24.1 Flashcards
A hormone is a ___-___ chemical mediator released from ___ glands that act on ___ targets
Blood-borne
Endocrine
Distant
What’s the difference between autocrine, paracrine, neurocrine and endocrine?
Autocrine – signal to neighbouring identical cell or back to self-cell
Paracrine – signal from one cell type to neighbouring different cell type by diffusion
Neurocrine – signal from a neuron down its axon via blood to distant target
Endocrine – hormone produced by endocrine gland and moves by blood to distant target
Lipophilic hormones are ___phobic and can diffuse across cell membranes.
Hydrophobic
Peptides and catecholamines bind to ___ ___ receptors, therefore are likely ___.
Cell surface receptors
Hydrophilic/lipophobic
Steroids and thyroid hormones bind to ___ receptors
Intracellular
Lipophilic hormones are synthesised ___ ___ from precursors
On demand - otherwise they would diffuse away
Peptide hormone synthesis?
Enzymes in the ER cleave off the signal sequence -> prohormone
Prohormone goes to Golgi apparatus and is packaged in secretory vesicles
In the vesicles are enzymes to active the prohormone
All steroid hormones are produced from ___.
Cholesterol
Amines include ___ and ___.
Catecholamines and thyroid hormones
Active ___ are stored in secretory vesicles, whereas the precursor of ___ hormones are stored in secretory vesicles.
Active catecholamines -> vesicles
Precursor of thyroid hormones -> vesicles
Catecholamines are ___ and dissolved in ___.
Thyroid hormones are ___ and bound to ___ proteins.
Catecholamines are hydrophilic and dissolved in plasma
Thyroid hormones are lipophilic and bound to carrier proteins
The precursor to amine hormones (catecholamines or thyroid hormones) is ___.
Tyrosine
Steroids are transported by ___ proteins in the blood.
ONLY ___ steroids can enter the cell membrane. Therefore ___ to proteins protects and ___ half-life of hormones.
Plasma/carrier
ONLY unbound steroids can enter cell membrane
Binding to proteins protects and increases the half-life of hormones
What does permissive mean?
The first hormone can’t work without the effects of the second hormone!
A primary endocrine disorder involves abnormality of the ___ ___ itself, but in secondary endocrine disorders the ___ is normal but rate of ___ is abnormal.
Primary - abnormal endocrine gland
Secondary - normal endocrine gland, abnormal secretion rate
