Introduction to endocrinology Flashcards
In the endocrine system, what are target cells?
Cells which have specific receptors for a given hormone
What is a hormone?
A molecule that circulates in the bloodstream and regulates the activity of certain cells or organs
What are the 3 pathways of hormonal communication?
Endocrine
Paracrine
Autocrine
What is the exocrine function of the pancreas?
Releases digestive enzymes into the small intestine
What is the endocrine function of the pancreas?
Releases insulin and glucagon to regulate blood glucose levels
What is the term for endocrine cells such as G cells of the stomach and juxtaglomerular cells which are not found in traditional endocrine glands?
Diffuse endocrine system
What are the 3 stimuli which regulate hormone secretion?
Hormonal stimuli
Humoral stimuli
Neural stimuli
What is humoral stimulation of hormones?
Changes in certain ion or nutrient concentration in the blood regulates hormone release
What are the 3 types of negative feedback loops?
Long feedback loop
Short feedback loop
Ultrashort feedback loop
Describe what is meant by a long negative feedback loop.
The endocrine hormone feeds back to the pituitary and hypothalamus
Describe what is meant by a short negative feedback loop.
Pituitary hormone feeds back to the hypothalamus
Describe what is meant by an ultrashort negative feedback loop.
Hypothalamic hormone inhibits its own secretion
What are the 3 classes of hormone?
Peptide hormones
Steroid hormones
Amine hormones
What are peptide hormones synthesised from?
Amino acids
What are steroid hormones synthesised from?
Cholesterol
What are amine hormones synthesised from?
The amino acid tyrosine
What are the 3 patterns of hormone secretion?
Episodic
Constant
Diurnal variation
The secretion of insulin follows which pattern of hormone secretion?
Episodic (triggered by specific stimuli)
The secretion of thyroid hormone (T4) follows which pattern of hormone secretion?
Constant
The secretion of cortisol follows which pattern of hormone secretion?
Diurnal variation (cortisol is highest in the morning, lowest at night)
How do binding proteins increase hormone plasma half-life?
By protecting them from renal filtration and peripheral metabolism
What are the 2 types of cell surface receptors for hormones?
G-protein coupled receptors
Receptor tyrosine kinase
G-protein coupled receptors can activate which 2 mechanisms to bring about a change in protein synthesis?
Adenylyl cyclase mechanism
Phospholipase C mechanism
Intracellular hormone receptors are otherwise known as what?
Transcription factors
