Endocrinology 13 and 14 Flashcards
What three things do Thyroid hormones do?
- Act on most tissues and change transcription and translation
- Increase metabolism
- Necessary for growth and development
How does thyroid hormone affect the basal metabolic rate?
They increase the BMR
How does thyroid hormone affect O2 consumption and heat production?
It increases both
How does Thyroid hormones affect CHO absorption and utilization?
It increases both
How does thyroid hormone affect proteins?
It increases protein breakdown (muscle)
How does Thyroid hormones affect fats?
It increases fat breakdown
How does Thyroid hormone affect cholesterol?
It increases cholesterol metabolism which decreases blood cholesterol level
How does thyroid hormone affect growth and development?
They can act as tissue growth factors
In what amounts can thyroid hormone increase protein synthesis?
In small amounts
How does thyroid hormone affect GH and IGF?
It increases the output of growth hormone which increases the output of insulin-like growth factor
What are the thyroid hormones essential for?
CNS maturation in fetus/newborn
How do the thyroid hormones affect the cardiovascular system?
They increase the rate and the force with which the heart is beating
How do the thyroid hormones affect the autonomic system?
They increase the activity of certain subtypes and receptors (like beta-adrenergic receptors)
How do the thyroid hormones affect the reproductive system?
Imbalance affects fertility
How do the thyroid hormones affect the bones?
It increases bone turnover
Where is Thyrotropin-releasing hormone (TRH) released from and what does it do?
It is released for the hypothalamus and stimulates the anterior pituitary to release TSH
Where is TSH released from and what does it do?
It is released from the anterior pituitary can causes T3 and T4 to be released from the thyroid gland
How is T3 and T4 release inhibited?
By T3 and T4 exerting negative feedback on the anterior pituitary and the hypothalamus to stop them from releasing TRH and TSH
What is the overactivity of the thyroid gland associated with?
Graves disease
What is Grave Disease?
An autoimmune disorder which stimulates the thyroid gland
What are the symptoms of Graves disease?
An increase in basal metabolic rate, exophthalmos and goitre
What is underactivity of the thyroid associated with?
Hashimoto’s Thyroiditis or Iodine deficiency
What is Hashimoto’s thyroiditis?
An autoimmune disorder which destroys the thyroid gland or blocks hormone synthesis
What are the symptoms of hypothyroidism?
- Myxedema
- Goitre
- Cretinism
Where is most of the calcium in the body located?
In the bone
Where is the rest of calcium not in bones found?
In other tissues
What can the calcium found in tissues be divided into?
The extracellular and intracellular fluid
Where is most of the calcium in the tissues found?
In the intracellular fluid
Of the intracellular calcium how much is in the bound form?
Majority in the bound form than free form
Of the extracellular calcium how much is in the bound form?
Equal mix (50/50)
Which calcium is under hormonal control?
The free calcium in the extracellular fluid
Which concentration of calcium is greater in the ECF than the ICF?
The concentration of free ionized calcium
Where can we get calcium from?
- Diet
* Bone
Why is calcium so important?
- Structural role
- Blood coagulation
- Intracellular messenger
- Regulation of excitability
What is phosphate important for?
- Structural role
- Metabolism
- Buffer
Where does Parathyroid hormone come from?
The parathyroid glands
Where can active vitamin D act as a hormone?
In the kidneys
Where is calcitonin derived from?
C-cells in the thyroid gland
What are the three targets of calcium influencing drugs?
- Bone
- GI tract
- Kidneys
What is bone made up of largely?
A calcified matrix
What is the calcified matrix made of?
- A protein framework (osteoid, mainly collagen)
* Calcium and phosphate salts (mainly hydroxyapatite)
What are the three types of cells present in the bone?
- Osteoblasts
- Osteoclasts
- Osteocytes
What are Osteoblasts known as?
Bone forming cells
What are Osteoclasts known as?
The bone destroying cells
What are the most common type of cell in the bone?
Osteocytes
