endocrinology 1 Flashcards
What are endocrine glands?
organs or groups of ells which synthesise and secrete hormones and pass them directly into blood
Do endocrine glands have ducts?
no
Name an exocrine gland?
salivary glands
What organ has exocrine and endocrine function?
pancreas
Is the hypothalamus a gland or cell?
cluster of neurones
Is the anterior pituitary a gland or cells?
gland
Is the posterior pituitary gland or cells?
extension of the hypothalamic neurones
What is a hormone?
chemical secreted from an endocrine gland (or cell) and travels in the blood to its target organ and mediates a specific effect
What are 3 types of hormones?
steroid
peptide
amine
Can prolonged activity of hormones be harmful?
yes, tight regulation is important - limitation of hormones is key
What happens as glucose levels increase?
insulin increase too
What happens if the insulin effects are not switched off/limited?
(unchecked insulin activity)
go into hypoglycaemic state
loss of nervous system function
What organs degrade blood hormone?
liver/kidney enzymes
How do hormones leave the body?
urine/bile
What is the balance of hormones regulated by?
half-life
time needed for conc to half
What re ways hormones are prodiuced?
1) chronic/constitutive
i.e. maintains constant conc in the blood
2) acute/stimulated
i.e. episodic release when required
3) cyclic/pulsatile
i.e. shows regular rhythm of release
What hormone is produced chronic/constitutively?
thyroid hormone
What hormone is released acute/stimulated?
insulin
What hormones are released cyclic/pulsatile?
growth hormone
linked to pineal gland - melatonin
What does the peak in cyclic/pulsatile hormones correlate to?
physiologically relevant times
e.g. growth development
What is the peptide hormone?
a protein
What is the parent compound of steroid hormones?
derived form cholesterol
What are 2 examples of steroid hormones?
aldosterone
estradiol
What are the 2 parent amino acids of amine hormones?
tyrosine and tryptophan
What are 2 types of tyrosine backbone amine hormones?
catecholamines
thyroid hormones
What is an tryptophan amine hormone?
melatonin
What are most hormones?
peptide hormones
these include: peptides. proteins and glycoproteins
Are peptide hormones pre-synthesised?
yes, stored in vesicles for release
Are peptide hormones hydrophillic or hydrophobic?
hydrophillic
What do peptides to in plasma for transport?
dissolve, they are water-soluble
Do peptide hormones have a long or short half-life?
short - can be degraded on way to target
What type of response are the peptide hormone signal transduction pathway?
rapid
if second messenger is altering gene expression it should be slow
if the peptide hormone is altering gene, what is the pathway like?
slow but long lasting
Where are steroid hormones found/synthesised in a cell?
s(smooth) ER
in the unbound form
stored in esterified form
How is a steroid hormone stored in a cell?
stored as lipid droplet
When release signal is receive from cell, what is the cholesterol pathway?
esterfied cholesterol to active hormone
in the unbound form - not stored a s a lipid droplet
Why can the steroid hormone diffuse across membrane into bloodstream?
it is lipophilic in nature
What does the steroid hormone need to travel in blood?
carrier proteins
as it has poor solubility
Is the steroid hormone stored in vesicles?
no, it is not pre-synthesised
What is a specific steroid carrier protein?
corticosteroid binding globulin
Does steroid hormone have long or short half-life?
long due to plasma carrier protein
What is a non-specific steroid carrier protein?
albumin
What do the steroid hormone act on in the cell?
HRE
hormone response elements
Why is the cellular response delayed in steroid hormones?
genomic effects
What does amine hormone tryptophan convert to?
melatonin
What 2 hormones is tyrosine the pre-cursor for?
- catecholamines (1 tyrosine)
- thyroid hormones (2 tyrosine’s + iodine )
What are types of catecholamines?
dopamine
norepi
epi
Name 2 types of thyroid hormones?
thyroxine (T4)
T3
What are amine hormones (catecholamies) associated with?
nervous system
What do the cateholamines behave like?
peptide hormones
What do the thyroid hormones behave like?
steroid hormones
