The endocrine system is a body-wide communication network. Its glands release hormones into the blood, helping coordinate functions across distant organs. This lesson introduces endocrine glands, how hormones act, and how their release is regulated.
The endocrine system is a network of glands and organs that produce hormones. Endocrine glands are ductless: rather than sending secretions through a tube, they release hormones directly into the blood. The blood carries these chemical messengers to target tissues elsewhere in the body.
All flashcards
What is an endocrine gland?
A ductless gland that releases hormones directly into the blood for delivery to target tissues.
What determines whether a cell can respond to a hormone?
The cell must have an appropriate receptor, either inside the cell or on its plasma membrane. Receptor number and sensitivity can change.
How do autocrine and paracrine signals differ?
Autocrines act on the cells that secrete them; paracrines act on nearby cells of a different type.
What are synergism and antagonism?
Synergism occurs when hormones reinforce or amplify effects together. Antagonism occurs when one hormone opposes or reverses another's effect.
What distinguishes primary, secondary, and tertiary endocrine disease?
Primary disease begins in an endocrine gland, secondary disease involves the pituitary, and tertiary disease involves the hypothalamus or its releasing hormones.
Quiz questions
Which hormones does the posterior pituitary store and release?Answer: Oxytocin and antidiuretic hormone made in the hypothalamus.
Which pituitary hormone stimulates thyroid gland activity?Answer: Thyroid-stimulating hormone.
What is the main effect of parathyroid hormone on blood calcium?Answer: It raises blood calcium through effects on bone, intestine, and kidneys.
Which hormone do pancreatic alpha cells release when blood glucose is low?Answer: Glucagon.
Which hormone interaction occurs when one hormone must be present for another to produce its full effect?Answer: Permissiveness.
Based on the Wikipedia article Endocrine gland, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.