Lecture 7 - Feb 6 Flashcards
What is mitral regurgitation?
A leaky valve between the left ventricle and left atrium.
When does retrograde perfusion occur in mitral regurgitation?
When the pressure in the ventricle is higher than in the atrium.
During which phase does backward blood flow likely begin in mitral regurgitation?
Phase 2, at the beginning of isovolumetric contraction.
What happens to backward blood flow in Phase 3?
It continues throughout systole.
When is backward blood flow expected to be the highest during Phase 4?
At the beginning of Phase 4 when ventricular pressure is highest.
What is the formula for ejection fraction (EF)?
Stroke Volume / End Diastolic Volume.
What is a normal ejection fraction value?
Approximately 58% (e.g., 70/120).
How does dilated cardiomyopathy affect ejection fraction?
It typically lowers the ejection fraction.
What type of hypertrophy is characterized by thin walls?
Eccentric hypertrophy.
What type of hypertrophy is characterized by thick walls?
Concentric hypertrophy.
In concentric hypertrophy, how are sarcomeres added?
In parallel.
In eccentric hypertrophy, how are sarcomeres added?
In series.
What typically causes concentric hypertrophy?
High afterload.
What does the thyroid gland influence in the cardiovascular system?
Metabolism, growth, and fluid balance.
What are the two main thyroid hormones?
T3 and T4.
What percentage of thyroid hormone released by the thyroid gland is T4?
93%.
What is another name for T4?
Thyroxine.
What is the chemical name for T3?
Triiodothyronine.
What condition is indicated by an unexplained high heart rate in a patient without heart problems?
Hyperthyroidism.
What is a goiter?
Protrusion of the neck due to an enlarged thyroid gland.
What is the role of the recurrent laryngeal nerve?
Innervates the muscles of the larynx.
What can happen if the recurrent laryngeal nerve is damaged during surgery?
The patient may have difficulty speaking.
What is the relationship between the left recurrent laryngeal nerve and the aortic arch?
It passes under the aortic arch before innervating the larynx.
What type of blood flow does the thyroid gland have?
Rich vascularity with a high rate of blood flow.
What is the significance of the thyroid’s rich vascular supply?
It aids in the rapid transport of thyroid hormones to the systemic circulation.
What is the first step in thyroid hormone synthesis?
Adding iodides to tyrosine.
What is monoiodotyrosine?
Tyrosine with one iodide stuck to it.
What is diiodotyrosine?
Tyrosine with two iodides stuck to it.
What is monoiodotyrosine?
Tyrosine with one iodide attached
It is a precursor molecule in thyroid hormone synthesis.
What is diiodotyrosine?
Tyrosine with two iodides attached
It is another precursor molecule in thyroid hormone synthesis.
What is the role of the enzyme in thyroid hormone synthesis?
Links monoiodotyrosine to diiodotyrosine to form larger compounds
This process is essential for the production of T3 and T4.
What are T1 and T2 in thyroid hormone synthesis?
Precursors that combine to form T3 and T4
T1 is monoiodotyrosine and T2 is diiodotyrosine.
What is the dietary requirement of iodine for thyroid hormone production?
50 milligrams per year
Iodine typically comes from table salt.
What is the main controller of thyroid gland activity?
TSH (thyroid stimulating hormone)
TSH is produced by the anterior pituitary gland.
What role does the hypothalamus play in thyroid hormone regulation?
It regulates TSH release from the pituitary gland
The hypothalamus monitors various bodily conditions to adjust hormone levels.
What hormone does the hypothalamus release to stimulate TSH production?
TRH (thyrotropin releasing hormone)
TRH increases TSH levels, which in turn regulates thyroid hormone release.
What is the predominant thyroid hormone released from the thyroid gland?
T4 (thyroxine)
T4 is released in larger amounts compared to T3.
What are the three main carrier proteins for thyroid hormones?
- Thyroxine binding globulin (TBG)
- Thyroxine binding prealbumin
- Albumin
All three are produced in the liver.
What is the primary effect of thyroid hormones on metabolism?
Increases metabolic rate
This includes increased protein production, oxygen consumption, and glucose absorption.
How does thyroid hormone affect the cardiovascular system?
Increases cardiac output and heart rate
Blood pressure may not necessarily increase due to reduced systemic vascular resistance (SVR).
What impact does thyroid hormone have on growth and development?
Essential for proper maturation of the nervous system
Deficiency can lead to cognitive and personality issues.
What unusual effect does hyperthyroidism have on cholesterol levels?
Reduces blood cholesterol levels
Cholesterol is consumed at the cellular level for various processes.
How long does it typically take for thyroid hormone effects to manifest?
6 to 8 hours for significant effects, up to 10 days for peak effects
This reflects the longer-term nature of thyroid hormone action.
What happens in the case of a pituitary tumor producing excess TSH?
Causes hyperthyroidism independent of hypothalamic control
TRH levels will be low as the hypothalamus stops producing it in response.
