Digestive System Sports Training and Physiology Kociuba

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 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… 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.