Posterior pituitary
Information about Posterior pituitary
) | |
| Pituitary gland. Posterior pituitary is in blue. Pars nervosa and infundibular stalk are not labeled, but pars nervosa is at bottom and infundibular stalk is at top.) | |
| Median sagittal through the hypophysis of an adult monkey. (Posterior lobe labeled at bottom right.) | |
| subject #275 1275 | |
| Artery | inferior hypophyseal artery |
| Vein | hypophyseal vein |
| Precursor | Neural tube (downward-growth of the diencephalon)[1] |
| MeSH | Pituitary+Gland,+Posterior |
| Dorlands/Elsevier | n_07/12569241 |
Anatomy
The Posterior Pituitary Gland consists mainly of neuronal projections (axons) extending from the supraoptic and paraventricular nuclei of the hypothalamus that secrete peptide hormones into the capillaries of the hypophyseal circulation.The neurohypophysis also contains a specialised type of astrocytic glial cell - "pituicytes".
Despite its name, the posterior pituitary gland is not a gland, per se; rather, it is largely a collection of axonal projections from the hypothalamus that terminate behind the anterior pituitary gland.
Classification of the posterior pituitary varies, but most sources include the three regions below:
| Region | Description |
| pars nervosa, or neural lobe, or posterior lobe[2] | This region consistutes the majority of the posterior pituitary, and is sometimes (incorrectly) considered synonymous with it. Notable features include Herring bodies and pituicytes. [3] |
| infundibular stalk | Also known as the "infundibulum" or "pituitary stalk". The term "hypothalamic-hypophyseal tract" is a near-synonym, describing the connection rather than the structure. |
| median eminence | This is only occasionally included as part of the posterior pituitary.[4] Other sources specifically exclude it from the pituitary.[5] |
A few sources include the pars intermedia as part of the posterior lobe, but this is a minority view.
Major hormones secreted
Hormones known classically as posterior pituitary hormones are synthesized by the hypothalamus. They are then stored and secreted by the posterior pituitary into the bloodstream.| Hormone | Other names | Symbol(s) | Target | Effect | Source |
|---|---|---|---|---|---|
| Oxytocin | - | - | Uterus, mammary glands | Uterine contractions; lactation | paraventricular nuclei |
| Vasopressin | Arginine vasopressin, argipressin, antidiuretic hormone | AVP, ADH | Kidneys or Arterioles | Stimulates water retention; raises blood pressure by contracting arterioles | supraoptic |
Role in disease
Insufficient secretion of vasopressin is central diabetes insipidus, in which the body loses the capacity to concentrate urine. Affected individuals excrete as much as 20 L of dilute urine per day.Oversecretion of vasopressin causes the syndrome of inappropriate antidiuretic hormone.
References
1. ^ Embryology at unc.edu
2. ^ l_13/12501193 at Dorland's Medical Dictionary
3. ^ Histology at BU 14004loa
4. ^ n_07/12569241 at Dorland's Medical Dictionary
5. ^ MeSH Median+eminence
2. ^ l_13/12501193 at Dorland's Medical Dictionary
3. ^ Histology at BU 14004loa
4. ^ n_07/12569241 at Dorland's Medical Dictionary
5. ^ MeSH Median+eminence
Additional images
| thumb|center]] thumb|center | thumb|center]] The posterior pituitary comprises the posterior lobe of the pituitary gland. | thumb|center]] | thumb|center]] Hypothalamic nuclei | thumb|center |
v]] • • [ e] Endocrine system > Pituitary gland | ||||
| Posterior pituitary | Pars nervosa - Median eminence - Infundibular stalk | |||
|---|---|---|---|---|
| Anterior pituitary | Pars intermedia - Pars tuberalis - Pars distalis - Acidophils (Somatotropes, Lactotropes) - Basophils (Corticotropes, Gonadotropes, Thyrotropes) |
v]] • • [ e]
Brain: diencephaloninfundibulum]] • median eminence • arcuate nucleus • Ventromedial nucleus • Dorsomedial hypothalamic nucleus • Tuber cinereum, Pituitary gland (Anterior pituitary, Posterior pituitary)
posterior nucleus]] • Mammillary body • Lateral nucleus
Thalamus]]/nuclei
Arteries are muscular blood vessels that carry blood away from the heart.[1] All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.
The circulatory system is extremely important for sustaining life.
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The circulatory system is extremely important for sustaining life.
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The inferior hypophysial artery is an artery supplying the pituitary gland. It is a branch of the cavernous carotid artery.[1]
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References
1. ^ Gibo H, Hokama M, Kyoshima K, Kobayashi S (1993).
