Homeostasis Flashcards
Define homeostasis; describe the components of a feedback system; contrast the operation of -ve and +ve feedback systems; explain how homeostatic imbalances are related to disorders
What is homeostasis?
The maintenance of relatively stable conditions in the body’s internal environment
What is a feedback system?
A cycle of events wherein the status of a controlled body condition is monitored, evaluated and changed to maintain homeostasis
What are the three basic components of a feedback system?
- Receptors
- Control centre
- Effectors
What is a receptor?
A body structure that monitors changes in a controlled condition and sends input to a control centre via the ‘afferent pathway’ e.g. baroreceptors
What is a control centre and what does it do?
A structure e.g. the brain which sets the range or set point within which a controlled condition should be maintained
Interprets input from receptors and generates output commands when needed via the ‘efferent pathway’ to effectors
What is an effector?
A body structure that receives output from the control centre and produces a response which changes the controlled condition e.g. skeletal muscles
What is the name for a disruption that changes a controlled condition (such as blood pressure)?
A stimulus
What is the main difference between negative and positive feedback?
Negative feedback aims to negate/reverse the change detected in a controlled condition whereas positive feedback seeks to enhance/reinforce the change.
Positive feedback systems rely on an event external to the system to shut it off as it is not self-limiting. What could happen if a positive feedback system isn’t stopped?
It can ‘run away’ and produce life-threatening conditions in the body.
Every structure in the human body contributes to maintaining homeostasis. What can happen if one component of the body loses it’s ability to contribute?
A homeostatic imbalance can occur among all of the body’s processes.
What can be the result of homeostatic imbalances, both moderate and severe, respectively?
Moderate: a disorder or disease
Severe: death
What is a disorder?
Any abnormality of structure or function
What is a disease?
An illness characterised by a recognisable set of signs and symptoms
What is the distinction between signs and symptoms?
Signs - objective, observable and measureable, e.g. weight loss, rash
Symptoms - subjective, not observable, e.g. nausea, headache
What is aging?
A normal process of progressive decline in the body’s ability to restore homeostasis
