Neurohumoral Control Quiz 8 Flashcards
Which sympathetic nerve receptor predominantly causes vasoconstriction?
Alpha
Which sympathetic nerve receptor predominantly causes increased contractility?
Beta 1
Which sympathetic nerve receptor predominantly causes bronchodilation?
Beta 2
The definition of chronotropy
heart rate
The definition of inotropy
contractility
The definition of dromotropy
conduction velocity
The definition of lusitropy
relaxation
What are some of the major differences between the sympathetic and parasympathetic nervous systems?
Heart
Symp Paras
Chronotropy (rate) +++ - - -
Inotropy (contractility) +++ - 1
Dromotropy(conduction velocity)++ - - -
Vessels (vasoconstriction)
Resistance (arteries, arterioles)+++ - 2
Capacitance (veins) +++ 0
Does the sympathetic nervous system primarily stimulate or inhibit the heart?
Stimulate
What is the “second messenger” that is involved with sympathetic stimulation of a cardiac muscle cell?
Cyclic AMP
Which catecholamine does the adrenal gland predominantly release with sympathetic stimulation?
Mostly epinephrine (80%) lesser amount norepinephrine (20%)
What is the Baroreceptor Reflex? Where are the receptors for this reflex located?
Sensor of change in BP, increases or decreases HR due to change. Located in carotid SINUS and Aortic Arch
How does the Baroreceptor Reflex help with blood pressure regulation?
Senses and Buffers Change in BP
Reduces the daily variation in BP by 1/2 to 1/3 from that which would occur if this system were not present
During what surgery does Baroreceptor Reflex activation frequently cause hemodynamic changes?
Carotid Endarectomy
What is the Bainbridge Reflex? Where are the receptors for this reflex located?
Low pressure receptors that respond to stretch, sense cardiovascular system volume
(example, fluid bolus given to dog increases heart rate)
Located: Vena Cava- Right Atrial Junction
Pulmonary Vein- Left Atrial Junction
In addition to receptor activation what also contributes to the heart rate changes seen with the Bainbridge Reflex?
Stretch of heart and Stretch of SA node
The Baroreceptor Reflex responds to changes in arterial blood pressure or to changes in blood volume?
Changes in arterial blood pressure
The Bainbridge Reflex responds to changes in arterial blood pressure or to changes in blood volume?
Changes in blood volume
What are some of the effects of Atrial Stretch Receptor activation?
Increased Urine Output
Decreased H2O reabsorption
Decreased BP
Increased natriuresis
What is the Bezold-Jarisch Reflex?
Strong contraction of an underfilled ventricle elicits the reflex, plays a role in blood pressure regulation, results in decreased BP and decreased HR
What is the CNS ischemic response?
Result of decreased blood flow to vasomotor center in medulla, increases local concentration of CO2 results in SNS stimulation in medulla, which increases BP
What is the Cushing Response?
Special type of CNS ischemic response, a result of increased ICP, results in increased BP until blood flows
What is Cushing’s Triad?
Bradycardia
Increased BP
Increased ICP
Under what circumstances can Peripheral Chemoreceptors cause hemodynamic changes? What hemodynamic changes occur?
Decreased arterial blood O2 tension, carbon dioxide excess, and or hydrogen ion excess results in the excitation of the vasomotor center, occurs from low blood pressure and inadequate blood flow to the chemoreceptors.
Increased MAP
What is the Diving Reflex? What receptors are involved?
Cold water on face activates thermoreceptors, decreases HR and peripheral vasoconstriction causes reduced O2 consumption by the body and myocardium
Thermoreceptors
An infusion of epinephrine will cause what changes in heart rate? Systolic blood pressure? Diastolic blood pressure?
Increases HR
Increases Systolic, Decreases Diastolic
An infusion of norepinephrine will cause what changes in heart rate? Systolic blood pressure? Diastolic blood pressure?
Heart Rate will increase, then decreases
Increases Systolic and Diastolic BP
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?
Pituitary
Increases BP
Renal Fluid Reabsorption= increases blood volume
What is the stimulus for release of Atrial Natriuretic Peptide? What are the effects of ANP on blood pressure?
Atrial Stretch/ Distention
Decreases BP
What converts angiotensinogen to angiotensin I?
Renin
What converts angiotensin I to angiotensin II?
ACE enzyme
What are the INDIRECT effects of hypoxia on the circulatory system? What are the DIRECT effects?
Indirect- SNS activation, Increased HR, CO, Contractility
Direct= Depressed Myocardial Contractility
What are the INDIRECT effects of hypercarbia on the circulatory system? What are the DIRECT effects?
Indirect- SNS activation, Increased HR, CO, Contractility
Direct= Depressed Myocardial Contractility
