Homeostasis Flashcards
Intrinsic (Auto-regulation)
Automatic response in a cell, tissue or organ to some environmental change
Extrinsic regulation
Responses controlled by nervous and endocrine systems
Receptor
Body structure that monitors changes in a controlled condition and Sons in Port to a control centre
Control centre
Evaluates the import it receives from receptors and generates output commands when they are needed
Output from the control centre typically occurs as nerve, impulses or hormones or other chemical signals
Effector
A body structures of receives output from the control centre and produces a response or affect the changes the controlled condition
Role of feedback systems, step-by-step diagram
Some stimulus disrupts homeostasis by increasing or decreasing a controlled condition that is monitored by receptors that sends an input sending nerve impulses or chemical signals to the control centre that receives the input and provides the output sending nerve impulses or chemical signals to the factors that bring about a change or response that alters the controls condition, and there is a return to homeostasis when the response brings the control condition back to normal
Positive feedback
Response of a factor increases change of stimulus
Body moved away from homeostasis, so normal range is lost
Negative feedback
Response of effector, negates stimulus
Body brought back into homeostasis
Normal range achieved
What is feedforward control
Process, in which one of the products of a metabolic pathway, induces an enzyme which participates in the metabolic pathway act
Feedback at the cell and molecular level
Cells express receptors upon the surface
Elevated levels of the receptor ligand will evoke a response in receptor expression on the target cell surface
Declines in circulating ligand And attenuation invokes up regulation in the density of Receptor expression upon target cell
When the feedback fails
Often results in disease
Through loss of biological signals or persistent and improper activation
Occurs in both positive and negative feedback systems
Hyperthyroidism - Graves’ disease
Hypothyroidism is the excessive production of thyroid hormones
Increased levels of T3, T4 and persistent TSHr stimulation
Decreased levels of TRH/TSH
Definition for homeostasis
The maintenance of the internal environment around a set point
