BP - The endocrine system Flashcards
What is the endocrine system?
A network of glands around the body that manufacture and secrete chemical messengers known as hormones, which are required to regulate bodily functions.
What does it provide?
A chemical system of communication for the body via the bloodstream. A required amount of a specific hormone is released from the endocrine gland to regulate the physiological processes e.g. growth, metabolism or reproduction
What does it work closely with?
The nervous system in order to regulate bodily function - the endocrine system uses blood vessels to deliver hormones to target sites rather than nerves to transmit information. As a result, it acts more slowly than the nervous system, but its effects are more powerful and widespread.
Endocrine glands
A special group of cells with the system, whose function is to produce and secrete hormones, chemical substances that regulate cell and organ activity.
The major glands:
- Pituitary gland
- Adrenal glands
- Reproductive organs (testes and ovaries)
Each gland produces different hormones which regulate activity of tissues and organs in the body
What are hormones?
Chemical messengers that travel via the bloodstream and are carried to target sites - they come into contact with most cells, but only affect these target cells, which are structured to react and respond to particular hormones as they have the receptors for that hormone.
When receptor sites are stimulated by the hormones, this results in a physiological reaction in the target cell. Hormones influence many processes including mood, stress response and bonding between a mother and baby.
How is the endocrine system regulated?
Feedback loops - one set of signals stimulates the release of hormones, and as levels of that hormone rise in the bloodstream, a second set of signals slows down the secretion of the hormone, resulting in stable concentrations of hormones circulating in the bloodstream.
What is the role of the pituitary gland?
- Located in the brain, this gland secretes the following hormones; LH, FSH, ACTH and oxytocin
- Key roles include producing hormones that control the release of hormones from other glands and acts as a master gland that regulates many of the body’s functions
Effects on behavior - when released in response to stress, it stimulates the adrenal gland to release cortisol
- In females, when released it stimulates ovaries to produce oestrogen and progesterone, and in males when released it stimulates testosterone production in the testes
- When released, it stimulates contraction of the womb in childbirth and is important for mother-infant bonding
The role of the adrenal glands
- Located on the kidneys, produces cortisol, adrenaline and noradrenaline
- Key roles - supports bodily function, such as cardiovascular and anti-inflammatory functions, as well as causing physiological changes associated with arousal, preparing the body for fight or flight
Effects on behavior - released in response to stress, affecting glucose metabolism, lowering sensitivity to pain and suppressing the immune system
- Helps the body to respond to stressful situations e.g. increasing heart rate, increasing blood flow to muscles and brain and converting glycogen to glucose
Role of the ovaries
- produces oestrogen and progesterone
- Key role - production of eggs and female sex hormones
Effects on behavior - Associated with increased sensitivity to social cues, which can be important in pregnancy
- Female reproductive function
Role of the testes
- Produces testosterone
- Produces sperm and male sex hormones
Effects on behavior - important for sex drive, sperm production and muscles strength, and is associated with general health and well-being in men
- the development of male characteristics such as facial hair, deepening of the voice, growth spurt etc
