Beyond Basics
The Normal Digestive Processes
in the Lower GI Tract
Gastrointestinal Function.
The functions of the GI tract are coordinated and regulated
to maximize digestion and absorption. To accomplish this, three types
of control mechanisms are used: paracrine, endocrine, and neural. Paracrine
regulation occurs when cells release a chemical substance that diffuses
into the space between them and influences the function of neighboring
cells. Endocrine regulation occurs when cells respond to a hormone stimulus
by releasing their contents into the bloodstream to act on distant target
cells. Target cells are those that have specific receptors
that are sensitive to the hormone stimulus. Cells without these specific
receptors do not respond to the stimulus. Neural regulation occurs when
nerves release chemicals that can either strengthen the force of peristaltic
and segmental contractions, or relax the muscles in the wall of the small
intestine. These chemical and neural control mechanisms are activated
in response to the physiological processes that occur in each phase of
digestion (Fig. 7).
Figure 7 –
The Three Principal Types of Control Mechanisms
This information
is provided as a general educational service
and is not intended to recommend any particular treatment plan
or to replace the advice of physicians. It is important that patients
seek and rely on the advice of a healthcare professional
about their individual medical conditions.
