The Pineal Gland The pineal gland is a

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The Pineal Gland The pineal gland is a small endocrine gland attached to the

The Pineal Gland The pineal gland is a small endocrine gland attached to the roof of the third ventricle – it is part of the epithalamus – The pineal gland secretes the hormone melatonin, which contributes to maintaining the biological clock (seasonal and daily cycles) • more melatonin is secreted in darkness; the pineal gland is very developed in nocturnal animals

The Thymus gland • The thymus gland secretes thymosin, which promotes the proliferation and

The Thymus gland • The thymus gland secretes thymosin, which promotes the proliferation and maturation of T cells – T cells are a type of white blood cell (lymphocyte) that destroys microorganisms and foreign substances through direct cellular contact

General Adaptation Syndrome • The general adaptation syndrome (GAS) or stress response refers to

General Adaptation Syndrome • The general adaptation syndrome (GAS) or stress response refers to the consequences of failure to respond appropriately to emotional or physical threats, whether actual or imagined – Interestingly, stressful situations can be events normally considered to be “good”, as well as bad • for instance, a marriage can be as stressful as a divorce, a birth as stressful as a death, etc.

General Adaptation Syndrome • It is impossible to remove all of the stress from

General Adaptation Syndrome • It is impossible to remove all of the stress from our everyday lives, and some levels of stress actually help us perform well and be productive. Regardless, the body’s homeostatic mechanisms attempt to counteract stress, and maintain a constant internal environment whenever possible – If stress is extreme, unusual, or long lasting, the normal mechanisms may not be enough, and they may elicit a series of changes called the stress response or GAS

General Adaptation Syndrome • There are three stages to a prolonged stress response: alarm

General Adaptation Syndrome • There are three stages to a prolonged stress response: alarm reaction, resistance reaction, and exhaustion – The alarm reaction is the short-lived fight-orflight response initiated by the hypothalamus and mediated by the sympathetic division of the ANS • it brings huge amounts of glucose and oxygen to the brain, the lungs, and skeletal muscles • the RAAS is also activated to maintain blood volume and BP

THE ALARM REACTION (Interactions Animation) • The Alarm Reaction You must be connected to

THE ALARM REACTION (Interactions Animation) • The Alarm Reaction You must be connected to the internet to run this animation

General Adaptation Syndrome • The three stages to the GAS continued… – The resistance

General Adaptation Syndrome • The three stages to the GAS continued… – The resistance reaction is initiated in large part by hypothalamic releasing hormones and is a longer-lasting response. The release of high levels of cortisol and thyroid hormones assures that the tissues of the body can sustain necessary metabolic needs

General Adaptation Syndrome The alarm reaction leads to a resistance response.

General Adaptation Syndrome The alarm reaction leads to a resistance response.

General Adaptation Syndrome • The three stages to the GAS continued… – Exhaustion occurs

General Adaptation Syndrome • The three stages to the GAS continued… – Exhaustion occurs when the body’s reserves become so depleted that they cannot sustain the resistance stage • Prolonged exposure to high levels of cortisol and other hormones causes wasting of muscle, suppression of the immune system, ulceration of the GI tract, and failure of pancreatic beta cells… disease often ensues

THE GAS (Interactions Animation) • General Adaptation Syndrome You must be connected to the

THE GAS (Interactions Animation) • General Adaptation Syndrome You must be connected to the internet to run this animation

End of Chapter 18 Copyright 2012 John Wiley & Sons, Inc. All rights reserved.

End of Chapter 18 Copyright 2012 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein.