Endocrine - Pt 2 Thyroid/Growth Hormone

Question 1

One of the main goals of the endocrine system is to properly maintain [] []

Answer 1

energy metabolism

Question 2

The main sites of hormonal action, in regards to maintaining energy metabolism, are the [], [] [], and []

Answer 2

The main sites of hormonal action, in regards to maintaining energy metabolism, are the liver, adipose tissue, and muscle

Question 3

• The goal of hormonal energy metabolism maintenance is to keep a constant supply of [] to the tissues
• Blood glucose is closely monitored and maintained between [] - [] mg/dL under normal conditions
• This is important for the tissues that rely heavily on glucose: [], [] [], and []

Answer 3

• The goal of hormonal energy metabolism maintenance is to keep a constant supply of glucose to the tissues
• Blood glucose is closely monitored and maintained between 90 - 120 mg/dL under normal conditions
• This is important for the tissues that rely heavily on glucose: brain, nervous tissue, and RBCs.

Question 4

T/F

The majority of energy stored in the body is stored as glucose/glucose derivatives.

Answer 4

FALSE

The majority of energy is stored in the form of fat (76%) or protein (23%)

Question 5

1. Glycogenesis = …
2. Glycogenolysis = …
3. Gluconeogenesis = …
4. Lipogenesis = …
5. Lipolysis = …
6. Proteolysis = …

Answer 5

1. Glycogenesis = glycogen formation
2. Glycogenolysis = glycogen breakdown
3. Gluconeogenesis = Formation of new glucose
4. Lipogenesis = Synthesis of lipids
5. Lipolysis = lipid breakdown
6. Proteolysis = protein breakdown

Question 6

T/F

You expect to see glycogenesis, lipogenesis, and protein Syntheis during fasting state.

Answer 6

FALSE

You expect to see those things in a fed state when you have “energy” to spare.

Question 7

T/F

You would expect to see gluconeogenesis, lipolysis, proteolysis, and glycogenolysis during a fasting state.

Answer 7

True!

While fasting you are starved of glucose. So you run all these processes to hopefully fuel your body with glucose.

Question 8

During starvations:

Rank, sequentially, which energy source is used during a starved state, from last to first: Lipid, protein, carbohydrate.

Answer 8

Proteins –> Lipids –> Carbohydrates

Question 9

• While “starved” your body produces [] [] as an alternative energy source for hte brain
• This is common in [] [] - which causes a metabolic acidosis called []
  
  • One way for a dentist to see this is through the patients [] [] due to acetone.

Answer 9

• While “starved” your body produces ketone bodies as an alternative energy source for hte brain
• This is common in Diabetes Mellitus - which causes a metabolic acidosis called ketoacidosis
  
  • One way for a dentist to see this is through the patients bad breath due to acetone.

Question 10

Thryoid Hormones:

1. Synthesized by [] cells of hte thyroid gland
2. Requires [] in diet
3. T₃ - []
4. T₄ - [] or []
5. Which thyroid hormone is more active and which is greater in number?

Answer 10

1. Synthesized by follicular epithelial cells of hte thyroid gland
2. Requires iodine in diet
3. T₃ - triiodothyronine
4. T₄ - tetraiodothyronine, or thyroxine
5. T₃ - more active and there is more T₄

Question 11

Thyroid Hormones:

• [] => enzyme that synthesizes T₄ –> T₃ at [] tissues.
  
  • This is required because [] is more active but [] is more abundant.

Answer 11

• Monoiodinase => enzyme that synthesizes T₄ –> T₃ at target tissues.
  
  • This is required because T₃ is more active but T₄ is more abundant.

Question 12

Thyroid Hormone Actions:

1. Acts on virtually every [] system in the human body
2. Acts synergistically with [] and [] to increase bone formation
3. Increases [] metabolic rate = induces synthesis and activity of [] pumps
4. Increases [] - positive inotrope ( []) and chronotrope ([])
5. Increases [] Rate
6. In perinatal period - essential for normal maturation of []…deficiency can lead to []

Answer 12

1. Acts on virtually every organ system in the human body
2. Acts synergistically with GH and somatomedins to increase bone formation
3. Increases basal metabolic rate = induces synthesis and activity of Na+/K+ pumps
4. Increases CO - positive inotrope (contractility) and chronotrope (Rate)
5. Increases Respiratory Rate
6. In perinatal period - essential for normal maturation of CNS…deficiency can lead to cretinism

Question 13

Do the symptoms show hypo- or hyper-thyroidism?

