Stress (biology)

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– Acute stress can lead to psychological changes like derealization, depersonalization, anxiety, and hyperarousal.
– Mental and behavioral disorders can result from severe stress and the subsequent adaptive response.
– Chronic stress without coping resources can lead to issues like delusions, depression, and anxiety.
– Prolonged stress can cause brain atrophy, resulting in the loss of neurons and connections.

– Stress triggers responses in multiple systems across the body.
– In humans and mammals, the autonomic nervous system and HPA axis are key stress-response systems.
– Adrenaline and cortisol are hormones produced during stressful situations.
– The SAM axis activates fight-or-flight response, while the parasympathetic system restores homeostasis.
– The HPA axis regulates cortisol release, impacting metabolic, psychological, and immunological functions.

Impact on Memory and Health:
– Stress can affect memory, reward systems, immune function, metabolism, and disease susceptibility.
– Chronic or severe stress is a common risk factor for mental illnesses.
– Disease risk, especially mental illnesses, is linked to chronic or severe stress.
– Stress can alter various bodily functions and increase vulnerability to diseases.

Neurohormonal Response:
– The SAM and HPA axes are regulated by brain regions like the limbic system and prefrontal cortex.
– Cortisol released by the HPA axis influences metabolic, psychological, and immunological functions.
– Stress can lead to alterations in memory, immune function, and susceptibility to diseases.
– Chronic or severe stress is a risk factor for various mental illnesses.
– The fight-or-flight response is activated by the SAM axis through the sympathetic nervous system.

Environmental Stress:
– Environmental stressors can trigger biological, physiological, and psychological responses.
– Stressors can impact an organism’s environment, leading to responses across the body.
– The body responds to environmental stress through various systems.
– Stress responses can influence metabolic, psychological, and immunological functions.
– Stress can alter memory functions, reward systems, and disease vulnerability.

Stress (biology) (Wikipedia)

Stress, whether physiological, biological or psychological, is an organism's response to a stressor such as an environmental condition. When stressed by stimuli that alter an organism's environment, multiple systems respond across the body. In humans and most mammals, the autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) axis are the two major systems that respond to stress. Two well-known hormones that humans produce during stressful situations are adrenaline and cortisol.

Schematic overview of the classes of stresses in plants
Neurohormonal response to stress

The sympathoadrenal medullary (SAM) axis may activate the fight-or-flight response through the sympathetic nervous system, which dedicates energy to more relevant bodily systems to acute adaptation to stress, while the parasympathetic nervous system returns the body to homeostasis.

The second major physiological stress-response center, the HPA axis, regulates the release of cortisol, which influences many bodily functions such as metabolic, psychological and immunological functions. The SAM and HPA axes are regulated by several brain regions, including the limbic system, prefrontal cortex, amygdala, hypothalamus, and stria terminalis. Through these mechanisms, stress can alter memory functions, reward, immune function, metabolism and susceptibility to diseases.

Disease risk is particularly pertinent to mental illnesses, whereby chronic or severe stress remains a common risk factor for several mental illnesses.

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