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vein is a blood vessel that carries blood toward the heart. The majority of veins in the body carry low-oxygen blood from the tissues back to the heart; the exceptions being the pulmonary and umbilical veins which both carry oxygenated blood.
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Embryology is the study of the development of an embryo. An embryo is defined as any vertebrate in a stage before birth or hatching. Embryology refers to the development of the egg cell (zygote) after fertilization and the differentiation of cells into tissues and organs.
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neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord. The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into a
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The diencephalon is the region of the brain that includes the thalamus, hypothalamus, epithalamus, prethalamus or subthalamus and pretectum. It is derived from the prosencephalon. The diencephalon is located at the midline of the brain, above the mesencephalon of the brain stem.
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea that sits in a small, bony cavity (sella turcica) covered by a dural fold (sellar diaphragm) at the base of the brain.
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1. Pineal gland 2. Pituitary gland 3. Thyroid gland 4. Thymus 5. Adrenal gland 6. Pancreas 7. Ovary 8. Testes]]
The endocrine system
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The endocrine system
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Neurons (also known as neurones and nerve cells) are electrically excitable cells in the nervous system that process and transmit information. In vertebrate animals, neurons are the core components of the brain, spinal cord and peripheral nerves.
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axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.
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Anatomy
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The supraoptic nucleus (SON) is a nucleus of magnocellular neurosecretory cells in the hypothalamus of the mammalian brain. The nucleus is situated at the base of the brain, adjacent to the optic chiasm, and, in humans, it contains about 3,000 neurons.
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The paraventricular nucleus (PVN) is an aggregation of neurons in the hypothalamus, which produces many hormones.
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Location
It is adjacent to the third ventricle (hence the name of the nucleus...... Click the link for more information.
The hypothalamus links the nervous system to the endocrine system via the pituitary gland (hypophysis). The hypothalamus, (from Greek ὑποθαλαμος = under the thalamus) is located below the thalamus, just above the brain stem.
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Peptide hormones are a class of peptides that are secreted into the blood stream and have endocrine functions in living animals.
Like other proteins, peptide hormones are synthesized from amino acids according to an mRNA template, which is itself synthesized from a DNA
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Like other proteins, peptide hormones are synthesized from amino acids according to an mRNA template, which is itself synthesized from a DNA
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The hypophyseal portal system (or hypothalamo-hypophyseal portal system) is the system of blood vessels that links the hypothalamus and the anterior pituitary. It allows endocrine communication between the two structures.
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Astrocytes (also known collectively as astroglia) are characteristic star-shaped glial cells in the brain. They perform many functions, including biochemical support of endothelial cells which form the blood-brain barrier, the provision of nutrients to the nervous tissue,
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Glial cells, commonly called neuroglia or simply glia (greek for "glue"), are non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin, and participate in signal transmission in the nervous system.
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A pituicyte is a glial cell of the posterior pituitary.[1][2]
They generally stain dark purple, and are among the easiest structures to identify in the region.[3][4]
However, their function is not well defined.
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They generally stain dark purple, and are among the easiest structures to identify in the region.[3][4]
However, their function is not well defined.
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axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.
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Anatomy
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The anterior pituitary (also called the adenohypophysis, from Greek adeno, "gland"; hypo, "under"; physis, "growth"; hence, glandular undergrowth) comprises the anterior lobe of the pituitary gland and is part of the endocrine system.
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Herring bodies are structures found in the posterior pituitary. They represent the terminal end of the axons from the hypothalamus, and hormones are temporarily stored in these locations.
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A pituicyte is a glial cell of the posterior pituitary.[1][2]
They generally stain dark purple, and are among the easiest structures to identify in the region.[3][4]
However, their function is not well defined.
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They generally stain dark purple, and are among the easiest structures to identify in the region.[3][4]
However, their function is not well defined.
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- Also see infundibulum for other uses of the term.
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The median eminence is part of the inferior boundary for the hypothalamus part of the human brain. A small swelling on the tuber cinereum posterior to the infundibulum - atop the pituitary stalk - the median eminence
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Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains three types of cells - basophils, chromophobes, and colloid-filled cysts. The cysts are the remainder of Rathke’s pouch.
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Oxytocin (ŏk'sĭ-tō'sĭn) (Greek: "quick birth") is a mammalian hormone that also acts as a neurotransmitter in the brain. In females, it is released in large amounts after distension of the cervix and vagina during labor, and after stimulation of the
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uterus or womb is the major female reproductive organ of most mammals, including humans. One end, the cervix, opens into the vagina; the other is connected on both sides to the fallopian tubes.
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Mammary glands are the organs that, in the female mammal, produce milk for the sustenance of the young. These exocrine glands are enlarged and modified sweat glands and are the characteristic of mammals which gave the class its name.
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