CV Controls/reflexes Flashcards
How are reflexes activated?
- Mechanoreceptors by stretch
2. Chemoreceptors by metabolic products
How does Mild to moderate exercise lead to increased cardia output?
Anticipation of activity —> inhibits vagus nerve to heart and increases sympathetic discharge. —> Increased HR and Contractility —> Increased Heart rate
What is the action of isoproterenol?
- Increaess signal to aquaporin
- Increases contractility of the heart
- Beta agonist Only
How does the preoptic anterior hypothalamus affect CV system?
Temperature center of the heart: Temperature changes alter HR and TPR
How does the Parahypogloassal area of the medulla affect the CV system?
Reciprocally activates Sympathetic and inhibits parasympathetic activity
What nucleus is the first to receive information from baroreceptors?
NTS: Nuceus of the tracts solitarius
What is the effect of the stimulation of NTS?
Inhibits sympathetic nerve outflow to peripheral blood vessels
What are the two locations of baroreceptors, and which are more sensitive?
Aortic
Carotid - More sensitive
How does NE affect Carotid Sinus sensitivity?
Enhances sensitivity; Increase in intravenous pressure produces greater depressor response
What are the two types of cardiopulmonary receptors? How are they activated?
- Type A: Tension activated during systole
2. Type B: Stretch activated during diastole
How to CP receptors modulate BP?
Initiated a reflex which lowers BP by inhibiting vasoconstrictor center in the cerebral medulla:
Inhibits:
- Angiotensin
- Aldosterone
- Vasopressin/ADH
Describe the relationship of change in Heart rate and Blood pressure reflex at different values.
- Inverse relationship btwn HR and BP is most pronounced at intermediate ranges
- At High and low values, HR is constant
What is the Bainbridge reflex?
Heart rate increases when Central venous pressure rises following right heart distention
Ho does the hypothalamus affect cardiovascular ulnar reflexes?
- Hypothalamus is responsible for behavioral and emotional control of CVS
Anterior: DEC BP and Bradycardia
Posterolateral: INC BP and HR
What is Cushing’s Phemomenon?
- Elevation in intracranial pressure caused by brain tumor results in increase in systemic blood pressure
- Ischemic stim of vasomotor regions in medulla
- Helps maintain cerebral blood flow in certain conditions such as expanding intracranial tumors
What are the pulmonary CV reflexes?
Lung Inflation —> Systemic vasodilation and DEC in BP
Lung collapse —> Systemic Vasoconstriction
- Fibers in Vagus nerve and sympathetic nerves
- Stretch receptors which inhibit vasomotor areas
- Magnitude Of depressor response directly related to degree of inflation
What is the response of central chemoreceptors to changes in blood chemistry?
- INC in PCO2 —> Vasoconstriction and INC Preiperal resistance
- DEC in PO2 —> Decrease tonic activity and decrease peripheral resistance
Lowering pH stimulates cerebral areas, ties in pH inhibits them
Where are the peripheral chemoreceptors located? What is their action?
On aortic arch just medial to carotid sinuses.
Stimulate vasoconstrictor regions in response to changes in PO2, PCO2, and pH
What is the primary reflex caused by peripheral chemoreceptors?
Activate medullary vagal center —> DEC HR
What are the secondary reflex responses to chemoreceptors?
Peripheral chemoreceptors —> Respiratory activity —> Hypocapnea + Increased Lungstretch —> Inhibits medullary vagal center
What is Coronary perfusion pressure?
Difference between aortic diastolic pressure and LVEDP
How does Left coronary artery physic pressure differ from Aortic and right coronary artery physic pressure?
- Dramatic downstroke at at end of of Diastole/beginning of systole
- Dramatic upswing after systole
What is Angina Pectoris?
Chest pains associated with myocardial ischemia
What are the most common treatments for Angina Pectoris?
Organic Nitrates —> Metabolized to NO which is a vasodilator
Calcium channel antagonist —> Cause Vasodilation
B-adrenergic antagonists
