[Exam 1] Lecture 7: Thyroid Flashcards
What is mitral regurgitation?
A leaky valve between the left ventricle and left atrium
It causes retrograde perfusion when ventricular pressure exceeds atrial pressure.
During which phase does backward blood flow begin due to mitral regurgitation?
Phase 2, at the beginning of isovolumetric contraction
The valve is leaking, making it no longer isovolumetric.
What factors influence backward blood flow in mitral regurgitation?
Delta P and the relative fullness of the atria
Delta P refers to the pressure difference between the ventricle and atria.
During which phase is backward blood flow expected to be highest?
Phase 3
Backward blood flow continues throughout systole.
What happens to backward blood flow during Phase 4 of mitral regurgitation?
There is still some backward blood flow, but it diminishes as ventricular pressure decreases
The highest backward blood flow occurs at the beginning of Phase 4.
True or False: Backward blood flow is constant throughout the cardiac cycle in mitral regurgitation.
False
Backward blood flow varies with different phases of the cardiac cycle.
What is the formula for calculating ejection fraction (EF)?
Stroke Volume divided by End Diastolic Volume
Normal EF is approximately 58%.
What does a high ejection fraction in mitral regurgitation indicate?
It may be falsely high due to backward flow
Echo measurements can be misleading in regurgitation cases.
What type of hypertrophy is characterized by thin ventricular walls?
Eccentric hypertrophy
Eccentric hypertrophy involves adding sarcomeres in series.
What type of hypertrophy is characterized by thick ventricular walls?
Concentric hypertrophy
Concentric hypertrophy involves adding sarcomeres in parallel.
Which endocrine system significantly impacts the cardiovascular system?
The thyroid system
Thyroid hormones influence metabolism and cardiovascular health.
What is a common sign of hyperthyroidism?
Increase in resting heart rate
This can occur in patients without any heart problems.
What is a goiter?
Protrusion of the neck due to an enlarged thyroid gland
It can be caused by various factors.
What is the role of the parathyroid gland?
Controller of calcium levels in the blood
It works alongside the thyroid gland.
What is the risk associated with manipulating the thyroid gland during surgery?
Bleeding due to its rich vascular supply
The thyroid has extensive blood vessels that pose a bleeding hazard.
What nerve controls the muscles inside the larynx?
Right recurrent laryngeal nerve
It branches off the vagus nerve.
What happens to the name of the recurrent laryngeal nerve after it curves around a blood vessel?
It may be referred to as the inferior laryngeal nerve
This occurs after the initial curve beneath the artery.
What is another name for the inferior laryngeal nerve?
Recurrent laryngeal nerve
The recurrent laryngeal nerve is named for its anatomical path, which involves a curve around major blood vessels.
Where does the left recurrent laryngeal nerve pass before turning back towards the voice box?
Under the aortic arch
What happens if one of the laryngeal nerves is cut during surgery?
The patient may have a hard time speaking
What is the predominant thyroid hormone released by the thyroid gland?
T4 (Thyroxine)
What percentage of thyroid hormone released by the thyroid gland is T4?
93%
What is the chemical name for T3?
Triiodothyronine
What is the other name for T4?
Thyroxine
What is monoiodotyrosine?
Tyrosine with one iodide stuck to it
What is the role of the hypothalamus in thyroid hormone regulation?
It controls the release of TSH from the pituitary gland
What does TRH stand for?
Thyrotropin releasing hormone
What is the main source of iodine in most people’s diets?
Table salt
Name the three main carrier proteins for thyroid hormones.
- Thyroxine binding globulin
- Thyroxine binding prealbumin
- Albumin
What is the effect of increased levels of thyroid hormone on metabolic rate?
Increases metabolic rate
What happens to cardiac output when thyroid hormone levels increase?
Cardiac output increases
True or False: Blood pressure typically increases when thyroid hormone levels are elevated.
False
Fill in the blank: The thyroid gland releases more __________ than __________.
T4, T3
What is the function of thyroid hormone at the cellular level?
Turns on genes to ramp up cell processes
What happens to glucose absorption when thyroid hormone levels are elevated?
Increases
How does thyroid hormone affect the respiratory system?
Increases respiratory rate or depth
What can result from a deficiency of iodine in the diet?
