Introduction to Hormones Flashcards
What are hormones?
Hormones = chemical signaling molecules secreted by specific cells that regulate biological processes in the body.
What are the general characteristics of hormones? Hint: There are seven.
1) They are synthesized by specific tissues called glands.
2) They are secreted directly to blood (without ducts).
3) They are transported to work in distant sites.
4) They have systemic action.
5) They are present at very low levels in the blood.
6) They act via specific receptors in target tissues/cells.
7) They have different special mechanisms of actions.
True or False: More than 50 hormones have been identified.
True
Hormones are classified according to the mechanism of extracellular activity - name them and give an example.
1) Autocrine - cytokines
2) Paracrine - estrogen, testosterone
3) Endocrine - growth hormone
4) Neurocrine - neurotransmitter
What are the different types of hormones?
1) Protein hormones
2) Peptide hormones
3) Tyrosine derivatives (Amine hormone)
4) Steroid hormone derivatives
What categories of hormones are considered to be “amino acid-derived hormones?”
Protein, Peptide, and amine hormones
How many amino acids do protein hormones have? Also, give me an example of a protein hormone.
- More than 20 amino acids.
- Insulin, IGF-1, growth hormone
How many amino acids do peptide hormones have? Also, give me an example of a peptide hormone.
- Less than 20 amino acids.
- Somatostatin, TRH, and GnRH
How many amino acids do amine hormones have? Also, give me an example of an amine hormone.
- modified amino acids
- thyroxin (T4), catecholamines, dopamine
What kind of metabolites do steroid hormone derivatives have? Also, give me an example of a steroid hormone.
- Cholesterol metabolites
- Estrogen, testosterone, and glucocorticoids
What categories of hormones are considered to be “cholesterol-derived hormones?”
Steroid hormones derivatives
All types of hormones _______ __________ on or in cells to initiate various responses.
bind receptors
What are the characteristics of peptide and protein hormones?
- water-soluble
- cannot penetrate cell membrane
- need to bind receptors on the cell surface
What are the characteristics of steroid hormones?
- lipid-soluble
- can penetrate cell membrane
- directly bind cytosolic or nuclear receptors
True or False: Receptors are not specific for the hormones they bind.
FALSE - Receptors ARE specific for the hormones they bind.
The cellular structure of hormone receptors allows them to bind hormones with great _________ (like a lock that fits a key).
specificity
Hormones are not stored so their concentration depends on a balance between _______ and ______. Are these translational, post-translational, transcriptional, or post-transcriptional?
- secretion, degradation
- post-translational
What is half-life?
The time is takes half of the hormone to be degraded.
What’s the half-life of the growth hormone and insulin?
What’s the half-life of the thyroid hormone?
- Few minutes
- Days
True or False: Bound hormones are not usually biologically active.
True
True or False: Bound hormones must first dissociate from the Binding Protein (BP) to bind receptors on or in cells.
True
Hormones regulate each other through multiple positive and negative feedback loops called __________ _________.
Hormone cascades
What are the advantages of hormone cascades?
- Redundancy
- Negative feedback
- Amplification (amplifies signaling)
- very sensitive control of biological effects
Where are signals transmitted to the part of the brain that initiates individual cascades?
Hypothalamus
The hypothalamus is the main _______________ control center.
Neurohormonal
The hypothalamus forwards these signals to an organ called the….
Pituitary gland
What does the pituitary gland do?
Releases hormones that affect multiple organ systems
What is the interaction between the hypothalamus and pituitary gland called?
Hypothalamic-pituitary axis (HPA)
What are the different areas of the pituitary gland?
Anterior pituitary and posterior pituitary
What does the anterior pituitary gland do?
The secretion of hormones from the anterior pituitary gland is controlled by the Hypothalamus “Releasing” or “Release-Inhibiting” Hormones (RH, IH)
What does the posterior pituitary gland do?
The secretion of hormones from the posterior pituitary gland is controlled by neuronal signal stimuli.
