Baroreceptors Flashcards
What is the formula for calculating blood pressure?
BloodPressure
Blood pressure is calculated using the formula:
CardiacOutput
×
SystemicResistance
BloodPressure=Cardiac Output× SystemicResistance
How does isoprenaline affect blood pressure and heart rate?
Isoprenaline affects beta adrenoreceptors, causing a significant increase in heart rate. However, blood pressure only decreases slightly because the arteries relax a little, which reduces systemic resistance.
How does the autonomic nervous system regulate cardiac output and peripheral resistance?
The autonomic nervous system regulates cardiac output and peripheral resistance through the parasympathetic and sympathetic nervous systems. The parasympathetic system releases acetylcholine, which slows the heart rate and reduces contraction force. The sympathetic system releases noradrenaline, which increases heart rate and contraction force, affecting the heart via M2 and beta1 receptors.
What is the effect of stimulating the vagus nerve on the heart?
Stimulating the vagus nerve in the parasympathetic nervous system causes a slower heart rate and less forceful contraction. This is due to the cholinergic effect of acetylcholine on M2 receptors.
How does the sympathetic nervous system affect the heart?
The sympathetic nervous system speeds up the heart by activating adrenoreceptors. This leads to increased production of cAMP and activation of protein kinase A. The kinases then phosphorylate proteins, increasing heart rate and the force of contraction.
What role does noradrenaline play in regulating systemic resistance and stroke volume?
Noradrenaline increases systemic resistance through beta-2 receptors, which causes an increase in stroke volume and heart rate via beta-1 adrenoreceptors.
What is the baroreceptor reflex and how does it stabilize arterial pressure?
The baroreceptor reflex adjusts cardiac output and peripheral vascular tone to stabilize arterial pressure. It involves the detection of pressure changes by baroreceptors, which send signals to the brain stem to modulate autonomic responses and stabilize blood pressure.
Where are baroreceptors located and how do they contribute to blood pressure regulation?
Baroreceptors are located in the aortic arch and carotid sinus. They detect the magnitude and rate of pressure changes and send this information to the brain via the vagus nerve and nerve 9, which then influences sympathetic and parasympathetic activity to regulate blood pressure.
How do the baroreceptors transmit information to the brain?
Baroreceptor fibers in the vagus nerve and nerve 9 release transmitters that activate neurons in the nucleus tractus solitarius (NTS). These neurons then activate the nucleus ambiguus, which increases vagus nerve activity, leading to a reduction in sympathetic activity through the CVLM and inhibition of RVLM sympathetic nerves.
How does the baroreceptor reflex interact with the brainstem and other brain regions?
The baroreceptor reflex, located in the medulla, is influenced by higher brain regions, including the hypothalamus and cortex, which help modulate the response to blood pressure changes.
What effect does acetylcholine have on stroke volume and heart rate?
Acetylcholine, released by the parasympathetic nervous system, reduces both stroke volume and heart rate through activation of M2 receptors.
How does the sympathetic nervous system affect heart contraction force?
The sympathetic nervous system increases the force of heart contraction by activating beta-1 adrenoreceptors, which triggers the production of cAMP and activates protein kinase A, leading to phosphorylation of proteins that enhance contraction force.
What are the key components involved in the baroreceptor reflex pathway?
The key components of the baroreceptor reflex pathway include baroreceptors in the aortic arch and carotid sinus, the vagus nerve and nerve 9, the nucleus tractus solitarius (NTS), nucleus ambiguus, CVLM, and RVLM.
What role do baroreceptors in the carotid sinus play in blood pressure regulation?
Baroreceptors in the carotid sinus respond to the stretch of the arteries and send signals to the brainstem, which adjusts autonomic activity to regulate blood pressure.
What happens in the body when the baroreceptor reflex detects high blood pressure?
When high blood pressure is detected, the baroreceptor reflex increases parasympathetic activity via the vagus nerve, and reduces sympathetic activity through inhibition of the RVLM, lowering heart rate and systemic resistance to normalize blood pressure.
What is the function of the vagus nerve in the baroreceptor reflex?
The vagus nerve plays a key role in the baroreceptor reflex by transmitting signals from the baroreceptors to the brainstem, where it helps activate parasympathetic responses to lower heart rate and reduce sympathetic activity.
How does the baroreceptor reflex help in responding to changes in blood pressure?
The baroreceptor reflex detects changes in arterial pressure and adjusts cardiac output and peripheral vascular tone to stabilize blood pressure by modulating autonomic nervous system activity.
What neurotransmitters are involved in regulating the sympathetic and parasympathetic nervous systems?
In the sympathetic nervous system, noradrenaline is released, activating beta adrenoreceptors. In the parasympathetic nervous system, acetylcholine is released, activating M2 receptors to reduce heart rate and contraction force.
