Lecture 3C Flashcards
What two things can you target to regulate cardiac output?
Pressure or Resistance
When MAP rises, what occurs to the HR and BP?
They are both elevated
When TPR rises, what occurs to the HR and BP
HR and BP decrease
Short term regulation of MAP occurs through what pathways and targets what vessels?
Occurs within seconds to minutes
- Occurs via neural pathways
- Targets the heart and blood vessels
Long term regulation of MAP occurs through what pathways and targets what vessels?
Occurs within hours to days
- Occurs primarily via endocrine pathways
- Targets the kidneys and blood vessels
What are Baroreceptors?
Neural receptors located in the carotid sinus and aortic arch that measure Pressure. They are placed in strategic positions.
Can Baroreceptors change the BP themselves?
No
What two nerves carry signals from the baroreceptors
CN IX and CN X
Where to the cranial nerves carry the signal to from baroreceptors?
To the Medullary Cardiovascular center of the brainstem
What are two ‘mini-centers’ of the medullary cardiovascular center
- Vasomotor area
2. Cardioinhibitory area
What is the role of the Medullary Cardiovascular center of the brainstem
It makes decision about what to do about hypertension or hypotension. Then it employs the services of the SNS and ParaNS to send those orders to various target tissues.
What two places are baroreceptors located?
Carotid sinus
Aortic arch
If Blood pressure increases, baroreceptors detect it and send signals to the medullary cardiovascular center. What actions are applied for BP increasing?
Decreased SNS cardiac nerve activity
Decreased SNS vasoconstrictor nerve activity
Increased ParaNS cardiac nerve activity
After the SNS and ParaNS have been alerted to changes based on increased BP, what occurs to the HR, SV, CO and TPR?
HR decreases SV decreases CO decreases TPR decreases Vasodilation
Go through scenario if BP is too low or too high as noted on another note card
- BP too high • Decrease in SNS activity and increase in PNS activity to lower HR (Contractility decreases and SV decreases, BVs are dilated and MAP falls)
- BP too low. • Increase in SNS activity and decrease in PNS activity to raise HR. (Contractility increases and SV increases, BVs are constricted and MAP increases)
The sensitivity of the baroreceptors can be altered by what?
Disease. In such cases like hypertension, baroreceptors will maintain the hypertension corrections rather than correct the hypertension.
A decrease in renal perfusion pressure (BP) causes kidneys to secrete what enzyme?
Renin
What is the long-term regulation of MAP
Renin-Angiotensin-Aldosterone Pathway (RAA)
Renin catalyzes the conversion of what?
Angiotensinogen to Angiotensin I in the plasma
The Angiotensin Converting Enzyme (ACE) catalyzes what conversion? Where does this occur?
Angiotensin I to Angiotensin II
In lungs
Angiotensin II has what effects?
- Vasoconstrictor
- Stimulates hypothalamus to increase thirst to increase blood volume and BP
- Stimulates aldosterone release from adrenal cortex
- Increase Na+-H+ exchange and Na reabsorption
Anti-diuretic hormone is also known as?
Vasopressin
ADH is associated with what type of MAP pathway?
Long-term pathways
ADH has what 2 effects that tends to increase blood pressure toward normal
- It is a potent vasoconstrictor that increases TPR by activating V1 receptors on the arterioles
- Increases water reabsorption by the renal distal convoluted tubules and collecting ducts by activating V2 receptors.
