hormones Flashcards
name the 2 chemical classes of hormones
lipid soluble
water soluble
explain lipid soluble hormones
(move quickly and readily across biological membranes) = Hydrophobic
- Steroids , e.g. testosterone, oestrogens, etc. ex of LIPIDS hormones
- thyroid hormones, e.g. T3, T4 Amino Acid (TYR) + Iodine rich hormones
- Nitric oxide (NO) Gasious in nature
explain water soluble hormones
(found in body water fluids) = Hydrophilic
- Amines - Amino acid derivatives, e.g. epinephrine, norepinephrine
- Peptides, e.g. antidiuretic Hormone (ADH), oxytocin
- Proteins, e.g. insulin & growth hormone
- Eicosanoids, e.g. prostaglandins & leukotrienes (immune system and inflammatory responses)
what does hormone action depend on
chemistry of hormone
summarise Prostaglandins & Leukotrienes
Act locally (so don’t spread around whole body) as hormones in most tissues of body so little found in blood
Released by virtually all cells - not Red blood cells
describe prostaglandins function and what they work on
work on smooth muscle, create blood flow, promote fever, intensify pain etc.
describe leukotrienes what they stimulate and do
stimulate White blood cell movement and mediate inflammation
explain Nonsteroidal anti-inflammatory drugs (NSAIDs)
Aspirin and Ibuprofen inhibit prostaglandin synthesis but do not affect leukotriene synthesis.
Both can cross into the cells lining the stomach – so fast acting but can cause bleeding (such as from stomach ulcers if have certain stomach problems)
Used to treat a wide range of inflammatory disorders e.g. tennis elbow, osteoarthritis and rheumatoid arthritis.
explain hormones operation
General chemical signal in circulation
Slower than nerve responses
Target cells must have a specific receptor
Response determined by responding cell, i.e. different cells may respond differently to the same hormone
Cell may respond to more than one hormone, i.e. they can have more than one type receptor
explain the stages of lipid soluble hormone action
- Hormone detaches from carrier (usually a protein) in blood stream
- Diffuses through interstitial fluid & cell membrane into cell
- Binds to and activates receptor
- Receptor-hormone complex alters gene expression
- If new mRNA then protein synthesis
- New proteins alter cell activity
explain the stages of water soluble hormone action
- Diffuses from blood and binds to receptor in plasma membrane (as cant move into cell)
- Starts reaction inside cell forming second messenger
- Cyclic AMP is a common one (enzyme involved is adenylatecyclase) - Second messenger causes activation of several proteins (enzymes)
- Activated proteins produce physiological responses
- Second messenger is inactivated
the control of hormone secretions occurs when
in short bursts
hormone secretions are controlled by what
negative feedback
what are the 3 ways to regulate hormone secretions
Signals from nervous system, e.g. adrenal medulla release of epinephrine
Chemical changes in blood, e.g. blood Ca2+ levels affect parathyroid hormone
Other hormones, e.g. adrenocorticotrophic hormone from pituitary stimulates cortisol release from adrenal cortex
name some endocrine disorders
Acromegaly – excessive growth hormone in adults
Pituitary Dwarfism – low levels of GH (growth hormone) in children
Pituitary Giantism – excessive levels of GH in children
Diabetes – insufficient insulin – Type 1 and 2.
Goitre (swelling in the neck) - insufficient iodine, excessive thyroxine
Hyperthyroidism – (Graves Disease) excessive thyroxine – sometimes accompanied by goitre
Hypothyroidism (myxoedema) – insufficient thyroxine, so body cant process things properly
