Lecture 8 Flashcards
Exam 2 content
Where do the baroreceptors we talked about in regards to CV reflexes hang out?
carotid sinus (at the bifurcation of the carotid artery)
aortic arch
Which nerves are associated with the carotid baroreceptors? The aortic baroreceptors?
carotid: glossopharyngeal nerves
aortic: vagus nerves
What NTs are responsible for systemic vascular resistance? What are the sources?
NE/Epi
local transmission via nerves
systemic supply by the adrenal glands
what are the two main functions of NE and Epi?
increased SVR and contractility
what are the two most important/protected circulatory beds?
coronaries > CNS> kidneys
What modulates vasopressin release?
changes in osmolarity
If we have too much blood volume what happens?
blood pressure goes up–> atrial stretch–> signals to kidneys to reduce volume by increasing UO
What is ANP?
atrial natriuretic peptide. A hormone released by the right atrium that increases urine output by the kidneys
what is potentially problematic if we have too much blood volume around?
- too much extra stretch in low pressure side of the circulation
- decreased rate of circulation- increased risk for blood clots
What is BNP?
brain natriuretic peptide but its released by the ventricles. It is a hormone that signals to the kidneys to increase UO
What is BNP a good marker for?
the severity of CHF.
Why do we need diuretics to treat CHF?
the ANP/BNP response only lasts a few weeks, diuretics help achieve the same fluid/volume management long term
what are crystalloids only a good short-term solution for hemorrhage?
the blood pressure will eventually taper down again d/t two things…
1. fluid gets third spaced
2. stretch relaxation reflex
what is the stretch relaxation reflex?
A response of smooth muscle of large veins when stretched by a fast infusion of fluid causing the veins to relax. This reduces venous pressure.
What is the reverse stretch relaxation?
SNS’s response to hemorrhage which overrides what the vasculature wants to do on its own–> tights the walls of the veins
what is the CNS ischemic response?
a response to a decrease in perfusion to the brainstem after a few minutes –> the strongest of all the CV responses
What is the oxygen content in the arterial blood?
20 mL of O2 in a dL of blood
What is the oxygen content of the venous blood?
15 mL of O2 in a dL of blood
What is the normal oxygen consumption for the average adult?
250 mL of O2 per minute
How could you calculate CO with oxygen content numbers and knowing what we know about the average oxygen consumption?
20mL/dL - 15 mL/dL = 5 mL/dL
250 mL/min / 5mL/dL = 50 dL/min or 5 L/min
What is the Fick equation?
If normal CO is 5L/min, what cardiac reserve do athletes have? Do we have?
athletes: above 600% (30L + 5L/min (BL) might be even higher = ^35L/min)
us: 400% (20L + 5L/min (BL) = 25L/min)
