Endocrine Flashcards
When did brown sequard carry out his extraction experiment
1889
When did brown sequard carry out his extraction experiment
1889
Definition of a gland
Epithelial tissue derivatives specialised for secreting
Definition of secretion
Biochemical release from a particular type of cell upon stimulation
Definition of endocrine
-internal secretion
-secretion enters the bloodstream
-ductless gland
Definition of hormones
‘chemical messengers” secreted into blood by endocrine glands in response to an appropriate signal, and exerting their effects on target cells that have receptors that bind with the hormone
How to classify hormones
-based on solubility
-based on structure
How do you classify a hormone based on their solubility
- hydrophilic or water soluble
- lipophilic or lipid soluble
How do you classify a hormone based on their structure?
- peptides
- amines
- steroids
Outline differences between peptide and steroid hormones
Peptides:
-produced by normal protein synthesis machinery
-travel in blood in solution
-cannot enter cells
-bind to cell surface receptor
-fast acting
Steroids:
-produced by modification of cholesterol by enzymes
-travel in blood bound to plasma proteins
-enter cells easily
-intracellular receptor
-act on DNA to alter cell function
-slow acting
What are the roles of the endocrine system
-metabolism, water and electrolyte balance
-stress response
-growth & development
-reproduction
-Red cell production
-coordination of circulation and digestion
Outline the hypothalamus and pituitary
Pea size
Weight 1g
Two lobes (anterior and posterior)
Connects the the hypothalamus via the pituitary stalk
What is the HPG axis
(hypothalamus-pituiatry-gonad axis)
GNRH from the hypothalamus stimulates cells in anterior pituitary which stimulates production of FSH and LH
What gland is involved in the HPT axis
Thyroid gland-> thyroid hormones
What gland is involved in the HPA axis
Adrenal gland-> adrenocorticosteroids
Functions of testosterone:
-Masculinise the reproductive tract and external genitalia during the foetal period
-promotes growth and maturation of the reproductive system at puberty
-spermatogenesis
Function of oestrogen and progesterone secreted from the ovaries:
Lh effect on leydig cells
Production on testosterone
FSH effect on sertoli cells
Stimulation ofspermatogenesis
What is the connection between the hypothalamus and pituiatry gland
Vascular connection
Give the names of two thyroid hormones and what they are stimulated by
Triiodothyronine (T3) & Thyroxine (T4)
Stimulated by the TSH ( Thyroid stimulating hormone) which is stimulated by the TRH (Thyrotropin releasing hormone)
Functions of thyroid hormones
-increasing metabolic rate and heat production
-sympathomimetic effect
-effect on cardiovascular system
-effect on growth and nervous system
Parathyroid hormone (PTH)
-calcium metabolism
-increases concentration of Ca2+ inn the plasma
-mobilises bone store
-reduces urine loss
-increases gut absorption
Parathyroid gland located on the back of the thyroid gland
Outline the thyroid gland
-located in the neck area, over the trachea, and just below the larynx
-made of two lobes of endocrine tissues joined by an isthmus, a narrow part of the gland
-the hormone-secreting cells are arranged in hollow spheres called follicles
Where are the adrenal glands located
-one above each kidney
-embedded in a capsule of fat
Are the adrenal glands exocrine or endocrine
Endocrine glands
What hormones does the adrenal cortex secrete?
Steroid hormones- cortisol, aldosterone and androgens
What hormones does the adrenal medulla secrete?
Catecholamines- adrenaline and noradrenaline
What is the HPA axis
Controls only cortisol production from adrenal cortex
What does cortisol do?
Increases blood glucose, blood. Amino acids and fatty acids to enable fuel metabolism during stress.
