Digestive System
Sports Training and PhysiologyKociuba
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Digestive System - Objectives
Describe the function of the digestive system Starting with the mouth describe the process
of swallowing Explain the whole process of digestion from
chewing to excretion Discuss the age-related changes that happen
to this system
Function of the Digestive System
Take in food Through the mouth
Break down the food from complex molecules to simple Mechanical Digestion
Chewing and mixing Chemical Digestion
Enzymes mix to breakdown food further
Absorb nutrients Simple molecules that
were broken down now are absorbed through the walls of the small intestine and used throughout the body
Eliminate waste We do not use all of the
food taken in, just what is needed. What is not used is waste and is excreted out of the body
The Digestive System and the Nervous System
The ENS or enteric nervous system is made up of enteric plexus which are sensory neurons which connect the digestive system to the CNS and ANS It helps in moving food through the digestive tract
by stimulating smooth muscle Detects chemical changes and causes secretions
of enzymes to aid in the digestive process Connects motor neurons to sensory neurons in
the digestive system
How do we swallow?
Three phases Voluntary phase: the ball of food we chew (bolus)
is pushed to the back of the mouth by our tongue Pharyngeal phase: when it gets to the back of the
mouth receptors receive the food and push it further down and the pharyngeal constrictor muscles take over the food down the pharynx
Esophageal phase: the swallowing phase takes about 5 -8 seconds and is responsible for getting the food from the pharynx to the stomach
Structure/Anatomy
Digestive Tract Tube extended from the mouth to the anus with
other organs attached to secrete fluids that aid in the digestion process
Gastrointestinal tract (GI tract) is often a synonym, but should only refer to the stomach and intestine
Structure/Anatomy
Oral Cavity Contain teeth for manual
breakdown of food
Pharynx Salivary Glands
Secrete enzymes for breakdown of food
Esophagus
Structure/Anatomy
Stomach Fundus: top part Body: main part Pyloric: joins to small
intestine Gastric Juice
Chyme
Structure/Anatomy
Small Intestine (6m long) Duodenum Jejunum Ileum
Peristaltic Contractions and Segmental Contractions move the food through the small intestine
Liver Largest internal organ Produces and stores bile in
the gallbladder Stores glycogen Nutrient interconversion Detoxification Phagocytosis Synthesis
Structure/Anatomy
Pancreas Part of endocrine system
as well Secretes enzymes that
aid in the breakdown of all food and proteins in particular
Large Intestine Cecum Colon Rectum Anal canal
While here, chyme turns into feces
Digestion, Absorption, and Transport
Digestion: breakdown of foodAbsorption: uptake of digestive tract contents by the lining of the tractTransport: the distribution of nutrients throughout the body
Food is broken down into…
Carbohydrates Lipids a.k.a. Fat Proteins Water
We will talk more about these in the nutrition portion.
Aging and the Digestive System
As you age, like the skin, the digestive structures become thin
and do not secrete as much enzymes.