Optic chiasm and pituitary gland relationship to thyroid

Pituitary tumors, adenoma, craniopharyngioma | Mayfield Brain & Spine, Cincinnati, OH

optic chiasm and pituitary gland relationship to thyroid

Fig – Anatomical position and relations of the pituitary gland. in size, it can compress surrounding structures, such as the optic chiasm. Thyroid eye disease is the most common systemic manifestation of Graves' disease, . thyroid stimulating hormone, and the gonadotropin hormones) (44). The pituitary gland is located in the sella turcica, also known as the pituitary The optic chiasm, containing the optic nerves and tracts, typically lies. The hypothalamus is located at the base of the brain, near the optic chiasm  where the the release of hormones in the pituitary gland, in addition to controlling water balance, The thyroid plays an important role in the body's metabolism.

The geometry of the glycoprotein molecules allows only for very specific hormones to attach to the receptor in the target cell surface. Think of it as a lock and key mechanism. Chemical mimics such as xenoestrogens petroleum-based hormone lookalikes and synthetic growth hormones in meat, etc. These are never good. Plant mimics such as phytoestrogens consumed in the diet or in supplements, which can fill receptor sites, making them unavailable to the stronger natural hormones or chemical mimics for that matter in the human body.

This effect can often be used to advantage to tone down overly strong hormonal responses in the human body. Each target cell has up toreceptors for a given hormone. When there is an excess of that hormone, the number of receptors decreases, reducing sensitivity.

  • Anatomy of the Pituitary Gland
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  • The Pituitary Gland

This reduction of sensitivity is known as "down regulation. Or in the case of some chemical mimics, up regulating them. Thus a single cell may actually have millions of receptor sites on its surface.

If an abnormally low number of hormone molecules is circulating, the number of receptor sites on individual cells will increase to raise the level of sensitivity and thus compensate. This is known as "up regulation. These hormones do not enter the general circulation.

There are two types -- one of which, in particular, is of special concern to us. These can play a critical role in terms of our health. Cancer cells use autocrine signaling to trigger growth.

This means that cancer cells are autonomous. They don't take orders from other cells in the body. They tell themselves what to do. That's one of their features that makes them so dangerous. Now that we have a basic understanding of what the endocrine system is, what it does, and how it works, let's start making our way down through the body and begin by taking a look at the three endocrine glands in the human brain: Hypothalamus The hypothalamus is located below the thalamus and posterior to the optic chiasm.

In humans, the hypothalamus is roughly the size of an almond.

Pituitary gland

But within that small size, it contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland.

The hypothalamus actually controls the pituitary gland; and it integrates many messages from parts of the brain based on feedback from all over the body and tells the pituitary what to do. Communication between the hypothalamus and the pituitary is effected through a portal blood capillary system, which connects the two glands over a very short distance. This provides a direct venous to venous connection.

optic chiasm and pituitary gland relationship to thyroid

The advantage of this type of direct connection is that a portal flow allows blood-borne molecules from the hypothalamus to act on the pituitary before they are diluted with the blood in larger vessels, thus it takes very, very few molecules to direct the pituitary. The hypothalamus synthesizes and secretes neurohormones, often called hypothalamic-releasing hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones.

Among other things, the hypothalamus, through its action on the pituitary, controls body temperature, hunger, thirst, fatigue, childbirth, emotions, growth, milk production, salt and water balance, sleep, weight, and circadian cycles. It is responsive to light the length of the day for regulating both daily circadian and seasonal rhythms. It is also responsive to olfactory stimuli including pheromonessteroids, neurally transmitted information from the heart, stomach, and reproductive system, stress, changes in body temperature caused by infection, and blood-borne stimuli including leptin and ghrelin appetite regulating hormonesangiotensin, insulin, pituitary hormones, cytokines, and glucose, etc.

For the most part, the hypothalamus functions pretty much problem free for the vast majority of people. However, any of the following can cause it to malfunction: Pituitary gland At one time, the pituitary gland, also called the hypophysis, was once thought to be the "master gland" that controlled all the other endocrine glands.

But, as mentioned above, we have since learned that the hypothalamus actually controls the pituitary gland; and it integrates many messages from parts of the brain based on feedback from all over the body and tells the pituitary what to do. The dimensions of the pituitary are mm from side to side, mm from front to back and mm from top to bottom. An important anatomical relation to the pituitary gland is the optic chiasm, which lies just above the pituitary fossa. Therefore, any expanding lesion of the pituitary or hypothalamus can present with visual field defects.

