The endocrine system Flashcards
What is the endocrine system?
Relates to glands that secrete hormones or other substances directly into the blood. Constantly monitors internal environment and releases hormones to endure maintenance of homeostasis
how many main endocrine hormones are there?
41
What is endocrine signalling?
Hormones enter the blood stream and transported to interact with tissues quite far away from their site of production
What is paracrine signalling?
Hormone leaves cell of production and acts on nearby cells without entering the circulation. e.g some released by thalamus with stay in the brain and not transported by the blood
What is autocrine signalling?
Hormone acts on the same cells that produced it. Acts on cell/tissue.organ where its produced
What are steroid hormones?
Similar structure to cholesterol which is a fatty substance
Lipid soluble
Are steroid hormones lipid soluble?
Yes
Give examples of steroid hormones
Testosterone, oestrogen, cortisol, aldosterone
What are non steroid hormones?
Protein and amino acid derived hormones
Lipid insoluble
Are non steroid hormones lipid soluble?
no
Give examples of non steroid hormones
Thyroxine, adrenaline, noradrenaline, insulin
Describe the role of the pancreas
Detects excess glucose and in response releases insulin. Insulin binds to muscle surface and stimulates muscle. The signal tells the muscle to take up more glucose from the blood and so blood glucose should decrease. Glucose back to normal levels.
What is meant by a negative feedback system?
Changes are reversed back to a set level
Describe how steroid hormones work
Lipid soluble hormones can move through fatty membrane of ell and enter the cell. Once in cell, attaches itself to a receptor which transports it in the cytoplasm to the nucleus. Hormone gets to nucleus and controls what type of proteins the cell is making. This changes function of cell
Describe how non steroid hormones work
Hormone can’t pass the membrane, can’t get into cell to nucleus to affect protein production. The hormone binds to a specific receptor on the surface cell membrane. Membrane receptors will transfer single from hormone into cell and active other processes within the cell which causes it to make a change which the hormone wants to make (second messenger)
