The Endocrine System Flashcards
The Endocrine system
- The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood.
- The Hypothalamus is the main link between the endocrine system and the nervous system.
- The endocrine system works alongside the nervous system to control vital functions in the body. The endocrine system acts more slowly than the nervous system but has very widespread and powerful effects.
- Glands in the body produce hormones
- Hormones are secreted into the bloodstream and affect any cell in the body that has a receptor for that particular hormone.
- The main gland is the pituitary gland which is located in the brain.
- The endocrine system receives feedback from the hormones secreted by the target gland. The hormones are detected and the hypothalamus responds by shutting down secretion of stimulating hormones. Thereby, the endocrine system works via a negative feedback loop.
What is the Hypothalamus?
A collection of specialised cells that is located in the lower central part of the brain.
Thyroid Gland
Produces thyroxine, which controls the rate of metabolism.
Pancreas
Produces insulin which controls blood sugar level.
Testes
Produces testosterone which causes the changes at puberty and stimulates sperm production.
Adrenal Glands
Produce adrenaline which prepares the body for rapid activity by increasing the heart rate and level of sugar in the blood and diverting bloof to muscles and brain.
Ovary
Produces Oestrogen which causes changes at puberty and helps control the menstrual cycle.
How do the glands interact?…
- HYPOTHALAMUS - sends signal to pituitary gland (via ‘secreting hormone’ e.g. CRH)
- PITUITARY GLAND - secretes a stimulating hormone into bloodstream (via ‘stimulating hormone’ e.g. ACTH)
- TARGET GLAND - e.g. Adrenal gland, then produces target hormone
(e.g. control) - Hypothalamus then shuts down secreting hormone and pituitary shuts down stimulating hormone, balancing target hormone levels
What is the role of the pituitary gland?
- Also known as the ‘master gland’, it is controlled by the hypothalamus and controls the release of hormones from all other endocrine glands in the body.
- The anterior (front) PG releases ACTH as a response to stress - ACTH stimulates the adrenal glands to produce cortisol.
- The posterior (back) PG releases LH and FSH. In females theses stimulate the ovaries to produce oestrogen and progesterone. In males they stimulate the testes to produce testosterone and sperm.
- The posterior PG also releases oxytocin to stimulate contractions in childbirth and aid mother-infant bonding.
What is a hormone?
Chemical messengers which circulate the blood stream, carrying messages to target cells in the body
Major glands in the endocrine system
- Adrenal
- Pituitary
What is a ‘target cell’?
Specific cells which have receptor sites which respond to only a particular hormone.
Psychological stress response
(FOFR)
- Stress can be acute or chronic.
- For fight or flight we will look at acute stress.
- In an acute stress reaction, we release adrenaline.
Fight or Flight response (overview)
- Endocrine system and ANS working together.
- Stressor perceived by hypothalamus which activates the pituitary gland - SNS.
- Parasympathetic activated once the threat has passed.
Sympathetic - fight or flight
- Increases heart rate and blood pressure to promote blood flow
- Widens bronchi in the lungs to allow us to take in more oxygen to carry to the muscles needed.
- Releases glucose into blood for energy.
- Dilates pupils so we take in more light making us more alert.
- Slows digestion to divert energy and oxygen to when it is needed.
- Saliva production is inhibited as it isn’t a priority because we don’t need to eat or digest food.
