Endocrinology Flashcards
What is a chemical secreted into the bloodstream for transport to a distant tissue called?
Hormone
Hormones are critical for communication between different parts of the body.
What types of receptors can hormones bind to?
- Membrane bound
- Cytosol
- Nucleus
What are some ways hormones can alter target activity?
- Altering rate of enzyme reactions
- Regulating transport across the cell membrane
- Regulating gene expression
At what concentrations do hormones alter cell activity?
Very low concentrations (nanomolar 10-9 or picomolar 10-12)
What is the term for the combined effect of two or more hormones being greater than the sum of their individual effects?
Synergistic
An example is glucagon, cortisol, and adrenaline in blood glucose regulation.
What does the term ‘permissive’ mean in relation to hormones?
One hormone requires another to fully exert its effect
Example: thyroid hormone required for maturation of the reproductive system in presence of gonadotropins.
What does ‘antagonistic’ mean in hormone actions?
Two or more hormones have opposing effects on a physiological response
Example: glucagon and insulin in blood glucose regulation.
How are peptide hormones synthesized?
As large, inactive preprohormones that include a signal sequence, one or more copies of the hormone, and additional peptide fragments.
What happens to the preprohormone during its synthesis?
The signal sequence is chopped off, creating an inactive prohormone.
What is the role of enzymes in the processing of prohormones?
Chop the prohormone into one or more active peptides plus additional peptide fragments.
What is a component of receptor tyrosine kinases?
They have intrinsic kinase activity.
What do tyrosine kinase linked receptors lack?
Intrinsic kinase activity.
What is the pathway for steroid hormones interacting with intracellular receptors?
Begins with a protein carrier binding with a steroid hormone in the blood vessel.
Where are steroid hormone receptors located?
- Cytoplasm
- Nucleus
What is the role of the receptor hormone complex?
Binds to DNA and activates or represses one or more genes.
What are the two hormones secreted by the posterior pituitary?
- Oxytocin
- Vasopressin (Antidiuretic hormone)
What is the anterior pituitary also known as?
Adenohypophysis
What is the posterior pituitary also known as?
Neurohypophysis
What is a primary endocrine disorder?
A problem in the last endocrine tissue in a reflex pathway.
What causes hormone excess leading to exaggerated response?
Hypersecretion, such as from endocrine gland tumors.
What is an example of a hormone deficiency leading to reduced response?
Pituitary dwarfism due to loss of growth hormone.
What is Hashimoto’s disease?
Autoimmune destruction of thyroid gland tissue.
What stimulates the anterior pituitary gland to release thyroid-stimulating hormone (TSH)?
Thyrotropin-releasing hormone (TRH).
What does TSH stimulate in the thyroid gland?
Synthesis of thyroid hormones T3 and T4.
