changes in BP
- Helps to rapidly changing pressure
10
Q
- During what surgery does Baroreceptor Reflex activation frequently cause hemodynamic changes?
A
• Carotid endarterectomy – pushing on carotid sinus (body thinks high BP) so you get profound hypotension.
11
Q
- What is the Bainbridge Reflex? Where are the receptors for this reflex located?
A
• Infusion of volume causes an increase in heart rate due to activation of atrial stretch receptors which causes medullary center activation of sympathetic output to the SA node
- Vena Cava – right atrial junction
- Pulmonary vein – left atrial junction
12
Q
- In addition to receptor activation what also contributes to the heart rate changes seen with the Bainbridge Reflex?
A
- Infusion of volume can increase HR
- Baroreceptor reflex often changes BP in opposite direction
• A small portion of the heart rate increase is d/t stretch of the SA node
13
Q
- The Baroreceptor Reflex responds to changes in arterial blood pressure or to changes in blood volume?
A
• Arterial blood pressure
14
Q
- The Bainbridge Reflex responds to changes in arterial blood pressure or to changes in blood volume?
A
• Blood volume (stretch)
15
Q
- What are some of the effects of Atrial Stretch Receptor activation?
A
- Decreased sympathetic activity to the kidneys - increases urine output
- Decreased vasopressin – increase urine output & decrease water reabsorption/BP
- Increased Atrial Naturetic Peptide – increased urine output/ Natriuresis & decreased BP
16
Q
- What is the Bezold-Jarisch Reflex?
A
- Strong contraction of an underfilled ventricle elicits the reflex
- This reflex plays a role in blood pressure regulation
- Could lead to vasovagal syncope or cardiac arrest during spinal
17
Q
- What is the CNS ischemic response?
A
- Result of decreased blood flow to vasomotor center in medulla
- Increased local concentration of carbon dioxide results in SNS stimulation in the medulla
- Results in increased BP
- Very powerful activator of the sympathetic nervous system
18
Q
- What is the Cushing Response?
A
- Special type of CNS ischemic response
- Result of increased ICP
- Increased ICP results in increased BP until blood flows once again in the vessels of the brain
19
Q
- What is Cushing’s Triad?
A
- Increased ICP
- Hypertension
- Bradycardia
20
Q
- What cardiovascular changes are mediated by stimulation of the Peripheral Chemoreceptors? Where are the Peripheral Chemoreceptors located?
A
- Increased SVR/MAP
- Primarily concerned with regulation of respiration
- Located in Aortic and carotid bodies
21
Q
- What is the Diving Reflex? Where are the receptors for this reflex located?
A
• When facial thermoreceptors are exposed to cold water → decreased HR and increased peripheral vasoconstriction (trying to conserve O2)
22
Q
- Vasopressin is released from which part of the brain? What are the effects of vasopressin on blood pressure? What are the effects of vasopressin on the kidney?
A
- Posterior Pituitary
- Blood Pressure → vasoconstriction with increased blood pressure
- Kidney → renal fluid reabsorption with resulting increased blood volume
23
Q
- What is the stimulus for release of Atrial Natriuretic Peptide? What are the effects of ANP on blood pressure? Blood volume?
A
Stimuli for Atrial Natriuretic Peptide (ANP) release: • Atrial distention • Sympathetic stimulation • Angiotensin II • Endothelin
Blood pressure → decreases SVR & CVP = decreased BP
Blood volume → decreased blood volume (natural diuresis)
24
Q
- What converts angiotensinogen to angiotensin I?
A
Renin
25
25. What converts angiotensin I to angiotensin II?
Angiotensin Converting Enzyme (ACE)
26
26. What effects does angiotensin II have on blood pressure? Blood volume? Adrenal cortex?
* Angiotension 2 simulates adrenal cortex to release alderstone
* Blood pressure → vasoconstriction which leads to increased BP
* Blood volume → promotes NA & fluid retention which leads to increased blood volume
* Adrenal cortex → Na & fluid retention
27
27. What are the INDIRECT effects of hypoxia on the circulatory system? What are the DIRECT effects?
* Indirect → cause sympathetic nervous system activation and cause increased HR/contractility/ SVR
* Direct → decrease contractility/HR
28
28. What are the INDIRECT effects of hypercarbia on the circulatory system? What are the DIRECT effects?
* Indirect → cause sympathetic nervous system activation and cause increased HR/contractility/ SVR
* Direct → decreased contractility
29
29. What is the "Fight or Flight" response?
Increased – BP, blood flow to activate muscles (with decreased blood flow to GI tract and kidneys), rated of intracellular metabolism, blood glucose, glycolysis in liver and muscle, muscle strength, mental activity, rate of blood coagulation
30
30. What are the 2 types of acetylcholine receptors?
* Muscarinic
| * Nicotinic
31
31. What are the differences between the innervation of the heart by the parasympathetic and sympathetic nervous systems?
Parasympathetic (vagus nerve)
pre & post ganglionic are very close to the heart and innervate only the atria (very little to the ventricles)
Sympathetic (T1-T4)
Preganglionic sympathetic chains, innervates both atria and ventricles.
32
32. Which cranial nerve carries parasympathetic nervous input to the heart?
Vagus nerve
33
34. Binding of norepinephrine to which adrenergic receptor causes inhibition of neurotransmitter release?
alpha 2
34
35. In which part of the brainstem is the vasomotor center located?
Bilaterally in medulla and lower third of pons
35
36. What is the neurotransmitter released at the junction between the pre-ganglionic and post-ganglionic sympathetic fibers? Between the post-ganglionic sympathetic fibers and the effector site? Between the pre-ganglionic sympathetic fibers and the adrenal medullae?
* pre-ganglionic and post-ganglionic sympathetic fibers → acetylcholine
* post-ganglionic sympathetic fibers and the effector site → norepi
* Between the pre-ganglionic sympathetic fibers and the adrenal medullae → ach
36
37. Blood vessels (except for capillaries) have predominantly sympathetic or parasympathetic nervous system innervation?
Sympathetic
