Lecture 7 - Cell Communication I, General Principles

Question 1

what are the 5 types of cell to cell communication?

Answer 1

contact-dependant communication
paracrine communication
autocrine communication
synaptic communication
endocrine communication

Question 2

what is contact-dependent communication?

Answer 2

communication by gap junctions or molecules on the cell surface where the signalling cell interacts with the target cell through a membrane-bound signal molecule

Question 3

what is paracrine communication?

Answer 3

the signalling cell releases a local hormone into the extracellular space (e.g lumen) producing effects on the neighbouring target cells in a local environment

Question 4

what is autocrine communication?

Answer 4

the signalling cell produces a local hormone that acts upon the receptor that produced it (acts on itself)

Question 5

what is synaptic communication?

Answer 5

a neuron initiates an AP from the cell body and propagates it down the axon to the synapse to be diffused into the target cell aka the neurotransmitter is diffused

Question 6

what is endocrine communication?

Answer 6

an endocrine cell produces a hormone and releases it into the bloodstream where it binds to a receptor on a distant target cell

Question 7

what is a hormone?

Answer 7

a signalling molecule that is transported in the blood

Question 8

what is the relationship between a hormone and a target cell?

Answer 8

hormones produced do not specifically find the target cell the target cell just expresses a specific receptor for a specific hormone

Question 9

what is the flight or fight response?

Answer 9

during stressful situations a coordinated multiple organ response is initiated

Question 10

where can circulating hormones be excreted?

Answer 10

hormones circulating in the bloodstream can excreted in the urine or faeces

Question 11

what inactivates or activates hormones?

Answer 11

metabolism

Question 12

what are hormones classified by?

Answer 12

by their chemical composition

Question 13

what are the 3 classes of hormones?

Answer 13

peptide hormones
amine hormones
steroid hormones

Question 14

what are peptide hormones composed?

Answer 14

composed of amino acids up to large proteins

Question 15

what is the effect of peptide hormones?

Answer 15

effects the endocrine system through the hormones of GH or FSH

Question 16

what are amine hormones?

Answer 16

hormones derived from the amino acid tyrosine

Question 17

what are 4 examples of amine hormones?

Answer 17

dopamine
norepinephrine
epinephrine
thyroid hormones

Question 18

what are amine hormones packaged into vesicles by?

Answer 18

packaged by catecholamines into vesicles

Question 19

what is a catecholamine?

Answer 19

a monoamine neurotransmitter

Question 20

what are steroid hormones?

Answer 20

hormones synthesised from cholesterol that are produced on command and provide long lasting effects upon slow synthesis

Question 21

what is the relationship between steroid hormones and vesicles?

Answer 21

steroid hormones are lipid soluble therefore they cannot not be packaged into vesicles as vesicles are composed of fats so they would just diffuse or ‘leak’ out of the vesicle

Question 22

what is the rate determining of steroid hormones?

Answer 22

synthesis of steroid hormones

Question 23

what is hormone targeting?

Answer 23

when the secretory cell produces a chemical messenger that will only bind to the receptor specific for the chemical messenger to produce a response

Question 24

what is synergy?

Answer 24

when there are 2 signalling molecules that produce the same effect both molecules will interact together to produce a bigger effect than if they were working separately

Question 25

what is the effect of synergy?

Answer 25

the maximum combined response is bigger than the addition of the maximum individual responses

Question 26

when is the only time synergy can occur?

Answer 26

when both individual stimuli are producing their maximal responses by second messengers improving translation

Question 27

why are steroid hormones produced on command?

Answer 27

because they are lipid-soluble and cannot be packaged into vesicles so they are released into the bloodstream

Question 28

what are peptide hormones?

Answer 28

water-soluble hormones that are produced and stored until required that produce rapid short lasting effects only when activated

Question 29

what is the relationship between peptide hormones and the cell membrane?

Answer 29

peptide hormones cannot cross the cell membrane therefore they must travel in the blood bound to carrier protein

Question 30

what receptors do lipophilic molecules use?

Answer 30

use cell surface receptors

Question 31

how do lipophilic molecules use cell surface receptors?

Answer 31

the signal molecule binds to plasma membrane receptors on the plasma membrane and intracellular receptors package the signal molecule into vesicles at the golgi apparatus.

Question 32

where does lipophilic molecule synthesis occur?

Answer 32

occurs at the rER

Question 33

where does storage of lipophilic molecules occur?

Answer 33

occurs at secretory vesicles

Question 34

how are lipophilic molecules secreted?

Answer 34

secreted by exocytosis

Question 35

what are second messengers?

Answer 35

intracellular signalling proteins that act on multiple target proteins that each perform a different function

Question 36

what is a common example of a second messenger?

Answer 36

cAMP produced from the first messenger by a signalling molecule that causes kinases to phosphorylate other molecules

Question 37

where does second messenger transcription activation begin?

Answer 37

begins at the metabotropic receptor

Question 38

what does second messenger transcription activate?

Answer 38

activates proteins that function as transcription factors

Question 39

what do primary response genes synthesise?

Answer 39

in the nucleus primary response genes synthesise different transcription factors from mRNA

Question 40

what do cell-specific genes produce?

Answer 40

produces mRNA

Question 41

what does the mRNA produced by cell-specific genes synthesise?

Answer 41

synthesises proteins that mediate the cells response to the first messenger (e.g proliferation and differentation)