1 - Intro to Hormone Signalling Flashcards
Stimuli triggers what?
Signal transduction
What is signal transduction?
Signal transduction is a cascade of biochemical changes that occur inside the cell which mediates how a cell responds to a particular stimulus
What does stimuli include in humans?
Hormones, neurotransmitters, and growth factors (but also light photons, odorants, and taste)
What do growth factors refer to?
A particular type of hormone that controls cell growth and division and have an intimate role in cancer
What do stimuli bind to?
Most stimuli bind to receptor proteins in the target cell causing responses, i.e., signal transduction and biochemical changes that control the activity of a cell
Example of stimuli binding
Neurotransmitters allow nerve cells to communicate across synapses by interacting with post-synaptic receptors and opening ion channels (response). In this case, the stimuli of the neurotransmitters bind receptors and trigger responses, which is the opening of the ion channels, and the entry and exit of ions is the signal transduction which controls changes in cell behaviour
Steps of hormone-initiated signal transduction
- BIOSYNTHESIS of a hormone
- STORAGE and SECRETION of the hormone
- TRANSPORT of the hormone to target cell
- RECOGNITION by the hormone receptor protein
- RELAY and AMPLIFICATION of the signal that leads to defined biochemical sections within the target cell
- REMOVAL of the hormone
- BIOSYNTHESIS of a hormone
Biosynthesis in the endocrine gland
- STORAGE and SECRETION of the hormone
- stored in the endocrine gland until they are required for secretion
- storage primes the system - don’t need to rely on de novo synthesis of new hormones
- often they are already stored and ready for action in their particular endocrine gland
- TRANSPORT of the hormone to target cell
The transport of hormones can involve a particular transport protein - which allows the hormone to mix with the bloodstream
- RECOGNITION by the hormone receptor protein
Causes a conformational change to take place
- RELAY and AMPLIFICATION of the signal that leads to defined biochemical reactions within target cell
Translated and amplified by biochemical changes or signal transduction inside the target cell which causes changes in cell activity
- REMOVAL of the hormone
- it is important to switch off the signal once a desired effect has been reached
- if we don’t then it can lead to serious disease states, so we often have what’s called “negative feedback” effects, whereby the production of hormone will then lead to changes resulting in the same production being switched off
- removal of the hormone from the system so it’s no longer able to interact with target receptors
- removal can involve degradation of the hormone by particular enzymes
What are hormones?
Chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body
Where do hormones travel? (include example)
- hormones reach all parts of the body but only target cells have receptors for that hormone
- for example, insulin will be secreted from the pancreas - it will travel through the bloodstream but will only regulate cells that express insulin receptors on the cell surface