lect 4 pt 3

Accessory structures of the oral cavity

Teeth, tongue, and salivary glands.

Heterodont dentition

Condition of having teeth with different structures specialized for different functions.

Homodont dentition

Condition of having teeth that are all essentially identical in structure and function.

Incisors (primary function)

Nipping or cutting off bites of food.

Canines (primary function)

Grabbing and anchoring food.

Molars (primary function)

Grinding food, including roughage and plant material.

Diphyodont

Having two lineages/sets of teeth: a deciduous (baby) set and a permanent (adult) set.

Mechanical digestion by teeth

Physically breaks food into smaller pieces, increasing its surface-area-to-volume ratio.

Primary benefit of increasing food surface area

Exposes more food to digestive processes and improves opportunities for nutrient absorption.

Tongue (digestive functions)

Tasting and manipulating food.

Role of the tongue during chewing

Moves food around and positions it beneath the teeth for effective mechanical breakdown.

Three major pairs of salivary glands

Parotid, submandibular, and sublingual glands.

Primary mechanical function of saliva

Moistens food, making it easier to mechanically break down and swallow.

Bolus

A moist, compact mass of chewed food ready to be swallowed.

Salivary amylase target substrate

Carbohydrates.

Site where enzymatic digestion begins

In the mouth (oral cavity).

Function of bactericides in saliva

Kills bacteria in the mouth and on ingested food.

Function of bicarbonate in saliva

Neutralizes acidic foods and gastric acid that moves upward from the stomach.

Voluntary phase of swallowing

Conscious movement of the bolus toward the back of the tongue.

Esophageal phase of swallowing

Movement of the bolus through the esophagus toward the stomach.

Function of the uvula during swallowing

Closes off the nasopharynx to prevent food from entering the nasal cavity.

Function of the epiglottis during swallowing

Flips closed over the trachea to prevent food from entering the airway.

Anatomical relationship between pancreas and duodenum

Positions the pancreas to secrete bicarbonate and digestive enzymes directly into the duodenum via the pancreatic duct.

Site where bile enters the digestive tract

The duodenum (via the common bile duct).

What nutrients are absorbed in the large intestine as a result of bacterial activity?

The large intestine absorbs bacterial byproducts that provide nutrients, accounting for up to 10% of overall nutrient uptake.

Key substances reabsorbed by the large intestine

Water and remaining electrolytes.

Mechanism of feces formation in the large intestine

Reabsorbs water to compact remaining waste into solid feces.

Primary storage role of the large intestine

Temporary storage of solid waste.

Rectum (primary function)

Receives waste and signals the brain that elimination is imminent.

Significance of rectal musculature

Thick muscular walls assist in the physical elimination of solid waste.