Functions of the Digestive System

What is the function of the digestive system?

To break down food into smaller nutrients that the body can use for energy, growth, and repair, and then eliminate the waste.

What are the steps of the digestive system?

Ingestion (eating), secretion (releasing enzymes and mucus), mixing and propulsion (moving food through the body), and mechanical and chemical digestion (breaking down food), absorption (taking nutrients into the body), and excretion (removing waste)

Oral cavity

Digestion, speech, and respiration

Lips

Essential for eating, speech, and facial expression

Teeth

Help with mastication and speech

Tongue

Help with tasting food, swallowing, and speaking

Salivary Glands

Produce saliva that has enzymes that help with the chemical break down of food into nutrients

Tonsils (palatine, lingual, pharyngeal)

Act as a first line of defense for your body’s immune system by trapping germs that enter through the mouth and nose

Hard palate

separates the oral and nasal cavities (functions in chewing and swallowing)

Soft palate 

blocks food from entering the nasal passages during swallowing

Uvula

helps with speech and swallowing, acts as parrt of the immune system, and keeps the throat moist

Pharynx (nasopharynx, oropharynx, and laryngopharynx)

passage way for air and food

Esophagus

transports food from the throat to the stomach via involuntary muscle contractions called peristalsis (moving food down and preventing stomach contents from coming back up)

Cardiac sphincter

prevents stomach contents from flowing back up into the esophagus

Stomach

Churning (mechincal digestion), store food temporarily, break it down through mechanical and chemical digestion, and release it in a controlled manner to the small intestine

Small Intestine

site of greatest amount of digestion and absorption of nutrients and water

Large Intestine

absorbs water and electrolytes, produes and absorbs certain vitamins through its gut bacteria, and forms and stores feces for elimination

Rectum

store waste, known as stool, before it is elimated from the body

Anal canal

the anal canal converys fecal matter from the rectum to the anus

Anus

Controls the expulsion of feces from the body through a process called defacation

Pancreas

It has two main functions: it is an exocrine gland that produces digestive enymes to break down food, and an endocrine gland that produces hormones like insulin to regulate blood sugar

Liver

Bile production

Gallbladder

Stores bile

Incisor

Biting and cutting food

Canine

to tear and rip food

Bicuspid (premolar teeth)

Chewing, grinding and crushing food

Molars

crush and grind food into smaller, more digestible pieces

Root

to anchor the tooth firmly in the jawbone and to transmit chewing forces to the jaw, which helps keep it healthy and dense

Crown

provides strength to the teeth

Neck

connects the crown to the root and is the site of attachment for the gums

Dentin

transmit sensations like hot, cold, and pressure to pulp

Enamel

protect the underlying layers of the tooth from damage and decay

Cementum

anchor the tooth to the surrounding bone by serving as the attachment point for the periodontal ligament

Gingiva

act as a protective barrier against bacteria

Periodontal ligaments

anchor the tooth in its socket

Pulp

provide nutriton and moisture (in pulp cavity)

Root canal

nourishment and sensation

Parotid salivary gland

Largest, serous (more watery) saliva that aids in chewing and swallowing and begins the digestion of starches

Submandibular salivary gland

Mucous and Serous Fluid (mixed), produce saliva

Sublingual salivary gland

Smallest. produce saliva that is a Mixed type, but primarily mucous

Papillae

help grip food and contain the taste buds that allows you to taste

Tastebuds

to detect the five basic tastes - sweet, salty, sour, umami, and bitter

Palatine tonsil

act as a first line of defense for the immune system by trapping and destroying germs that enter the body through the mouth or nose

Lingual tonsil

to act as a first line of defense for the immune system by fighting off infections that enter the body through the mouth

Pharyngeal tonsil

serve as a first line of defense in the immune system by trapping and destroying pathogens that are inhaled or ingested

oropharynx

to act as a passageway for air, food, and fluids, connecting the mouth to the esophagus

laryngopharynx

to act as a shared passageway for both air and food, directing air to the larynx and food to the esophagus

nasopharynx

serve as a passageway for air from the nasal cavity to the rest of the respiratory system

cardia

to serve as a gateway for food and liquids entering the stomach from the esophagus and to prevent stomach contents from flowing back up

fundus

to store undigested food and gases, acting as a reservoir that can expand to accommodate a meal

body

temporarily store food, churn it mechanically, and pre-digest it by mixing it with gastric juices containing acid and enzymes

pylorus

to act as a gatekeeper, controlling the flow of partially digested food, or chyme, from the stomach into the small intestine (duodenum)

pyloric sphincter (valve)

to act as a gatekeeper, controlling the flow of partially digested food (chyme) from the stomach into the small intestine

rugae

to allow the organ to expand and stretch to accommodate varying amounts of food, while also increasing the surface area for digestion and absorption

duodenum

to continue the digestion of food coming from the stomach by mixing it with bile and pancreatic juices, which breaks down food into nutrients

jejunum

to absorb the majority of nutrients from digested food

ileum

absorb nutrients

ileocecal valve

to act as a one-way gate between the small and large intestines, preventing the backward flow of contents and bacteria from the colon into the small intestine

plicae circularis

to increase the surface area for nutrient absorption in the small intestine and slow the passage of chyme

duodenal papillae

serve as the entry point for bile and pancreatic juice into the small intestine, where they aid in digestion

villi

to increase the surface area of the small intestine to maximize the absorption of digested nutrients from food

cecum

to absorb water and salts from the remaining indigestible food matter coming from the small intestine and to mix it with mucus to form feces

appendix

likely functions as a safe house for beneficial gut bacteria, helping to repopulate the intestines with good bacteria after illnesses like diarrhea

ascending colon

to absorb the remaining water, electrolytes, and nutrients from indigestible food matter and solidify it into stool

transverse colon

to move waste along the large intestine

descending colon

to store waste and continue the process of absorbing water and electrolytes from digestive material

sigmoid colon

to store feces before it is eliminated from the body

taenia coli

to contract and shorten the large intestine to form sac-like pouches called haustra, which helps in the movement of fecal matter through the colon