Endocrine System Flashcards
Give a brief summary of endocrine transmission
- chemical secreted
- sent to all parts of the body via the blood stream
- hormones act only in cells with correct membrane receptor proteins
Describe communication by hormones
- many cells in different parts of the body
- coordinated
- slow to act
- effects persist
What are the endocrine glands
- hypothalamus
- pituitary
- thyroid
- parathyroid
- pancreas (islets)
- adrenal
- GI tract endocrine cells
- gonads (ovaries and testes)
- placenta
- pineal gland
- thymus
What are the two classifications of hormones
- steroids
- non steroids
What are steroid hormones based on
Based on the cholesterol ring structure
Give some examples of steriod hormones
- cortisol
- aldosterone
- testosterone
- oestrogen
- progesterone
What are non steroid hormones
Amino acid derivatives
- amines - adrenaline ect
- noradrenaline
- melatonin
Iodinated amino acids
- triiodothyronine
- tetraiodonthyronine (thyroxine)
What else can non-steroid hormones be composed of
- long chain(proteins) and short chain peptides
Give some examples of some short chain non steroid hormones
- oxytocin
- somatostatin
Give some examples of long chain non steriod hormones
- growth hormone
- insulin
- glucagon
Give some examples of non steriod hormones which are glycoproteins (protein with attached carbohydrate groups to amino acids)
- follicle stimulating hormone
- luteinizing hormone
- thyroid stimulating hormone
What are local tissue hormones
Some hormone like substances have a local (paracrine) effect
- prostagrandins
- leucotrienes
- thromboxanes
What are the functions of local tissue hormones
- blood flow regulation
- haemostasis
- mucosal protection (stomach)
- inflammation
Why are non steroid hormones commonly referred to as second messengers
- most non steroid hormones act via second messenger systems within the target cell
- two common ones are cAMP and Ca++
- steroid hormones can pass through the outer cell and directly reach Intracellular receptors
Give an overview of hormone action
- synthesis and storage
- release in response and stimulus
- transport in blood
- action on target cells (role as 2nd messengers)
- metabolism and/or excretion
What is the difference between steroid hormones and non steroid hormones
Steroid hormones can pass right through the cells on the other hand non-steroid hormones need to activate a second messenger in the cells to induce a response
How is the endocrine system commonly controlled
Most hormone systems are regulated by negative feedback
What is the function of parathyroid hormone
Controls Ca++ concentration in the body
What word is used to describe excess secretion of hormones
Hypersecretion
What word is used to describe decreased secretion of hormones
Hyposecretion
What word is used to describe more receptors
Upregulation
What word is used to describe fewer receptors
Downregulation
What is hyperfunction
Excess production and secretion
Upregulation of receptors
Failure to metabolise hormone
What is hypofunction
Decreased production and secretion
Downregulation of receptors
Receptors non functioning
Describe pro hormones
Pre-prohormone are inactive forms of the hormone contained in the endoplasmic reticulum > prohormone is a slightly active form of the hormone which is contained within the Golgi apparatus > active hormone is then secreted from the vesicles
Why does the body store preprohormones
In case the body needs the preprohormone to be converted into the active form
Why can people with type 1 diabetes die without adequate glucose
The brain will be starved of glucose - hypoglycaemia
What organ metabolises hormones
Liver
What organ is responsible for excreting hormones
Kidney
What is negative feedback control
Most hormone systems are regulated by negative feedback
Give an example of negative feedback control
Raised blood plasma calcium levels acts on parathyroid glands to reduce secretion of PTH
What is the word used to describe excess secretion
Hypersecretion
What is the word used to describe decreased secretion
Hyposecretion
What is sensitivity of target cells related to
Number of membrane receptors
More receptors = …
Upregulation
Fewer receptors = …
Downregulation
What are the effects of hyperfunction
- excess production and secretion
- Upregulation of receptors
- failure to metabolise hormones
Effects of hypofunction
- decreased production and secretion
- Down-regulation of receptors
- receptors non functioning
