5.5 Baroreceptor Reflex Flashcards
What is the equation for blood pressure
Blood Pressure = Cardiac Output x Total Peripheral Resistance
How does blood pressure remain relatively constant
The baroreceptor reflex
What is orthostatic hypotension
When you stand up after sitting and your blood pressure drops significantly. This can cause dizziness.
Where is the coordinating centre for blood pressure in the brain
The NTS in the medulla oblongata of the brain stem
What do baroreceptors detect
Baroreceptors detect vessel stretch. This is sue to a rise in blood pressure in a close system, however the baroreceptors do not detect the rise in pressure itself
Briefly describe the action of the baroreceptor reflex
Baroreceptors detect a stretch in blood vessels following an increase in blood pressure. This signal is then sent to the NTS. The NTS then responds by decreasing heart rate and dilating blood vessels to counteract this rise in blood pressure.
What happens to the nerves innervating the heart following increased NTS activity during the baroreceptor reflex.
There is increased parasympathetic activity down the vagus nerve. However in the NTS, this stretch signal is also reversed by inhibitory interneurons meaning that less activity is sent down sympathetic neurons. So the parasympathetic effects on the heart rate are promoted and the sympathetic effects on the heart rate are inhibited, hence heart rate decreases.
Describe the activity of the vagus nerve
The vagus nerve is always working and active, constantly causing the release of acetylcholine and decreasing the heart rate. Without any nervous innervation, the heart rate would be 100 so the vagus nerve is constantly working to bring this down.
What are piezo channels
Piezos are ion channel proteins sitting in membranes. They detect the stretch in the membrane. During the stretch, the piezo channels open and Ca and Na ions enter. This allows for the transmission of action potentials and activation for downstream signalling as piezos are voltage dependent so that once the initial piezo is activated, further piezos downstream can be activated.
Describe the two types of piezo channels
Piezo 1 - mainly found in the cardiovascular system, lungs, bladded, colon, kidney and skin (the traditional areas where there will be stretch)
Piezo 2 - mainly found in sensory neurons (like the nodose ganglia) and the dorsal root ganglion
