E.R. Distruptions to Homeostasis (Human Biology)

Question 1

Describe the role of the pituitary gland in controlling the thyroid

Answer 1

Monitor and regulate the activity of glands.

Thyroid regulation:
A.L pituitary controls it by secretion of Thyrotropin (TSH). Circulates in the blood, stimulates the breakdown of thyroglobulin in turn forming T4 (Thyroxine) and T3 (Triiodothyronine).
T4 is the primary hormone
TSH ultimately results in the stimulation of the thyroid to release T4 and T3.

Question 2

How are the secretion of the hormones regulated?

Answer 2

Via a negative feedback loop.
As T4 and T3 rise, TSH falls, vice-versa.
Higher T4 and T3 lead to lower TSH, vice-versa.
If the feedback loop becomes malfunctioned, the levels of certain hormones become unbalanced leading to symptoms of either hyper/hypothyroidism.

Question 3

How does the thyroid regulate metabolism?

Answer 3

Local activation of T4 into the biologically active form T3 by deiodinase D2.
The hormones travel to various tissues, binding to specific receptors within cells, initiating a cascade of metabolic processes. This includes an increase the rate at which cells utilize oxygen and produce heat (a process known as thermogenesis), leading to an overall increase in metabolism.

Question 4

What is the basal metabolic rate (BMR)?

Answer 4

The amount of energy expended while at rest.

Question 5

How does the thyroid regulate Temperature? (BMR, Blood Vessels, and Sweat)

Answer 5

When it’s cold, the thyroid increases the basal metabolic rate (BMR)
Increase in metabolism generates heat as a by-product, maintaining temperature (Thermogenesis).

When it’s hot, the thyroid decreases the production of metabolic rate which in turn reduces the metabolism and heat production.

When its hot, thyroid hormones also influence the dilation (widening) of blood vessels, particularly in the skin. The blood vessels are dilated so more blood flows near and at the surface of your body to allow heat to be lost to the air.

When its cold, thyroid hormones also influence the constriction of blood vessels, particularly in the skin. The blood vessels are constricted so less blood flows near and at the surface of your body to allow less heat to be lost to the air.

increasing sweat production when necessary to help cool the body during times of increased heat production or environmental temperature.

Decrease in sweat production when the body is cold.

Question 6

How does the thyroid regulate growth?

Answer 6

Thyroid hormones increase the basal metabolic rate (BMR), ensuring that sufficient energy is available for various cellular activities involved in growth and development, such as protein synthesis, DNA replication, and cell division.

Question 7

How does the thyroid regulate calcium
levels?

Answer 7

The thyroid gland produces a hormone called calcitonin. Calcitonin plays a minor role compared to other hormones, such as parathyroid hormone (PTH), in regulating calcium levels, but it still contributes to calcium homeostasis. When blood calcium levels rise above normal, calcitonin is released into the bloodstream.

Question 8

What causes Hyperthyroidism?

Answer 8

Autoimmune Graves’ Disease:
The body’s immune system produces antibodies that stimulate the thyroid gland to produce excess thyroid hormone. These antibodies mimic the action of thyroid-stimulating hormone (TSH), leading to the overproduction of thyroid hormones.
Thyroid Nodules:
Can become overactive and produce excess thyroid hormones independently of the body’s normal regulatory mechanisms.
Thyroiditis:
Can lead to the release of excess thyroid hormone into the bloodstream.

Question 9

What causes Hypothyroidism?

Answer 9

Autoimmune Thyroiditis:
The body’s immune system mistakenly attacks the thyroid gland, leading to inflammation and eventual destruction of thyroid tissue.

Iodine Deficiency:
Thyroid gland can’t produce adequate amounts of thyroid hormone, leading to hypothyroidism.

Pituitary or Hypothalamic Disorders:
Hypothyroidism can also result from disorders affecting the pituitary gland or hypothalamus in the brain. These glands produce hormones that regulate thyroid function. If they malfunction, they can disrupt the production of thyroid-stimulating hormone (TSH), which is necessary for the thyroid gland to produce thyroid hormones.

Question 10

What people in society are most at risk for developing hyperthyroidism?

Answer 10

Women are more prone to developing hyperthyroidism than men.
People older than 60 have an increased risk of hyperthyroidism.
A family history of thyroid disorders (including hyperthyroidism) raises the risk. Certain chronic conditions are associated with hyperthyroidism, Type 1 diabetes, Pernicious anemia.

Question 11

What people in society are most at risk for developing hypothyroidism?

