Digestive System Flashcards
what is digestion
Digestion is the physical and chemical breakdown of food
into simpler forms which are soluble in the bloodstream
what IS physical digestion
Mechanical (physical) digestion: the physical breakdown of large pieces of food into smaller pieces by chewing and stomach churning.
what are the stages of human nutrition- IDAE
- Ingestion: The taking of food into the body at the mouth.
- Digestion: The physical and chemical breakdown of food into small
pieces which are soluble in the bloodstream - Absorption: The taking in by the blood and lymph systems, of the end
products of digestion (small intestine) - Egestion: Elimination of faeces and unwanted material through the anus
WHAT IS CHEMICAL DIGETSION
Chemical Digestion: The breakdown of food into simpler molecules by enzymes and digestive juices.
What ways does digestion occur in the mouth
Occurs in two ways:
Physical breakdown by the teeth- increase scf for enzymes to act and sppeds up digestion
Chemical breakdown by enzymes like amylase which breaks down starch
what do insiders do
Incisors Cutting and slicing food.
what do canines do
Canines Gripping and tearing food.
what do pre molars do
Pre-molars Chewing and grinding food.
what do molars do
Molars Chewing and grinding food.
what does amylase do
Amylase is found in saliva which is produced by the salivary glands. These glands are located under the tongue, at the back of the jaws and in the cheeks.
what ensures food doesn’t go down the trachea
A flap of tissue called the epiglottis covers the trachea (windpipe) to ensure that the bolus enters the oesophagus.
what is the oesophagus made up of
The oesophagus is lined with circular muscles
pushed food along by peristalsis
what is persistalsis
Peristalsis: an involuntary wave of muscular contraction that causes food to move through the alimentary canal.
where does food enter the stomach
enters the stomach through the cardiac sphincter muscle at the top of the stomach
A sphincter muscle is a circular muscle that can open and close.
what is the stomach
The stomach is muscular bag that stores food
what will you find in th stomach
Mucous: Produced by goblet cells lining the stomach. It protects the stomach wall from being digested by its own enzymes and acid (prevents self-digestion).
Hydrochloric acid (HCl): Provides a pH of 1-2, kills bacteria, and activates pepsinogen. HCl is not an enzyme.
Pepsin: An enzyme that breaks down proteins into peptides.
what is pepsinogen
Pepsinogen is an inactive enzyme produced by glands lining the stomach.
It is activated by HCl to form pepsin.
Pepsin digests proteins into smaller units called peptides.
how does the stomach physically digest food
The stomach churns food and mixes it with gastric juices to form a liquid called chyme.
This increases the surface area of the food, allowing enzymes to digest the food more quickly.
what are the two parts of the small intestine and what is first
Duodenum and ileum in that order
how is the stomach protected from gastric juices
Mucous lines the stomach. This reduces the acidity near the stomach
wall
Pepsin is released in the inactive form pepsinogen
The cells lining the stomach are packed tightly together and can be
replaced very rapidly
what can occur if the stomach is not protected
If these mechanisms fail an ulcer may result
what happens in the duodenum
Cells lining the duodenum produce digestive enzymes.
The liver and pancreas release substances (e.g., bile, pancreatic juice) into the duodenum to assist in digestion.
what is the function of the ileum
The function of the ileum is absorption.
The ileum has numerous infoldings called villi. These increase the surface area for absorption.
what is the function of the duodenum
completes digestion of food
