Endocrine system Flashcards by Katie Davidson

Identify the location of the pituitary gland

Sella turcica of sphenoid bone

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Describe the overall function of the endocrine system

Reproduction, growth and development, internal homeostasis, helps to cope with environmental changes

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Contrast endocrine and exocrine glands

Endocrine make hormones & are released into the bloodstream; exocrine make a substance released directly onto skin surface or into a duct, e.g. salivary duct.

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Define Hormone

Hormone is made by an endocrine gland & is a chemical messenger traveling in the bloodstream.

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What are target cells

The target cell responds to the hormone because it has matching receptors for the hormone

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Explain how a hormone affects the activity of target cells

It can go to the nucleus and act upon the genes, or it can stimulate and intermediate compound such as cAMP, which acts as a second messenger and stimulates or inhibits a process or metabolic pathway in the cell.

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Dexcribe the structure and transport mechanisms of hormones

Most are amino acids, some are cholesterol based. All are organic compounds and are transported in the bloodstream; usually they are attached to some carrier protein making them physically larger so that they are not urinated out.

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Describe the 2 lobes of the pituitary gland

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What are the hormones of the anterior pituitary gland?

FSH

LH/ICSH

TSH

ACTH

Prolactin

MSH

endorphins (not endocrine)

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Posterior pituitary

releases: ADH causes water reabsorption (from urine to blood) in kidney; Oxytocin causes uterine contractions during childbirth and milk secretion.

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What is an endorphine

Morphine like compound made by anterior pituitary gland, but is really a neuromodulator, not a hormone.

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Describe the controls of the pituitary gland

Hypothalamus makes stimulatory hormones called releasing hormones and inhibitory hormones; Negative feedback

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Expaine why the posterior pituitary is not a true endocrine gland.

It doesn’t make ADH and Oxytocin. They are made by hypothalamus but stored and released by posterior pituitary.

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Describe the location and histology of the tyroid gland

Inferior to larynx, and histology shows follicles filled with thyroid hormone (colloid), and the surrounding follicle cells make the hormone. The interstitial cells are called parafollicular cells and make calcitonin.

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Name and describe the formation and function of thyroid hormones

Made from an amino acid called tyrosine. Three iodine molecules in T3 and four in T4.

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How are thyroid hormones transported in the blood stream

Attached to TBG

Most thyroid hormones are carried in plasma bound to tyroid binding globilin

Describe the controls over thyroid hormone synthesis and release

Negative feedback, TSH from ant. pituitary and Thyroid releasing hormone from hypothalamus.

Name the gland and cells that make calcitonin

Parafollicular cells of thyroid gland = C cells

Describe the function and control of calcitronin

Decreases blood calcium levels

Describe the location of the parathyroid gland and the function of its hormone and the controls of its release

Embedded in the thyroid gland. It makes Parathyroid hormone which increases blood calcium levels. Obviously, blood calcium levels determine whether PTH or Calcitonin should be released.

Describe the location and the 2 portions of the adrenal gland

Above the kidneys. Outer region is adrenal cortex, inner region is adrenal medulla.

Name the 2 hormones made by the adrenal medulla and describe their functions and the controls of their release

Epinephrine & Norepinephrine are released under fight of flight situations. They exaggerate the fight or flight response. Mostly, epinephrine is released.

Name the 3 layers of the adrenal cortex.

Zona Glomulrtosa-Outermost layer

Zona Fasciculata-Middle layer

Zona reticularis-Innermost Layer

Adrenal medulla

Chromafin cells

Produces: 80% Epinephrine, 20% Norepinephrine

Action: Glucose, HT, bl. vessels, bl. pressure, airways

Release: Pregang, neurons, excitement, injury

Zona glomerulosa

Outermost layer of adrenal cortex * production 90% aldosterone* * involved with Na rebsorbtion, K excretion-in Kidneys* Renin/Angiotensinogen *Renin is an enzyme made by the kidneys in response to low blood pressure. It causes inactive angiotensinogen to activate into Angiotensin, which stimulates Aldosterone release*.

Renin/angiotensinogen

Zona fasciculata

Thick middle layer Glucocorticoids Conserves and supplements energy Anti-inflammatory Release-ACTH, CRH, stress

Zona reticularis

Innermost layer Sex hormone

Name the 3 layers of the adrenal cortex. Name and describe the effects of the hormones made by each layer. Describe the controls of their release.

Outer is the zona glomerulosa where aldosterone is made which causes sodium reabsorption in the kidneys (sodium goes from urine back to blood, and water passively follows); Zona fasciculata is middle layer making glucocorticoids that help one deal with long term stress by conserving energy for later. It is also anti-inflammatory. Inner zone is zona reticularis making sex hormones to be discussed under reproduction. ## Footnote Of course ACTH from the ant. pituitary stimulates the release of these hormones. Also, low blood sodium would stimulate release of aldosterone. If your blood pressure is low, the kidneys release renin. Renin is an enzyme that converts angiotensinogen to angiotensin. These will be discussed under cardiovascular system. However, angiotensin can cause the adrenal cortex to release aldosterone. Since aldosterone causes more salt to be in the bloodstream, and water passively follows, it will help to restore the low blood pressure to a more normal value.

Name the 2 hormones made by the adrenal medulla and describe their functions and the controls of their release

.Epinephrine & Norepinephrine are released under fight of flight situations. They exaggerate the fight or flight response. Mostly, epinephrine is released.

# Define the islets of langerhans, pancreatic islets, and chromaffin cells.

Islets of Langerhans = pancreatic islets and are the endocrine cells of the pancreas. The chromaffin cells are the endocrine cells of the adrenal medulla.

Name the organ that has both exocrine and endocrine functions

Pancreas

Describe the location and structure of the pancreas

Inferior to stomach. The pancreas is mostly exocrine - only the islets are the endocrine portion

Name the cells that make inulin, glucogon, and somatostatin. Describe their effects.

The islets, specifically beta cells make insulin which lowers blood glucose by allowing it to go into cells. Alpha cells make glucagon which raises blood glucose by bringing it out of storage, and delta cells make somatostatin which opposes GH release.

Describe the controls of insulin and glucagon release

High blood glucose leads to insulin release; Low blood glucose leads to glucagon release.

Name the male and female gonads and briefly describe their endorine roles

Male - testes; Female - Ovaries

Describe the location and function of the pineal gland

Roof of third ventricle. Makes melatonin which depresses reproductive activity

Name the gland that is replaced by connective tissue and fat in adults. Briefly describe its location and function

Thymus. It has a lymphatic role, in that T lymphocytes are made and "trained" here. The endocrine role is that it releases thymic hormone to stimulate these T cells.

Describe the structure and function of prostaglandins

Fatty acids that have a variety of functions. They are unique in that they tend to act locally. For example, a prostaglandin released by the uterus into the bloodstream has target cells in the uterus and acts upon the uterus.