Answer 11

Women are more prone to developing hypothyroidism than men.
People older than 60 have an increased risk of hypothyroidism.
A family history of thyroid disorders (including hyperthyroidism) raises the risk. Certain chronic conditions are associated with hypothyroidism, Type 1 diabetes, Pernicious anemia.

Question 12

What are the risk factors of hyperthyroidism?

Answer 12

Some causes include:
- Autoimmune diseases causing excessive thyroid hormone production, e.g. Graves’ Disease
- Abnormal growths in the thyroid causing excessive production of T4 and T3.
- Thyroiditis i.e. inflammation of thyroid causing excessive production of hormones
- Overconsumption of iodine
- Certain drugs, e.g. amiodarone

Question 13

What are the risk factors of hypothyroidism?

Answer 13

Some causes include:
- Autoimmune diseases attack the thyroid tissue causing reduced hormone production (i.e. Hashimoto’s Disease)
- Surgical removal of part or whole thyroid.
- Congenital disorder of hypothyroidism meaning underdeveloped or absent thyroid
- Certain drugs e.g. Lithium
- Failing of the production of TSH
- Thyroiditis i.e. inflammation of thyroid inhibiting production or reduced secretion

Question 14

What are the symptoms of hyperthyroidism?

Answer 14

Losing weight without trying
Irregular heartbeat (arrhythmia)
Heart Palpitations (Pounding Heart)
Increased hunger
Tremor, usually a small trembling in the hands and fingers
Sweating
Increased sensitivity to heat
Changes in bowel patterns, especially more-frequent bowel movements,
Enlarged thyroid gland, sometimes called a goiter, which may appear as a swelling at the base of the neck,
Tiredness

Question 15

What are the symptoms of hypothyroidism?

Answer 15

Tiredness
More sensitivity to cold
Constipation
Dry skin
Weight gain Coarse hair and skin
Muscle weakness
Muscle aches
Slowed heart rate (bradycardia)
Memory problems.

Question 16

What are some treatments for hyperthyroidism?

Answer 16

Anti-thyroid medicine (e.g. methimazole). Symptoms usually begin to improve within several weeks to months. The goal is to achieve a euthyroid state (normal thyroid function) while avoiding hypothyroidism (underactive thyroid).
Thyroidectomy. This is surgery to remove
part of or all of the thyroid gland. It is not used often to treat hyperthyroidism.

Question 17

How does the treatment of hyperthyroidism work with reference to understanding of thyroid gland, its control, hormones and diseases.

Answer 17

Anti-Thyroid Medicine
These drugs inhibit an enzyme called thyroid peroxidase, which is essential for the production of T4 and T3. By blocking this enzyme, thionamides reduce the synthesis of thyroid hormones within the thyroid gland. Thionamides prevent the incorporation of iodine into the amino acid tyrosine, a crucial step in thyroid hormone synthesis. As a result, the production of T4 and T3 decreases.

Question 18

What are the treatments of hypothyroidism?

Answer 18

Taking the thyroid hormone medicine levothyroxine (Levo-T, Synthroid, others) every day. This medicine is taken by mouth. It returns hormone levels to a healthy range, eliminating symptoms of hypothyroidism. After time, a blood test may be required.

Question 19

How does the treatment of hypothyroidism work with reference to understanding of thyroid gland, its control, hormones and diseases.

Answer 19

Levothyroxine is a synthetic form of T4. When you take levothyroxine orally, it enters your bloodstream. Within the body, levothyroxine is converted to T3 (the active form of thyroid hormone). T3 and T4 play vital roles in regulating metabolism, energy production, and overall bodily functions. By providing an external source of T4, levothyroxine compensates for the deficiency and helps normalize thyroid function.

The goal of levothyroxine treatment is to restore normal thyroid hormone levels. By increasing T4 levels, levothyroxine indirectly influences T3 production. Adequate T4 levels help maintain the balance of TSH, ensuring proper thyroid function.

Question 20

What are some of the side effects and risks of the treatment for hyperthyroidism?

Answer 20

Although rare, serious liver damage can happen with anti-thyroid medications.

Risks of this surgery include damage to the vocal cords and parathyroid glands.

Question 21

What are some of the side effects and risks of the treatment for hypothyroidism?

Answer 21

Too much levothyroxine can cause side effects, such as:
Tiredness.
Increased appetite.
Sleep problems.
Shakiness.
Pounding of the heart, sometimes called heart palpitations.