communication between cells

Question 1

define endocrine signaling

Answer 1

hormone travels within blood vessels to act on distant target cell

Question 2

define paracrine signaling

Answer 2

hormone acts on adjacent cell

Question 3

define autocrine signaling

Answer 3

hormone acts on same cell

Question 4

example of endocrine and paracrine signaling

Answer 4

glucose homeostasis

Question 5

hypoglycaemia: endocrine and paracrine signaling

Answer 5

glucagon secreted by a-cells of Islets of Langerhans in pancreas; travels via blood vessels (endocrine) to liver to stimulate glycogenolysis and gluconeogenesis (intercellular); paracrine effects as inhibits insulin secretion from adjacent b-cells (intracellular)

Question 6

Hep C: signalling between membrane-attached proteins

Answer 6

blood borne virus detected within blood stream by APC; APC digests pathogen, expressing MHC class II molecules on surface

Question 7

IL-2: autocrine signaling

Answer 7

activated TCR will initiate reaction cascade; activated T-cell expressed IL-2 surface receptor; also secretes IL-2, which bind to IL-2 receptor on same and adjacent cells

Question 8

define agonist

Answer 8

substance which initiates a physiological response when combined with a receptor

Question 9

example of agonist

Answer 9

salbutamol