Exam 2: AI Lecture 1 Flashcards
What typically maintains arterial pressure and cardiac output during shock?
Neurological reflexes and various compensatory mechanisms
These systems work together to deliver nutrients and maintain blood flow.
What happens to blood when a person stands up from a seated position?
Blood may pool in the legs if no reflex occurs
The body has reflexes to prevent this pooling and maintain blood pressure.
Where are the carotid baroreceptors located?
At the bifurcation of the carotid artery, in the carotid sinus
They are connected to the brainstem via the glossopharyngeal nerve.
What is the role of norepinephrine in the cardiovascular system?
It regulates systemic vascular resistance (SVR) and contractility
Norepinephrine is a primary pressor in maintaining blood pressure.
Which circulatory beds are prioritized during circulatory stress?
- Coronary circulation
- Central nervous system
- Kidneys
These areas receive blood flow even when overall blood output is low.
What is the primary function of vasopressin in the cardiovascular reflex system?
To increase systemic vascular resistance (SVR) during low blood pressure situations
Vasopressin release typically occurs in response to changes in osmolarity.
What does the Renin Angiotensin Aldosterone System (RAAS) do?
Regulates blood pressure and fluid balance
RAAS activation leads to aldosterone release, increasing sodium and water retention.
True or False: Removing components of compensatory mechanisms can impair the cardiovascular system’s ability to respond to stress.
True
Loss of components like angiotensin II can significantly impact blood pressure regulation.
What reflex occurs in response to increased stretch in the atria?
Increased urine output from the kidneys
This reflex aims to reduce blood volume when there’s overdistension.
What is Atrial Natriuretic Peptide (ANP) primarily responsible for?
Increasing urine output by promoting sodium excretion
ANP is released from the right atrium when overstretched.
Where is Brain Natriuretic Peptide (BNP) produced?
In the ventricles of the heart
BNP levels are used to monitor heart failure treatment efficacy.
What happens to BNP levels if heart failure treatment is effective?
BNP levels decrease
A reduction indicates less pathological stretch on the ventricles.
What is the effect of elevated blood volume on circulation rate?
It typically decreases the circulation rate
Higher blood volume can lead to slower blood flow, increasing the risk of clot formation.
What is the relationship between ANP and blood volume?
ANP helps reduce blood volume when it becomes excessive
This prevents complications from overdistension of the heart.
Fill in the blank: ANP and BNP are examples of _______.
natriuretic peptides
These peptides promote the excretion of sodium and water.
What happens to the effectiveness of ANP over time?
It typically lasts about two weeks before becoming ineffective
This limitation necessitates the use of diuretics for long-term management.
What is the purpose of using diuretics in patients with heart failure?
To override the kidneys’ tendency to retain volume
This helps prevent fluid overload in patients with compromised heart function.
What is the body’s built-in way to manage volume expansion in the cardiovascular system?
The heart’s system to prevent unchecked volume expansion
This mechanism effectively works for a limited duration, necessitating the use of diuretics for prolonged management.
What is the estimated blood volume in a typical adult human?
About 5 liters
This includes approximately 3 liters of plasma and 2 liters of hematocrit.
What percentage of extracellular fluid (ECF) is typically found in plasma?
1/4 to 1/5 of the ECF
The remaining portion is primarily located in the interstitium.
What is the oncotic pressure of the blood and its primary components?
28 millimeters mercury, primarily made up of albumin, fibrinogen, immunoglobulins, antibodies, and coagulation factors
Oncotic pressure helps keep fluid within the cardiovascular system.
What happens if approximately 20% of blood volume is lost?
The individual is likely to experience significant issues but may not die immediately
Losing 1 liter of blood results in the loss of about 600 cc’s of plasma and 400 cc’s of red blood cells.
What is the role of plasma proteins in the cardiovascular system?
They help maintain oncotic pressure, which keeps fluid in the cardiovascular system
Loss of plasma proteins can decrease oncotic pressure, complicating volume maintenance.
Which fluid is commonly used for volume replacement during hemorrhage?
