Body Systems: Digestion (Ingestion) Flashcards
Ingestion:
Taking in nutrients.
Digestion:
Breakdown of nutrients.
What are the types of digestion?
Physical/mechanical digestion and chemical (enzymes) digestion.
Absorption:
Transportation of digested nutrients via blood.
Elimination:
Removal of undigested waste.
The human digestive tract is about how long?
6.5-9 m long.
The 4 components of digestion are:
Ingestion, digestion, absorption, and elimination.
What type of digestion does the mouth do?
Physical (mechanical) digestion.
Digestion begins in the mouth where:
Food is chewed to form a bolus.
The mouth:
Breaks food into smaller pieces to increase the surface area for chemical digestion.
Teeth are:
Covered in enamel, hardest substance in the human body.
What is saliva?
Fluid produced by salivary glands.
What are the two functions of saliva and what do they do?
- Contains salivary amylase enzymes: breakdown complex carbs (starches), chemical digestion. 2. Dissolves food particles: flavour receptors on tongue, lubricates food.
What is the esophagus?
A tube from your mouth to your stomach.
Food bolus enters the esophagus and activates:
- Walls of esophagus to stretch. 2. Peristalsis: smooth muscle that lines the esophagus involuntarily. Contracts to help move food down.
What is the esophageal sphincter?
It is a ring like muscular structure that controls food entry into the stomach.
The stomach:
Is a J-shaped organ, is a site of food storage and initial protein digestion, contains folded layers that increase surface area, preforms physical digestion- churning of food by stomach muscles.
What pH range does the stomach have?
1.0-3.0 (acidic).
The pyloric sphincter:
Controls the emptying of stomach contents into the small intestine.
The stomach contains:
Gastric juices, HCl, pepsinogen, mucus.
Gastric juices:
Secreted by cells lining the stomach.
What contributes to the chemical digestion of food and converts food into chyme?
The stomach.
HCl:
Kills harmful substances and converts pepsinogen into its active form “pepsin”.
What is pepsin?
A protein digesting enzyme.
What is mucus?
A protective alkaline layer that prevents the stomach from being broken down by HCL.
Ulcers:
Mucus layer in the stomach breaks down. Stomach wall exposed to HCl (aq) and pepsin. Increased acid production. Very painful, may be due to bacteria, diet and stress contribute.
