Endocrine System Flashcards
What are endocrine glands?
Secrete their product into the extracellular space around the secretory cells. Secretion then diffuses into blood capillaries to be carried to target cells e.g. hormones
What are exocrine glands?
Secrete their product into ducts. Ducts carry the secretion into body cavities, into the lumen of an organ, or to the outer surface of the body. e.g. saliva, sweat, tears etc
What is the hypothalamus?
Works with the pituitary to regulate nearly all aspects of growth, development, metabolism and homeostasis
What is the job of releasing hormones?
To instruct the pituitary gland to produce and release its hormones made in the glands anterior lobe.
Which hormones are releasing hormones?
- CRH - Corticosteroid releasing hormone
- GHRH - Growth hormone releasing hormone
- GnRH - Gonadotrophic releasing hormone
- TRH - Thyrotrophic releasing hormone
What is the pituitary?
A small sized grape like gland attached to the hypothalamus by the infundibulum
What is the infundibulum?
Contains the hypophyseal portal veins and axons of the hypothalamic neurones. It is split into the anterior and posterior
What is the posterior pituitary?
Stores and releases the hypothalamus hormones ADH and oxytocin
What is anterior pituitary?
This manufactures and secretes hormones in response to releasing or inhibiting hormones from the hypothalamus
What is the thyroid gland?
Butterfly shaped gland situated below the larynx
What are follicular cells?
Secrete and store T3 and T4 (both forms of thyroxin) to regulate the metabolic rate it requires iodine to produce these hormones
What are parafollicular cells?
Make calcitonin inhibits the activity of osteoclasts to decrease calcium in the blood
What are parathyroid glands?
The number of parathyroid glands varies, some are attached to the thyroid gland but there may also be some free glands in the neck. Produces parathyroid hormone to regulate the levels of Ca2+, Mg2+ and HPO42- in the blood by enhancing the breakdown of bones and reducing or increasing loss by kidneys.
What are pancreatic islets?
Main products are glucagon and insulin
What is insulin?
reduces blood glucose levels by enabling glucose to enter the cells for use in the mitochondria and into the liver for storage
What is glucagon?
Increases blood glucose by triggering the livers capacity to convert glycogen (the storage form of glucose) back to glucose. The glucose can circulate and be used by the cells energy
What is diabetes mellitus?
The loss or inability to maintain blood glucose homeostasis. Chronically high levels of blood glucose can damage capillaries and caused vascular disease