Digestive System Flashcards
What are the functions and contents of the digestive system?
The function of digestive system includes:
- Ingestion of food in mouth
- Movement of food along digestive tract.
- Mechanical preparation of food for digestion
- Chemical digestion of food
- Absorption of food into the circulatory and lympathic system.
- Elimination of waste products and indigestible substances through defacation.
The contents include: Mouth, Pharynx, Esophagus, Stomach, Small intestine, Large intestine
Where does food molecules go to before it is distributed to the rest of the body?
Liver, through the hepatic portal vein.
How does food move from mouth to anus: Start with mouth and pharynx
Ingested food is broken from large to small by process of chewing, and saliva helps to ease swallowing and dissolves food particles to be tasted by taste buds on the tongue. It is then swallowed into the pharynx, a pathway that is shared by both digestive system and respiratory system. Food that is swallowed are called bolus, bolus slides past the epiglottis, the entrance to the lungs to prevent choking.
How does food move from mouth to anus: Esophagus and Stomach
From the pharynx, bolus moves to a muscular tube called esophagus that connects the pharynx and stomach. Bolus is propelled by waves of contraction in esophagus called peristalsis until it reaches the cardiac sphincter, which is the entrance of the stomach.
The stomach then prepares the ingested food for digestion through chemical and mechanical means.
The chemical process breaks down food particles and the mechanical action grinds the the suspension of particles into a thick mixture called chyme.
The stomach will then store chyme to be emptied into the small intestine through the pyloric sphincter at a rate appropriate for optimal digestion and absorption.
How does food move from mouth to anus: Small intestine
Chyme is then move into small intestine through pyloric sphincter. Small intestine is where the digestion and absorption of food, nutrients, minerals, water, salt and vitamins.
Small intestine is separated into three different segments , duodenum, jejunum and ileum.
In the small intestine, contractions known as segmentation, similar to peristalsis, squeezes the intestine and forces contents to move backwards, allowing the digestive juices and absorbing cells to have better contact with the nutrients.
In the duodenum, chyme is exposed to bile from gallbladder and liver for aiding in digestion of fats as well as pancreatic enzymes for digestion of fats, carbs and proteins.
Most absorption occurs in the duodenum and jejunum. In the duodenum, a large surface area of microvilli and villi are present, each owning their network of capillaries and lymph vessels and allows the nutrients to pass through into the bloodstream and body fluids immediately.
How does food move from mouth to anus: Large intestine
Most absorption of nutrients are done when chyme reaches the large intestine/colon. Final absorption of salt and water takes place in the large intestine, leaving semisolid waste left for excretion through the anus.
Indigestible substances and fiber can add to the bulk of it.