• Hypoventilation -
• Exophthalmos -
• Increased cardiac Output -
• Myxedema -
• Goiter -

Answer 13

• Hypoventilation - hypothyroidism
• Exophthalmos - - Hyperthyroidism
• Increased cardiac Output - Hyperthyroidism
• Myxedema - Hypothroidism
• Goiter - Both!

Question 14

Origin of thyroid hormone disturbance helps classify the disorder…

• 1° - origin is the [] []
• 2° - origin is the [] []
• 3° - Origin is the []
• []-[] - disturbance is at a site other than the hypothalamic-pituitary-thyroid axis

Answer 14

• 1° - origin is the thyroid gland
• 2° - origin is the anterior pituitary
• 3° - Origin is the hypothalamus
• Ectopic-Origin - disturbance is at a site other than the hypothalamic-pituitary-thyroid axis

Question 15

[] deficiencies often lead to hypothyroidism, and are one of the major causes of [] development.

Answer 15

Iodine deficiencies often lead to hypothyroidism, and are one of the major causes of goiter development.

Question 16

[] [] is an autoimmune disease in which antithyroid antibodes are produces. This is a common example of [] hypothyroidism

Answer 16

Hashimoto’s Thyroiditis is an autoimmune disease in which antithyroid antibodes are produces. This is a common example of primary hypothyroidism

Question 17

• Grave’s disease is an autoimmune disease in which the body produces [] [] [] (TSI) which are similar in structure to [].
• TSI stimulates the thyroid gland and results in an [] of the thyroid hormones.

Answer 17

• Grave’s disease is an autoimmune disease in which the body produces thyroid stimulating immunoglobulins (TSI) which are similar in structure to TSH.
• TSI stimulates the thyroid gland and results in an overproduction of the thyroid hormones.

Question 18

Thyroid Hormone Production:

1. 1st Step - Iodide []. Iodide is brought into follicular cells from the diet by [] transporters located on the [] membrane.
   
   1. These transporters use [] [] transport with Na+ to push I- [] its concentration gradient
2. 2nd Step - within the follicular cell, Iodide is oxidized into [] via the enzyme [] []

Answer 18

1. 1st Step - Iodide trapping. Iodide is brought into follicular cells from the diet by symport transporters located on the basolateral membrane.
   
   1. These transporters use secondary active transport with Na+ to push I- against its concentration gradient
2. 2nd Step - within the follicular cell, Iodide is oxidized into Iodine via the enzyme thyroid peroxidase

Question 19

Thyroid Hormone Production:

1. Thyroglobulin is produced in the [] cells and released into the colloid
2. Thyroglobulin can now become [] at [] residues.
   
   1. Each residue can have either 1 or 2 Iodines added. For T₁ ([]) or T₂ ([])
3. Now the T₁ and T₂ can join to form either [] or [] which are still attached to [] at this time.

Answer 19

1. Thyroglobulin is produced in the follicular cells and released into the colloid
2. Thyroglobulin can now become iodinated at tyrosine residues.
   
   1. Each residue can have either 1 or 2 Iodines added. For T₁ (MIT) or T₂ (DIT)
3. Now the T₁ and T₂ can join to form either T₃ or T_{<strong>4</strong>} which are still attached to thyroglobulin at this time.

Question 20

Thyroid Hormone Production:

• Once the thyroglobulin is endocytosed into the follicle cell, it fuses with a [] creating and [].
• Theses enzymes break down the thyroglobulin and release [] and [].
• Thyroid hormones then diffuse into capillaries where they bind to transporter proteins, like []-[] [].
• [] of thyroid hormones are bound to transporter proteins.

Answer 20

• Once the thyroglobulin is endocytosed into the follicle cell, it fuses with a lysosome creating and endolysosome.
• Theses enzymes break down the thyroglobulin and release T₃ and T₄.
• Thyroid hormones then diffuse into capillaries where they bind to transporter proteins, like thyroxine-binding globulins.
• 99% of thyroid hormones are bound to transporter proteins.

