Lecture 25: Blood Pressure I and II Flashcards
Mean arterial blood pressure
- Force exerted by the blood against a vessel wall
- Result of push exerted by cardiac contraction (volume of blood contained within the vessel) and the compliance (dispensibility/elasticity of the vessel wall)
Mean arterial blood pressure is responsible for
Driving blood forward into the tissues throughout the cardiac cycle
Mean arterial blood pressure is regulated by
- Baroreceptor reflex
2. Renin-angiotension-aldosterone system
Aortic arch baroreceptor location and purpose
- Located in arch of aorta
- Relays information about blood pressure in the circulation to the cardiovascular center in the medulla oblongata
Carotid sinus baroreceptiors
- Triggers reflexes to maintain blood flow to the brain
- Pressure sensors that relay info about bp to the cardiovascular centers in the medulla oblongata
What is the most important mechanism for short term (within seconds) regulation of bp
Baroreceptor reflex
Purpose of baroreceptor reflex
Adjusts cardiac output and total peripheral resistance to control bp
Baroreceptor reflex arc
- Receptor
- Afferent pathway
- Integrating center
- Efferent pathway
- Effector organs
When does baroreceptor accommodation occur?
When a receptor becomes less sensitive to a sustained stimulus over time
Accommodation of baroreceptors is a significant complicating factor in the treatment of
high blood pressure
Renin-Angiotension Aldosterone System
Involves adjusting total blood volume through mechanisms that regulate urine output and thirst
Where is ANP produced?
Atrial muscle cells
ANP release is regulated by
Atrial stretching
What hormone opposes Angiotensin II?
ANP
Three ways ANP opposes angiotension II
- Promotes the loss of Na and H2O at the kidneys
- Inhibits the secretion of water - conserving hormones such as ADH and aldosterone
- Suppresses thirst
Secretion form the posterior pituitary is increased by two types of stimuli
- Increase in serum osmolarity
2. Decrease in arterial bp
Two types of chemoreceptors
- Peripheral
2. Central
Peripheral chemoreceptors are located where?
In the carotid bodies near the carotid sinus, aortic bodies near aortic arch
Central chemoreceptors are located where?
Medulla oblongata
An increase in blood CO2 and a decrease in pH and blood O2 leads to
An increased heart rate, contractility, and vasoconstriction
Do chemoreceptors regulate the cardiovascular system during normal conditions?
Nope only in emergency situations
Chemoreceptor stimulation normally affects the ___ ___ in the ___ _____
Respiratory center
Medulla oblongata
Coordination of cardiovascular and respiratory activity is vital because
accelerating tissue blood flow is only useful if the circulating blood contains adequate O2