Goiters
What is the role of TSH in thyroid hormone regulation?
Stimulates the release of T3 and T4 from the thyroid gland
What is the anterior pituitary gland’s role in thyroid hormone regulation?
Releases TSH
What is the significance of T3 and T4 being lipid soluble?
They can easily cross cell membranes
What happens to oxygen consumption when thyroid hormone levels are elevated?
Increases
What is the thyroid hormone’s primary target within cells?
Nucleus
What is the consequence of liver failure on thyroid hormone transport?
Difficulty in creating carrier proteins, affecting thyroid hormone levels
What happens to heart rate during increased blood flow and nutrient delivery?
Heart rate typically increases.
Does blood pressure always increase with enhanced cardiac output?
No, blood pressure doesn’t necessarily go up due to reduced systemic vascular resistance (SVR).
What changes occur in the respiratory system to meet increased oxygen demand?
Respiratory rate or depth increases.
Why is thyroid hormone important during growth and development?
It is required for processes critical to maturation and development, particularly of the nervous system.
What can happen if there is an absence of thyroid hormone during development?
Major deficiencies in the central nervous system can manifest, leading to personality issues and cognitive deficits.
What effect does hyperthyroidism have on blood cholesterol levels?
It typically causes blood cholesterol levels to drop.
What is the reason for the drop in cholesterol levels in hyperthyroidism?
Cholesterol is consumed at the cellular level to build compounds, leading to faster usage than normal.
How quickly does thyroid hormone typically take effect?
It may take six to eight hours for changes to manifest, and up to 10 days for effects to peak.
What is thyroid storm?
A condition where thyroid hormone problems can occur rapidly.
What is a pituitary tumor’s effect on TSH and thyroid hormone levels?
It can cause elevated TSH and thyroid hormone levels, leading to hyperthyroidism.
What happens to TRH levels in the presence of a pituitary tumor?
TRH production stops as the pituitary gland releases excess TSH independently.
How does a thyroid gland tumor affect TSH and TRH levels?
It causes a reduction in both TRH and TSH levels due to excess thyroid hormone production.
What is the expected outcome of a hypothalamic tumor secreting excess TRH?
Elevated levels of TSH, TRH, and thyroid hormones.
What is the predominant form of thyroid hormone delivered to cells?
T4 (thyroxine) is 93% of circulating thyroid hormone.
What enzyme converts T4 to the more active form T3?
Iodinase.
What is the primary function of T3 in the body?
T3 binds with thyroid hormone receptors to exert effects.
What is the relationship between thyroid hormone and metabolic rate?
Thyroid hormone increases metabolic rate and nutrient requirements.
What is Graves’ disease?
An autoimmune disorder where antibodies activate TSH receptors, increasing thyroid hormone production.
What is exophthalmos and its concern in Graves’ disease?
Protrusion of the eyes, which can lead to corneal injury.
What is Hashimoto’s thyroiditis?
An autoimmune condition where antibodies destroy the thyroid gland.
What happens during iodine deficiency regarding thyroid hormone production?
The thyroid gland cannot produce enough thyroid hormone, leading to elevated TRH and TSH levels.
What type of goiter can result from iodine deficiency?
An enlarged thyroid gland that is not producing sufficient thyroid hormone.
How is radioactive iodine used in treating thyroid cancer?
Radioactive iodine targets thyroid cells, minimizing effects on other body parts.
What happens with excessive iodine intake in relation to thyroid hormone production?
It can decrease the thyroid gland’s ability to produce thyroid hormone.
What is a potential consequence of consuming a massive dose of iodine?
It confuses the cellular system and reduces thyroid hormone production.
What happens when a very high dose of iodine is taken?
The cells can’t handle that much iodine; it can lead to oxidative stress and dysfunction.
Can excessive iodine intake be used for hyperthyroidism?
Yes, sometimes a high iodine intake can be used for acute issues with hyperthyroidism.
What is amiodarone and its relation to iodine?
Amiodarone is packaged in a solution with high iodine content, and care must be taken with iodine levels when administering it.
Does exophthalmos occur in iodine deficiency with goiter?
No, exophthalmos is a result of excessive thyroid hormone, not iodine deficiency.
