CHAPTER 5 - DIGESTIVE SYSTEM PART 1

CHAPTER 5 – DIGESTIVE SYSTEM

·       Functions of the digestive system are; ingestion, digestion, absorption and elimination

·       Digestive enzymes speed up chemical reactions and aid in breakdown

·       Complex proteins are digested to simpler “amino acids” complicated sugars are reduced to simpler sugars such as glucose. Large fat molecules called Triglycerides are broken down to fatty acids.

·       Digestion occurs in the mouth, stomach and small intestine

·       Absorption = nutrients from digested food pass through the lining cells or epithelium of small intestine and into the blood stream. Nutrients then travel to all cells of the body, cells then breakdown nutrients in the presence of oxygen to release energy.

·       Oral = (or/o) means pertaining to the mouth

·       Hard palate = roof of mouth

·       Soft palate = behind hard palate, uvula hangs off it

·       Rugae = irregular ridges in the roof of mouth

·       Uvula = hangs from the back of mouth helping with speech and sounds.

·       Tongue = is attached to the lower jaw bone by muscles

·       Mastication = chewing

·       Deglutition = swallowing

·       Papillae = raised areas on tongue with taste buds

·       Tonsils = mass of lymphatic tissue on both sides of the oropharynx ( part of throat near mouth ). They are filters that protect the body from invasive microorganisms and produce lymphocytes which are disease fighting white blood cells

·       We have 32 permanent teeth

·       Gums = fleshy tissue surrounding the teeth

Teeth

·       Buccal surface = faces the cheeks

·       Lingual surface = faces the tongue

·       Labial surface = faces the lips

Facial (Faci/o) = face

Inner anatomy of the tooth

1.    Crown – above gum line, top of tooth

2.    Root – lies within the bony tooth socket

3.    Enamel – outermost layer of the crown that protects the tooth. Enamel is the hardest tissue in the body

4.    Dentin – main substance of tooth, lies beneath enamel and goes throughout the crown. Dentin affects teeth color but enamel is clear.

·       Cementum = covers, protects and supports the dentin in the root.

·       Periodontal membrane = surrounds cementum and holds the tooth in place

·       Pulp = lies under the dentin and fills the center of the tooth

·       Pulp/Root canal = contains blood vessels, nerve endings, connective tissues and lymphatic vessels.

·       Root canal therapy happens when there is an infection in the pulp canal.

·       Three pairs of salivary glands surround and empty into the oral cavity. These endocrine glands produce saliva, lubricating the mouth.

·       Saliva = contains digestive enzymes and healing growth factors.

·       Saliva is released from 3 glands called; parotid gland, submandibular gland, sublingual gland on both sides of the mouth. They produce 1.5L of saliva daily.

Pharynx

·       Pharynx is a muscular tube, about 5 inches long lined with mucous membrane.

·       Serves as a passage way for air to the nose and windpipe and for food travelling from oral cavity to esophagus

·       When swallowing a cartilaginous flap of tissue called epiglottis covers the trachea so food cant enter.

Esophagus

·       9-10 inch fibromuscular tube extending from the pharynx to the stomach.

·       Peristalsis happens in the esophagus and is an involuntary, progressive, rhythmic contraction of muscles that propels a bolus which is a mass of food down towards the stomach like squeezing a marble through a tube.