1 Foundations of Homeostasis Free Online FlashCards

What is homeostasis?

Homeostasis continually adjusts internal conditions within ranges that support normal function; it is a dynamic steady state, not a perfectly fixed condition.

What are the body's levels of physiological organization, from smallest to largest?

Cells form tissues, tissues form organs, organs work together in organ systems, and organ systems support the organism.

What does the internal environment usually refer to in physiology?

The internal environment usually means extracellular fluid (ECF), including interstitial fluid and blood plasma.

How do cells exchange materials with the extracellular fluid?

Cells take oxygen, nutrients, water, and ions from the ECF and release carbon dioxide and other wastes into it.

What are the main stages of a homeostatic control pathway?

A typical pathway is stimulus, receptor, control center, effector, and response.

How does negative feedback affect an initial change?

Negative feedback opposes the initial change, tending to move the regulated variable back toward its functional range.

How do temperature responses illustrate negative feedback?

When temperature rises, sweating and increased heat loss help lower it; when temperature falls, shivering and reduced heat loss help raise it.

How do insulin and glucagon contribute to blood glucose regulation?

After a meal, insulin promotes glucose uptake and storage, tending to lower blood glucose. When glucose falls, glucagon mobilizes stored fuel, tending to raise it.

What distinguishes positive feedback from negative feedback?

Positive feedback amplifies the initial change, often driving a process toward an endpoint that stops the loop.

What is feedforward regulation?

Feedforward control begins a response in anticipation of a predictable change, before the regulated variable shifts substantially.

How do the respiratory system and kidneys contribute to homeostasis?

The respiratory system helps regulate carbon dioxide and pH, while the kidneys adjust water, electrolyte, and acid–base balance.

What can cause a homeostatic variable to leave its functional range?

Homeostatic control can fail when a disturbance is too large or prolonged, or when receptors, control centers, effectors, or their communication pathways do not function properly.