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Flashcards in Endocrinology Deck (659)
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31

Give examples of IC "second messengers"

  • cAMP
  • cGMP
  • Ca2+
  • Diaglycerol (DAG)
  • Inositol triphosphate (IP3)

32

Which processes occur between:

  •  Signals being received
  • The appearance of biological effects

Signal transduction processes

33

What are the reasons that a hormone-like substance could have varying effects on different cells?

  • There are separate receptors in the different tissues
  • The receptor is the same but a different signalling pathway is initiated

34

Title the figure

Scatchard analysis

35

Bmax (No. of binding sites) given by the point of intersection

 

 

36

What is a Scatchard analysis used for?

Used for measuring the properties of receptor-ligand interaction

37

Which parameters can be estimated from a Scatchard analysis?

  • The total number of binding sites
  • Strength (affinity) of binding between the receptor and the ligand

38

Title the figure

Regulation of receptor number

39

  • Either:
    • Long lasting hormone treatment
    • The decrease of cellular metabolic needs

40

"Down-regulation"

Inhibition of receptor expression

41

Either:

  • Removal of the endocrine gland
  • Increase of cellular metabolic needs

42

"Up-regulation"

Facilitation of receptor expression

 

43

How do lipophilic hormones have an effect on cells?

  1. They easily pass the cell membrane
  2. Binding to cytoplasmic proteins
  3. They then reach the nucleus
  4. Modification of genetic expression of proteins

44

How do water-soluble/hydrophilic peptides and glycoprotein hormones have an effect on cells?

Exert actions by binding to membrane surface receptors

45

G-protein dependent transduction outcomes

  1. ​Migration of G-protein to ion channel protein, activating/inactivating it
  2. Activate enzymes bound to the IC side of the membrane
  3. Influence adenylate cyclase activity → IC cAMP conc.
  4. Control phospholipase C activity → Produces messengers
  5. Control PLA2 enzyme → Arachidonic acid

46

Describe the receptor of G-protein independent transduction

The receptor is a transmembrane protein:

  • EC ligand binding part
  • Central part
  • IC part which exhibits phosphorylase activity

47

Describe G-protein independent transduction

  1. Ligand bond formation
  2. IC polypeptide chain phosphorylates
  3. Receptor activates
  4. Biological action

48

Describe cell activation when the receptor is in the cytoplasm

  1. Lipophilic hormones pass the cell membrane
  2. Hormones bind to cytoplasmic proteins (receptors)
  3. Receptor-ligand complex formation
  4. DNA-binding domain of the receptor protein 'finds' HRE
  5. Biological response initiated through transcription of a protein

49

Title the figure

Fine structure of the nuclear receptor

50

Lypophilic hormone

51

LBD

Ligand binding domain

52

DNA-BD

DNA binding domain

53

HRE

Hormone-responsive element

54

BPE

Basal promoter element

55

VD

Variable domain

56

The function of the VD

Locating of the base-pair segment of the DNA

Specific to the particular hormone

57

The function of HRE

Binds the DBD

58

DBD

DNA binding domain

Amino acid segment of the hormone-receptor complex

59

The function of the BPE

  1. Activated by receptor-DNA complex
  2. Expression of the structural gene begins

60

Title the figure

The receptor in the form of an ion channel