L4 - Homeostasis and Signalling

Flashcards about homeostasis and cell signaling

Homeostasis

Maintaining stability in the body through various processes.

Negative Feedback Loop

Mechanisms that kick in to bring the system back to its normal state when disturbed.

Positive Feedback Loop

Amplifies an initial stimulation, moving the system away from its starting point to create change in the body.

Endocrine System

A slower acting chemical-based messaging system that maintains homeostasis by releasing hormones into the bloodstream.

Hormone

A chemical, organic molecule (peptide, protein, etc.) that acts as a messenger, made by endocrine cells and secreted directly into the bloodstream.

Exocrine Gland

A gland that releases its secretions via ducts to the epithelial surface. Eg. Sweat gland

Affinity

The ability of a receptor to bind to its ligand; the higher the affinity, the less hormone concentration is needed.

Specificity

The extent to which a receptor responds only to a specific ligand and not to others.

Ligand

A signalling molecule that binds to a receptor.

Tyrosine Kinases

Enzymes that cause phosphorylation, especially of tyrosine residues on other proteins.

Kinases

Enzymes transferring a phosphate to activate a target protein.

G Protein-Coupled Receptors

Receptors that lead to the generation of a second messenger inside the cell.

Second Messengers

Molecules whose presence is a signal. They act as amplifiers, are synthesised/released from storage and act as intracellular ligands.

Adenylate Cyclase

Converts ATP into cyclic AMP.

Phosphodiesterases

Enzymes that cleave cyclic AMP to leave adenosine monophosphate.

Calcium ATPase

Utilizes ATP to extrude calcium from the cell and maintain low intracellular calcium concentration.

Steroid Hormones

Hormones derived from cholesterol that can pass through the cell membrane and act on receptors inside the cell.

Pituitary Gland

A gland that produces various hormones to regulate kidney function, muscles, mammary glands, ovaries, testes, bone, adrenal cortex, and thyroid gland.

Oxytocin

A hormone involved in childbirth that stimulates uterine contractions and breast milk production.

Antidiuretic Hormone (Vasopressin)

A hormone that prevents water loss through the kidneys, increasing fluid levels and relieving changes in osmolarity and blood pressure.