Cardiovascular control: Baroreceptor and chemoreceptors: physiology

Receptors that monitor blood pressure. They send signals to the central nervous system that then induce compensatory mechanisms to adjust blood pressure as needed

What are Baroreceptor

Vasoconstriction/vasodilation and urination

What compensatory mechanisms are used to influence blood pressure

When blood pressure is abnormally high or low, the nervous system activate mechanisms to cause the blood pressure to go back to normal

What is complete compensation

When the blood pressure is abnormally high or low, the nervous system activates mechanisms to get blood pressure CLOSER to normal (still remains slightly abnormal)

What is partial compensation

The blood pressure and flow are controlled locally to ensure delivery to certain capillary beds

What is local control of blood flow and pressure

Systemically, blood pressure and flow are monitored and controlled to ensure proper delivery to vital organs and survival of the body as a whole

What is systemic control of blood flow and pressure

Myogenic mechanism, nitric oxide, and metabolic regulation

Examples of local control of blood flow and pressure

Autonomic nervous system innervation, Baroreceptor, chemoreceptors, atrial stretch receipts, and humoral agents

Examples of systemic control o blood pressure and flow

The cardiovascular center in the medulla

What is the primary control of the heart and blood vessels

The cardiac pressor center, cardiac depressor center, and vasoconstrictor center

What is the cardiovascular center of the medulla made up of

The sympathetic nervous system

What controls the cardiac pressor center and the vasoconstrictor center

The parasympathetic nervous system

What controls the cardiac depressor center

To increase heart rate, conduction velocity, and contractility

What is the function of the cardiac pressor center

To decrease heart rate

What is the function of the cardiac depressor center

The increase or decrease vasoconstriction ONLY (no vasodilation)

What is the function of the vasoconstriction center

Baroreceptor are located in major blood vessels (aorta and carotid sinus) walls. As blood pressure and/or blood volume increase the Baroreceptor are stretched causing them to fire action potentials to the cardiovascular center in the medulla causing an increase in PNS and a decrease in SNS till blood pressure goes back to normal

What is the Baroreceptor reflex

Sudden on set orthostatic hypotension. Initial blood was spread evenly laying down however when standing up gravity forces blood toward the lower half of the body away from the brain and causes venous return to decrease when then causes decrease in preload and cardiac output.

What happens when someone gets up from laying down too fast

There is low blood volume/pressure in the major vessels as the blood pools in the lower body causing the Baroreceptors to not be stretched which would send signals to the cardiovascular center of the medulla to increase sympathetic and decrease parasympathetic drive. There would also be skeletal muscle pumps in action to push pooled blood in the legs back to the heart.

What happens to Baroreceptor during orthostatic hypotension

Chemoreceptors located in the medulla that monitor arterial CO2 and interstitial fluid pH levels

What are central chemoreceptors

Located in same areas as baroreceptors, detect CO2, pH, and O2 in the blood

What are peripheral chemoreceptors

Increase in CO2 (hyper apnea), decrease in pH(acidosis), decrease in O2

What increase chemoreceptor action potentials

Stimulates vasoconstriction center to increase vasoconstriction of skeletal muscle, renal, and splanchnic vascular beds which causes systemic vascular resistance to increase moving blood away from periphery and toward the brain. Also effects ventilation in lungs

What happens when chemoreceptor action potential increases

Receptors that monitor blood pressure and volume

What are atrial stretch receptors

The atrial stretch receptors are stretched (stimulated) and the atria releases the hormone Atrial Natriuretic peptide (ANP) that stimulates vasodilation and decrease systemic vascular resistance (SVR) causing increased blood flow to the kidneys and increase in sodium and water excretion which lower blood volume

What happens when blood volume or filling pressure of the atria increase

Molecules that are released from different body parts that cause vasoconstriction and vasodilation

What are humoral agents

Norepinephrine and epinephrine

What humoral agents cause vasoconstriction

Histamine and acetylcholine

What humoral agents cause vasodilation