Exam 1 (Lecture) Flashcards
Why don’t hormones affect all cells they contact?
Cells must have specific membrane or intracellular receptors to which hormones can bind.
What is a target cell?
A cell that bears receptors for a hormone, drug, or other signaling molecule
What are the 2 major classes of hormones (endocrine, not paracrine)?
Water-soluble and lipid-soluble
Where are the receptors for water-soluble hormones located?
Cell membrane
Where are the receptors for lipid-soluble hormones located?
Inside the cell. Bind to intracellular receptors
Which class of hormone uses a 2nd messenger system to stimulate its target cell?
Water-soluble hormones
What is a G-protein?
A cell membrane protein coupled to cell surface receptors.
Upon stimulation of the receptor by an extracellular signaling molecule (i.e. hormone, neurotransmitter) bind to GTP to form an active complex which mediates an intracellular event (e.g. activation of adenylate cyclase)
Which class of hormone binds to its receptor inside the cell, migrates to the nucleus, and acts as a transcription factor?
Lipid-soluble hormones (steroids & thyroid hormone). Direct gene activation occurs when a hormone binds to an intracellular receptor, which activates a specific region of DNA, causing the production of mRNA and initiation of protein synthesis.
Which class of hormone induces a more rapid response?
Water-soluble hormones
Which class of hormone has effects that are typically of longer duration?
Lipid-soluble hormones
What is half-life?
The duration of time a hormone remains in the blood (shortest for water-soluble hormones)
What are the three ways endocrine glands/tissues are stimulated to release their hormones?
Humoral, neural, or hormonal stimulus
What is the difference between humoral and hormonal stimulation?
Humoral stimulation causes hormones to be released by altered levels of certain critical ions or nutrients
Hormonal stimulation causes hormones to be released by the action of another hormone (a tropic hormone)
What is a tropic hormone?
Hormones that have other endocrine glands as their target
What type of homeostatic mechanism regulates the blood level of most hormones?
Negative feedback
What are the hormones that are synthesized in the posterior pituitary?
No hormones are synthesized in the posterior pituitary
What are the hormones that are released from the posterior pituitary?
Oxytocin and ADH
What are the hormones that are synthesized in the anterior pituitary?
Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Adenocorticotropic hormone (ACTH) Thyroid-stimulating hormone (TSH) Prolactin (PL) Growth hormone (GH)
What are the hormones that are released from the anterior pituitary?
Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Adenocorticotropic hormone (ACTH) Thyroid-stimulating hormone (TSH) Prolactin (PL) Growth hormone (GH)
Which pituitary hormones have releasing hormones?
Growth hormone – Growth hormone releasing hormone (GHRH)
Thyroid stimulating hormone – Thyroid releasing hormone (TRH)
ACTH – Corticotropin-releasing hormone (CRH)
LH & FSH – Gonadotropin-releasing hormone (GnRH)
Which pituitary hormones don’t have releasing hormones?
Prolactin
Where do releasing hormones come from?
Hypothalamus
Which pituitary hormones have inhibiting hormones?
Prolactin – Prolactin-inhibiting hormone (dopamine)
GH – Growth hormone inhibiting hormone (GHIH, somatostatin)
Which pituitary hormones don’t have inhibiting hormones?
a. FSH
b. LH
c. ACTH
d. TSH
These don’t have inhibiting hormones because they are tropic hormones!