Endocrine system Flashcards
What is the endocrine system
Collection of glands that produce hormones that regulate physiological functions
What are the parts of the endocrine system
Pituitary gland
Hypothalamus
Thyroid gland
Parathyroid glands
Adrenal glands
Pancreas
Ovaries
Testes
What must a hormone possess to elicit a specific response
Specific receptor proteins
What speed are hormones travel
Slow
What are target cells
Cells of only certain tissues and organs that hormones respond to
What are the 3 chemical classes of hormones
Steroid hormones
Peptide and protein hormones
Amine hormones
Where are steroid hormones synthesised
Cholesterol in the liver
Where are steroid hormones secreted from
Gonads
Adrenal cortex
Placenta of pregnant animals
What happens in pathway of steroid hormones
The 6 carbon side is cleaved from cholesterol to form pregnenalone then different enzymatic processes produce different specific steroid molecules and different steroid secreting cells possess different enzymes to modify pregnenalone
Are steroid hormones lipid soluble
Steroid hormones pass through cell membrane to reach receptor
What are peptide and protein hormones structured from
Chains of amino acids
How are peptide and protein hormones secreted
Exocytosis
Peptide hormones synthesis pathway
- A prepropeptide is synthesised and released into the rough ER
- Proteolytic enzymes in RER cleave off some amino acids to yield pro peptides.
- In the smooth ER, propeptides are packaged into transport vesicles
- The vesicles are transported to the Golgi complexes
- Golgi complexes packag the propeptide into secretory vesicles
- The peptides are released by exocytosis
What amino acids are amine hormones made from
Tyrosine
Tryptophan
Where are amine hormones stored
Cytosolic vesicles
Are steroid hormones lipid soluble
Yes-They need a carrier in plasma
Transporters for steroid hormones
Transcortin
Albumin
Sex hormone binding globulin
Post receptor cell response for steroid hormones
Can enter cell and interact directly with the cell nucleus through the formation of a complex with its cytosolic receptor
Hormone interacts with receptor
Translocates to the nucleus
Interacts with response elements
Produce mRNA
Biological effect
Post receptor cell response for protein hormones
Need a second messenger because they cannot enter the cell
Hormone interacts with receptor
Activation of adenylate cyclase
Production of cAMP
Protein kinase phosphorylation
Biological effect
What is a negative feedback system
Increased hormone concentration means less production of hormone
What does hypothalamus control
Secretion of tropic hormones from anterior pituitary
Features of the hypothalamus
Master gland
Function- control centre
Attached to roof of third ventricle
Monitors composition and temperature of blood
Plays role in feedback systems that govern secretions of endocrine system
Features of anterior lobe
Pars tuberalis
Pars intermedia
Pars distalis
Features of posterior lobes
Pars nervosa