Blood Supply The blood supply to the hypothalamus and pituitary is derived from the circle of Willis at the base of the brain. The most important blood supply is from the superior hypophysial arteries which arise from the internal carotids.

The blood from this artery enters a primary capillary plexus at the median eminence. Most are benign not cancer and are often curable. Treatment options aim to remove the tumor or control its growth and correct hormone levels with medications.

Endocrinology - Overview

Anatomy of the pituitary and sella The pituitary gland is a small, bean-shaped organ that sits at the base of the brain, behind the bridge of the nose Fig. It has a large anterior lobe gland cells that produce hormones and a smaller posterior lobe nerve cells that release hormones. It sits in a small pocket of bone in the base of the skull called the sella turcica.

The gland is connected to the hypothalamus in the brain by the pituitary stalk. The pituitary gland is bordered on either side by the cavernous sinuses and below by the sphenoid sinus. The sphenoid sinus is an air-filled sinus that drains into the nose. The internal carotid arteries and the nerves that control eye movement lie on the sides of the pituitary. Directly above the pituitary gland is the optic chiasm, which is responsible for vision.

When pituitary tumors grow they can compress the above-mentioned structures and cause symptoms. A cross-section of the pituitary gland green shows its relationship to the optic chiasm, the sphenoid sinus, and the cavernous sinuses on each side. Side view of the pituitary gland sitting inside the bony sella. The pituitary gland green is located deep within the skull in an area called the sella.

The pituitary gland is related to the optic chiasm above and the sphenoid sinus below. Known as the master gland, the pituitary controls the other endocrine glands in the body. It releases secretions into the bloodstream and provides feedback to the hypothalamus. The hypothalamus then regulates pituitary hormone levels, depending on the needs of the body.

Hormones made by the pituitary gland include: Cortisol helps control the use of sugar, protein, and fats in the body and helps the body deal with stress. Antidiuretic hormone ADH or vasopressin: Too little of this hormone can cause diabetes insipidus.

Too much of this hormone can cause syndrome of inappropriate ADH secretion. Luteinizing hormone and follicle-stimulating hormone: What is a pituitary tumor? A tumor that grows from the pituitary gland is called an adenoma. Most adenomas are benign, slow growing, and relatively common. Tiny tumors or cysts are often found on an MRI scan performed for another reason. Most of these never grow or cause symptoms. Functioning pituitary tumors secrete high levels of hormones and interfere with other body organs.

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These tumors behave according to their cell of origin and are named for the specific hormone they produce. For example, a prolactinoma grows from prolactin-producing cells. Nonfunctioning pituitary tumors do not secrete hormones. Instead, they grow until their size and mass effect cause headache, vision loss, nausea, vomiting, or fatigue.

The Endocrine System, Hormones & Natural Alternatives -- Natural Health Newsletter

These tumors may compress the normal pituitary gland decrease hormone production hypopituitarism. Based on size, pituitary tumors may be classified as microadenomas less than 10mm or macroadenomas larger than 10mm.

Large tumors can press on the optic nerves and invade the cavernous sinuses, which house the carotid arteries and the nerves involved in eye movement. These grow from embryonic remnant cells in the pituitary gland.

optic chiasm and pituitary gland relationship to thyroid

Craniopharyngiomas typically grow from the pituitary stalk upward into the third ventricle and cause symptoms similar to pituitary adenomas. What are the symptoms? Symptoms of a pituitary tumor vary depending on its size and hormone secretion; many are asymptomatic. The most common pituitary tumor, a prolactinoma, causes an overproduction of the hormone that helps control sexual function. In women, the tumor can cause menstruation to stop amenorrhea or inappropriate production of breast milk galactorrhea.

In men, prolactinomas may cause enlarged breasts gynecomastiaerectile dysfunction or impotence, infertility, decrease in body hair, and low sex drive. More common in men, these pituitary tumors may cause gigantism in children or acromegaly in adults. Symptoms include enlargement of the bones in the hands, feet, or face. Other symptoms include excess sweating, high blood pressure, heart disease, diabetes, and arthritis. Adrenocorticotropic hormone ACTH -producing tumors.

Thyroid, Parathyroid, Adrenal, Endocrine Surgery, Anatomy of the Pituitary Gland

More common in women, these tumors stimulate the adrenal gland to secrete cortisol. Excess cortisol causes Cushing's disease, a fatty hump between the shoulders; weight gain in the face, neck, and trunk of the body; and pink or purple stretch marks on the skin. TSH-secreting tumors can cause hyperthyroidism.