Endocrine Secretion and Cell Communication

Endocrine Secretion

• Endocrine secretion involves releasing chemical messengers directly into the bloodstream.
• Exocrine secretion involves releasing substances into a ductal system, like saliva glands.
• Endocrinology studies internal secretions, called hormones.
• Hormones are produced by ductless glands.
• Hormones travel through the vascular system to target cells throughout the body.

Modes of Intercellular Communication

• Intercellular communication requires a signaling cell, chemical signal, and a target cell.
• Cell-cell contact involves a direct transfer of molecules between cells via gap junctions.
• Autocrine signaling involves the signaling cell releasing a chemical that affects itself.
• Paracrine signaling involves a chemical signal affecting nearby cells. An example is histamine secreted by gut cells affecting nearby cells to release stomach acid.
• Endocrine signaling involves hormones traveling through the bloodstream to target cells. A pituitary and thyroid gland communication is an example of this type of signaling.
• Synaptic signaling is a type of paracrine signaling where neurotransmitters pass between neurons or between neurons and muscle cells.

Signaling Through Cell-Cell Contact

• Gap junctions allow direct transfer of signaling molecules between cells.
• Granulosa cells in ovarian follicles use gap junctions to signal to oocytes.

Autocrine Signaling

• Prolactin stimulation of human breast cancer cells is an example.

Paracrine Signaling

• Histamine, secreted by enterochromaffin-like cells in the gut, stimulates nearby parietal cells to release hydrochloric acid.

Endocrine Communication

• Endocrine communication is chemical in nature.
• Hormones are released by signaling cells.
• Blood hormone concentrations are generally very low.

Hormones and Target Cells

• Hormones can potentially contact all cells in the body, but not all cells respond to every hormone.
• Target cells have specific receptors to bind hormones.
• Receptor binding generates an intracellular response.

Hormone/Receptor Interactions

• Sensitivity is the hormone concentration needed for a response. Biologically relevant hormone-receptor pairs often have high sensitivity.
• Specificity is the limited range of molecules a receptor can bind. Hormone-receptor systems often have high specificity.

This quiz explores the concepts of endocrine and exocrine secretion, along with modes of intercellular communication. It delves into the roles hormones play as chemical messengers within the body and different signaling methods between cells. Test your understanding of these essential biological processes.