Digestive System

3 main functions– Digestion – Absorption – Elimination

2 main divisions– Alimentary canal

• Tube from mouth to anus

– Accessory organs• Aid in digestion

Digestive System

Digestive System

Digestion– Process of breaking

down food into molecules the body can absorb.

Absorption– Process of

molecules passing from the alimentary canal to blood stream.

Elimination– Process of

the body getting rid of unabsorbed solids and liquids• Feces• Urine

Alimentary Canal Tube from mouth

to anus– Mouth / oral cavity

• Ingestion– Putting food in

your mouth

• Mastication– Chewing

• Bolus– Mass of chewed

food

Tube from mouth to anus– Mouth / oral cavity

• Ingestion– Putting food in

your mouth

• Mastication– Chewing

• Bolus– Mass of chewed

food

Alimentary Canal Throat / Pharynx

– Connects mouth to esophagus

– 3 sections • Nasopharynx• Oropharynx• laryngopharynx

– Deglutition• swallowing

Throat / Pharynx– Connects mouth

to esophagus– 3 sections

• Nasopharynx• Oropharynx• laryngopharynx

– Deglutition• swallowing

Alimentary Canal

Esophagus– Connects throat

to the stomach• Epiglottis

– Covers the trachea during swallowing

– Peristalsis• Contraction of

smooth muscle to move food through digestive tract.

Alimentary Canal Stomach

– Sac like organ• Bolus mixes with

gastric juices…– Hydrochloric acid– Pepsin

• Chyme – Soupy mass of

food and gastric juices

– Digestion continues– Absorption begins

Alimentary Canal Small intestine

– Connects stomach to the large intestine

– 3 main parts• Duodenum• Jejunum • Ileum

– Most nutrient absorption occurs here.

– Fat is broken down by bile.

Alimentary Canal

Large intestine– 3 main sections

• Cecum• Colon• Rectum

– Anus – Opening to the

rectum

– Elimination occurs here

Accessory Organs

All the organs that aid in the digestive process.– Teeth– Salivary glands– Saliva– Tongue– Muscles – Liver– Pancreas

Accessory Organs

Teeth– Incisors – cut– Cuspids – tear– Premolars – chew– Molars – grind,

chew• Chewing

– mastication

• Mechanical break down of food.

Accessory Organs

– Saliva glands• 3 pair

– Parotid– Sublingual– Submandibular

• Produce saliva

– Saliva • Lubricates food• Enzyme

– Salivary amylase

– Chemically breaks down food

Accessory Organs

Tongue (glossus muscle)

– Moves and holds food between teeth.– Moves food (bolus) towards throat.

Muscles– Mastication =

• chewing

– Deglutition = • swallowing

– Paristalsis = • contraction of smooth muscle

Accessory Organs Liver

– Produces bile• Breaks down

fat for absorption

• Stored in the gallbladder

• Yellowish-green alkaline fluid

• Found in small intestine

Accessory Organs

Pancreas– Produces and

secretes pancreatic juices containing digestive enzymes• Empty into small

intestine• Completes the

breakdown of carbohydrates

Conclusion

Understanding the digestive is very important.

Teeth are organs of the digestive system, and tooth decay (caries) is a disease of the digestive system.

Any questions??