Lecture 3 The Endocrine System Flashcards
Name the three hormone categories
Steroid
Amine
Peptides
Properties of Steroid Hormones
Derived from cholesterol
Very hydrophobic
Raw material can either be derived from dietary cholesterol (LDL) or from metabolism of acetyl coenzyme A
How is cholesterol transported throughout the body?
Transported as low density lipoprotein (LDL)
What happens when you stimulate LDL?
Cholesterol esterase stimulates the release of free cholesterol.
Free cholesterol diffuses across the membrane of cells and its processed by organelles (Smooth ER and Mitochondria) into steroid hormone
Where do you find steroid hormones in the body?
Adrenals
Ovaries
Testes
What are amine hormones made out of?
Tyrosine
Tryptophan
What are steroid hormones made out of?
Cholesterol
either from diet or from the metabolism of acetyl coenzyme A
Are amine hormones hydrophilic or hydrophobic?
They are both. Hormones produced from the same amino acid can exhibit different polarity.
E.g
Catecholamines are hydrophilic, thyroid hormones are hydrophobic
What are peptide hormones made of?
Chains of amino acids
Some small chains being only 5 AA long (enkephalin) or larger chains being 191 AA long (human growth hormone)
Are peptide hormones hydrophilic?
Yes
What is clearance?
The rate at which hormone levels are removed from the blood
What does binding to proteins help with?
Protects the hormones from being cleared as quickly. Protects from blood enzymes and the complex is too big to be filtered out by the kidney
Name the two feedback patterns
Positive Feedback
Negative Feedback
Name the two glands dangling from the hypothalamus
Posterior pituitary
Anterior pituitary
How does the body transport cholesterol?
Because it’s hydrophobic the body uses transport proteins to cover the hydrophobic areas of the fat
Where does LDL deposit cholesterol?
Deposits cholesterol in the testes/ovaries and adrenal glands.
Can deposit in the blood vessels which causes it to narrow
What breaks down cholesterol?
Cholesterol esterase breaks down cholesterol into three smaller molecules of cholesterol which diffuses into the cytoplasm until it reaches the mitochondria and smooth ER
Where is epinephrine and norepinephrine produced?
Adrenal medulla in the adrenal glands
Other names for Thyroxine and Tri-iodothyronine
T4
T3
What cells is the anterior pituitary gland made out of?
Glandular anterior cells
What is the difference between the posterior pituitary and the anterior pituitary glands?
The posterior pituitary glands don’t contain glandular anterior cells. It contains axons from the nerves in the hypothalamus
What kind of stem cell does the anterior and posterior glands come from?
Oral ectoderm
Name the 5 types of endocrine cells found in the anterior pituitary gland
Gonadatrophs Thyrotrophs Somatotrophs Lactotrophs Corticotrophs
What hormone do gonadotrophs produce?
FSH and luteinizing hormone
What hormone do thyrotrophs produce?
Thyroid stimulating hormone
What hormone do somatotrophs produce?
Human Growth Hormone
What hormone do corticotropes produce?
Adenocorticotrophic hormone (ACTH)
What is the posterior pituitary responsible for producing?
Oxytocin
Vasopressin/Anti-diuretic hormone
Where are the hormones produced in the posterior pituitary gland?
Produced by the supraoptic and paraventricular neurones. Released into the portal supply in the posterior pituitary
How long is vasopressin?
9 amino acids
What type of hormone is vasopressin
Peptide hormone
What hormone do lactotrophs produce?
Prolactin
What is the effect of vasopressin?
Osmoreceptors can detect the osmotic pressure of the blood. Causes the vasoconstriction of arterioles and decreases urine production
What type of hormone is oxytocin?
Peptide hormone
How long is oxytocin?
9 amino acids
What is the role of oxytocin?
Promotes contraction of the uterus
Stimulates ejection of milk from mammary glands
Mother-child bond
Love hormone
Why can oxytocin and vasopressin trigger each other’s receptors?
They both evolved from a common ancestor after a gene duplication event there was a sequence divergence
What hormone do pinealocytes produce?
Melatonin which is derived from serotonin which is derived from tryptophan (amino acid)
What is the role of melatonin?
Regulates the circadian clock
