S1: Overview to Endocrinology Flashcards
List some major endocrine glands/organs in the body
Hypothalamus Pituitary Gland Thyroid Adrenal Pancreas Parathyroid
What forms the hypothalamic-pituitary axis?
Hypothalamus
Pituitary Gland
What major endocrine structures are regulated by the hypothalamic-pituitary gland?
Thyroid
Adrenal cortex/medulla gonads
What regulates the pancreas and parathyroid glands?
They are regulated by other controlled variables e.g. insulin in pancreas and glucagon, which are dependent on glucose levels, parathyroid regulate calcium levels
What structure is responsible for releasing and inhibiting hormones?
Hypothalamus
What hormones does the thyroid gland release?
Thyroxine
Triidothyronine
What hormones does the adrenal glands release?
Adrenal Cortex: Cortisol and Aldosterone
Adrenal Medulla: Adrenaline and Noradrenaline
What hormones does the gonads release?
Oestrogens
Androgens
Progestagens
What hormones does the pancreas release?
Insulin
Glucagon
What hormone does the parathyroid gland release?
Parathyroid hormone
GIve examples of other tissue releasing hormones
kidneys (vitamin D, EPO), CVS (ANP, endothelins), pineal gland (melatonin), thymus gland (thymic hormones), bone (phosphate) and adipose tissue (leptin).
What are the 4 types of signalling mechanisms?
- Endocrine
- Paracrine
- Autocrine
- Intracrine
What does endocrine mean?
Hormones are released by an endocrine cell into the general circulation and act on distant target sites
What does paracrine mean?
Hormones released by endocrine cell which act on locally adjacent cells
What does autocrine mean?
Hormones released by a cell which act back on the same cell
What does intracrine mean?
Conversion of an inactive hormone to an active hormone that acts within the cell
What are the general functions of hormones?
- Reproduction, growth and development: sex steroids, thyroid hormones, prolactin, growth hormones
- Homeostasis (maintenance of internal enviroment) : Aldosterone, parathyroid hormone, vitamin D
- Energy production, utilisation and storage: Insulin, glucagon, thyroid hormones, cortisol, growth hormones
How are hormones chemically classified?
- Protein/peptide hormones (long chain amino acids)
- Steroid hormones (derivatives of cholesterol)
- Amino acid derivatives (one or two amino acids, mostly deriving from tyrosine and is very small)
- Fatty acid derivatives
Give examples of protein/peptide hormones
Hypothalamic hormones Pituitary hormones Insulin PTH Calcitonin
These tend to act in classical endocrine signalling
Give examples of steroid hormones
Cortisol Aldosterone Oestrogen Androgens Progestagens Vitamin D
Give examples of amino acid derivatives
Adrenaline
Noradrenaline
Thyroid hormones (all from tyrosine)
Melatonin (from tryptophan)
Give examples of fatty acid derivatives
Prostaglandins
Thromboxanes
Prostacyclin
What type of hormone starts out as a prohormone?
Protein and Peptide Hormones
What is the precursor of all steroid hormones?
Cholesterol