4.2 - the mouth, pharynx, and esophagus

TWO MAIN PROCESSES OF DIGESTION OCCUR BEFORE ABSORPTION CAN TAKE PLACE

mechanical digestion: is the physically breaking down of large food items to prepare for digestion

chemical digestion: acids and enzymes break down macromolecules into smaller organic molecules or even monomers

ASSOCIATED STRUCTURES OF THE MOUTH

  1. the teeth

  2. the tongue

  3. the hard palate

  4. the soft palate

  5. salivary glands

THE TEETH

used to chew food into smaller pieces, convenient for swallowing

  • 32 teeth in adults, 20 in children

remember: enamel, dentine, pulp

enamel: very hard substance covering the tooth

dentine: the softer bone-like tissue

pulp: living part of the tooth

MOUTH ANATOMY

THE TONGUE

  • the primary function is the form the bolus after chewing is complete

  • assists in swallowing by pushing food down into the pharynx

SALIVARY GLANDS

produce saliva which helps lubricate, soften, and break food down

the 3 primary paired glands are:

  1. parotid glands

  2. sublingual glands

  3. submandibular glands

serous cells in these glands produce salivary amylase

amylase - begins starch digestion, breaking it down into maltose

amylase is hydrolytic. hydrolytic enzymes break bonds using water

THE PHARYNX

the pharynx is a passageway that connects the nasal passage to the trachea and our oral cavity to the esophagus

during swallowing, an automatic reflexive response occurs. the soft palate moves up and closes off the nasalpharynx passage while the epiglottis covers the passageway to the trachea - glottis

THE ESOPHAGUS

esophagus: muscular pathway that passes the bolus from the pharynx to the stomach

normally collapsed but opens when swallowing

peristalsis begins here and continues throughout the organs in the rest of the digestive tract

PERISTALSIS

peristalsis is the process by which food is pushed down along the digestive tract through wave like contractions

circular muscles and longitudinal muscles play a key role in this process

in front of the bolus circular muscles relax and longitudinal muscles contract - widening and shortening the esophagus

behind the bolus circular muscles contract and longitudinal muscles relax, pinching the esophagus and pushing the bolus down