View
261
Download
9
Category
Tags:
Preview:
Citation preview
LESSON 1TRANSPORT AND DEFENSE
Chapter 7
Body’s Organization
Groups of organs work together in an Organ system
The organs systems work together to maintain homeostasis
Homeostasis- maintaining constant internal conditions when external conditions change
Digestion
The body needs nutrients and substances from food
Digestion is the process that breaks down food into small molecules so they can be absorbed and moved into the blood. Two types of Digestion Mechanical Chemical
Mechanical Digestion
Food is chewed, churned, mixed, grinded etc.Major organs that use mechanical digestion
are the teeth, mouth, and stomach
Chemical digestion
Chemical reactions occur that break down large molecules of food into smaller molecules
There are several enzymes that help digestionAn enzyme is a special protein that speeds up
a chemical reaction but does not get used up or changed in the reaction
Ex- amylase in saliva
Organs of Digestion
Digestive TractMouthEsophagusStomachSmall intestineLarge intestineRectumAnus
Accessory organsTongueTeethSalivary glandsLiverGall bladderPancreas
Mouth
Both mechanical and chemical digestionFood is chewed, grinded, and made into smaller
pieces with the help of the tongue (mechanical)Saliva mixes with the food to moisten it and to start
the breakdown of carbohydrates (amylase and chemical)
Saliva is produced by three sets ofglands
Esophagus
The tongue has pushed the food into the back of the mouth
The epiglottis covers the trachea or windpipe so food does not pass into the lungs.
The esophagus is a muscular tube that pushes the food into the stomach by wave like contractions called peristalsis
Mucus lines the esophagus to keep the food moist
No Digestion
Stomach
Both Mechanical and chemical digestionMuscular bag that churns and mixes the food
(mechanical)Mixed with enzymes and hydrochloric acidHydrochloric acid works with an enzyme,
pepsin, to break down proteinsThe acid also kills bacteriaStomach also produces mucus which protects
the stomach from the acid and makes the food slippery
Chyme
Thin, watery liquid mixture of food, acid, and enzymes
Small intestine
Only chemical digestionAbout 30 feet in lengthSmall diameter compared to the large
intestineMost digestion occurs in the upper portion
called the duodenum.Greenish chemical, bile from the liver, is
mixed hereBile emulsifies fatSodium bicarbonate ( baking soda) is added
to neutralize the stomach acid
Small intestine
The pancreas makes the sodium bicarbonate and also produces insulin important in the regulation of the amount of glucose in your body
Absorption of nutrients occurs hereVilli- small finger- like projections increase
the surface area for absorption of nutrients
Large intestine
It is important for the absorption of waterPeristalsis slows down so water can be
absorbedThe material becomes more solid and
remains here until it is released from rectum and anus
Accessory organs
Teeth- chewingTongue- moving food to the back of the throatSalivary glands- produce salivaLiver- produces bileGall bladder- storage for bile until neededPancreas- makes enzymes, sodium
bicarbonate, and insulin for glucose regulation
Recommended