Feedback Systems: Homeostasis and Stress

Vocabulary flashcards covering negative and positive feedback mechanisms, homeostasis, thermoregulation, and physiological stress based on the lecture material by Noel Ways.

Homeostasis

The process by which the body regulates physiological variables within precise and optimal ranges necessary for maintaining health.

Set Point

A genetically predetermined optimal level around which a physiological variable fluctuates under normal conditions.

Stress

A state that occurs when a physiological variable deviates above or below its genetically predetermined set point.

Negative Feedback System

A physiological feedback system that functions to counteract, negate, or remove a stress to restore homeostasis.

Receptors

Specialized cells or groups of cells responsible for detecting changes in specific physiological variables, such as chemoreceptors, baroreceptors, light receptors, and stretch receptors.

Afferent Pathway

The pathway along which information detected by receptors is transmitted to the control center.

Control Center

The component of a feedback system that monitors physiological variables, evaluates incoming information against a genetically predetermined set point, and signals responses when stress is present.

Efferent Pathway

The pathway along which signals are sent from the control center to an effector.

Effector

A body structure responsible for executing responses to restore a physiological variable to its normal state.

Disease State

A condition resulting from unresolved physiological stress due to the failure of a control mechanism, where physiological variables are no longer maintained within an acceptable range of the set point.

Thermoregulation

A negative feedback system that regulates body temperature using thermoreceptors, the nervous system, and effectors such as superficial vasculature, musculature, and sweat glands.

Hyperthermia

A form of thermal stress defined as an elevated body temperature above the set point.

Hypothermia

A form of thermal stress defined as a decreased body temperature below the set point.

Vasodilation

The widening of superficial vasculature during hyperthermia to bring warm blood to the surface of the body, aiding in heat loss.

Vasoconstriction

The narrowing of superficial vasculature during hypothermia to retain warm blood deeper within the body.

Shivering

Rapid, involuntary contractions of skeletal muscles initiated by the hypothalamus during hypothermia to produce heat and increase body temperature.

Positive Feedback System

A system in which an initial deviation from stasis is progressively amplified until a specific threshold is reached, triggering a defined physiological event.

Stasis

The stable physiological baseline state in a positive feedback system before activation and after the occurrence of a physiological event.

Oxytocin

A hormone secreted by the pituitary gland into the bloodstream during labor to stimulate uterine muscle contractions.

Childbirth Positive Feedback Mechanism

A process where cervical stretching signals the hypothalamus to prompt oxytocin release from the pituitary gland, intensifying uterine contractions and pressure until the baby is expelled and stasis is restored.