AnS 3360 Lecture 3 — History of Stress and Stress Responses (Vocabulary Flashcards)

Vocabulary flashcards covering key terms and concepts from the lecture on the history of stress, stress mechanisms, and farm-animal well-being.

Stress

A complex psychobiological process defined as the effect of physical or psychological stressors that alter an animal’s homeostasis or adaptive state.

Milieu intérieur

Bernard’s concept of the internal environment, the basis for maintaining a stable internal state.

Homeostasis

The body's tendency to maintain a stable internal environment; term coined by Walter Cannon.

Fight, flight, or freeze

The immediate, instantaneous response to threat mediated by the nervous system and SA/SNS pathways.

Sympatho-adrenal (SA) system

The rapid neural–hormonal response coordinating the initial stress reaction, involving the sympathetic nervous system and adrenal medulla releasing catecholamines.

General Adaptation Syndrome (GAS)

Selye’s three-stage model of the body's response to stress: alarm, resistance, exhaustion.

Distress

Negative stress; a state involving factors like lack of control, unpredictability, and threat.

Eustress

Positive or beneficial stress that can enhance performance or adaptation (e.g., reproductive or playful activities).

Hypothalamic–pituitary–adrenal (HPA) axis

Endocrine pathway for longer-term stress responses: hypothalamus releases CRH, which drives ACTH release from the pituitary, leading to glucocorticoid production.

CRH (Corticotropin-Releasing Hormone)

Hypothalamic hormone that stimulates ACTH release from the anterior pituitary.

ACTH (Adrenocorticotrophic Hormone)

Pituitary hormone that stimulates cortisol/corticosterone release from the adrenal cortex.

Cortisol

A glucocorticoid hormone released by the adrenal cortex; shows diurnal variation with higher levels in the morning.

Limbic system

Brain region (including thalamus, hippocampus, amygdala, hypothalamus) that modulates emotions, learning, and stress responses.

Thalamus

Relay station for sensory information; part of the limbic network involved in stress processing.

Hippocampus

Limbic structure essential for memory formation and contextualization of stress.

Amygdala

Limbic structure central to emotion processing and threat appraisal; triggers stress responses.

Hypothalamus

Brain region that integrates neural and hormonal signals to regulate the autonomic nervous system and HPA axis.

Autonomic Nervous System (ANS)

Part of the peripheral nervous system controlling involuntary functions; comprises sympathetic and parasympathetic divisions.

Sympathetic Nervous System (SNS)

Branch of the ANS responsible for rapid “fight or flight” responses, including catecholamine release.

Parasympathetic Nervous System (PNS)

Branch of the ANS that promotes “rest and digest” activities to restore homeostasis.

Five Freedoms

Five welfare aims: freedom from hunger and thirst, discomfort, pain/injury/disease, to express normal behavior, and from fear/distress.

Five Domains model

Welfare framework expanding Five Freedoms to include Nutrition, Environment, Health, Behavior, and Mental State.

Physiological stress

Stress arising from physical or environmental factors (e.g., cold, heat, radiation, noise, vibration, chemicals, metabolism).

Psychological stress

Stress arising from emotional, cognitive, or social factors (e.g., anxiety, fear, information overload, social defeat).

Cold stress

Stress induced by exposure to low ambient temperatures.

Heat stress

Stress induced by high ambient temperatures and thermal load.

Noise stress

Stress resulting from exposure to elevated noise levels.

Chemical stress

Stress due to exposure to chemicals or harmful metabolites.

Metabolic stress

Stress associated with disruptions in metabolism or energy balance.

Cortisol diurnal variation

Pattern where cortisol peaks in the early morning and decreases through the day.