General Endocrinology Flashcards
What is Endocrinology?
Study of hormones
What are 4 forms of intercellular communication?
- direct cell-cell
- paracrine/autocrine
- neural
- endocrine
What are the differences between the nervous and endocrine signals?
- speed
- duration
- specificity
How does speed differ between nervous and endocrine signals?
Nerves are faster
How does duration differ between nervous and endocrine signals?
- nerves have brief duration
- hormones can have permanent consequences
How does specificity differ between nervous and endocrine signals?
- nerves very specific
- hormones have a widespread action (not specific)
What is a hormone?
- chemical substance
- synthesised + secreted by a specific gland
- secreted in small amounts into bloodstream
- acts at a site distant from site of secretion
- acts on specific receptors to give a specific physiological effect
Give an example of a hormone and it’s specifities.
- adrenaline
- from adrenal medulla
- <10 ng/ml at rest
- acts on heart
- stimulates receptors to increase heart rate
List the endocrine glands of the body.
(Brain): Hypothalamus
Pituitary
(Throat): Thyroid
Parathyroids
(Lungs): Thymus
(Kidneys): Adrenals
Pancreas
Ovaries
Testes
What do hormones do?
- reproduction
- growth & development
- maintenance of internal environment
- regulation of digestion & energy availability
What are the types of hormone molecules?
- peptides (proteins)
- amine derivatives
- lipid based (steroids)
What is the solubility property of hormones?
peptide & amine derivatives:
- water soluble
(lipid based) steroid & thyroid:
- lipid soluble
How much storage do hormones have in cells?
peptide & amine derivatives:
- substantial storage
(lipid based) steroid & thyroid hormones:
- minimal storage
How are hormones transported in blood?
peptide/protein/amino derivative:
- dissolve in plasma
steroid & thyroid hormones:
- bind to carrier proteins
How are hormone molecules catabolised and excreted?
peptide & amine derivatives:
- broken down by proteases (in bloodstream/tissues)
- excreted in urine
steroid & thyroid hormones:
- modified in liver to become water soluble
- excreted in bile/urine
What is the ‘half-life’ of hormones?
peptide & amine derivatives:
- short (mins)
(lipid based) steroid & thyroid hormones:
- long (hrs)
Where is the ‘site of action’ for hormones?
peptide & amine derivatives:
- plasma membrane
(lipid based) steroid & thyroid hormones:
- nucleus
Where is the ‘cell binding site’ for hormones?
peptide & amine derivatives:
- cell surface receptor
(lipid based) steroid & thyroid hormones:
- cytoplasmic/nuclear receptor
How long is the course of action for hormones?
peptide & amine derivatives:
- rapid onset
- short duration
(lipid based) steroid & thyroid hormones:
- long latency + duration
- may be permanent
How do hormones act on target cells?
- act on specific receptors
- regulate activity of target cell
- mechanism of action depends on nature of hormone
What hormones cannot enter the cell?
- peptides
- catecholamines
What hormones can enter the cell?
- steroids
- thyroid hromones
How is hormone secretion controlled/regulated?
- neural regulation
- endocrine & neuroendocrine regulation
- non-neural/non-endocrine regulation
- positive & negative feedback
- bioavailability