What occurs with a thyroid gland tumor?
Produces excess thyroid hormone independently of TSH or TRH
This leads to reduced TRH and TSH levels due to feedback mechanisms.
What is the effect of a TRH-secreting hypothalamic tumor?
Increases TSH and thyroid hormone levels
This leads to elevated metabolic activity.
What does TSH stand for?
Thyroid-Stimulating Hormone
What is the role of TSH in thyroid hormone release?
TSH binds to receptors on the thyroid gland and causes more thyroid hormone to be released
In a case where the problem is within the hypothalamus, what are the expected levels of TSH?
Elevated
What is the predominant form of thyroid hormone that binds with thyroid hormone receptors?
T3
What enzyme is responsible for converting T4 to T3?
Iodinase
What percentage of circulating thyroid hormone is typically T4?
93%
What happens to metabolic rate with increased thyroid hormone?
Metabolic rate picks up and everything increases
What is Graves’ disease?
An autoimmune disorder where antibodies activate TSH receptors, increasing thyroid gland activity
What is a common side effect observed in patients with Graves’ disease?
Exophthalmos (protruding eyes)
What is Hashimoto’s thyroiditis?
An autoimmune condition where antibodies attack and destroy the thyroid gland
What dietary deficiency can lead to insufficient production of thyroid hormone?
Iodine deficiency
What is the relationship between iodine deficiency and goiters?
Goiters can result from insufficient thyroid hormone production due to iodine deficiency
What is the typical treatment for thyroid cancer?
Radioactive iodine, typically I131
What effect does excessive iodine intake have on thyroid hormone production?
Decreases the ability to produce thyroid hormone
What happens to cholesterol levels in individuals with hyperthyroidism?
Cholesterol and triglycerides are usually low
What is the chief cardiovascular concern with untreated hypothyroidism?
Atherosclerosis
What is cardiogenic shock?
Shock caused by pumping problems of the heart
What is neurogenic shock?
Shock due to loss of sympathetic tone, often induced by anesthetics
What triggers anaphylactic shock?
Massive histamine release from mast cells in response to allergens
What type of bacteria is usually associated with septic shock?
Gram-positive bacteria
What is hypovolemic shock?
The most common form of shock related to blood loss or dehydration
How does the sympathetic nervous system affect cardiovascular maintenance during shock?
It helps maintain blood pressure and nutrient delivery
Fill in the blank: The primary hormone that increases metabolic activity in the body is _______.
Thyroid hormone
True or False: T4 has more activity than T3.
False
What is the body’s response to blood volume loss?
Clamp down on blood vessels in the systemic circulation
This response helps preserve arterial pressure and shunt blood to vital organs.
What happens to cardiac output when systemic vascular resistance (SVR) increases?
Cardiac output is reduced
Increased SVR can be problematic, especially during a myocardial infarction (MI).
How much blood loss can a healthy individual typically survive?
About 20% of their starting blood volume
Survival becomes uncertain past this threshold.
What might be misleading when only measuring blood pressure?
It may not indicate a serious problem despite normal readings
Cardiac output may still be compromised.
What is a non-invasive method to estimate cardiac output?
Using an arterial line and Edwards FloTrac
This method analyzes the arterial pressure waveform.
What is the significance of a blood pressure drop to 50% of normal in an experiment?
Animals can recover provided blood pressure doesn’t drop past this point
Recovery is unlikely if blood pressure falls below 45%.
What characterizes non-progressive shock?
The body’s compensation mechanisms are able to stabilize the condition
Fluid shifts and catecholamines help in this state.
What leads to progressive shock?
Inability of the body to compensate for blood loss
This often results in major organ failure.
How much blood volume can typically be lost without affecting cardiac output or blood pressure?
About 10%
Beyond this, cardiac output may begin to decrease.
What is the role of the spleen in response to blood loss?
It serves as a storage pool for red blood cells
The spleen can release additional hemoglobin into circulation.
What happens to kidney function during low blood pressure situations?
The kidneys retain fluid and electrolytes
This is an attempt to normalize blood pressure.
What is the Black Compensation Curve used to illustrate?
The heart’s failure to achieve necessary cardiac output
It shows a decline in the body’s ability to compensate.
What are potential treatments for improving cardiac function in heart failure?
Cardiac glycosides or phosphodiesterase inhibitors like milrinone
These can help increase cardiac output temporarily.
What is the impact of diuretics in chronic heart failure?
They prevent the kidneys from over-retaining fluid
This is crucial to avoid excessive stretching of the heart.
What is the correlation between blood pressure and cardiac output?
Monitoring solely blood pressure is insufficient for assessing cardiac function
It may overlook other critical aspects of cardiovascular health.
Fill in the blank: The heart’s filling pressures increase due to _______.
[tightening of blood vessels]
True or False: The kidneys stop retaining fluid once blood pressure normalizes.
False
In chronic heart failure, kidneys may continue to retain fluid despite low blood pressure.