Question 21

• At the tissues…T₄ diffuses into the [] and is converted into T₃ via [].
• T₃ then diffuses into the [] and binds to a [] [] receptor.
  
  • This complex binds to the [] [] [] [], on DNA, and initiates transcription/translation…ultimaley making the protein that can initiate the hormone []

Answer 21

• At the tissues…T₄ diffuses into the cytosol and is converted into T₃ via monodeiodinase.
• T₃ then diffuses into the nucleus and binds to a thyroid hormone receptor.
  
  • This complex binds to the thyroid hormone response element, on DNA, and initiates transcription/translation…ultimaley making the protein that can initiate the hormone response

Question 22

An abnormal increase in TSH levels, is usually a sign of a [] disorder

Answer 22

Goiter

Question 23

• Growth hormone can act directly on target tissues such as skeletal [], [], [] []
• It can also indirectly through []

Answer 23

• Growth hormone can act directly on target tissues such as skeletal muscle, liver, adipose tissue
• It can also indirectly through IGFs

Question 24

• Growth hormone acts to mobilize energy stores by
  
  • decreasing [] uptake and use by muscle and adipose tissue
  • Increase []

Answer 24

• Growth hormone acts to mobilize energy stores by
  
  • decreasing glucose uptake and use by muscle and adipose tissue
  • Increase lipolysis

Question 25

* There are growth hormone receptors in the liver, which lead to the production of **[]-[] [] []**, or IGFs. * These are produced in **[]-[]** organs like the liver, kidney, and muscle * IGFs mediate growth of **[] []** and **[]** by increasing the uptake of **[] []** and stimulating **[]** of DNA, RNA, and proteins.

Answer 25

* There are growth hormone receptors in the liver, which lead to the production of **Insulin-like growth factors**, or IGFs. * These are produced in **non-endocrine** organs like the liver, kidney, and muscle * IGFs mediate growth of **soft tissues** and **bone** by increasing the uptake of **amino acids** and stimulating **synthesis** of DNA, RNA, and proteins.

Question 26

The general theme of factors which stimulate/inhibit growth hormone release: * _Stimulate_ - when our nutrient levels are **[]**, and at night, 1-2 hours after **[]** onset * _Inhibit_ - when we have an **[]** in nutrients.

Answer 26

* _Stimulate_ - when our nutrient levels are **low**, and at night, 1-2 hours after **sleep** onset * _Inhibit_ - when we have an **excess** in nutrients.

Question 27

During pregnancy, high levels of estrogen inhibit the breakdown of TBG by the liver, and TBG levels **[]**. What are the other effects... * Total T₃ and T₄ (bound/unbound) - **[]** * Free, physiologically active T₃ and T₄ - **[]** * Thyroid disorder? - **[]**

Answer 27

During pregnancy, high levels of estrogen inhibit the breakdown of TBG by the liver, and TBG levels **rise**. What are the other effects... * Total T₃ and T₄ (bound/unbound) - **increase** * Free, physiologically active T₃ and T₄ - **unchanged** * Thyroid disorder? - **euthyroidism**

Question 28

T/F The visible epiphysial line is a defining characteristic of adolescent bone growth.

Answer 28

FALSE An adolescent bone will have a visible **epiphysial plate**

Question 29

Adults afflicted with Hypersecretion GH will exhibit signs... 1. Usually due to GH-secreting pituitary **[]** 2. **[]** bone growth 3. **[]** hand and foot size, and organ size 4. **[]** of tongue, 5. **[]** of facial feature 6. insulin **[]** 7. glucose **[]**

Answer 29

1. Usually due to GH-secreting pituitary **adenoma** 2. **Periosteal** bone growth 3. **Increased** hand and foot size, and organ size 4. **enlargement** of tongue, 5. **coarsening** of facial feature 6. insulin **resistance** 7. glucose **intolerance**

Question 30

Hyposecretion of GH --\> 1. Childhood 1. leads to **[]** 2. Adulst 1. Leads to a mild **[]**

Answer 30

1. Childhood 1. leads to **dwarfism** 2. Adulst 1. Leads to a mild **hypoglycemia**