Digestive system

Mesenteries

connective tissue sheets that hold the abdominal organs in place

Mesentery Proper

Also applied specifically to the mesentery associayed with small intestine, sometimes called the?

Mesenteries

Routes by which vessels and nerve pass from body wall to organs

Lesser Omentum

connect the lesser curvature of the stomach to the liver and diaphragm

Greater Omentum

• long, double folds of mesentery

• connects the greater curvature of the stomach to the transverse colon & posterior body wall

Greater Omentum

“ fatty apron “

Fatty Apron

Contains fat to insulate, cushion, and protect the abdominal organs

Alimentary Canal

• Continuous, coiled, hollow, muscular tube

• Open at both ends

Organs of alimentary tract

• Oral cavity

• Pharynx

• Esophagus

• Stomach

• Small Intestine

• Large Intestine

• Anus

Oral Cavity ( MOUTH)

• Mucous membrane lined cavity

• mastication

Parts of Oral Cavity

• Lips

• Cheecks

• Hard Palate

• Soft Palate

• Uvula

• Tongue

• Palate

• Tonsils

• Teeth

Lips

Protect the anterior opening of the mouth

Orbicularis Oris

Muscle that surrounds the mouth

Cheecks

Form the lateral walls of the mouth

Buccinator Muscle

muscle and buccal fat pad of the mouth

Uvula

Fleshly projection of the soft palate

Uvula

Fleshly projection of the soft palate

Uvula

Fleshly projection of the soft palate

Tongue

it is a large muscular organ that occupies most of the oral cavity

Lingual frenulum

Tongue is attached to the? ____ to the floor of the mouth

MOUTH

• moves foof in the mouth

• helps hold the food in place during mastication

• major role in the process of swallowing

• major sensory organ of the taste

Palate

• seperates the oral cavity from the nasal cavity

• prevents food from passing into the nasal cavity during chewing and swallowing

Parts of Palate

• Hard Palate

• Soft Palate

Hard Palate

Anterior part of the palate that contains bone

Soft Palate

Posterior part of the palate that contains skeletal muscle and connective tissue

Uvula

posterior part of the palate extension of the soft palate

parts of tonsils

Palatine - posterior end

Lingual- base of the tongue

Regions of the Teeth

• Crown

• Neck

• Root

Crown

• enamel-covered part of the tooth

• visible portion of a tooth

Neck

enameled part of tooth below gum line

Root

largest region of the tooth and anchors it in the jawbone

Enamel

• outermost layer of anatomical crown

• Non- living acellular. Protective.

Othe parts of the teeth

• Dentin

• Pulp cavity

• Periodontal ligamennts

• Gingiva

Dentin

living cellular, calcified tissue surrounding the pulp

Pulp Cavity

filled with blood vessels, nerves, and connective tissue

Periodontal Ligament

Hold tooth in socket

Gingiva

dense, fibrous C. T. covered by stratified squamous epithelium

3 Parts sa Salivary Glands

• Parotid

• Submandibular

• Sublingual

Parotid

• Largest in SG

• just anterior to wach ear

• Serous (watery) secretion

Submandibular

• Along the inferior border of the mandiible

• Mixed secretion, but more serous than mucous

Sublingual

• smallest in SG

• in the floor of the oral cavity

• primarily mucous secretion

Salivary Glands

• Prevents bacterial infection

Mucin

• Lubrication

Salivary amylase

• breaks down starch into disaccharides maltose and isomaltose

Bolus

Helps to form ____ for swallowing

MOUTH

• Matication of food

• Mixing masticated food with saliva

• Initiation of swallowing by the tongue

• Allows for the sense of taste

Nasopharynx

Not part of the digestive system

Oropharynx

Posterior to oral cavity

Laryngopharynx

below the oropharynx and connected to the esophagus

Esophagus

• muscular tube that runs from pharynx to stomach through the diaphragm

• transports food from the pharynx to the stomach

1o in (25 cm )

Esophagus is about how long?

