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Flashcards in digestive system Deck (50)
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1

Ingest, transport and digest food (Mechanical: peristalsis & segmentation & Chemical)

Absorbs nutrients into blood.

Expels the waste products from the body (defecation).

Two separate categories of organs:
Digestive organs and accessory digestive organs.

Collectively make up the gastrointestinal (GI) tract (digestive tract or alimentary canal)

starts at mouth & ends at anus

digestive system

2

Forms a continuous tube, about 30 feet (9–10 meters) from the mouth to the anus.

From the esophagus through the large intestine is a tube composed of four concentric layers (Tunics)

GI tract

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oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.

GI tract organs

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epithelium, connective tissue (CT), smooth muscle, glands. May have folds to increase surface area & expansion.

Mucosa (GI tract tunics)

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CT, glands, blood vessels

submucosa (GI tract tunics)

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two layers of smooth muscle (circular and longitudinal), sphincters. Mechanical processing, propulsion, parasym & sym innervation

Muscularis: (GI tract tunics)

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serous membrane, protective outer layer

Adventitia/serosa (GI tract tunics)

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Protects against corrosive effects of digestive enzymes and acids

Defense against swallowed/resident pathogens

Mechanical stresses/abrasions

GI tract lining

9

Food is taken into the mouth where mechanical and chemical digestion takes place.

introduction

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Entrance to the GI tract.

Initial site of mechanical digestion (mastication) and chemical digestion (enzymes in saliva).

Anteriorly by the teeth/lips Posteriorly by the oropharynx Superior by the hard/soft palates Inferiorly contains the tongue and Laterally by the cheeks.

Vestibule is the space between the cheeks, lips and gums.

Tongue: manipulates material inside mouth that leads to swallowing. Papilla, skeletal muscle, lingual frenulum, lingual tonsils

Oral cavity (mouth)

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When swallowing, the soft palate and the uvula elevate to close off the opening of the nasopharynx.

palate

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anterior two-thirds, maxilla & palatine bones

hard palate (palate)

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: posterior one-third is soft and muscular

soft palate (palate)

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: extends inferiorly from the posterior part of the soft palate

uvula (palate)

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: lateral walls of oral cavity

palatine tonsils (palate)

16

Moistens ingested food, turns into bolus.

Moistens and cleanses the oral cavity structures.

Contains antibodies and an antibacterial element that help inhibit bacterial growth.

First step in chemical digestion occurs when amylase begins to break down carbohydrates.

Watery medium into which food molecules are dissolved so taste receptors can be stimulated.

Volume secreted daily ranges from 1.0 to 1.5 L. Most is produced during mealtime

salivary gland functions

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Three pairs of salivary glands:

parotid, submandibular, sublingual glands

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largest salivary glands, anterior and inferior to the ear, partially overlying the masseter muscle.

Produce about 25–30% of the saliva

Secretes fluid rich in amylase to breakdown carbs.

Parotid (salivary gland)

19

Inferior to the body of the mandible. A duct from each gland opens on the lateral sides of the lingual frenulum.

Produces most of the saliva (about 60–70%).

Secretes semi-viscous fluid

submandibular (salivary gland)

20

: Inferior to the tongue. Each gland extends multiple tiny ducts that open onto the inferior surface of the oral cavity.

Contribute only about 3–5% of the total saliva.

Secretes thick, stringy mucous

sublingual (salivary gland)

21

Responsible for mastication, the first part of the mechanical digestion process.

A tooth has an exposed crown, a constricted neck, and one or more roots that anchor it in the jaw.

Roots of the teeth fit tightly into alveoli, within the alveolar processes of both the maxillae and the mandible.

Two sets of teeth develop and erupt during a normal lifetime.

In an infant, 20 deciduous/primary teeth erupt between 6 and 30 months.

These teeth are eventually lost and replaced by 32 permanent/secondary teeth.

teeth

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incisors, cuspids/canines, bicuspids/premolars, molars.

types of teeth

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the roots, alveoli, and ligament (that binds the roots to the alveolar processes)

Gomphosis joint

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passageway for food, air and liquids, pharyngeal muscles initiate swallowing of bolus

Pharynx

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long muscular tube (1 ft). Posterior to trachea, goes into peritoneal cavity (esophageal hiatus) and empties into stomach

Esophagus

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leakage can cause ‘heart burn’ or ‘reflux’

Upper esophageal sphincter, lower esophageal (cardiac) sphincter

27

Located in upper left quad. of abdominal cavity

Acts as temporary storage for food with limited amount of absorption

Mechanical breakdown of food, digestion of proteins aided by gastric juices (hydrochloric acid pH2.0) and digestive enzymes.

Lined by simple columnar epithelium and renewed every 3-6 days.

Regions/parts: cardia, fundus, body, pylorus, rugae, pyloric sphincter

Bolus becomes chyme

stomach

28

Stabilize position of attached organs, access for B.V., nerves and lymphatic

Mesentaries

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between stomach and liver

Lesser omentum

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posterior to stomach body wall to anterior surface of intestines

greater omentum