The Endocrine System Flashcards
Glands of the endocrine system include:
Pituitary, thyroid, parathyroid, adrenal, pancreas, gonads, hypothalamus
The endocrine system is an important system of
Communication
Hormone levels are regulated by
Negative feedback inhibition
Water soluble hormones include:
Peptides and catecholamines
Lipid soluble hormones include:
Steroid and thyroid hormones
When hormones act locally on cells other than those that produce the hormone
Paracrine
When hormones exert action on the cells from which they were produced
Autocrine
Peptides and catecholamines are produced:
In advance and stored in vesicles. They are released by exocytosis with calcium signal.
Peptides and catecholamines are transported:
Without a carrier to Target tissue
Peptides and catecholamines find their receptors:
On target cell surface and use second messenger systems
Steroids and thyroid hormones are synthesized:
On demand, cannot be stored and use diffusion once made.
Steroid and thyroid hormones are transported:
Require a protein carrier to target tissue inside of the cell- either cytoplasm or nucleus and alter gene transcription.
These disorders originate in the gland responsible for producing the hormone:
Primary endocrine disorders
These disorders are caused by decreased hormone production or release from the pituitary:
Secondary endocrine disorders
These disorders are due to dysfunction of the hypothalamus:
Tertiary endocrine disorders
Growth hormone, also called somatotropin, is a general metabolic hormone that:
- Promotes growth of skeletal muscle and stimulates extension of the long bones before puberty by acting on epiphyseal plate.
- Metabolic effects include stimulation of protein anabolism and fat catabolism, while sparing glucose to help maintain glucose homeostasis.
- Many of the effects of GH are mediated by insulin like growth factors.
Most common cause of hypothalamic-pituitary dysfunction in adults:
Pituitary adenine
Deficits in growth hormone in children leads to
Dwarfism
Growth hormone excess in children leads to
Gigantism
Excess of growth hormone in adults leads to
Acromegaly
Thyroid gland produces these 2 hormones
- Thyroid hormone
2. Calcitonin
A reduction in the amount of thyroid hormone produced, leading to a decreased rate of metabolism and a slowing of physiologic processes
Hypothyroidism
Hypothyroidism in children result in
Cretinism
Hypothyroidism in adults results in this and the most common cause is this:
Myxedema and hashimoto’s disease
An overproduction in thyroid hormone with the most common cause being this:
Hyperthyroidism and Graves’ disease
An enlarged thyroid is referred to as a
Goiter
In hypothyroidism the thyroid gland enlarges in an attempt to produce more thyroid hormones due to these 2 reasons:
- Insufficient iodine intake is the most common cause of increased thyroid stimulating hormone leading to goiter
- Diffuse enlargement of the thyroid is most commonly caused by prolonged stimulation by TSH
Autoimmune destruction of the thyroid gland
Hashimoto’s disease
Autoimmune disease involving the production of antibodies against TSH receptor. The antibodies overstimulate the thyroid gland to produce TH independently of TSH leading to excess TH and goiter.
Graves’ disease
This hormone reduces plasma calcium levels by causing calcium to be deposited into the bone.
Calcitonin
This hormone is necessary for normal growth and development and is an important regulator of metabolism through life.
Thyroid hormone
Adrenal glands has two main regions:
Medulla (neural)
Cortex (glandular)
Adrenal cortex produces these 3 steroid hormone types:
Mineralcorticoids- aldosterone
Glucocorticoids- cortisol
Androgens- androgens
Adrenal medulla produces these catecholamines released after sympathetic stimulation:
Epi and norepinephrine
These hormones regulate minerals sodium and potassium. They stimulate sodium and water retention to maintain fluid and electrolyte homeostasis.
Mineralcorticoids
These hormones promote cellular metabolism and response to long-term stress by regulating glucose levels. They also have anti-inflammatory activities.
Glucocorticoids
This is a key steroid hormone from the adrenal cortex that modulates long-term stress. It acts to alter metabolism to maintain elevated blood glucose levels and it suppressed inflammatory and immune responses.
Cortisol
The adrenal medulla is neural tissue that secretes these neurohormones into the blood:
- Epinephrine
2. Norepinephrine
This type of insufficiency occurs when there is damage to the adrenal cortex. It is mainly caused by autoimmune disease and tb.
Primary insufficiency
This type of insufficiency occurs when there is a lack of ACTH from the anterior pituitary. It may also occur with exogenous glucocorticoid therapy or with a pituitary or hypothalamic tumor.
Secondary insufficiency
This is caused by atrophy of the adrenal glands due to an autoimmune response. It is a primary insufficiency.
Addison’s disease
Signs and symptoms of Addison’s disease are:
- Hyperpigmentation
- Hypoglycemia
- Hypotension
- Decreased cardiac size
- Decreased mineralcorticoid activity
- fluid and electrolyte abnormalities
- changes in white blood cell ratios
- Also: weakness, fatigue, anemia, anorexia, vomiting, diarrhea, and muscle and joint pain
This is often due to insufficient glucocorticoids. It can be life threatening and may be precipitated by severe infection, trauma, surgery, or dehydration.
Adrenal crisis
Adrenal crisis signs and symptoms include:
- Often presents with confusion, headache, nausea, vomiting, muscular weakness, hypotension, dehydration, and vascular collapse.
- Can present as the rapid onset of hypotensive shock
- May include hypoglycemia, hyperkalemia, and hyponatremia as a consequence of glucocorticoid and mineralcorticoid loss
This is the physical and physiologic manifestation of the overproduction of cortisol. Often occurs because of excess production of ACTH from a pituitary tumor.
Cushing’s syndrome
Cushing’s disease is caused from a:
Pituitary tumor
Cushing’s syndrome arises from:
Adrenal gland (cortex)
Signs and symptoms of Cushing’s syndrome:
- Fat redistribution- moon face or Buffalo hump
- Altered protein metabolism- muscle wasting resulting in weakness and thin extremities
- Accelerated bone metabolism- increased risk of fracture and osteoporosis, renal calculi
- Altered glucose metabolism- often with appearance of diabetes
- Increased risk of infection due to anti-inflammatory properties of cortisol
- Increased androgens- hirsutism, acne, irregular menstruation
These are hormone producing tissue that release both insulin and glucagon.
Pancreatic islets
These cells release insulin in response to high blood glucose.
B-islets
These cells release glucagon in response to low blood glucose levels.
A-islets
This is caused by a complete or near absence of insulin from destruction of B-islet cells.
Type 1 diabetes
This is caused from a decreased responsiveness to insulin due to decreased receptor number or sensitivity.
Type 2 diabetes.
This hormone acts to raise blood calcium levels by actions in bones, intestines, and kidneys.
Parathyroid hormone
This is a decreased secretion of PTH or decreased hormonal response to PTH in the tissues. Removal or destruction of parathyroid gland. Decreased calcium levels causes increased neuromuscular and symptoms of tetany.
Hypoparathyroidism
Enhanced activity of the parathyroid glands result in hyper secretion of PTH. Caused elevated serum calcium levels and excessive secretion of potassium by the kidneys. Caused by adenoma.
Hyperparathyroidism
The 2 hormones that regulate calcium levels in the body are:
- Calcitonin- released from thyroid
2. Parathyroid hormone
