Digestive system

What are the two main groups of the digestive system organs?

Alimentary (nourish) canal and accessory digestive organs

What does the alimentary canal do?

Performs all digestive functions (ingests, digests, absorbs, and defactes)

What does the accessory organs do?

Accessory organs (Teeth, tongue, and sever large digestive glands) assist the process of digestive breakdowns in various ways

What is the alimentary canal also called?

The gastrointestinal (GI) tract

What is the GI tract?

a continuous, coiled,hollow muscular tube that winds through the ventral body cavity and is open at both ends

What are the organ of the GI tract?

The organs include the mouth, esophagus, stomach, intestines, and pharynx

How long are the alimentary canal?

about 30 feet in humans

The mouth

Also known as oral cavity, mucous membrane lined cavity

The lips

Also known as labia, protect its anterior opening

Soft palate

Back part of the mouth which forms the posterior roofT

The Uvula

Fleshy fingerlike projection of the solf palatem which extends downward from the soft palate.

The vestibule

Space between the lips and gums, leading to the oral cavity.

What is the area contained by the teeth

The oral cavity proper

The tongue

A muscular organ in the mouth that assists with tasting, swallowing, and speaking.

What are the bony attachments of the tongue

The bony attachments of the tongue are primarily the hyoid bone and the styloid processes of the skull

What is the lingual frenulum

A fold of mucous membrane, secures the tongue to the floor of the mouth and limits its posterior movements

What is tongue tied?

A condition where the lingual frenulum is shorter than normal, restricting tongue movement and affecting speech.

Can tongue tied be corrected?

Yes, it can be corrected surgically by cutting the fenulum

Palatine tonsils

At the posterior end of the oral cavity

Lingual tonsils

Covers the base of the tongue just beyond

What happens when food enters the mouth

When food enters the mouth it is mixed with saliva and is masticated (chewed)

Where does food pass through?

Passes posteriorly into the oropharynx and laryngopharynx

The walls of the alimentary canal organs from the esophagus to the large intestine are made up of the same 4 tissue layers or tunics:

mucosa, submucosa, muscularis externa, and serosa.

Mucosa

Innermost layer of membrane that lines the caivty (lumen) of the organ.

Submucosa

Found just beneath the mucosa, soft connective tissue layer containing blood vessels, nerve endings, lymphatic vessels, and lymphoid tissue.

Muscularis externa

Muscle layer made up of inner circular layer and an outer longitudinal layer of smooth muscle cells

Serosa

Outermost layer of the wall. Consists of single layer flat, serious fluid producing cells.

Peritonitis

Inflammation of the peritoneum, the tissue lining the abdominal wall and covering the abdominal organs, often due to infection or injury.

What two important intrinsic nerve plexuses are in the alimentary canal wall and what do they do?

The submucosal nerve plexus and myenteric nerve plexus; they are part of the autonomic nervous system and regulate mobility and secretory activity of GI tract organs

Stomach

Located on the left side of abdominal cavity, it is responsible for digesting food, mixing it with gastric juices, and breaking it down into a semi-liquid form called chyme.

cardioesophageal sphincter

A circular muscle at the junction of the esophagus and stomach that regulates the flow of food and prevents the backflow of stomach contents.

pyloric sphincter

A circular muscle at the junction of the stomach and small intestine that controls the passage of chyme into the duodenum and prevents backflow into the stomach.

How long is the stomach?

Varies from 15-25 cm

How much cant ehs stomach hold when full?

4 liters

Greater omentum

A large fold of peritoneum extending from the stomach to the intestines, providing support and insulation, and containing fat.

lesser omentum

A fold of peritoneum extending from the stomach to the liver.

Gastric pits

Depressions in the stomach lining that contain specialized cells producing gastric juices, including acid and enzymes.

gastric glands

Structures in the stomach lining that secrete gastric juices, such as hydrochloric acid and digestive enzymes. They play a key role in digestion.

instrinsic factor

A glycoprotein produced by the parietal cells of the gastric glands, essential for vitamin B12 absorption in the intestines.

Chief cells

Produce protein-digesting enzymes, mostly pepsinogens.

pepsinogens

Inactive precursors to pepsin, secreted by chief cells in the gastric glands, which are activated in the acidic environment of the stomach.

What do the parietal cells produce?

corrosive HCL

Enteroendocrine cells

release hormones like gastrin that regulate digestive processes.

Chyme

The substance (kinda like heavy cream) produced after being processed in the stomach, goes through the small intestine through the sphincter

Small intestine

The long, coiled tube where most digestion and nutrient absorption occurs, following the stomach.

Large intestine

The part of the digestive system that absorbs water and forms waste for elimination, also known as the colon.

Duodenum of small intestine

The first section of the small intestine, where a significant amount of digestion occurs, receiving bile and pancreatic juices to aid in processing food.

Jejunum of small intestine

The second section of the small intestine, involved in further digestion and nutrient absorption, following the duodenum.

Ileum of small intestine

The final section of the small intestine, where the majority of nutrient absorption continues before food passes into the large intestine.

Ileocecal valve

valve located at the junction of the ileum and the cecum, regulating the flow of material from the small intestine to the large intestine.

pancreatic ducts

tubes that carry digestive enzymes from the pancreas to the small intestine, aiding in the digestion of food.

bile duct

The tube that carries bile from the liver and gallbladder to the small intestine, playing a crucial role in fat digestion.

Microvilli

tiny projections of the plasma membrane of the mucosa cells that give the cell surface a fuzzy appearance, also known as the brush border

Villi

finger like projections of the mucosa that increase the surface area for absorption of nutrients in the small intestine.

Lacteal

a lymphatic capillary located in the center of a villus, responsible for the absorption of dietary fats and fat-soluble vitamins in the small intestine.

circular folds

Deep folds of both mucosa and submucosa layers

What is the # of permanent teeth

32

What are incisors

Front two teeth that are adapted for cutting

What are canines

Pointy teeth used for tearing food apart

What are Salivary glands functions in the mouth

The salivary glands are exocrine glands that produce saliva, which contains enzymes that begin the digestive process and help in lubricating food for swallowing.

What are parotid glands functions in the mouth

The parotid glands are the largest salivary glands that produce and secrete saliva, which helps with digestion and keeps the mouth moist. They play a crucial role in the initial stages of digestion by releasing enzymes.

Mumps

Common childhood disease, inflammation of the parotid glands

What are the functions of submandibular glands and sublingual glands

They empty their secretions into the floor of the mouth through tiny ducts

Bolus

A soft mass of chewed food formed in the mouth, which is later swallowed.

Pancreas

Extends across the abdomen and produces enzymes that break down all categories of digestible foods

Liver

Largest gland in the body that processes nutrients, detoxifies harmful substances, and produces bile for fat digestion.

falciform ligament

A thin ligament that connects the liver to the anterior abdominal wall and diaphragm.

What are the processes of the GI tract

Ingestion, propulsion, food breakdown: mechanical digestion, and food breakdown: chemical digestion

what happens in ingestion

The act of taking in food and liquids into the body, typically through the mouth.