Is the effect of very high iodine intake on the thyroid gland permanent or temporary?
Temporary, it may be used to shut down the thyroid gland in certain situations.
What happens to blood cholesterol levels in hyperthyroidism?
In hyperthyroidism, blood cholesterol and triglycerides are probably low.
What is a chief concern with hypothyroidism in older adults?
Atherosclerosis due to elevated cholesterol levels.
What happens to cholesterol and fatty acids in hypothyroidism?
Their levels in the bloodstream rise because low thyroid hormone leads to less usage.
What is the primary risk associated with untreated hypothyroidism?
Significant cardiovascular risks, particularly atherosclerosis.
What is the patient compliance rate for synthetic thyroid hormones like Synthroid?
Incredibly low due to side effects like insomnia and anxiety.
What is shock in a medical context?
A problem getting required nutrients to tissues.
What characterizes cardiogenic shock?
Problems with the heart’s ability to pump sufficient cardiac output.
What can cause neurogenic shock?
Loss of sympathetic tone, often induced by anesthetics or high spinal procedures.
What is anaphylactic shock driven by?
Histamine released from mast cells due to an immune response.
What type of bacteria is usually involved in septic shock?
Usually gram-positive bacteria.
What is the most common form of shock?
Hypovolemic shock, often due to blood loss or dehydration.
What role does the sympathetic nervous system play in cardiovascular maintenance?
It helps maintain blood pressure and cardiac output during blood loss.
What happens to arterial pressure and cardiac output when 20% of blood volume is lost?
Arterial pressure may appear normal, but cardiac output is low.
What is the significance of measuring cardiac output?
It provides a clearer picture of cardiovascular health than blood pressure alone.
What happens to animals when blood pressure drops to less than 45% of normal?
Those animals typically do not survive.
What compensatory mechanisms occur after significant blood loss?
Catecholamines increase, kidneys conserve volume, and fluid shifts happen.
What happens to the body when blood pressure is reduced to about 50% of normal during hemorrhage?
The body compensates through catecholamines and kidney efforts to conserve volume
Fluid shifts may occur to maintain blood volume, utilizing water reserves in cells and interstitial spaces.
What is non-progressive shock?
A state where the body’s compensation mechanisms successfully manage to stabilize blood pressure and organ function despite blood loss
This is typically seen in the first three animals described.
What occurs during progressive shock?
The body’s compensation fails, leading to insufficient perfusion of vital organs and potential organ failure
This is observed in animals four, five, and six.
What percentage of blood volume can be lost without affecting cardiac output or blood pressure?
About 10%
Losing 20% can still be survivable for a healthy individual.
At what percentage of blood volume loss does survival become very difficult?
Around 40%
Rapid blood loss beyond this point typically leads to poor outcomes.
What role does the spleen play during blood loss?
It serves as a storage for extra hemoglobin and red blood cells that can be released into circulation
This is part of the body’s compensatory mechanisms during hemorrhage.
What is the primary function of the kidneys in response to low blood pressure?
To retain fluid and electrolytes to increase blood volume
This response is aimed at normalizing blood pressure.
What is the significance of a failing heart’s filling pressure increase?
It helps compensate for the heart’s reduced ability to pump effectively
This is part of the body’s strategy to maintain necessary cardiac output.
What is the purpose of medications like Digoxin and Milrinone?
To assist in increasing cardiac output in patients with heart failure
They provide temporary support but are not cures.
What does the Black Compensation Curve represent?
It illustrates a failing heart’s inability to reach the required cardiac output level
Points on this curve indicate worsening conditions over time.
What is the role of diuretics in chronic heart failure management?
To prevent the kidneys from retaining excessive fluid that could worsen heart function
They help manage fluid overload and maintain a safer blood pressure.
True or False: Blood pressure is a reliable substitute for measuring cardiac output.
False
While blood pressure is useful, it does not provide a complete picture of cardiac health.
What does the Edwards FlowTrac monitor?
Pulse pressure variation to assess cardiac function
It is an algorithm-based tool that may not significantly enhance clinical assessments.
What is the critical output level required for a young, healthy individual to survive?
Approximately five liters of blood per minute
This is essential for maintaining necessary organ perfusion.
