lec 1-Homeostasis and Fundamentals of Physiology

This set of vocabulary flashcards covers the core principles of physiological homeostasis, including feedback mechanisms, signaling pathways, and hormone classifications based on the Fundamentals of Physiology lecture.

Homeostasis

The dynamic maintenance of physiological variables within a predictable range.

Physiological variable

A measure of a bodily condition or bodily function, such as blood glucose concentration or blood pressure.

Set-point

The normal ‘basal’ or ‘at rest’ value for a physiological variable, such as a core temperature of $37^\text{o}C$ or arterial carbon dioxide of $5.3\text{ KPa}$.

Negative Feedback

The most common mechanism for the maintenance of physiological variables where a sensed change initiates a response to reverse that change.

Feed-forward

A control mechanism where the anticipation of a change brings about a response before the change can be detected by negative feedback sensors.

Positive feedback

A mechanism where a change in a variable triggers a response that causes further change in that variable, resulting in amplification rather than normalization.

Integrating centre

A component of a feedback loop that compares inputs from sensors against physiological set-points and elicits a response.

Sensors

Elements that detect changes in a physiological variable and initiate the feedback process.

Effectors

Tissues or organs that produce responses to bring a physiological variable back toward its set-point.

Afferent pathway

The pathway that carries signals from sensors to the integrating centre.

Efferent pathway

The pathway that carries signals from the integrating centre to the effectors.

Sympathetic nervous system

A branch of the autonomic nervous system that commonly uses noradrenaline to communicate with effectors.

Parasympathetic nervous system

A branch of the autonomic nervous system that commonly uses acetylcholine to communicate with effectors.

Tyrosine derivatives

A class of hormones including Thyroxine ($T_4$) and Adrenaline.

Peptides and Polypeptides

A class of hormones including Anti-diuretic hormone, Oxytocin, Insulin, and Growth hormone.

Steroids

A class of hormones derived from cholesterol, including Cortisol, Aldosterone, Estradiol, and Testosterone.

Paracrine homeostatic control

A type of control where sensors, integrating centres, and effectors are all located in the same tissue, often involving the secretion of diffusible substances to nearby cells.

Nitric Oxide ($NO$)

A paracrine signaling molecule released by endothelial cells that causes nearby smooth muscle cells to relax, resulting in vasodilation.

Parturition

The process of uterine contractions to expel a fetus, which serves as an example of a positive feedback loop terminated by the birth of the baby.

Hierarchy of importance

The principle that some variables, like plasma osmolality, are more critical to immediate survival than others, like blood pressure, leading the body to prioritize one over the other.