endocrine system

What is the role of the edocrine system?

to influence the activity of cells by the release of chemical messengers known as hormones.-These hormones detects changing internal conditions (to keep homeostasis), -produces hormones that affect body cells. -hormones can enter cells and. change their function

What is homeostasis and how does the body know when this is reached?

the ability to maintain a relatively stable internal environment in an ever-changing outside world. Feedback mechanisms allow processes to stop when homeostasis has been reached.

What is the difference between endocrine and exocrine system?

Endocrine System: secretes hormones into the extracellular fluid that surrounds the cells that make up the cell. The secretion usually passes into the capillaries to be transported by the blood. Exocrine System: secretes into a duct that carries the secretion to the body surface ir to one of the body cavities.

What are some examples of exocrine glands?

mucous, sweat, oil, and salivary glands

What are organs in the endocrine system?

Hormone-producing organs, pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid gland, adrenal gland, thymus, pancreas, kidneys, ovaries, testicles. Different glands secrete diff hormones

What are hormones?

are chemical messengers secreted by endocrine glands that are transported around the body in the blood.

What is the function of hormones?

They are able to interact with receptors on or in the cell to change the functioning of cells, by changing the type, activities, or quantities of proteins produced. Hormones are NOT enzymes but may influence the enzyme activity/ concentration.

How may hormones affect a cell?

hormones may… activate certain genes in the nucleus so that a particular enzyme or structural protein is produced. -change the structure if enzyme so it is 'on' or 'off', -change the rate of transcription or translation for a different rate of production of structural proteins or enzymes

Are hormones enzymes?

nope! However they can influence enzyme activity and concentration

What is the other name of endocrine glands?

ductless glands

What is a target cell?

A cell that has receptors for a particular hormone

What is a target organ?

organ or tissue that responds to a hormone

What are the different types of hormones?

protein/ amines or steriods

What is the slowest acting hormone group?

is the steroid hormone because this hormone is involved in synthesising proteins inside of the cell altering gene expression

What is the structure of the endocrine system?

a series of glands that secrete hormones into the bloodstream. Different glands secreting different hormone.

What are hormone receptors?

proteins that are on or in cells to which hormones can bind. Receptor proteins are specific and can only bind to one type of hormone, some hormones will only affect specific organs (target organs) or groups of cells (target cells) because they have the correct receptor.

Are the number of receptors on a cell fixed?

no, different types of cells have different numbers of receptors. this is why there is variation on how and where different hormones act in the body.

What model is used by hormone receptor proteins?

the lock and key model. only one type of hormone for a receptor.

What is hormone saturation

condition in which all the receptor molecules are occupied by hormone molecules- adding more hormone cannot produce any greater effect

receptor proteins are…

Specific

Explain how receptor proteins are specific

each type of receptor can only bind with one type of hormone. some hormones only effect specific organs (target organs) or groups of cells (target cells) because they only have the correct receptors.

What analogy is used to describe hormones and a protein receptor

lock and key model.

Why do some hormones affect all cells

because all cells have receptors for them

What happens when no more hormone must be secreted?

the hormone levels are detected by the endocrine gland which then stops production of hormones. Hormone levels become normal. This is called negative feedback

What are negative feedback systems?

a situation in which feedback brings about a change opposite to, or reduce the effect of, the original stimulus

What is hormone clearance?

is the breaking down of a hormone once the hormone has produced its required effect.

Where do hormones get broken down?

Some get broken down inside the target cell. However most get broken down in the liver and kidneys and the degraded hormones are excreted in either bile or urine.

hormones are chemical….

messengers

the endocrine system is a….

messenger system

Why are receptors on so many cells?

hormones effect many cells so their effect is widespread

What are the different hormone types?

steroid and amine hormones, their chemical structure affecting how they have action on the target cell.

What are some examples of steroid hormones?

Oestrogen, progesterone, testosterone, aldosterone, cortisol,

Are steroid hormones lipid soluble or water soluble?

lipid soluble therefore do not dissolve in water and therefore can pass through the cell membrane.

What is the pathway of a steroid hormone?

hormone is produced and secreted into the extracellular fluid by the endocrine gland. Hormone will bid to a transport protein in the blood. Once at the target cell, hormone separates from the transport protein. Then the hormone diffuses across the cell membrane. When inside the cell the hormone will work to combine with the receptor protein in either the cytoplasm or the nucleus. Hormone receptor complex will then activates the genes controlling the formation of particular proteins by binding to the promotor section of a certain gene (inhibiting/ amplifying transcription)

What are transport proteins?

The proteins steroid hormones bind to in the blood to allow them to move through the body from the blood.

Where can a steroid hormone bind to the receptor protein?

in the cytoplasm or nucleus in the target cell.

How fast do steroid hormones act?

they are slow but their effect is long lasting

How do steroid hormones have an effect on a cell?

activates genes to change the type, activities or quantities of protiens produced in the target cell.

What are some examples of amine hormones?

Growth hormone and oxytocin

Are amine hormones water or lipid soluble?

water soluble, therefore cannot diffuse through the cell membrane

Do amine hormones require a transport protein?

nope! because they are soluble in the blood.

What is the pathway of an amine/ protein/ peptide hormone?

an endocrine gland detects an imbalance in body systems therefore will produce and secrete the hormone into the extracellular fluid. Then the hormone will diffuse into the blood and be circulated to the target cell. The target cell will have a receptor protein in its membrane for the hormone to bind to. The combination of hormone/ receptor complex triggers a secondary messenger substance to diffuse into the cell. this seccondary messenger substance activates/ amplifies particular enzymes that change cell functioning.

How fast acting are amine hormones?

they are very fast but their effect is short lasting.

What is enzyme amplification?

one hormone does not juts activate or manufacture one molecule of an enzyme. thousands are activated.

How does enzyme amplification occur?

the hormone will trigger a cascading effect in which the number if molecules involved is increases hundreds or thousands of times for each step in the metabolic pathway.

How are chemical secretions controlled?

negative feedback system. it is feedback that reduces the effect or eliminates the original stimulus. It is necessary the an endocrine gland is over or under secreting a hormone, if this didn't occur the body will function abnormally.

What is a hormone that relies on positive feedback?

oxytocin (the more that is released the more contractions, therefore a baby can be born)