Endocrine System Flashcards
Define endocrine glands
Ductless glands that secrete hormones directly into the bloodstream
What is the difference between endocrine, autocrine and paracrine ?
Endocrine - site of production and action different
Autocrine - site of production and action same
Paracrine - site of action nearby of the site of production
What are the three classes that the hormones are grouped based on their structure ?
Steroids
Peptides
Amines
Most hormones are what ?
Peptides
Steroids are secreted by what ?
Gonads, adrenal cortex, and placenta
Amines are derived from what ?
From the amino acid tyrosine
Amines are secreted from what?
Thyroid and adrenal medulla
What are the two types of receptors of mechanism of action of hormones
Receptors located inside the cell
Receptors located on the outer surface of cell membrane
What are the two types of receptors located inside the cell?
Cytoplasmic receptors - for steroid hormones
Nuclear receptors - for thyroid hormones
All protein hormones act how ?
By binding to cell surface receptors
Secretions of the hormones are regulated by what ?
Neural mechanism
Feedback mechanism - negative and positive feedback
What is negative feedback ?
Means the hormones actions include inhibition of its further release
What is positive feedback ?
It’s uncommon and means that the hormones action includes increase of its secretion
What is the need of positive feedback ?
Release of oxytocin hormone during delivery of the baby
What connections does the Hypothalamic-Hypophyseal connections include ?
Vascular connection
Nervous connection
List the releasing hormones of pituitary gland