Normal saline
Normal saline lacks colloids, leading to only 1/4 to 1/5 of the volume remaining in the cardiovascular system.
What is a potential consequence of administering too much normal saline?
Pulmonary edema
Excessive normal saline can lead to fluid accumulation in the lungs, particularly problematic due to limited space for interstitial fluid.
What are synthetic colloids used for in volume replacement?
Dextran and hetastarch are used to maintain oncotic pressure and keep volume in the cardiovascular system
These are large sugar molecules that resemble proteins and can help manage volume loss.
What happens to blood pressure after a bolus of fluid is administered?
Blood pressure increases initially but may not remain elevated
This is due to fluid relocating to the interstitium and the phenomenon of stretch relaxation.
What is stretch relaxation?
A response of large veins where smooth muscle relaxes over a period of minutes following distension
This process reduces venous pressure.
What is reverse stretch relaxation?
A sympathetic nervous system response that tightens the walls of veins during hemorrhage
This counters the typical stretch relaxation response.
What is the CNS ischemic response?
A strong sympathetic nervous system response occurring during low brain perfusion
It aims to stabilize blood pressure and blood volume when critically low.
What can result from prolonged shock and inadequate tissue perfusion?
Tissue dysfunction, cell necrosis, and release of intracellular contents
This can lead to complications like hyperkalemia and acidosis.
Which organ is particularly sensitive to underperfusion during shock?
The liver
It often begins to fail before other organs like the kidneys.
What methods can be used to measure cardiac output?
PA catheter, thermal dilution, software analysis of blood pressure tracing
Estimations can also be made from blood gas measurements.
What does the Fick Equation relate to in terms of cardiac output?
It connects oxygen delivery and consumption in the body
It involves arterial and venous oxygen levels to estimate required cardiac output.
What is the process of oxygen consumption and carbon dioxide production in the body?
Consume the oxygen -> produce CO2 -> CO2 blows closed in the veins -> returned to the lungs to blow off CO2 and reoxygenate blood.
How can we determine the required liters of output for oxygen delivery?
By knowing the patient’s oxygen demands, oxygen consumption, and the oxygen content in the blood.
What are the typical oxygen content numbers in arterial and venous blood?
- Arterial blood: 20 mLs O2/deciliter
- Venous blood: 15 mLs O2/deciliter
How much oxygen is dropped off by each deciliter of blood in systemic circulation?
5 mLs of O2.
What is the normal oxygen consumption for an average healthy adult?
250 mLs O2/minute.
How do you calculate cardiac output using oxygen consumption?
Cardiac output = Total oxygen consumption / Oxygen delivered per deciliter.
What is the Fick Equation?
A formula used to calculate cardiac output based on oxygen consumption and delivery.
What is digoxin and its primary action?
A sodium-potassium ATPase pump inhibitor, primarily used to improve heart function.
Why is digoxin considered a drug of last resort?
It has widespread effects on the body and can cause various complications.
What is cardiac reserve?
The maximum amount of cardiac output above normal.
If normal cardiac output is 5 liters per minute, what would a cardiac output of 25 liters represent in terms of cardiac reserve?
400% cardiac reserve.
How does age affect cardiac reserve?
Cardiac reserve typically decreases with age.
What are common causes of reduced cardiac reserve?
- Valve diseases
- Coronary artery diseases
What does a stenotic valve indicate?
A valve that is hard to open due to calcification and cholesterol deposits.
What happens to coronary artery perfusion in aortic stenosis?
Coronary arterial perfusion is compromised due to obstruction.
What is the prevalence of congenital bicuspid aortic valves in the population?
Estimated at 1-2%.
What is the common treatment for severe congenital bicuspid aortic valves?
Replacement of the valve may be necessary if it becomes problematic.
True or False: Everyone with a congenital bicuspid aortic valve will need it replaced.
False.
Fill in the blank: The normal oxygen content in arterial blood is _____ mLs O2/deciliter.
20
Fill in the blank: The oxygen consumption in a healthy adult is approximately _____ mLs O2/minute.
250
