The endocrine system Flashcards
What kind of responses is the endocrine system used for?
Slower and more prolonged responses
What do endocrine cells secrete?
Hormones
How do the hormones from endocrine cells move throughout the body?
Via the blood
What do endocrine glands do?
release hormones which are secreted into the bloodstream and then carried to the target by the blood
What do exocrine glands do?
secrete enzymes that are released in the lumen of the organ (usually then used in digestion)
How many types of hormones can one gland secrete?
Many
How many cell types are there in one gland?
Several
What are the three major hormone classes?
Amine hormones, peptide and protein hormones and steroid hormones
What are amine hormones derived from?
Tyrosine
What are some examples of amine hormones?
Thyroid hormone, thyroxine, epinephrine and norepinephrine
What secretes dopamine?
Hypothalmus
What are epinephrine, norepinephrine and dopamine called?
Catecholamines
What class of hormones make up the majority of hormones?
Peptide and protein hormones
What are some examples of peptide and protein hormones?
Insulin, glucagon, growth hormone, leptin
What organelle synthesises protein prehormones?
Ribosomes
What is done with protein prehormones once they are synthesised in ribosomes?
They are packaged into a secretory vesicle, and cleaved into peptides
Where are peptide and protein hormones stored?
Inside the cells
What are all steroid hormones derived from?
choleserol
Steroid hormones relationship on water?
Hydrophobic
Where are steroid hormones produced (organ)?
Adrenal cortex and gonads (testes and ovaries)
What does the effect of a hormone depend on?
Its concentration
What does hormone concentration depend on?
The secretion of the hormone from its gland, and its metabolism and excretion
What are the major sites of metabolic inactivation?
Liver and kidneys
How do hormones circulate in the blood?
Free or bound to plasma proteins
What are hormones excreted in?
Urine or feces
What two things can metabolism do to hormones?
Activate or inactivate them
What are tropic hormones?
Hormones which induce the secretion of other hormones
How do tropic hormones induce the secretion of other hormones?
They induce the growth and development of the target gland
What characteristics of a hormone does their transport in the blood depend on?
Their chemical composition and hydrophilicity
What kinds of hormones are transported dissolved in plasma?
Protein and peptide hormones
Why are protein and peptide hormones transported dissolved in the blood?
They are hydrophillic
