the endocrine system

• hypothalamus is the brain region controlling the pituitary gland
• pituitary gland secretes many different hormones some of which affect other glands
• adrenal glands help trigger the fight or flight response
• ovaries secrete female sex hormones
• testes secrete male sex hormones
• endocrine glands: they produce and secrete hormones, chemical substances that regulate the activity of cells or organs in the body
• endocrine glands: the major glands of the endocrine system include the pituitary glands, adrenal glands and the reproductive organs (ovaries and testes)
• endocrine glands: each gland in the endocrine system produces different hormones which regulate the activity of organs and tissues in the body
• endocrine glands: the endocrine system is regulated by feedback similar to how a thermostat regulates temperature in a room e.g. a signal is sent from the hypothalamus to the pituitary gland in the form of a 'releasing hormone'
• endocrine glands: this causes the pituitary gland to secrete a 'stimulating hormone' into the bloodstream, this hormone signals the target gland (e.g. the adrenal glands) to secrete its hormone
• endocrine glands: as levels of this hormone rises in the bloodstream the hypothalamus shuts down secretion of the releasing hormone and the pituitary gland shuts down secretion of the stimulating hormone, this slows down secretion of the target gland's hormone, resulting in stable concentrations of hormones circulating in the bloodstream
• hormones: hormones are chemicals that circulate in the bloodstream and are carried to target sites throughout the body
• hormones: the word 'hormone' comes from the Greek word hormao meaning 'I excite' which refers to the fact that each hormone 'excites' or stimulates a particular part of the body
• hormones: although hormones come into contact with most cells in the body a given hormone usually affects only a limited number of cells known as target cells
• hormones: target cells respond do a particular hormone because they have receptors for that hormone, cells that do not have such a receptor can't be influenced directly by that hormone
• hormones: when enough receptor sites are stimulated by hormones this results in a physiological reaction in the target cell, timing of hormone release is critical for normal functioning as are the levels of hormones released
• hormones: too much or too little at the wrong time can result in dysfunction of bodily systems e.g. too high a level of cortisol can lead to Cushing's syndrome characterised by high blood pressure and depression
• hormones: the most common cause of excess cortisol is a tumour in the pituitary gland which makes too much of a hormone called adrenocorticotrophic hormone (ACTH) which stimulates the adrenal glands to make too much cortisol
• pituitary gland: the pituitary gland produces hormones who primary function is to influence the release of hormones from other glands and in so doing regulates many of the body's functions
• pituitary gland: the pituitary is controlled by the hypothalamus a region of the brain just above the pituitary gland
• pituitary gland: the hypothalamus receives information from many sources about the basic functions of the body, then uses this information to help regulate these functions
• pituitary gland: one of the ways it does this involves controlling the pituitary gland, as the 'master gland' the pituitary produces hormones that travel in the bloodstream to their specific target
• pituitary gland: these hormones either directly cause changes in physiological processes in the body or stimulate other glands to produce other hormones
• pituitary gland: high levels of hormones produced in other endocrine glands can stop the hypothalamus and pituitary releasing more of their own hormones, this is called negative feedback and prevents hormone levels from rising too high
• hormones produced by the pituitary gland: the pituitary gland has 2 main parts = the anterior (front) pituitary and the posterior (back) pituitary
• hormones produced by the pituitary gland: these 2 parts release different hormones which target different parts of the body
• hormones produced by the pituitary gland: the 2 sections of the pituitary gland produce a number of different hormones which act on different target glands or cells e.g. the anterior pituitary releases ACTH as a response to stress
• hormones produced by the pituitary gland: ACTH stimulates the adrenal glands to produce cortisol, the anterior pituitary also produces 2 hormones important in the control of reproductive functioning and sexual characteristics luteinising hormone (LH) and follicle-stimulating hormone (FSH)
• hormones produced by the pituitary gland: in females these hormones stimulate the ovaries to produce oestrogen and progesterone and in males they stimulate the testes to produce testosterone and sperm
• hormones produced by the pituitary gland: the posterior pituitary releases oxytocin which stimulates contraction of the uterus during childbirth and is important for mother-infant bonding
• hormones produced by the pituitary gland: recent research using mice has found that oxytocin is indispensable for healthy maintenance and repair and that it declines w/ age
• target cells respond to a particular hormone because they have receptor cells for that hormone whereas cells w/o these specific receptor cells are not affected
• the adrenal glands: the 2 adrenal glands sit on top of the kidneys
• the adrenal glands: the name 'adrenal' relates to their location, each adrenal gland is made up of 2 distinct parts
• the adrenal glands: the outer part of each gland is called the adrenal cortex and the inner region is known as the adrenal medulla, the adrenal cortex and the adrenal medulla have very different functions
• the adrenal glands: one of the main distinctions between them is that the hormones released by the adrenal cortex are necessary for life, those released by the adrenal medulla are not
• hormones produced by the adrenal glands: the adrenal cortex (the outer part of the adrenal gland) produces cortisol which regulates or supports a variety of important bodily functions including cardiovascular and anti-inflammatory functions
• hormones produced by the adrenal glands: cortisol production is increased in response to stress, if the cortisol levels are low the person has low blood pressure, poor immune function and an inability to deal w/ stress
• hormones produced by the adrenal glands: the adrenal cortex also produces aldosterone which is responsible for maintaining blood volume and blood pressure
• hormones produced by the adrenal glands: the adrenal medulla (the inner part of the adrenal gland) releases adrenaline and noradrenaline = hormones that prepare the body for fight or flight