Presented by:- Mr. Bhartendu vimal Guest

Transcript:Presented by:- Mr. Bhartendu vimal Guest:
Presented by:- Mr. Bhartendu vimal Guest faculty-Asst. Prof. Stress & it's responses Stress is the physiological, biochemical and behavioural response to a stimulus in an attempt to adapt that stimulus. Stress is defined as the response of the cell, or organism itself to any demand placed on it such that it causes an extension of a physiological state beyond the normal resting state (Barton, 1997). What is stress ??? Stress is a state produced by an environmental or other factor which extends the adaptive response of an animal beyond the normal functioning to such an extent that, in either case, the chances of survival are significantly reduced (Brett, 1958). Stress means the sum of the physiological responses by which an animal tries to maintain or establish a normal metabolism on the face of physical or chemical force (Selye, 1950) Cont… The word “stress” and its concept in common use is generally associated with a system that is severely challenged and often fatigued. The stress response is intended to be adaptive in nature, so stress by itself is not a bad thing. Stress is an unavoidable component of fish farming and its possible detrimental effects on important fish performance features such as metabolism and growth, disease resistance and reproductive capacity. Why stress is important ??? Any factor which causes fish to depart from a state of optimal functions is a stressor or stress factor. Stress can be either acute or chronic in nature. Stressor that induce a “fight or flight” response are considered acute while others are chronic stressors. These stressors can be classified into four general categories. When stress occurs ??? Cont… The sum of the physiological changes that occur as fish reacts to physical, chemical, biological or perceived challenges and attempts to compensate are commonly referred to as the stress response. The stress response in fish has been broadly categorized into the primary, secondary and tertiary response. Stress response ??? Release of adrenocorticotropic hormones (ACTH) from the adenohypophysis. Release of “stress hormones” (catecholamines and corticosteroides) from the head kidney. In fish, an adverse condition stimulates the afferent neural pathway that runs in the sympathetic nervous system from the hypothalamus to the chromaffin tissue of the head kidney and stimulates the chromaffin tissue which results release of catecholamines. (i) Primary stress response CRH released from hypothalamus stimulates corticotropic cells of adenohypophysis to secrete ACTH, which stimulates interrenal cells (adrenal cortex