W8 - Endocrine system Flashcards
(12 cards)
Describe the basic function of the endocrine system
Describe the basic components of the endocrine system
Endocrine glands
Pituitary gland
Small, oval-shaped gland located inferior to the hypothalamus and connected to it by the infundibulum (thin stalk)
It sits in the hypophyseal fossa.
It is the main endocrine interface between the central nervous system and the rest of the body.
It acts as the body’s “master gland”, as it tells the other glands of the body what to do.
Structurally and functionally, the pituitary gland can be divided into an anterior pituitary gland and a posterior pituitary gland.
divisions of pituitary glands
pineal gland
Small, cone-shaped gland attached to the posterior region of the epithalamus.
Produces a hormone called melatonin, which regulates circadian rhythm (i.e. the 24-hour body clock)
thyroid gland
Butterfly-shaped gland located in the neck, inferior to a cartilage of the larynx called the thyroid cartilage and anterior to the trachea
It is composed of two lobes (right and left) that are connected by a narrow band called the isthmus.
It produces a hormone called thyroid hormone (TH), which comes in two forms – T3 and T4.
This hormone increases the metabolic processes of the body by acting on many body cells.
The thyroid gland also produces a hormone called calcitonin, which decreases blood calcium levels and is involved in calcium homeostasis in the body.
parathyroid glands
Small nodules located on the posterior surface of the thyroid gland.
There are usually four
They produce a hormone called parathyroid hormone (PTH), which increases blood calcium levels.
Together with calcitonin from the thyroid gland, parathyroid hormone is a key hormone for calcium homeostasis in the body.
adrenal/superarenal glands
Paired, pyramidal-shaped glands located on the superior aspect of the kidneys.
Internally, each adrenal gland has an outer region called the adrenal cortex and an inner region called the adrenal medulla.
adrenal cortex and medulla
Describe the location of the pancreas and the function and histology of its endocrine portion
The pancreas is a mixed gland with both endocrine and exocrine functions.
Location
Located in the abdominal cavity, posterior to the stomach and in between a part of the small intestine called the duodenum and the spleen.
Histology
The exocrine portion of the pancreas makes up the majority of the pancreatic tissue and consists of secretory portions called pancreatic acini.
Scattered amongst the clusters of pancreatic acini are small clusters of endocrine cells called pancreatic islets, or islets of Langerhans.
Produce insulin and glucagon to regulate blood glucose levels – insulin decreases blood glucose levels, while glucagon increases blood glucose levels.
Provide examples of other organs containing endocrine cells
Heart, thymus, gastrointestinal tract, kidneys and gonads (testes in male and ovaries in female)
Tissues of the body such as adipose tissue, bone and skeletal muscle also produce hormones.
