Baroreceptor & Chemoreceptor Regulation Flashcards
What are vascular reflexes?
internal sensory-feedback systems that “sense” changes in important circulatory parameters and respond via pathways that alter the tonic autonomic control of the heart and vasculature
Vascular reflexes work to maintain and optimize what?
cardiovascular performance in rpaidly changing physiological situations
What are the types of vascular reflexes?
- peripheral baroreceptors
- peripheral chemoreceptors
- pulmonary stretch receptors
- hypothalamus
What are arterial baroreceptors are present during?
- posture changes
- exercise
- hemorrhage
Where are stretch receptors of arterial baroreceptors located?
in carotid sinuses and aortic arch
What is the role of stretch receptors of arterial baroreceptors?
detect physical deformations in the vessel wall due to blood pressure changes
What is the innervation of the carotid sinus baroreceptors?
the afferents travel the sinus nerve to the glossopharyngeal nerve to the NTS
What is the innervation of the aortic arch baroreceptors?
afferents travel along the vagus nerve to the NTS
How does the firing rate change between systole and diastole?
decreases during late systole and diastole
How does baroreceptor stimulation affect sympathetic and parasympathetic activity?
- decreases sympathetic
- increases parasympathetic
What does an increased baroreceptor firing rate lead to?
vasodilation and bradycardia
What is the sympathetic pathway in baroreceptor stimulation?
increased BP -> increased baroreceptor firing -> decreased sympathetic discharge -> decrease vasoconstriction -> decrease BP
negative feedback occurs once at the bottom and goes back to the top
What is the parasympathetic pathway in baroreceptor stimulation?
increased BP -> increased baroreceptor firing -> increased vagal discharge -> decrease heart rate -> decrease BP
How do arterial baroreceptors adapt?
occurs during long-term changes in mean arterial BP, having a decreased sensitivity to pressure changes
In low pressure baroreceptors, where are mechanoreceptors located?
atria and pulmonary vessels
What do afferent neurons run to the medulla?
the vagus
Increased stimulation has what affect on medullary centers?
increases stimulation of centers
An increase in stimulation of the medullary centers causes what?
- decreased parasympathetic output to the heart (increase HR)
- increased sympathetic output to the heart (increase HR)
What are the 2 types of chemoreceptors?
central and peripheral
What are the peripheral chemoreceptors organized into?
aortic and carotid bodies
What are aortic and carotid bodies?
highly vascularized cells in aortic arch and carotid sinus that are sensitive to blood, O2, CO2, and pH
What are aortic and carotid bodies involved in?
respiratory regulation
What do central chemoreceptors have a primary role in?
respiratory regulation
What does increased blood CO2 cause?
- stimulate central chemoreceptors
- causes increase in sympathetic outflow and vasoconstriction
What does increased ventillation cause?
- decreases blood CO2 levels
- results in vasodilation
- reduces stimulation of central chemoreceptors
What are hte mechanisms involved in long term blood pressure regulation?
- pituitary antidiuretic hormone
- secretion
- renin-angiotensin-aldosterone system
- atrial natriuretic peptides
What does long term control of blood pressure involve?
regulating systemic blood volume by the kidneys
What is the mm Hg of a hypertensive individual?
- mean arterial blood pressure: >100 mm Hg
- diastolic pressure: >90 mm Hg
- systolic pressure: >135 mm Hg
What is the mm Hg of a severe individual?
- mean arterial blood pressure: 150-170mm Hg
- diastolic pressure: up to 130 mm Hg
- systolic pressure: up 250 mm Hg
In essential hypertension, how much is the mean blood pressure increased?
40-60%
In essential hypertension, how much is TPR increased?
40-60%
In essential hypertension, how much is renal resistance increased?
2-4 times
What is the response to standing?
- pooling of blood in veins> decrease arterial pressure> increase sympathetic outflow
When standing, what does an increase in sympathetic outflow cause?
- increase in heart rate, contractility, cardiac output
- increase in TPR
- decrease in unstressed volume
