Lesson 4 Endocrine System Flashcards
Endocrine system
The endocrine system provides a chemical system of communication in the body via the blood stream. Endocrine glands produce and secrete hormones into the bloodstream which are required to regulate many bodily functions. The major glands of the endocrine system include the pituitary gland and the adrenal glands. Each gland produces different hormones which regulate activity of organs/tissues in the body.
Although hormones come into contact with most cells in the body, they only affect a limited number of cells, known as target cells. Target cells respond to a particular hormone because they have receptors for that hormone. When enough receptor sites are stimulated by that hormone there is a physiological reaction.
Pituitary gland
The pituitary gland is located in the brain. It produces hormones whose primary function is to influence the release of other hormones from other glands in the body. The pituitary gland is controlled by the hypothalamus, a region of the brain just above the pituitary gland.
The hypothalamus receives information from many sources about the basic functions of the body. The hypothalamus then sends a signal to the pituitary gland in the form of a releasing hormone. This causes the pituitary gland to send a stimulating hormone into the bloodstream to tell the target gland to release its hormone. As levels of this hormone rise in the bloodstream the hypothalamus shuts down production of the releasing hormone and the pituitary gland shuts down secretion of the stimulating hormone
What are the two divisions of pituitary gland
Anterior pituitary gland
Posterior pituitary gland
Anterior pituitary gland
The anterior pituitary gland releases the hormone called ACTH which regulates levels of the hormone cortisol.
Posterior pituitary gland
The posterior pituitary gland is responsible for releasing the hormone oxytocin which is crucial for infant/mother bonding.
Adrenal gland
We have two adrenal glands situated on top of the kidneys. Each adrenal gland is made up of two distinct parts.
Two parts of the adrenal glands
Adrenal cortex
Adrenal Medulla
Adrenal cortex
The outer section of the adrenal gland is called the adrenal cortex. It produces the hormone cortisol which is produced in high amounts when someone is experiencing chronic (long-term) stress. Cortisol is also responsible for the cardiovascular system, for instance it will increase blood pressure and causes blood vessels to constrict.
Adrenal medulla
The inner section of the adrenal gland is called the adrenal medulla which produces adrenaline, the hormone that is needed for the fight or flight response that is activated when someone is acutely (suddenly) stressed. Adrenaline increases heart rate, dilates pupils and stops digestion.