Esophagus

Anterior to the vertebrae and posterior to the trachea

Skeletal Muscle

Upper 2/3 of the esophagus

Smooth Muscle

lower 1/3 of esophagus

2 types of Sphinters

• Upper esophageal sphincter (UES)

• Lower esophageal sphincter (LES)

Lower Esophageal Sphincter

Contains numerous mucous glands

STOMACH

C-shaped organ; enlarged segment of the digestive tract that houses food for mixing with hydrochloric acid and other secretions

LUQ

Stomach is located in the?

cardiac sphincter

Food enters at the

Pyloric Sphincter

Food empties into the small intestine at the

Regions of the stomach

• Cardiac region

• Fundus

• Body

• Pylorus

Cardiac Region

Near the heart

Fundus

Most superior part of the stomach

Body

midportion, largest part

Pylorus

Funnel- shaped terminal end

External Regions of the stomach

• Lesser curvature

• Greater Curvature

3 Layers of muscle in the Stomach

• outer longitudinal layer

• middle circular layer

• inner oblique layer

Rugae

• large folds of submucosa and mucosa

• esp when the stomach is empty

• fold disappear when the stomach is filled

STOMACH

Temporary storage tank for food

Stomach

site of food breakdown

Stomach

Chemical breakdown of proteins begins

Stomach

Chemical breakdown of proteins begins

Stomach

Delivers chyme to the small intestine

Structures of stomach mucosa

• Surface Mucus cells

• Mucous neck cells

• Endocrine cells

• Chief cells

• Parietal cells

Gastric Pits

• openings for gastric glands

• lined with simple columnar epithelium

Surface Mucus Cells

• produce mucus

• coats and protects the stomach lining

Mucous neck cells

produce mucus

Endocrine cells

Produce regulatory chemicals

Chief cells

produce protein-digesting enzymes (pepsinogen)

Parietal cells

poduce hydrochloric acid and intrinsic factors

Secretions of the stomach

• Mucus

• Intrinsic factors

• HCI

• Pepsin

Chyme

Ingested food plus stomach secretions

Mucus

surface and neck mucous cells

Mucus

• Viscous and alkaline

• Protects from acidic chyme and enzyme pepsin

Intrinsic Factor

• Binds with vitamin B12 and helps it to be absorbed in the ileum.

Vit B12

necessary for DNA synthesis and RBC production

HCI

• Parietal Cells

• Kills bacteria (found in ingested food)

• Denatures proteins

• Helps convert pepsinogen to pepsin

Pepsin

• Chief Cells

• breaks the covalent bonds in proteins

Cephalic Phase

"get started" phase; stomach secretions are increased in anticipation of incoming food

1st step

( Cephalic. Phase ) The taste or smell of food, tactile sensations of food in the mouth, or thoughts of food stimulate medulla oblongata

2nd step

( Cephalic Phase )Parasympathetic action potentials are carried by the vagus nerves to the stomach.

3rd Step

( Cephalic Phase) Parietal and Chief cells
(HCI and pepsin) stimulate the secretion of the hormone gastrin and → histamine.

4th step b

( Cephalic Phase) Gastrin and histamine stimulate further secretion of.HC/and pepsin

Gastrc Phase

• "go for it." phase, most of the stimulation of secretion occurs

• activated by the presence of food in the stomach

1st Step

( Gastrric Phase) Distention of the stomach → parasympathetic reflex → vagus nerve the medulla oblongata

2nd step

( Gastric Phase) Medulla oblongata stimulates further secretions of the stomach.

3rd step

(Gastric Phase) Distention also stimulates local reflexes that amplify stomach secretions.

Intestinal phase

• "slow down" phase; stomach secretion decreases

• Chyme in the duodenum with a pH less than 2 or containing lipids inhibits gastric

1st mechanism of Intestinal Phase

Sensory input to the medulla from the duodenum inhibits the moto from the medulla the stomach. Stops secretion of pepsin and HCI.

2nd mechanism of intestinal phase

Local reflexes inhibit gastric secretion