Cell Communications

Question 1

what are the ways of cellular communication BETWEEN cells

Answer 1

electrical and chemical communication

Question 2

what is electrical transmission?

Answer 2

direct contact via gap junctions

Question 3

what do gap junctions allow?

Answer 3

flow of current from cell-cell

Question 4

what is a syncytium?

Answer 4

linked cells acting together as one unit

Question 5

where is chemical transmission used?

Answer 5

cell-cell and cell-several cells and many cells-many cells

Question 6

where is cell-cell chemical transmission used?

Answer 6

synpase

Question 7

where is cell-several cells chemical transmission used?

Answer 7

paracrine

Question 8

where is many cells-many cells chemical transmission used?

Answer 8

endocrine

Question 9

describe the chemical synpase

Answer 9

cell-cell. Effect depends on transmitter and the receptor it acts on. One way transmission.

Question 10

where is chemical synapse common?

Answer 10

nervous system

Question 11

what is the first step in the chemical synapse?

Answer 11

impulse arrives at terminal of presynaptic cell

Question 12

what is the second step in the chemical synapse?

Answer 12

transmitter released from storage vesicles

Question 13

what is the third step in the chemical synapse?

Answer 13

transmitter diffuses in synaptic cleft

Question 14

what is the fourth step in the chemical synapse?

Answer 14

transmitter binds to receptor on postsynaptic cell

Question 15

what alters the postsynpatic cell?

Answer 15

excitatory/inhibitory

Question 16

what is paracrine communication?

Answer 16

one cell-several cells. can be part of a cascade of reactions

Question 17

what cells often use paracrine communication?

Answer 17

Defence cells

Question 18

what is autocrine communication?

Answer 18

where chemical acts on cell releasing it (feedback)

Question 19

what is endocrine transmission?

Answer 19

chemical sent to all parts of the body via the blood stream. hormone acts only on cells with the correct membrane receptor protein

Question 20

describe nerve communication

Answer 20

actions often very specific or localised, quick impulse transmission and is suitable for rapid responses

Question 21

give examples of communication by nerves

Answer 21

control of voluntary muscle contractions, sensory systems, salivary gland responses, control of blood pressure

Question 22

where does communication by hormones (humoral) affect?

Answer 22

many cells in different parts of the body

Question 23

describe humoral communication

Answer 23

coordinated, body-wide actions. slow to act but effect persists

Question 24

give some examples of humoral communication

Answer 24

gastro-intestinal gland responses, control of metabolism and growth, regulation of menstrual cycle

Question 25

what can many intracellular signalling molecules act as?

Answer 25

second messengers

Question 26

what are first messengers?

Answer 26

chemical transmitter which acts on a receptor

Question 27

what can some first messengers do?

Answer 27

pass through the target cell membrane and act on receptors inside the target cell

Question 28

what are steroids?

Answer 28

lipids that can pass through the outer cell membrane

Question 29

what do steroids do?

Answer 29

act on receptors inside the target cell

Question 30

what does the steroid-receptor complex do?

Answer 30

act on the DNA in the nucleus to initiate protein synthesis

Question 31

what does the protein produced from steroid transmitters do?

Answer 31

alters cell function

Question 32

can peptide transmitters pass through the cell membrane?

Answer 32

no

Question 33

how do peptide transmitters transmit their signal?

Answer 33

they bind to the plasma membrane receptors and set up a series of reactions controlled by G-proteins

Question 34

what do G-proteins do?

Answer 34

activate second messengers

Question 35

give 2 examples of second messengers

Answer 35

Cyclic AMP (cAMP) and calcium ions (Ca++)

Question 36

what is the first step in hydrophilic signal transmission?

Answer 36

the transmitter binds to a membrane receptor

Question 37

what is the second step in hydrophilic signal transmission?

Answer 37

G-protein is activated

Question 38

what is the third step in hydrophilic signal transmission?

Answer 38

guanosine triphosphate (GTP) activates the G-protein

Question 39

what is the fourth step in hydrophilic signal transmission?

Answer 39

ATP is converted to cyclic AMP by the enzyme adenyl cyclase

Question 40

what are steps 5 and 6 of hydrophilic signal transmission?

Answer 40

cAMP activates an enzyme called protein kinase

Question 41

what is step 7 of hydrophilic signal transmission?

Answer 41

protein kinase activates a specific enzyme which catalyses a chemical reaction

Question 42

what is step 8 of hydrophilic signal transmission?

Answer 42

formation of a molecule

Question 43

what is step 1 of calcium as a second messenger

Answer 43

transmitter binds to a membrane receptor

Question 44

what is step 2 of calcium as a second messenger

Answer 44

G-protein activates which activates the phospholipase enzyme which causes the opening of calcium channels and calcium enters by diffusion

Question 45

what is step 3 as calcium as a second messenger?

Answer 45

calcium binds to a protein in the cytosol

Question 46

what does Ca2+-calmodulin complex act as?

Answer 46

a second messenger

Question 47

what is step 4 of calcium as a second messenger?

Answer 47

Ca2+-calmodulin regulates an enzyme which regulates a chemical reaction