A&P - Chapter 40 (Part 1) Flashcards
What are the primary functions of the digestive system suppose to do?
Bring essential nutrients into the body and make them available to all cells
What are the steps in digestion? (7)
- Ingestion
- Digestion
- mechanical and chemical - Motility of the GI wall
- Secretion
- Absorption
- Elimination
- Regulation
Ingestion
Food is taken into the body
- through the mouth
Digestion
Complex nutrients (eg. carbs, fats, proteins) are broken down into simple nutrients (e.g. monosaccharides, amino acids, fatty acids, etc)
Motility of the GI wall
Mechanical breakdown and movement of food through GI tract
Secretion
Digestive enzymes
- chemical digestion
Absorption
Movement of nutrients
- GI mucosa –> internal environment
Elimination
Excretion of unabsorbed material
Regulation
Coordination of all digestive system functions
What are the 2 types of digestion?
- Mechanical
2. Chemical
Mechanical digestion
Physically breaks large chunks of food into smaller bits and pieces
Chemical digestion
Breaks molecules apart and chemically changes the food
- e.g. protein break down into amino acids
What happens during mechanical digestion?
Churns contents of the GI lumen to mix with digestive juices and ensure contact with the surface of the intestinal mucosa, facilitating absorption
What does mechanical digestion propel?
Food along the alimentary tract, eliminating digestive waste from the body
What does mechanical digestion involve? (5)
- Mastication
- chewing - Deglutition
- swallowing - Peristalsis and segmentation
- Regulation of motility
- Intestinal Motility
Mastication
Reduces size of food particles and mixes food with saliva to prepare it for deglutition
- chewing
What is another word for swallowing?
Deglutition
What are the 3 stages of deglutition?
- Oral stage
- Pharyngeal stage
- Esophageal stage
What kind of control is the oral stage of swallowing?
Voluntary
Oropharynx
Mouth
Oral stage
Food bolus is formed and is pushed against the palate by the tongue, then moved back into the oropharynx
What kind of control is the pharyngeal stage of swallowing?
Involuntary
What does the pharyngeal stage of swallowing require?
Blockage of mouth
- nasopharynx and larynx
How is the pharyngeal stage of swallowing accomplished? (2)
- Contraction
2. Gravity
What kind of control is the esophageal stage of swallowing?
Involuntary
How is the esophageal stage of swallowing accomplished? (2)
- Contraction
2. Gravity
What are two main types of motility produced by smooth muscle of the GI tract? (2)
- Peristalsis
2. Segmentation
Peristalsis
Wave-like ripple of the muscle layer of a hollow organ that moves matter forward in the GI tract
What is peristalsis triggered by?
The presence of food
Segmentation
A forward-and-backward mixing movement within a single segment of the GI tract
What does segmentation help with?
The breakdown food, by mixing food with digestive juices and bringing it in contact with the intestinal mucosa where absorption takes place
Gastric motility
Food in stomach is churned and mixed with gastric juices to form chyme
- via peristaltic contractions called propulsion and retropropulsion
How often does chyme exits the stomach?
Every 20 secs
