Transcript Digestive System

Digestive System
Sports Training and Physiology
Kociuba
http://kidshealth.org/PageManager.jsp?lic=1&article_set=59299&cat_id=20607
Digestive System - Objectives
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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
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Take in food
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Through the mouth
Absorb nutrients
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Break down the food
from complex
molecules to simple
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Mechanical Digestion
 Chewing and mixing
Chemical Digestion
 Enzymes mix to
breakdown food further
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Simple molecules that
were broken down now
are absorbed through the
walls of the small
intestine and used
throughout the body
Eliminate waste
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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
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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
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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?
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Three phases
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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
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Digestive Tract
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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
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Oral Cavity
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Pharynx
Salivary Glands
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Contain teeth for manual
breakdown of food
Secrete enzymes for
breakdown of food
Esophagus
Structure/Anatomy
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Stomach
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Fundus: top part
Body: main part
Pyloric: joins to small
intestine
Gastric Juice
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Chyme
Structure/Anatomy
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Small Intestine (6m
long)
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Duodenum
Jejunum
Ileum
Peristaltic Contractions
and Segmental
Contractions move the
food through the small
intestine
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Liver
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Largest internal organ
Produces and stores bile in
the gallbladder
Stores glycogen
Nutrient interconversion
Detoxification
Phagocytosis
Synthesis
Structure/Anatomy
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Large Intestine
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Pancreas
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Part of endocrine system
as well
Secretes enzymes that
aid in the breakdown of
all food and proteins in
particular
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Cecum
Colon
Rectum
Anal canal
While here, chyme
turns into feces
Digestion, Absorption,
and Transport
Digestion: breakdown of food
Absorption: uptake of digestive tract
contents by the lining of the tract
Transport: the distribution of
nutrients throughout the body
Food is broken down into…
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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.