Chapter 23: Digestive System Flashcards by roxy rios

Alimentary canal (gastrointestinal or GI TRACT):

◼️mouth to anus
◼️digests food and absorbs fragments
◼️mouth, pharynx, esophagus , stomach, small intestine, large intestine

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Two groups of organs:

◼️alimentary canal

◼️accessory digestive organs

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Accessory digestive organs:

◼️teeth, tongue, gallbladder 
◼️digestive glands:
▪️salivary glands 
▪️liver 
▪️pancreas

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6 essential activities:

1⃣ingestion
2⃣propulsion
3⃣mechanical breakdown
4⃣digestion
5⃣absorption
6⃣defecation

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GI tract regulatory mechanisms:

◼️mechanoreceptors and chemoreceptors

◼️intrinsic and extrinsic controls

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Mechanoreceptors and chemoreceptors :

◼️respond to stretch, change in osmolarity and pH , and presence of substrate and end products of digestion
◼️initiate reflexes that :
▪️activate or inhibit digestive glands
▪️stimulate smooth muscle to mix and move lumen contents

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Intrinsic and extrinsic controls:

◼️short reflexes: enteric nerve plexuses (gut brain) respond to stimuli in GI tract
◼️long reflexes : respond to stimuli inside or outside GI tract ; involves CNS centers and autonomic nerves
◼️hormones from cells in stomach and small intestine stimulate target cells in same or different organs to secrete or contract

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Peritoneum:

◼️serous membrane of abdominal cavity
◼️visceral peritoneum on extern surface of most digestive organs
◼️parietal peritoneum lines body wall

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Peritoneal cavity :

◼️between two peritoneums

◼️fluid lubricates mobile organs

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Mesentary:

◼Double layer of peritoneum
◼️routes for blood vessels, lymphatics , and nerves
◼️holds organs in place ; stores fat

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Retroperitoneal organs:

Posterior to peritoneum

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Intra peritoneal :

Surrounded by peritoneum

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Peritonitis:

◼️inflammation of peritoneum
◼️causes by ex piercing abdominal wound, perforating ulcer , ruptured appendix
◼️peritoneal covering stick together, localizing infection
◼️dangerous and lethal if widespread
◼️treated with debris removal and antibiotics

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Splanchic circulation:

◼️branches of aorta serving digestive organs :
▪️hepatic, splenic, left gastric
▪️inferior and superior mesenteric

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Hepatic portal circulation:

◼️drains nutrient -rich blood from digestive organs

◼️delivers it to the liver for processing

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Four basic layers of the alimentary canal:

◼️mucosa
◼️sub mucosa
◼️muscularis externa
◼️serosa

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Mucosa lines what?

Lines lumen

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Mucosa 3 functions:

◼️secretes mucus, digestive enzymes, and hormones
◼️absorbs end products of digestion
◼️protects against infectious disease

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Mucosa has what three layers?

◼️epithelium
◼️lamina propria
◼️muscularis mucosae

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Epithelium :

◼️simple columnar epithelium and mucus secreting cells (most of tract)
▪️mucus : protects digestive organs from enzymes
And
Eases food passage
◼️May secrete enzymes and hormones (ex: in stomach / small intestine)

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Lamina propria:

◼️loose areole connective tissue
◼️capillaries for nourishment and absorption
◼️lymphoid follicles (part of MALT)
▪️defend against microorganisms

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Muscularis mucosae:

Smooth muscle ➡️ local movements of mucosa

Sub mucosa :

◼️areolar connective tissue

◼️blood and lymphatic vessels lymphoid follicles, and submucosal nerve plexus

Muscularis externa:

◼️responsible for segmentation and peristalsis
◼️inner circular and outer longitudinal layers
▪️circular layer thickens in some areas ➡️sphincters
▪️myenteric nerve plexus between two muscle layers

What tissue type is Visceral peritoneum?

◼️️areolar connective tissue covered with mesothelium in most organs

Visceral peritoneum is replaced by what __ in the esophagus?

Adventitia

Retro peritoneal organs have both _ and _ ?

Adventitia and serosa

Where does is the intrinsic nerve supply of alimentary canal come from?

Enteric neurons (more than spinal cord)

Major nerve supply to GI tract wall; control motility :

◼️Submucosal nerve plexus | ◼️myenteric nerve plexus

Submucosal nerve plexus :

Regulates glands and smooth muscle in the mucosa

Myenteric nerve plexus:

Controls GI tract motility

Enteric nervous system:

◼️linked to CNS via afferents visceral fibers ◼️long ANS fibers synapse with enteric plexuses ▪️sympathetic impulses inhibit digestive activities ▪️parasympathetic impulses stimulate digestive activities

Oral (buccal) cavity:

◼️bounded by lips, cheeks, palate, and tongue ◼️oral office is anterior opening ◼️lined with stratified squamous epithelium

What is the oral cavity lined with?

Stratified Squamous epithelium

Which muscles so the lips and cheeks contain?

◼️Oris | ◼️buccinator

Oral vestibule:

Recess internal to lips (Labia) and cheeks, external to teeth and gums

Oral cavity:

Proper lies within teeth and gums

Labial frenulum:

Median attachment of each lip to gum

Hard palate:

◼️Palatine bones and palatines processes of maxillae | ▪️slightly corrugated to help create friction against tongue

Soft palate :

Folded form mostly skeletal muscle

What does the soft palate do?

Closes off nasoparynx during swallowing

Uvula projects __ from its free edge ?

Downward

Tongue is what kind of muscle ?

Skeletal

3 functions of the tongue:

◼️repositioning and mixing food during chewing ◼️formation of bolus ◼️initiation of swallowing , speech, and taste

What do intrinsic muscles do with tongue?

Change shape

What do extrinsic muscles do with tongue?

Alter tongues position

Lingual frenulum:

Attachment to floor of mouth

The tongues surface bears 4 papillae:

◼️filiform ◼️fungiform ◼️vallate (circumvallate) ◼️foliate

Filiform:

◼️whitish, give the tongue roughness and provide friction; do not contain taste buds

Fungiform:

Reddish, scattered over tongue; contain taste buds

️Vallate :

V- shaped row in back of tongue; contain taste buds

Foliate:

On lateral aspects of posterior tongue; contain taste buds that function primarily in infants and children

Lingual lipase:

◼️secreted by serous cells beneath foliate and ️vallate papillae secrete ◼️fat-digesting enzyme functional in stomach

Terminal sulcus marks division between:

◼️body- anterior 2/3 residing in oral cavity ◼️root- posterior third residing in oropharynx ◼️just posterior to vallate papillae