Lecture 1 (Test 2) Flashcards
What is the primary function of the cardiovascular system in response to blood loss?
To maintain arterial pressure and cardiac output to deliver nutrients
This involves multiple systems working together to ensure blood is delivered where needed.
What happens to blood when a person stands up from a seated position without reflexes?
Blood pools in the legs
This can lead to a drop in blood pressure if not counteracted by reflexes.
Which nervous system typically responds to positional changes in blood circulation?
Sympathetic Nervous System (SNS)
The SNS responds almost instantaneously to changes in position to maintain blood pressure.
Where are the carotid baroreceptors located?
At the bifurcation of the carotid artery (carotid sinus)
These baroreceptors are crucial for monitoring blood pressure.
What is the role of norepinephrine (NorEpi) in the cardiovascular system?
It regulates systemic vascular resistance (SVR) and contractility
NorEpi is the main pressor in the cardiovascular system.
Which organs are prioritized for blood flow during low blood pressure situations?
- Coronary circulation
- Central nervous system
- Kidneys
These organs are protected during circulatory compromises.
What is the function of vasopressin in response to low blood pressure?
To increase systemic vascular resistance (SVR)
Vasopressin release is typically triggered by changes in osmolarity.
What does the Renin-Angiotensin-Aldosterone System (RAAS) regulate?
Blood pressure and fluid balance
RAAS plays a critical role in maintaining blood pressure during emergencies.
What happens when compensatory mechanisms like Angiotensin 2 are taken away?
The ability of the system to maintain cardiac output and blood pressure is impaired
This can lead to severe consequences for blood circulation.
What are the low-pressure circulation areas of the body where stretch receptors are located?
Stretch receptors in large veins and atria
These receptors respond to increases in blood volume.
What is the effect of increased stretch in the atria on kidney function?
It increases urine output
This is a compensatory mechanism to reduce blood volume.
What is Atrial Natriuretic Peptide (ANP) and its role?
A hormone released from the right atrium that promotes sodium and water excretion
ANP helps to decrease blood volume when the atria are overstretched.
What does Brain-Type Natriuretic Peptide (BNP) indicate?
It indicates ventricular stretch and heart failure status
Elevated BNP levels suggest worsening heart failure.
What happens to BNP levels when heart failure treatment is effective?
BNP levels decrease
This indicates reduced strain on the ventricles.
What is the consequence of having a high blood volume in terms of blood flow?
Slower circulation and increased risk of clotting
Sluggish blood flow can lead to coagulation problems.
What role do the kidneys play in response to excessive blood volume?
They increase urine output to reduce blood volume
This is part of the body’s mechanism to prevent overdistension.
What is the normal blood volume in a healthy adult?
Approximately 5 liters
This includes both plasma and hematocrit.
What is the plasma portion of the blood volume?
About 3 liters
Plasma is the liquid component of blood.
What is the oncotic pressure of the blood primarily composed of?
- Albumin
- Fibrinogen
- Immunoglobulins
Oncotic pressure helps to maintain fluid balance in the vascular system.
What happens if about 20% of blood volume is lost?
It can be serious but not immediately fatal
The body has compensatory mechanisms to handle moderate blood loss.
What is the interstitium’s volume in relation to blood?
4/5s is the interstitium
What is the hematocrit value mentioned?
0.4
What is the oncotic pressure of the blood?
28 millimeters mercury
What primarily makes up the oncotic pressure?
- Albumin
- Fibrinogen
- Immunoglobulins
- Antibodies
- Coagulation factors
What happens if we lose about 20% of our blood volume?
We’re probably not going to die from it
If 1 liter of blood is removed, how much plasma is lost?
About 600 cc’s
If 1 liter of blood is removed, how much red blood cells are lost?
About 400 cc’s
What happens to fluid distribution after losing blood?
Fluid redistributes between different compartments
What is the normal ratio of extracellular fluid in the cardiovascular system?
1/4 to 1/5 of ECF
What happens to oncotic pressure if plasma proteins are lost?
Oncotic pressure decreases
What is a common treatment for blood loss?
Replace what’s missing
What is a common intravenous solution given for volume loss?
Normal saline
Why could normal saline be problematic when replacing blood volume?
Normal saline doesn’t have any colloids
What percentage of normal saline stays in the cardiovascular system?
About 1/4 to 1/5
What is the risk of giving too much normal saline?
Fluid may accumulate in the lungs
What are synthetic colloids mentioned for volume replacement?
- Dextran
- Hetastarch
What is the function of synthetic colloids?
They provide oncotic pressure and stay in the cardiovascular system
What happens when fluid is pushed intravenously quickly?
Increased cardiac output and blood pressure expected
Why doesn’t a bolus of fluid have a lasting effect on blood pressure?
Fluid relocates and stretch relaxation occurs
What is stretch relaxation?
Relaxation of smooth muscle in large veins over time
What is reverse stretch relaxation?
Sympathetic nervous system overriding smooth muscle relaxation
What triggers the CNS ischemic response?
Really low brain or brainstem perfusion
What is the strongest response from the sympathetic nervous system?
CNS ischemic response
What are the consequences of inadequate tissue perfusion?
- Cell necrosis
- Cell death
- Hyperkalemia
Which organ is especially sensitive to shock?
Liver
What are some ways to measure cardiac output?
- PA catheter
- Thermal dilution
- Software and blood pressure tracing
What does the Fick equation relate to?
Cardiac output and oxygen consumption
What is the normal oxygen consumption for an average healthy adult?
250 mLs O2/minute
How much oxygen does each deciliter of blood deliver?
5 mLs of O2
What happens to oxygen in the tissues?
Tissues consume oxygen and produce CO2
What is the total oxygen content in arterial blood?
20 mLs O2/deciliter
What is the total oxygen content in venous blood?
15 mLs O2/deciliter
What happens to the heart during a massive myocardial infarction?
The heart may fail to sustain life despite compensation
What is the primary function of digoxin?
Sodium potassium ATPase pump inhibitor
Digoxin is often used as a last resort for patients with heart failure.
What does cardiac reserve refer to?
Maximum amount of cardiac output above normal
Normal cardiac output is approximately five liters per minute.
What is the cardiac reserve percentage for an output of 25 L/min?
400%
This is calculated based on a normal output of 5 L/min.
How does athletic conditioning affect cardiac reserve?
Can exceed 600%
Athletes may have higher baseline cardiac output and greater reserve.
What impact does aging have on cardiac reserve?
Reduces cardiac reserve
Sedentary lifestyles as people age can mask the decrease in reserve.
What are common causes of reduced cardiac reserve?
- Valve diseases
- Coronary artery problems
- Aging
These factors limit the heart’s ability to pump efficiently.
What are early signs of valve disease (physiologic)?
Inflammation, calcium, and cholesterol deposits
These changes can affect the functioning of heart valves.
What is a congenital bicuspid aortic valve?
Aortic valve with only two cusps
It is a common congenital heart defect affecting 1-2% of the population.
How does severe valvular disease affect cardiac reserve?
May eliminate cardiac reserve
Severe conditions can prevent the heart from pumping effectively.
True or False: Aortic stenosis is the most common heart valve problem.
True
Aortic stenosis significantly impacts heart function.
Fill in the blank: Cardiac reserve can be measured as the _______ amount of cardiac output above normal.
[maximum]
