17.1 Endocrine

Hypothalamus

An important control center for hormone action; key in the anatomy and functions of the endocrine system.

Endocrine System

The system of glands, tissues, and cells that secrete hormones; responsible for chemical messaging and physiological regulation.

Hormones

Chemical messengers transported by the bloodstream to stimulate physiological responses in cells of another tissue or organ.

Gap Junctions

Structures that join cells together allowing direct passage of nutrients and signaling molecules between their cytoplasm.

Neurotransmitters

Chemicals released by neurons that diffuse across a synaptic cleft and bind to receptors on the surface of target cells.

Paracrines

Local hormones secreted by one cell that diffuse to nearby cells in the same tissue to stimulate their physiology.

Exocrine Glands

Glands that secrete their products through ducts onto epithelial surfaces, such as the skin or digestive tract.

Endocrine Glands

Ductless glands that release hormones directly into the bloodstream, affecting cells throughout the body.

Fenestrated Capillaries

A special type of blood capillary with large pores that allow for the easy uptake of matter from gland tissue.

Neuroendocrine Cells

Cells that act as both neurons and endocrine cells, releasing hormones into the bloodstream.

Transport Maximum (Tm)

The rate at which substances are transported by membrane proteins; relevant for understanding conditions like diabetes mellitus.

Growth Hormone

A hormone that stimulates growth and cell reproduction; one of the well-known hormones produced by the pituitary gland.

Thyroid Stimulating Hormone (TSH)

A hormone that specifically stimulates the thyroid gland; serves as an example of selective hormone action.

Dihydrotestosterone (DHT)

A more potent form of testosterone converted by specific target cells that have the enzyme for this process.

Endocrinology

The study of the endocrine system and the diagnosis and treatment of its disorders.

Norepinephrine

A neurotransmitter that also functions as a hormone; can stimulate similar effects in the body when secreted in either role.