introduction to homeostasis (E1)

What is homeostasis?

The state of maintaining a steady internal environment through feedback mechanisms within the body.

What are the three vital body systems that maintain homeostasis?

Excretory system, endocrine system, and nervous system.

What does it mean to maintain homeostasis?

Adjusting to changes in the external environment to keep your internal environment at optimal levels for your health.

What are examples of things being regulated inside your body?

Water levels, food distribution and waste removal, temperature and pH adjustment, cellular activity.

What do all homeostatic systems consist of?

Start with a stimulus, have three functional components, and end with a response.

What are the three functional components of a homeostatic control system?

A receptor/monitor, integrator/coordinating centre, and regulator (effector).

Homeostatic control processes can be one of two things:

Voluntary/conscious (behavioural responses) and involuntary/unconscious (physiological responses).

What are negative feedback systems?

Mechanisms that make adjustments to bring the systems of the body back to within an acceptable range; the system reacts to stimulus by doing the opposing action.

What are positive feedback systems?

The opposite of negative feedback; reinforces small changes to make them amplified and moves the target variable further away from its steady state.

What is positive feedback used for?

Can be beneficial to allow a process to be accomplished rapidly; once a goal is reached, an external force is required to cause the positive feedback to stop (i.e. childbirth).

What are endotherms?

Organisms that are able to maintain a constant internal body temperature through metabolic processes that generate heat from organs such as the kidney and liver.

What are the steps of the physiological response to heat stress?

Stimulus, thermoreceptors that signal to the brain, the hypothalamus initiating sweating, effectors such as vasodilation (dilated blood vessels)/increased breathing and heart rate, which act as a response to keep the body cool.

How can the body’s cooling systems fail?

Sweating releases a lot of water and salts, which if not replenished can lead to loss of cellular functions.

What are the steps of the physiological response to cold stress?

Stimulus of dropping body temperature, thermoreceptors, the hypothalamus signalling to organs and tissues, effectors such as vasoconstriction (limiting blood flow to slow heat loss/smooth muscle contractions (goosebumps)/shivering which stimulates ATP production.

How does metabolic activity respond to external changes in temperature?

Prolonged cold can lead to increased metabolic activity, where a portion of the potential energy in the proton gradient is converted into heat; prolonged heat may cause reduced metabolic activity.