Cell biology Theme 2 Flashcards
Why do cells need to communicate ?
To define their position , fate and growth
to function as a community
to respond to the environment
What is the generic cell signal pathway ?
An extracellular signal interacts with a receptor and recieves the signal
the signal is transduced
new intracellular signaling molecules are produced
this leads to a molecular change that alters the cell behaviour
Examples of cell signals ?
cholesterol based steriods peptide hormones fatty acid derivatives amino acids nucleotides
What is endocrine signaling ?
When endocrine cells release hormones that act on distant target cells.
Where are hormones produced ?
in endocrine organs such as the pancreas
How do the hormone molecules reach their target cells ?
`via the blood - a very public system
how do amino acid derivatives and peptide hormones act ?
via receptors on the plasma membrane to regulate metabolism
How do steroid hormones act ?
via intracellular receptors to regulate metabolism
What is endocrine signaling used for ?
respond to nutritional changes , inducing a wide range of changes and in changes to do with development
What is autocrine signaling ?
When a cell secretes a hormone or messenger that binds to autocrine receptors on the same cell that secreted it , leading to changes in that cell
How does autocrine signaling promote cancer ?
In cancer there is an over production of growth factors that lead to the formation of tumours. Due to a disfunctional autocrine signaling pathway
What is lidocaine and how does it work ?
An anaesthetic used to block pain , it moves to the inside of the cell and and binds to sodium channels blocking the influx of sodium ions. This stops nerve conductance and prevents further signals reaching the brain
Why is adrenaline used with lidocaine ?
adrenaline keeps the lidocaine local because lidocaine stimulates dilation of the blood vessels. increasing its absorption. Adrenaline constricts the blood vessels to counteract this
How do cells respond selectively to signals ?
because it depends which receptors the cells have and express
How do different cells respond to the same signal ?
in different ways
Cells having many different receptors allows for what ?
A small number of signaling molecules
Why do signals not act independently of one another ?
the presence of a signal can modify the responses to another signal
What do signals work in to regulate the behaviour of the cell ?
combinations
What can happen to a cell if it is deprived of signals ?
apoptosis
how can cells produce different responses to signals ?
by the interaction of intracellular systems
Why do some extracellular signals have a rapid effect ?
Because they have an effect on a proteins that are already present in the cell
Why do changes cell growth and cell division take hours to execute ?
the response requires changes in gene expression and production of new proteins
What is paracrine signaling ?
A form of cell to cell communication in which a cell produces a signal to induce changes in nearby cells altering the behavior of these cells.
What are common paracrine signaling molecules ?
cytokines and growth factors