Endocrine Flashcards
(30 cards)
What is the primary requirement for maintaining homeostasis in the body?
Coordination of cells, tissues, and organs
What are the modes of intercellular communication?
Neurotransmitters, endocrine hormones, neuroendocrine hormones, paracrines, autocrines, cytokines
Define neurotransmitters.
Chemical messengers released by neurons that act locally to control nerve cell functions
What are endocrine hormones?
Hormones released by glands into the blood that influence target cells at distant locations
What are paracrines?
Substances secreted by cells that affect neighboring target cells of a different type
What are autocrines?
Substances secreted by cells that affect the function of the same cells that produced them
What are cytokines?
Peptides secreted by cells that can function as autocrines, paracrines, or endocrine hormones
List the three major classes of hormones.
- Peptide hormones
- Amine hormones
- Steroid hormones
How are peptide hormones synthesized?
They are synthesized in the rough endoplasmic reticulum as inactive preprohormones
What are catecholamines?
A group of amine hormones that includes dopamine, epinephrine, and norepinephrine
What is the primary source of steroid hormones?
Cholesterol
What factors affect plasma hormone concentration?
- Rate of hormone secretion
- Rate of hormone elimination
- Extent of hormone binding to plasma proteins
What is simple negative feedback in hormone secretion?
A hormone inhibits its own further secretion
What is a primary endocrine disorder?
An excess or deficiency of secretion by the target gland
What is a secondary endocrine disorder?
An excess or deficiency of secretion by the pituitary gland
What is a tertiary endocrine disorder?
An excess or deficiency of secretion by the hypothalamus
What is meant by positive feedback in hormone secretion?
The effects of a hormone result in further hormone secretion
Fill in the blank: Peptide hormones dissolve in plasma and are carried as _______ molecules in blood.
free
What are the locations of hormone receptors?
- Cell membrane (for protein, peptide, catecholamines)
- Cytoplasm (for steroid hormones)
- Nucleus (for thyroid hormones)
What is receptor down-regulation?
A decrease in the number of receptors in response to increased hormone concentration
What is up-regulation of receptors?
An increase in the number of receptors or intracellular signaling proteins in response to a hormone
What is the first step of a hormone’s action?
Binding to specific receptors at the target cell
What are second messengers?
Molecules that relay signals from receptors to target molecules inside the cell
List some molecules that function as second messengers.
- cAMP
- Ca2+
- Products of membrane phospholipid breakdown
