Biology(homeostasis)

Define homeostasis.

The maintenance of a relatively stable internal environment despite changes in the external or internal environment.

Why is homeostasis essential?

It keeps conditions within the narrow ranges required for enzymes, cells, and organs to function properly.

What is meant by the internal environment?

The extracellular fluid surrounding cells, mainly blood plasma and tissue fluid.

Name six variables regulated by homeostasis.

• Body temperature

• Blood glucose

• Blood pH

• Water balance

• Electrolyte concentration

• Blood pressure

What is a set point?

The target value or normal range that the body attempts to maintain through homeostatic mechanisms.

Define negative feedback.

A mechanism that reverses a change and returns a variable toward its set point.

Define positive feedback.

A mechanism that amplifies a change until a specific process is completed.

Which type of feedback is most common in the human body?

Negative feedback.

Give two examples of positive feedback

• Childbirth

• Blood clotting

Compare negative and positive feedback.

• Negative feedback restores stability.

• Positive feedback reinforces change until completion.

What are the three components of every homeostatic control system?

• Receptor

• Control centre

• Effector

Function of receptors?

Detect changes (stimuli).

Function of the control centre?

Compares the variable to the set point and coordinates the response.

Function of effectors?

Carry out the response that restores homeostasis.

Correct sequence of a homeostatic response.

Stimulus → Receptor → Control centre → Effector → Response.

Which organ regulates body temperature?

Hypothalamus

What happens when body temperature rises?

• Sweating

• Vasodilation

What happens when body temperature falls?

• Shivering

• Vasoconstriction

Difference between nervous and endocrine regulation?

• Nervous: fast, short-lasting.

• Endocrine: slower, longer-lasting.

Why is homeostasis described as dynamic?

Variables fluctuate within normal limits rather than remaining perfectly constant.