10. Intro to Endocrinology

Question 1

Homeostasis

Answer 1

maintenance of a constant internal environment

Question 2

Endocrine hormone

Answer 2

produced by a ductless gland

Question 3

Paracrine

Answer 3

released from effector cell (E)

interact with a different target cell (T)

Question 4

Autocrine

Answer 4

secreted by E interact with original E cell or similar cell types

Question 5

Juxtacrine

Answer 5

expressed on surface of effector cell and interacts with target cell via direct cell-cell contact

Question 6

Intracrine

Answer 6

Secretes own ligand intracellularly to bind to an internal receptor

Question 7

Type I NR (nuclear receptor)

Answer 7

monomers in cytosol

When activated form homo-dimers and migrate to nucleus

Bind specific gene signals to activate gene expression

Question 8

Type II NR

Answer 8

Heterodimers bound to target DNA

When activated they promote gene expression

Question 9

Steroid hormones

Answer 9

activate Gene Transcription

production of mRNA
Switched off by the action of other proteins or being degraded

Question 10

Amide and peptide hormones

Answer 10

bind to receptors on the exterior (i.e. on the membrane)

Question 11

Second messengers

Answer 11

Small molecules, free to diffuse

Allows AMPLIFICATION

Allows CROSS-TALK

Question 12

G Protein coupled receptors

Answer 12

7 transmembrane proteins (7TMs)

Binding of ligand results in change of conformation within the receptor

external signal is transferred across the membrane

G PROTEIN binding involved

Question 13

G protein Unactivated state

Answer 13

GDP bound

α subunit

Question 14

G protein Activated state

Answer 14

GTP bound

Question 15

Resetting of G-proteins

Answer 15

Reaction is slow

binding of GTP

Question 16

Two major ways of resetting the G Protein receptor

Answer 16

1) Endocytosis of receptor

2) Recycled at plasma membrane

Question 17

Role of IP3

Answer 17

causes rapid release of Ca2+ ions

Results in muscle contraction, glycogen breakdown and vesicle release