Homeostasis and Feedback Systems

These flashcards cover key concepts related to homeostasis, feedback systems, and their mechanisms.

What is homeostasis?

Maintenance of a constant internal environment.

Process of keeping the environment inside the body fairly constant despite external changes.

What is the primary function of homeostasis?

To ensure optimum concentrations of nutrients, ions, gases, and water in tissue fluid.

What systems control homeostasis?

The nervous system and the endocrine system.

What is a feedback system?

A circular situation where the body responds to a stimulus and alters the original stimulus.

What are the components of a feedback system?

A stimulus, a receptor, a modulator, an effector and feedback.

How does negative feedback work?

Homeostasis is maintained by producing a response that is the opposite of the original change (stimulus).

What happens during exercise in relation to blood glucose levels?

Exercise causes glucose levels to drop, the liver converts glycogen into glucose, raising blood glucose levels.

What is positive feedback?

When a response to a stimulus reinforces and intensifies the stimulus, not leading to homeostasis.

Give an example of a positive feedback mechanism.

Childbirth, blood clotting, fever, or action potentials.

What does the receptor do in a feedback system?

Detects a change in the environment.

What are the aspects of internal environment?

• Core body temp

• pH & concentration of dissolved substances in body fluid

• Levels of water

• Concentration of Glucose in blood

• Concentration of O2 & CO2 in blood and other body fluids

• Blood pressure

• Concentration of Metabolic waste

• Salt concentration (osmotic pressure)

What is dynamic equilibrium?

The input & output of internal conditions fluctuating within a range while maintaining overall stability. Materials and Energy are balanced.

Stimulus

Change in environment that causes system to operate

Receptor

Stimulus is detected by sensory cells of change

Modulator

Control centre responsible for processing info recieved from the receptor & for sending info to effector

Effector

Carries out response counteracting/enhancing effect of stimulus

Feedback

Achieved because original stimulus has been changed by response.

What is the role of Positive feedback in homeostasis?

Nothing

Positive feedback - childbirth

1. STIMULUS - Head of foetus pushes against cervix

2. Nerve impulses from cervix transmitted to brain

3. MODULATOR - Brain stimulates pituitary gland to secrete oxytocin

4. Oxytocin carried in bloodstream to uterus

5. Oxytocin stimulates uterine contractions (effector) & pushes foetus towards cervix