Lecture 7: Cell Communication | General Principles Flashcards
What are the 5 types of cell to cell communication?
- contact dependent
- paracrine
- autocrine
- synaptic
- endocrine
Describe contact dependent communication
the cells are ______ to each other and there is a _________ ________ _________ molecule to allow interaction on the ____________ ___________
the cells are stuck to each other and there is a membrane bound signal molecule to allow interaction on the cell surface
Give an example of a contact dependent cell to cell communication
gap junctions (electrical synapses affecting their neighbour)
Describe paracrine cell to cell communication
the signalling cell secretes hormones into the local environment to have an effect on target cells in the local environment
Describe autocrine communication
the signalling cell secretes a local hormone which targets a receptor in the signalling cell so that this call can self regulate its own activity
Describe synaptic communication
a neurotransmitter is released from the axon terminal of a neuron into the synaptic cleft to act on receptors on the post-synaptic cell
Describe endocrine communication
an endocrine cell releases a hormone into the bloodstream and it is transported to a distant target cell to have an effect on the receptor
An endocrine cell secretes a hormone which circulates in the blood. What are four potential fates for this secreted hormone?
- it could be excreted into the urine or faeces
- it could be inactivated by metabolism
- it could be activated by metabolism (if it is inactive when secreted)
- it could bind to a receptor and produce a cellular response
Describe the process of synergy
When two hormones act together, they don’t have an added effect, they interact with one another to have an even bigger effect
Give an example of synergy occurring
Thyroid hormone and epinephrine both cause very small amounts of fatty acids to be released from lipocytes but when they are both used, they interact with each other and causes a really large amount of fatty acids being released.
What is the key thing about synergy?
the maximum combined response is bigger than the addition of the maximum individual responses
Describe the process of hormone targeting
A secretory cell releases a chemical messenger which is able to cause an effect on the cell which expresses the receptor for that specific messenger. However, the messenger just diffuses randomly and sometimes it reaches the right receptor
Explain why the target cell is self selecting
the secretory cell doesn’t chose the target cell, it just releases the chemical messenger which goes everywhere and the target cell choses to have receptors for that hormone
What does the sensitivity of a target cell depend on?
the number of receptors expressed
Why are receptors constantly degraded and synthesised?
to ensure efficiency
What is the process of upregulation?
this is when the synthesis of receptors on the cell surface exceeds the degradation which increases the number of receptors expressed
Does up regulation increase or decrease sensitivity?
it increases it
What is the process of down-regulation?
this is when the degradation of receptors exceeds the synthesis of receptors which decreases the number of receptors
Does down-regulation increase of decrease sensitivity?
decrease
Receptor up-regulation makes a target cell more sensitive to a hormone BECAUSE receptor up-regulation makes more of the hormone receptors available for hormone binding
both statements are true, and the second statement causes the first
What are the three chemical classifications of hormones?
- peptides
- amines
- steroids
Peptide hormones can be made from what?
from three amino acids to large protiens