ICPP1 and 2 - Intro and Biological Signalling

Question 1

Where does an endogenous signalling molecule originate from?

Answer 1

Within the body.

Question 2

Where does an exogenous I signalling molecule originate from?

Answer 2

These are natural/plant-based, eg aspirin.

Question 3

Where does an exogenous II signalling molecule originate from?

Answer 3

These are synthetic/man-made.

Question 4

Give some examples of physiochemical parameters under homeostatic control.

Answer 4

Temperature, pH, O2, CO2, H2O, Na+, K+, Ca2+, Cl-, glucose

Question 5

Which is more tightly controlled - the extracellular or intracellular environment?

Answer 5

The extracellular environment is kept within extremely tight limits, while the intracellular environment is kept within wider dynamic performance limits.

Question 6

Explain the system of “negative feedback”.

Answer 6

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.

Question 7

What is the internal controller of body temperature?

Answer 7

The hypothalamus.

Question 8

At which temperature does coma and loss of temperature regulation occur?

Answer 8

42-44 degrees

Question 9

At what temperature does cardiac fibrillation occur?

Answer 9

26-28 degrees.

Question 10

What are the three main extracellular signalling groups?

Answer 10

Endocrine, paracrine, autocrine.

Question 11

Which system communicates via hormones?

Answer 11

Endocrine

Question 12

Where are endocrine signalling molecules secreted?

Answer 12

Into the blood stream, where they are circulated around the whole body.

Question 13

What are the three types of endocrine signalling molecules?

Answer 13

Hydrophilic 1 (amines), hydrophilic 2 (peptides/proteins), lipophilic (steroids - receptors for these are intracellular as can pass through membrane.).

Question 14

Why are the receptors for amines, peptides and proteins located on the plasma membrane?

Answer 14

They are hydrophilic so they cannot pass through the plasma membrane, unlike steroids which are lipophilic.

Question 15

What do exogenous endocrine analogue molecules do?

Answer 15

They attempt to mimic an endogenous signalling molecule.

Question 16

Which type of signalling is this? Cells communicate via the bloodstream with other cells which are a distance away.

Answer 16

Endocrine

Question 17

Which type of signalling is this? Signalling coupled from cell to cell, or cells within nearby volume.

Answer 17

Paracrine, eg. Neurotransmitters.

Question 18

Where are paracrine signalling molecules released?

Answer 18

Into the extracellular environment.

Question 19

What does an excitatory neurotransmitter do?

Answer 19

It increases the firing rate post-synaptically.

Question 20

What does an inhibitory neurotransmitter do?

Answer 20

It decreases the firing rate post-synaptically.

Question 21

Someone cuts their finger while cutting an avocado. Which sort of signalling molecules would be responsible for the response?

Answer 21

Paracrine

Question 22

A cell releases autocrine signalling molecules. Which cell is it targeting?

Answer 22

Itself

Question 23

What are the four signalling molecule targets?

Answer 23

Receptors
Ion channels
Transporters
Enzymes

Question 24

Which are the four types of receptors targeted by signalling molecules?

Answer 24

Kinase-linked receptors
Ion channels (ligand gated)
Nuclear/intracellular
G-protein coupled receptors

Question 25

Which type of receptor that is targeted by signalling molecules takes the least time to show the effect?

Answer 25

Ligand-gated ion channels, as the effect (hyperpolarisation or depolarisation) takes milliseconds to become apparent.

Question 26

What do kinase linked receptors do?

Answer 26

They phosphorylate certain groups, setting signalling cascades into motion.

Question 27

What do nuclear/intracellular receptors do?

Answer 27

They activate or inactivate a gene by binding to transcription factors.

Question 28

What do ion channels do?

Answer 28

They selectively allow ion current to flow across the plasma membrane, maintaining the membrane potential.