Control of circulation 2 Flashcards
What is peripheral and central control sensitive to?
Peripheral- V sensitive to PO2 decrease
- Sensitive PCO2 increase, pH decrease
Central- sensitive to CO2 and pH (less O2)
What occurs when peripheral system senses decrease pO2?
Decreased PO2
Decreases parasympathetic output to heart
Increase HR
Increases CO
How is there central control?
Increased firing leads sympathetic flow
Vasoconstriction
Where are baroreceptors present?
Carotid sinus
Aortic arch
What is baroreceptor firing rate proportional to?
Medulla
What is barorceptor afferent route (toward CNS)
Glossopharyngeal nerve to medulla
What is barorceptor efferent route
Sympathetic and vagus X
What occurs when there is increased bp?
Increased bp sensed by baroreceptors
Sent via glossopharyngeal to medulla
Increased firing of medulla
Stimulates parasympathetic nerve
Decrease in sympathetic stimulation
Decreased CO and TPR
State equation involving BP?
BP= CO X TPR
What is responsible for short term regulation of bp?
Arterial baroreceptors
New baseline if deviation for few days
What are the two types of baroreceptors?
Cardiopulmonary
Arterial
Where are cardiopulmonary baroreceptors located?
Atria, ventricles, pulmonary arteries
What occurs when cardiopulmonary baroreceptors stimulated?
Baroreceptors stimulated
Decreased vasoconstrictor, decreased bp
Decreased release angiotensin, aldosterone and vasopressin
Lead fluid loss
Vital in blood volume
What controls bp?
Baroreceptors
Chemoreceptors
Where are chemosensitve regions located?
Medulla
What are chemoreceptors responsive to?
Mainly PaCO2
Less O2
Name 3 central effectors?
Blood vessels (vasoconstrict and vasodilation)
Heart (rate and contractility)
Kidney- fluid balance
What do peripheral chemoreceptors detect?
Change partial pressure of oxygen
What happens when increased CO2 detected?
Detect increase pCO2
Receptors send impulses to respiratory centres
Increase ventilation
More CO2 exhaled
pCO2 decreases returns normal
What happens when decrease CO2 detected?
Detect decrease pCO2
Receptors send impulses to respiratory centres
Decrease ventilation
Less CO2 retained in lungs
pCO2 increases and returns normal
How do central chemoreceptors detect changes in arterial pCO2?
Changes in pH of Cerebral Spinal Fluid (CSF)
What occurs when high CO2 levels detected?
What occurs when low levels of pH detected?
High CO2 lvls detected by central chemoreceptors
Medulla
Arteriolar and venous constriction
Increase total peripheral resistance
Increase blood pressure
