This document provides an overview of cellular secretion and communication. It defines cellular secretion as the external elimination of substances produced by cells, such as hormones and mucus. There are two main modes of secretion: merocrine secretion which involves exocytosis and holocrine secretion where gland cells rupture to release their products. The document also discusses three key processes in cellular communication - reception, transduction, and response. It outlines three main modes of indirect cell signaling: endocrine signaling through hormones, paracrine signaling between neighboring cells, and autocrine signaling where cells respond to molecules they produce.

1. AMJAD AL-BLEAHID
DENTISTRY
Cellular secretion and
communication

2. overview about Cellular
secretion

3. The definition of cell secretion :
 Cell secretion is the external elimination of
substances produced by the cell .

4. Examples :
 Hormones
 Mucus

5. Modes of Secretion :
 Merocrine :
 most abundant form of multicellular exocrine
gland .
 products are secreted by exocytosis (e.g.,
pancreas, sweat, and salivary glands)
 Holocrine :
 products are secreted by the rupture of gland
cells [e.g., sebaceous (oil) glands of the skin]

6. Cellular communication

7. Overview about communication :
 Cell-to-cell communication is essential for both
multicellular and unicellular organisms
 Multicellular organism’s cells communicate by
chemical messengers
 Cells most often communicate with each other
via chemical signals

8. Sutherland suggested that cells receiving signals went
through three processes :
 Reception
 Transduction
 Response

9. :Modes of cell-cell signaling
 1- Direct cell-cell or cell-matrix .
 2 - Indirect: Secreted molecules .
 A - Endocrine signaling. The signaling molecules are
hormones secreted by endocrine cells and carried
through the circulation system to act on target cells at
distant body sites.
 B - Paracrine signaling. The signaling molecules
released by one cell act on neighboring target cells
(neurotransmitters).
 C - Autocrine signaling. Cells respond to signaling
molecules that they themselves produce (response of
the immune system to foreign antigens, and cancer
cells).

10. Plasma membranes
Gap junctions
between animal cells
Cell junctions
Cell-cell recognition
Plasmodesmata
between plant cells