Homeostasis and Thermoregulation Vocabulary

Vocabulary practice flashcards covering homeostasis, thermodynamic laws, feedback loop components, human body temperature regulation, fevers, and hibernation.

2nd Law of Thermodynamics

A fundamental law of nature stating that the universe and everything in it is always moving in the increasing direction of disorder.

Homeostasis

The ability of life to maintain a constant, stable, and organized internal environment separate from its external environment.

Osmoregulation

The process of regulating water balance in cells, where hypotonic solutions cause cell bursting/lysis, hypertonic solutions cause shriveling/plasmolysis, and isotonic solutions maintain normal cell stability.

Homeostatic Receptors

Sensors that monitor baseline conditions under homeostatic control, such as temperature ($37\,^\circ\text{C}$), blood pressure ($120/80\,\text{mmHg}$), blood sugar ($0.07\%$), osmolarity ($0.1\,\text{M}$), and pH ($7$).

Feedback Loop

A linked series of receptors and corrective mechanisms linked by nerves or hormones capable of restoring or altering a biological state.

Negative Feedback Loop

A feedback loop where the output inhibits itself or shuts off at a certain set point to reverse changes and bring a system back to normal.

Positive Feedback Loop

A feedback mechanism that amplifies movement away from a normal state rather than returning it to normal.

Thermoreceptors

Receptors located in the skin that detect external temperature changes and in the hypothalamus that detect blood temperature changes.

Hypothalamus Thermoregulatory Set Point

The normal internal temperature range maintained by the brain's thermoregulatory center in most mammals, equal to $37.5 \pm 0.5\,^\circ\text{C}$.

Stimulus

A change in the internal or external environment that can elicit a response once a threshold is reached.

Control Centre

The brain or spinal cord, which receives sensory signals, analyses them, and determines the appropriate physiological response.

Effector

Cells, organs, muscles, or glands that produce a physical or chemical response to a stimulus.

Normal Adult Body Temperature

The baseline temperature range for human adults, which is $36.6\text{--}37.2\,^\circ\text{C}$.

Pyrogens

Chemicals released by white blood cells during infection to raise the hypothalamus set point by $2\text{--}3\,^\circ\text{C}$ to help kill bacteria.

Critical Fever Thresholds

Temperature milestones including fever ($38\,^\circ\text{C}$), high fever needing medical care ($> 40\,^\circ\text{C}$), neurological damage ($42\text{--}43\,^\circ\text{C}$ or $108\text{--}109\,^\circ\text{F}$), and death ($44\text{--}45\,^\circ\text{C}$ or $111\text{--}113\,^\circ\text{F}$).

Fever Onset Shivering

Shivering that occurs at the beginning of a fever because the internal set point has been reset higher, making normal body temperature feel cold and triggering skeletal muscle activity to generate heat.

Cold Sweat Break

Sweating that occurs when healing cells stop releasing pyrogens and the body resets its temperature set point back to normal.

Hibernation Set Point

A reduced thermoregulatory set point near $5\,^\circ\text{C}$ achieved by hibernating mammals via hormone release to drastically reduce metabolic rate and conserve food reserves.