15 - Cell Signalling 1

Question 1

3 different forms of signalling

Answer 1

Electrical, Physical and Chemical

Question 2

Chemical signalling

Answer 2

Facilitates communication between cells that are not adjacent (distant organs). e.g. synapse

Question 3

What is common between all forms of chemical signalling

Answer 3

Signalling molecule binds to a protein receptor

Question 4

General structure of chemical signalling protein receptor

Answer 4

• Hormone (ligand) binding domain, for specific signalling molecule
• Signal transduction domain (varies with receptor type)
• Transmembrane domain (if receptor is transmembrane protein)

Question 5

Endocrine signalling

Answer 5

Hormone travels through bloodstream, from endocrine cell to distant target cell (tissue). Target cell has receptors which bind to hormone

Question 6

signalling pathway

Answer 6

Stimulus, Hormone synthesis, Hormone secretion, Hormone transport, Hormone detection, Signal transduction, Target proteins altered (response), Signal termination

Question 7

Insulin target cells

Answer 7

Muscle, Liver and adipose tissue

Question 8

How can tissues be specifically targeted by specific hormones

Answer 8

As some cells do not have the receptor for the specific hormone, cells without receptor cannot receive the signal.

Question 9

Signal transduction into cell

Answer 9

Extracellular signal received as intracellular signal (second messenger system)

Question 10

Two types of cell response

Answer 10

• Changes in protein function (inactive/active): modifies existing enzymes, rapid (seconds to minutes)
• Changes in expression of proteins: regulation of gene transcription, slow but long lasting effects (mins to hours)

Question 11

types of hormone transport

Answer 11

• Endocrine signalling
• Paracrine signalling
• Autocrine signalling
  Difference is range of the signal (signal cell to target cell)

Question 12

Paracrine signalling

Answer 12

Signalling molecule released into extracellular space, acts on neighbouring cell (same tissue)

Question 13

Autocrine signalling

Answer 13

Target cell secretes its own hormone. e.g Heart muscle stretched –> produces own growth hormone

Question 14

Pathology of autocrine signalling

Answer 14

Tumour cells producing signal to promote their own growth

Question 14

Example of paracrine signalling

Answer 14

Synapses. Electrical impulse passed along axon of neuron and signalling molecule (neurotransmitter) are released at the synapse. Target cell is another neuron or muscle

Question 15

Juxtacrine signalling

Answer 15

Cells that are in physical contact through gap junctions or tight junctions

Question 16

Ligand/Receptor interactions

Answer 16

Membrane bound ligand on signalling cell interacting with receptor of target cell

Question 17

Hormone

Answer 17

Chemical signalling molecule synthesised by endocrine cells that travel through the bloodstream

Question 18

Hormone detection variation

Answer 18

Different cells may have different functions but can have the same hormone receptor

Question 19

Side effects of medication example

Answer 19

ACh decreases heart rate. Drug blocks ACh receptor to treat low heart rate. Salivary glands have same receptor which is also blocked resulting in dry mouth

Question 20

Side effects of medication example

Answer 20

ACh decreases heart rate. Drug blocks ACh receptor to treat low heart rate. Salivary glands have same receptor which is also blocked resulting in dry mouth