Endocrine System Flashcards
Important glands
○ Hypothalamus
○ Pituitary gland
○ Thyroid gland
○ Adrenal gland
○ Ovary/testes
Hypothalamus
○ Located at the base of the brain
○ Wide range of functions
○ Links to the endocrine system via the pituitary gland and the central nervous system
Pituitary gland
○ Sits below the hypothalamus
○ The ‘master gland’
○ Produces many hormones
Thyroid gland
○ Sits in front of the neck
○ Influences metabolic rate
Adrenal gland
○ Top of the kidney
○ Produces hormones such as adrenaline and cortisol
Ovaries
○ Produce oestrogen and progestogen which controls the menstrual cycle
Testes
○ Produces testosterone which regulates male characteristics
How does the endocrine system work
○ Glands and tissues secrete hormones (a specialised signaling molecule) which then directly enter the bloodstream
○ The bloodstream carries the hormone to the target cells which then initiates a specific response to the hormone
○ The target cells have specific receptors for the hormone that it responds to
○ This means that only the intended organ will respond to the hormone in the bloodstream
Hypothalamus and pituitary gland
○ The hypothalamus controls the pituitary gland
○ The pituitary gland has two lobes that store and releases hormones, which are regulated by negative feedback mechanisms
○ The pituitary gland often releases hormones that trigger other glands to release further hormones
ADH (ANTIDIURETIC HORMONE)
○ Negative feedback to maintain homeostasis
Adrenal glands
○ The adrenal glands release several hormones involved in the body’s response to stress
○ Each adrenal gland is composed of an outer layer called the adrenal cortex, and an inner part called the adrenal medulla
○ The adrenal medulla is stimulated by neurons from the hypothalamus
- In the short-term stress response, also called the fight-or-flight response, the adrenal medulla is stimulated to release epinephrine/adrenalin
- This causes an increase in the body’s metabolism, breathing rate, and heart rate. This provides more energy for the body to respond to danger
Pancreas
○ Blood glucose levels
- Insulin
□ Released by the pancreas to lower blood glucose levels
- Glucagon
□ Released by the pancreas to increase blood glucose levels
Response to exercise
○ Exercise requires energy that is produced via cellular respiration.
- Cellular respiration requires glucose – this will lower blood glucose levels
- Pancreas will release glucagon to raise blood glucose
○ Exercise causes sweating
- Sweating lowers water content in the blood
- Pituitary gland releases ADH and the kidneys absorb more water
○ Your pituitary gland releases endorphins – producing a feeling of euphoria and reducing the communication of pain signals
○ Epinephrine is released by adrenal glands à increased heart rate, breathing rate, and blood flow to muscles, decrease blood flow to the digestive tract, increases glucose availability in blood
○ Growth hormone is produced by the pituitary gland after exercise building of muscles, repair of tissues
Hormonal vs nervous control
○ The nervous and endocrine systems provide internal communication between cells and coordination of the systems of the body
○ Nervous system
- consists of nerve cells and conveys nerve impulses
- Nerves send signals from your brain to parts of your body
○ Endocrine system
- Consists of ductless glands and secretes hormones into the bloodstream
- Hormones are secreted by different organs into the bloodstream and are picked up by the target organ
- The target organ then responds to the hormone
Endocrine vs nervous
Endocrine
- Chemical hormones
- Receptors on target cells
- Relatively slow, hormones travel in bloodstream (seconds to hours)
- Short
