Glossary :: The Hypothalamus

ACTH

Adrenocorticotropic hormone- is a polypeptide hormone which is produced and then secreted from the anterior pituitary gland.

Adenohypophysis

Another name for the anterior pituitary

Adenoma

Is a benign tumour which grows in glands

Anosmia

Is a term used to describe those with a lost sense of smell

Autonomic nervous system

Controls the peripheral nervous system and does not require concious regulation of the nervous system.

Autonomous cell

Directs its fate independently:doesn't require signals from other cells to differentiate

Chemoattractant

Is a signalling protein which attracts axons during development to the location at which they are secreted in a concentration dependent manner.

Chemorepullsant

Is a signalling protein which repells axons during development away from the location at which they are secreted in a concentration dependent manner.

Circadian rythm

The natural sleep/wake cycle of the body

Embryogenesis

The process by which the embro develops

Endocrine system

Groups of glands around the body which work together to regulate hormonal secretion all over the body

Fate mapping

An experimental method used by researchers to determine what cells in part of an embryo during development acquire a certain fate.

Heterochromia

The difference in colour between the two eyes

Homeostasis

The process by which the internal environment of an organism is stabilised.

Hyperplasia

The proliferation of normal cells within a tissue more than normal.

Infundibulum

A small outgrowth of cells from the hypothalamus which contains neurons and allows commuinication between the hypothalamus and the Pituitary gland.

Leptin

Is a hormone secreted by adipose cells after someone has eaten.

Are neurons which extend their axons directly into the postrior pituitary gland. They derive from either the periventricular or supraoptic nucleus where they are involved in the production and secretion of oxytocin and vasopressin.

Median eminence

Is located at the top of the pituitary behind the infundibulum and is part of the hypophyseal portal system.

Medulla Oblongata

Is located at the lower part of the brainstem and is involved in regulating breathing as part of the autonomic nervous system as well as other functions.

Metabolism

Chemical reactions which occur within the cell which allow growth and proliferation of each cell. It is a process which is essential for cells to live.

Milieu interior

Is another way of describing 'homeostasis'

Morphogen

A substance which diffuses and elicits differential concentrations spatially to create a certain response at different points in a developing tissue.

Morphogenesis

The process by which an embryo acquires its form during development

Neurohormone

A hormone which is produced and released by hormones

Neurohypophysis

Is another name for the posterior pituitary gland

Neurotransmitter

A chemical found naturally within the body which: modulates, relays and amplifies either excitatory or inhibitory signals between neurons.

Nodal

Is a protein which determines left or right asymmetry in cell differentiation

Non-autonomous

Requires the signals from other cells eg. morphogens, to acquire its own fate

OB

Is the name for the gene which codes for the protein leptin.

Orexigenic

Is to increase appetite

Overexpression

An experimental method used by researchers where a certain gene is expressed more than normal to determine the function of this gene.

Parvocellular neurons

Are neurons which extend their axons form the periventricular zone of the hypothalamus through the infundibular stalk where their neurosecretory neurons release hormones into the hypothalamo-pituitary portal system.

Preprohormone

A precursor protein from which pro-hormones are produced via various mechanisms such as glycosylation or cleavage of the protein into a more stable form.

Pyrogen

A substance which causes an increase in body temperature when it enters the blood stream.

Satiety

The state of feelling full

Shh

abbreviation of the morphogen: Sonic hedgehog which is involved in patterning the neural tube during development allowing cells to acquire a ventral fate.

T-box genes

Are genes which encode proteins which become transciption factors involved in regulating development of cells.

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