ICPP1 and 2 - Intro and Biological Signalling Flashcards
Where does an endogenous signalling molecule originate from?
Within the body.
Where does an exogenous I signalling molecule originate from?
These are natural/plant-based, eg aspirin.
Where does an exogenous II signalling molecule originate from?
These are synthetic/man-made.
Give some examples of physiochemical parameters under homeostatic control.
Temperature, pH, O2, CO2, H2O, Na+, K+, Ca2+, Cl-, glucose
Which is more tightly controlled - the extracellular or intracellular environment?
The extracellular environment is kept within extremely tight limits, while the intracellular environment is kept within wider dynamic performance limits.
Explain the system of “negative feedback”.
The system (eg. The body) gives off a system output. The sensor gives off an equal output. The system set point comparator compares these, and if one is larger than the other then the controller emits a signal that is the same size as the difference but opposite (eg signal is 3 so -3 is emitted). This causes the effector to proportionately correct the issue.
What is the internal controller of body temperature?
The hypothalamus.
At which temperature does coma and loss of temperature regulation occur?
42-44 degrees
At what temperature does cardiac fibrillation occur?
26-28 degrees.
What are the three main extracellular signalling groups?
Endocrine, paracrine, autocrine.
Which system communicates via hormones?
Endocrine
Where are endocrine signalling molecules secreted?
Into the blood stream, where they are circulated around the whole body.
What are the three types of endocrine signalling molecules?
Hydrophilic 1 (amines), hydrophilic 2 (peptides/proteins), lipophilic (steroids - receptors for these are intracellular as can pass through membrane.).
Why are the receptors for amines, peptides and proteins located on the plasma membrane?
They are hydrophilic so they cannot pass through the plasma membrane, unlike steroids which are lipophilic.
What do exogenous endocrine analogue molecules do?
They attempt to mimic an endogenous signalling molecule.
Which type of signalling is this? Cells communicate via the bloodstream with other cells which are a distance away.
Endocrine
Which type of signalling is this? Signalling coupled from cell to cell, or cells within nearby volume.
Paracrine, eg. Neurotransmitters.
Where are paracrine signalling molecules released?
Into the extracellular environment.
What does an excitatory neurotransmitter do?
It increases the firing rate post-synaptically.
What does an inhibitory neurotransmitter do?
It decreases the firing rate post-synaptically.
Someone cuts their finger while cutting an avocado. Which sort of signalling molecules would be responsible for the response?
Paracrine
A cell releases autocrine signalling molecules. Which cell is it targeting?
Itself
What are the four signalling molecule targets?
Receptors
Ion channels
Transporters
Enzymes
Which are the four types of receptors targeted by signalling molecules?
Kinase-linked receptors
Ion channels (ligand gated)
Nuclear/intracellular
G-protein coupled receptors
Which type of receptor that is targeted by signalling molecules takes the least time to show the effect?
Ligand-gated ion channels, as the effect (hyperpolarisation or depolarisation) takes milliseconds to become apparent.
What do kinase linked receptors do?
They phosphorylate certain groups, setting signalling cascades into motion.
What do nuclear/intracellular receptors do?
They activate or inactivate a gene by binding to transcription factors.
What do ion channels do?
They selectively allow ion current to flow across the plasma membrane, maintaining the membrane potential.
