Signalling Molecules Flashcards
What does a cell require in order to act on and respond to a signal
A receptor
Autocrine signals?
A cell secretes signalling molecules that bind to itself
Paracrine signals?
Released into the cells extracellular medium in their neighbourhood and act locally
Endocrine signals?
Produced in endocrine glands and secreted into the blood stream and can be distributed around the body
Where are hormones produced?
Glands
What is the difference between a protein and a steroid hormone?
Protein hormones have a receptor outside the membrane and need help to diffuse through the membrane because they are what is called water soluble hormones whereas a steroid hormones receptor is inside the cell as it is lipid soluble so it moves into the cell by simple diffusion
What happens when the signalling molecule fits the receptor?
It sets off a transaction pathway which will bring about the eventual intended response
Definition of negative feedback response
A response that is negates the stimulus or is opposite to
Positive feedback response?
A response that enhances the stimulus or increases it such as in child birth more of the hormone to cause contractions is made
What is the function of insulin in terms of blood glucose levels
Insulin encourages the uptake of glucose into the cells to lower blood glucose
Role of glucagon?
Breaks down glycogen the form of which glucose is stored to increase blood glucose levels
If a beta cell is stimulated, what is secreted and what happens as a response to that secretion
Insulin
Uptake of glucose by cells. Conversion of glucose to stored glycogen or fat in the liver.
Decrease in BG levels
If an alpha cell is stimulated, what is secreted and what happens as a response to that secretion
Glucagon
Breakdown of glycogen to glucose in the liver
Increase in BG levels
Signalling molecule
Receptor
Transduction pathway
Response
.
Stimulus Receptor Control centre Effector Response Negative or positive feedback
Increase in blood CO2 Receptors in arteries or veins Respiratory centre in brain Respiratory muscles in lungs More CO2 Exhaled Negative feedback
What are signalling molecules
Molecules that enable cells to receive information and communication with other cells
What is the chemical nature of a neurotransmitter?
Peptides or modified amino acids
How are neurotransmitters produced?
They are produced in the neutrons and stored in synaptic vesicles
How are neurotransmitters transported
Synaptic vesicles fuse with the cell membrane
Electrical signal
Neurotransmitter released
Neurotransmitter targets
Dendrites of other neurons and cells stimulated by neurons
What is a neurotransmitter
a chemical released by the axon that enters the synapse and carries the message to the target cells
Can neurotransmitters pass through the cell membrane?
No they can’t, they are not lipid soluble
What happens when a neurotransmitter binds to its receptor
It opens the protein channel and allows Na+ to enter the cell
Endocrine system definition
The system in the body that is responsible for the production and release of hormones
