ANAT241 L2

Question 1

What are the 4 different modes of cell signalling?

Answer 1

1. juxtacrine
2. autocrine
3. paracrine
4. endocrine

Question 2

What is required for the juxtacrine mode of signalling?

Answer 2

• direct cell-cell contact
• may be mediated by gap junctions

Question 3

What is a gap junction composed of

Answer 3

• composed of proteins called connexions

Question 4

What is a key feature of a gap junction?

Answer 4

bi-directional

Question 5

What are the 3 key functions of a gap junction?

Answer 5

• allow ions and small molecules to move between cells
• provide electrical and chemical coupling between cells
• allow very rapid communication between groups of cells, e.g. cardiac muscle cells

Question 6

How is juxtacrine specifically achieved?

Answer 6

by direct contact

Question 7

What are 2 functions of juxtacrine?

Answer 7

• can involve receptors
• can deliver more complex information

Question 8

What are 2 features of juxtacrine’s signal molecule?

Answer 8

• is not released
• membrane bound

Question 9

What is juxtacrine important in?

Answer 9

development

Question 10

How is juxtacrine specificity achieved?

Answer 10

by receptor expression AND direct contact

Question 11

What is an example of a juxtacrine?

Answer 11

notch pathway

Question 12

What is the main role of autocrine?

Answer 12

signalling between nearby cells of the same type

Question 13

What are 2 functions of autocrine?

Answer 13

• release and reception of signal molecule
• can coordinate activity between a group of similar cells

Question 14

How is specificity achieved?

Answer 14

by selective receptor expression and rapid degradation of signal molecule

Question 15

What is the main role of paracrine?

Answer 15

local signalling between different cell types

Question 16

What is required for paracrine to occur?

Answer 16

the release and reception of signal molecules

Question 17

What is an example of the release and reception of signal molecules in paracrine?

Answer 17

endothelial cells communicate with nearby vascular smooth muscle via release of nitric oxide

Question 18

How is specificity achieved in paracrine signalling?

Answer 18

by selective receptor expression and rapid degradation of signal molecule

Question 19

What occurs during neuronal signalling?

Answer 19

• signal molecules are neurotransmitters
• released from neurone and specialised highly localised synaptic sites

Question 20

What type of effect is created during neuronal signalling?

Answer 20

rapid and often short-lasting effects

Question 21

How is specificity achieved in neuronal signalling?

Answer 21

by precise contacts and rapid removal of neurotransmitter to prevent diffusion

Question 22

How does endocrine signalling occur?

Answer 22

usually involves signalling between distant cells

Question 23

What are signals called in endocrines, how are they carried and where are they produced?

Answer 23

signals are called hormones, and are carried in the blood

Question 24

Where are the signals, in endocrine, produced?

Answer 24

produced from endocrine glands, tissues and isolated cells

Question 25

How is endocrine produced?

Answer 25

produced from endocrine glands, tissues and isolated cells

Question 26

Endocrine signalling involves many types of hormones, what are some examples?

Answer 26

steroids, modified amino acids and peptides

Question 27

How is specificity achieved?

Answer 27

by selective receptor expression

Question 28

What type(s) of signalling is required in selective receptor expression?

Question 29

What type(s) of signalling is required in rapid uptake/degradation of signal?

Question 30

What type(s) of signalling is required in direct contact?

Question 31

What needs to happen to signal molecules, with regards to the target cell?

Answer 31

signal molecules need to be produced, released, and transported to the target cell

Question 32

What is a ligand?

Answer 32

a molecule that binds specifically to another molecule

Question 33

What are the 3 types of ...

Answer 33

- lipid soluble - water soluble - gases (e.g. nitric oxide)

Question 34

What happens to signal molecules with regard to ...

Answer 34

interact with protein on target cell: the receptor

Answer 35

specific ligands bind to specific receptors

Question 36

How are water soluble ligands stored?

Answer 36

can be stored in vesicles within cell

Question 37

How are lipid soluble ligands stored?

Answer 37

cannot be stored in vesicles within cell

Question 38

What is the rate of release of water soluble ligands?

Answer 38

rapid release via exocytosis

Question 39

What is the rate of lipid soluble ligands?

Answer 39

slow response - made on demand

Question 40

How do water soluble ligands travel?

Answer 40

can travel in blood without a carrier

Question 41

How do lipid soluble ligands travel?

Answer 41

travels in blood with carrier protein (may be longer lasting)

Question 42

Where can/can't water soluble ligands enter?

Answer 42

cannot enter target cell (message transduce via cell surface receptor)

Question 43

Where can/can't lipid soluble enter?

Answer 43

can enter target cells by crossing membrane

Question 44

What do lipid soluble ligands act on?

Answer 44

intracellular receptors (often to directly regulate gene expression)

Question 45

What are some common ligands?

Answer 45

hormones, growth factors and neurotransmitters

Question 46

How do hormones travel?

Answer 46

in the blood

Question 47

What are some examples of common ligands?

Answer 47

testosterone, estradiol, insulin, glucagon

Question 48

What is the function of growth factors?

Answer 48

stimulate cell proliferation, wound healing

Question 49

What is a growth factor normally seen as?

Answer 49

normally a protein or steroid hormone

Question 50

What is an example of some growth factors?

Answer 50

IGF1 (skeletal muscle hypertrophy), cytokines (fas = apoptosis)

Question 51

How does a neurotransmitters occur?

Answer 51

sent across a synapse

Question 52

What are some examples of neurotransmitters?

Answer 52

acetylcholine (activates skeletal muscle), epinephrine (acts on blood vessels)

Question 53

What are the 2 types of signal receptors?

Answer 53

intracellular and extracellular

Question 54

Where are intracellular signal receptors located?

Answer 54

receptor protein located inside cell (nucleus, cytoplasm)

Question 55

What

Answer 55

ligands need to be lipid soluble

Question 56

What do intracellular signal receptors do?

Answer 56

usually alter gene expression

Question 57

Where are extracellular signal receptors found?

Answer 57

ion channels

Question 58

What are some examples of extracellular signal receptors?

Answer 58

- g-protein coupled receptors - enzyme-linked receptors (cytokine receptors)

Question 59

What do extracellular signal receptors do?

Answer 59

- change membrane conductance - alter protein activity - regulate cellular events

Question 60

What must be noted about signal receptors?

Answer 60

different receptors for different pathways