14 The Endocrine System 3.3 Flashcards
The endocrine system
Composed of ductless glands scattered thoughout the body. Their function is to produce hormones -Adrenal glands -gonads -pancreas -pineal glands -pituitary glands -Thyroid glands -parathryoid glands None of these glands are connected to each other
Hormone
(Gr) ‘impulse’, ‘Urge on’
One of their jobs is to stimulate ‘target’ cells to react in specific ways. They act as messengers to control cell metabolic rate, and regulate body fluid homeostasis.
Endocrine gland regulation systems
- positive feedback
- negative feedback
Positive Feedback
A system is activated by a stimulus. ie, a baby sucking stimulates the release of prolactin, stimulating the mammary glands.
Negative feedback
A system by which the endocrine system keeps the other system in balance. If there’s too much stimulus, the gland stops or slows production; if there’s too little stimulus, the gland increases production
Hormones controlled by the nervous system
ie, adrenaline, which is released in response to outside stimuli, such as being startled or perceiving danger.
Thyroid gland
The largest of the endocrine glands is located in the front and sides of the neck and has two lobes on either side of the trachea. Hormones:
- Thyroxine (T3) and trilodothyronine (T4) regulate metabolism in body cells
- Calcitonin stimulates the passage of calcium from the blood into the bones
T3 and T4
In the bloodstream they enable the body’s cells to consume oxygen at an increased rate, which allows the cells to use carbohydrates and break down proteins
Calcitonin (thyrocalcitonin)
Important in calcium metabolism, prevents calcium loss in the bones, lowering the amount of calcium in the blood stream. Also helps let you know when you’ve had enough to eat
Pancreas
- Located behind the stomache, it serves as an accessory digestive organ by secreting pancreatic juices which contain enzymes to digest carbohydrates, proteins, and fats
- It’s surface has clusters of microscopic cells, call the pancreatic Isles, or the Isles of Langerhan, which secrete insulin and glucagon
Insulin
Helps push glucose from our blood into our cells, which decreases blood sugar levels, and effects the way our bodies use carbohydrates, proteins, and lipids for energy.
Glucagon
Glucose is stored in the liver as glycogen. Glucagon speeds up it’s conversion to glucose, which increases the blood sugar level.
Adrenal (Suprarenal glands)
Called Suprarenal because they’re located on top of the kidney
- Cortex
- Medula
Adrenal Cortex
Helps regulate the body’s metabolism and stress responses by releasing 3 types of steroid hormones (corticosteroids)
- Cortisol (glucocorticoid) regulates the quantities of sugars, fats, and proteins in cells
- Aldosterone (mineralocorticoid) regulates the amount of salt in the body
- Estrogen and testosterone (gonadocorticoids) maintain secondary sex characteristics
Glucocorticoids
Have an anti immune/allergy effect. Given to patients to stop the body’s natural defense to allergens or irritants
- Cortisone (hydrocortisone)
- Cortisol