Podcast
Questions and Answers
What happens primarily when stretch receptors are stimulated by small balloons?
What happens primarily when stretch receptors are stimulated by small balloons?
At a constant cardiac output, what effect does a fall in total peripheral resistance (TPR) have?
At a constant cardiac output, what effect does a fall in total peripheral resistance (TPR) have?
How does eating a meal affect venous and arterial pressure?
How does eating a meal affect venous and arterial pressure?
What is the primary problem caused by the great increase in venous pressure during exercise?
What is the primary problem caused by the great increase in venous pressure during exercise?
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What physiological response occurs to prevent overfilling of the ventricles during exercise?
What physiological response occurs to prevent overfilling of the ventricles during exercise?
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What occurs when a person stands up in relation to central venous pressure?
What occurs when a person stands up in relation to central venous pressure?
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During exercise, how does muscle pumping affect blood flow back to the heart?
During exercise, how does muscle pumping affect blood flow back to the heart?
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What can occur if the outputs of the right and left ventricles cannot be matched?
What can occur if the outputs of the right and left ventricles cannot be matched?
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What initiates the afferent limb of the cardiovascular reflex response in the carotid sinuses?
What initiates the afferent limb of the cardiovascular reflex response in the carotid sinuses?
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What effect does increased blood pressure have on baroreceptor activity?
What effect does increased blood pressure have on baroreceptor activity?
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Where are the carotid bodies primarily located?
Where are the carotid bodies primarily located?
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Which condition can decrease baroreceptor sensitivity?
Which condition can decrease baroreceptor sensitivity?
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What is the role of chemoreceptors in the carotid and aortic bodies during severe hypoxia?
What is the role of chemoreceptors in the carotid and aortic bodies during severe hypoxia?
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Stretch receptors are known to be located in all of the following except:
Stretch receptors are known to be located in all of the following except:
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What physiological response occurs from the stimulation of atrial receptors?
What physiological response occurs from the stimulation of atrial receptors?
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Which of the following has no effect on baroreceptor response?
Which of the following has no effect on baroreceptor response?
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Study Notes
Cardiovascular Reflex Responses and Their Integrated Control
- Curriculum: Phase 1/ Semester 3/ CVS/ Session 6/L
- Lecturer: Dr. Shahlaa Khazaal Chabuk
- Degrees: MSc/Ph.D. Physiology
Objectives
- Describe cardiovascular reflex response control
- Describe reflex heart origination
- Effect of meal, exercise, and standing up
Carotid Sinuses
- Dilatations at carotid artery bifurcation
- Innervated by a branch of the glossopharyngeal nerve (IX cranial nerve, also called the nerve of Hering) acting as afferent limb
- Sensitive to stretch, located in the adventitia of the arterial wall
Carotid Bodies
- Small, rounded organs near carotid sinuses
- Contain sensory cells responding to chemical stimuli
- Afferent pathway lies in the glossopharyngeal nerve
Aortic Bodies
- Chemoreceptors near the aortic arch and pulmonary and coronary arteries
- Chemoreceptors
Other Receptors
- Stretch receptors in atrial wall, pulmonary vein-left atrial junctions, lungs, coronary arteries, and ventricles
- Both vagal and sympathetic nerves
Baroreceptor Control
- Sensitive to stretch, affected by blood pressure rate change, or pulse pressure increase
- Stimulation by increased blood pressure (BP) results in decreased heart rate, decreased left ventricle (LV) contractility, and lowered blood pressure
- Not sensitive to pressures below 50mmHg
Baroreceptor Response Modulation
- Essential prolonged hypertension, heart failure, or increased Na+ in the arterial wall can decrease baroreceptor sensitivity
Chemoreceptors Control
- Stimulation during severe hypoxia (low oxygen) causes decreased heart rate, decreased cardiac muscle contractility, and increased blood pressure
- Stimulation in the left ventricle causes bradycardia (slow heart rate) and hypotension (low blood pressure)
- Stimulation also occurs with metabolites and hypoxia during myocardial injury.
Atrial Receptors (Atrial Stretch Receptors)
- Vagal nerve endings sensitive to stretch or distension
- Located mainly in the right atrium and at pulmonary vein-left atrial junctions
- Stimulation by stretch or distension leads to a reflex increase in heart rate without affecting heart contractility or blood pressure.
Rules of the CVS (Cardiovascular System)
-
Total Peripheral Resistance (TPR): Inversely proportional to blood need at constant cardiac output
- Decreased TPR = increased venous pressure, decreased arterial pressure
- Increased TPR = decreased venous pressure, increased arterial pressure
-
Cardiac Output (CO):
- Constant TPR: Increased CO = decreased venous pressure, increased arterial pressure
- Constant CO: Decreased TPR = increased venous pressure, decreased arterial pressure
Summary of Effect of eating a meal
- Increased gut activity leads to local vasodilation, decreasing TPR and increasing venous pressure, and lowering arterial pressure. This leads to a rise in cardiac output.
- Arterial pressure rises to meet the need.
Summary of Exercise
- Enormous increase in demand leads to significant muscle pumping. This causes increased venous pressure and decreased arterial pressure.
- To accommodate this, heart rate rises to maintain CO.
- Increased venous pressure is a problem that can result in overfilling of the heart (pulmonary edema risk).
Summary of Standing Up
- Blood pooling in the legs due to gravity decreases central venous pressure. By Starling's law, cardiac output, and thus arterial pressure, falls.
- Heart rate is already high, and both arterial and venous pressure changes are in the same direction.
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Description
Test your knowledge on cardiovascular reflex responses and their integrated control in the human body. This quiz covers the anatomy and functions of carotid sinuses, bodies, and other receptors, as well as the impact of various physiological activities. Perfect for MSc and Ph.D. physiology students.
