Test 4 Flashcards by Kieran Martin

How does digestion maintain homeostasis

Turns food into energy in forms the body can use
Absorbs water, vitamins, minerals
Eliminates wastes from the body

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What is our only source of chemical energy

Food

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Function of digestion

Break down food into molecules small enouogh to enter cells

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Study of stomach and intestines

Gastroenterology

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Study of the rectum

Proctology

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Other name for GI tract

Alimentary canal

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What does the alimentary canal travel through

From mouth to anus through the thoracic cavity and abdominopelvic cavity

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Parts of the GI tract

Mouth, most of pharynx, esophagus, stomach, small intestine, large intestine, anus

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Accessory digestive organs

Teeth, tongue, salivary glands, liver, gallbladder, pancreas

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Six basic processes of digestion

Ingestion
Secretion
Mixing and propulsion
Digestion
Absorption 
Defecation

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Layers of GI

Serosa or adventitia
Muscularis
Submucosa
Mucosa

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Where isn’t the serosa found

Esophagus

Proximal portion of duodenum

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Other term for serosa

Visceral peritoneum

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Adventitia is composed of

Single layer of connective tissue for the esophagus and proximal duodenum

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What digestive muscles are voluntary

Skeletal muscle
Mouth, pharynx, superior aspect of esophagus
Also in external anal sphincter, permits voluntary control of defecation

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Where is the myenteric plexus

Muscularis

Also known as plexus of Auerbach

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Areolar connective tissue that binds the mucosa to muscularis

Submucosa

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Where is the submucosal plexus

Submucosa

Also known as plexus of Meissner

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Three layers of GI mucosa

Muscularis mucosae
Lamina propria
Epithelium

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Thin layer of smooth muscle
Causes the mucous membrane of small intestine and stomach to have folded appearance
Increase surface are for digestion/absorption
Movement of layer ensures absorptive cells are exposed to contents of GI tract

Muscularis mucosae (outer layer)

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Areolar connective tissue containing blood and lymph
Supports epithelium and binds to muscularis mucosae
Contains MALT

Lamina propria

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Replaced every 5-7days
Nonkeratinized in where penis can go - protection
Simple columnar found in stomach and intestine - secretion/absorption
Exocrine - secret mucous fluid
Enteroendocrine - secrete hormones

Epithelium of GI

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What innervates the gut

Intrinsic nervees (enteric nervous system) and extrinisc nervees (autonomic nervous system)

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Two plexuses of enteric nervous system

Myenteric (aurbach)

Submucosal (meissner)

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Supplies motor impulses to longitudinal and circular smooth muscle Controls majority of GI motility

Myenteric (auerbach) plexus

Motor neurons supply secretory cells of the mucosal epithelium Controls secretion

Submucosal (meissner) plexus

Connect the myenteric and submucosal plexuses

Interneurons

Helps regulate enteric nervous system Vagus nerve supply parasympathetic fibers Stimulation of parasympathetic nerves increase GI secretion and motility

Autonomic Nervous System

Exception to vagus nerve stimulation in GI

Last 1/2 of large intestine is supplied by parasympathetic fibers from sacral spine

Effect of sympathetic stimulation of GI

Decrease in secretion and motility Don't have to poo in front of the raper

Largest serous membrane in the body

Peritoneum

Divisions of the peritoneum

Parietal and visceral

What type of tissue makes the peritoneum

A layer of simple squamous epithelium (mesothelium) with underlying layer of areolar connectiv

Peritoneal cavity

Space between two layers of peritoneum containing serous fluid

Organs covered anteriorly by pertioneum

Organs in retroperitoneum ``` Kidney Ascending colon Descending colon Duodenum Pancreas ```

Five major folds of peritoneum

``` Greater omentum Falciform ligament Lesser omentum Mesentery Mesocolon ```

Largest peritoneal fold Drapes over transverse colon and small intestine Contains lots of adipose Many lymph nodes

Greater omentum

Where does the greater omentum attach

Portions of stomach and duodenum extending downward anterior to small intestines folds and extends upwards to attach to transverse colon

Peritoneal fold that attaches the liver to the anterior surface of the abdominal wall

Falciform ligament

Free border of this ligament contains the ligamentum teres (round ligament, umbilical vein)

Falciform ligament

What is the only digestive organ attached to anterior abdominal wall

Liver

Arises as anterior fold in the serosa of the stomach and distal duodenum Pathway for blood vessels entering liver Contains portal vein, common hepatic artery, common bile duct and some lymph nodes

Lesser omentum

What suspends the stomach and distal duodenum from the liver

Lesser omentum

Fan shaped fold Binds jejunum and ileum of small intestine to posterior peritoneal wall Large fold, adding abdominal girth

Mesentery

Where is the mesentery

Extends from posterior peritoneal wall, wraps around small intestine returns to origin

Two seperate folds that bind portions of large intestine to posterior abdominal wall

Mesocolon

What attaches to the mesocolon

Transverse colon and sigmoid colon

Function of mesocolon

Carries blood and lymph vessels to intestine | Aids the mesentery to hold small intestines loosely in place

Parts of oral and buccal cavity

Cheeks Hard and soft palates Tongue

Attaches inner surface of each lip to gum

Mucous membrane called labial frenulum

What muscles keep food in mouth while chewing

Orbicularis oris and buccinator

Oral space completely bound by cheeks lips gums and buccal side of teeth

Oral vestibule

Space that extends from lingual side of teeth back to the fauces

Oral cavity proper

Forms the roof of the mouth Wall or septum that separates the oral cavity from nasal cavity Allows us to chew and breathe at the same time

Palate

Anterior portion of roof of mouth Formed by palatine and maxillae bones Covered by mucous membrane

Hard palate

Posterior portion of roof of mouth | Arch shaped muscular partition between oropharynx and nasopharynx line with mucous membrane

Soft palate

Hangs from free border of soft palate | Conical muscular process

Uvula

What happens during swallowing

Soft palate and uvula drawn superiorly | Closes nasopharyx

Two muscular folds of uvula

Palatoglossal arch - anterior | Palatopharyngeal arch - posterior

Small masses of lymphatic tissue that produce antibodies

Tonsils

Name the tonsils

Palatine Lingual Pharyngeal

What increases in the mouth when food is consumed

Saliva

Function of saliva

Lubricate, dissolve, and chemically break down food

Types of salivary glands

Minor, major

Minor salivary glands are where and what

``` Lips, cheeks, palate, tongue Labial Buccal Palatal Lingual ```

What are the major saliva glands

Parotids Submandibular Sublingual Secrete most of the saliva

Located inferior and anterior to the ears between skin and masseter Secrete saliva into oral cavity via duct

Parotid

Stenson's duct is

Parotid duct, pierces the buccinator muscle to open into oral vestibule opposite the second maxillary molar

Found on the floor of the mouth, medial and partly inferior to the mandible bone Submandibullar ducts open on either side of the lingal frenulum in the oral cavity proper

Submandibular glands

Wharton's ducts are

Submandibullar glands

Found beneath the tongue and just superior to the submandibular glands Their ducts open into the floor of the mouth in the oral cavity proper

Sublingual glands

Chemical compound of saliva

99.5 water .5 solute

What do parotid glands secrete

Serous liquid containing salivary amylase

What do submandibular glands secrete

Serous fluid, salivary amylase, and mucous glands

What do sublingual glands secrete

Thick fluid containing a small amount of salivary amylase

Purpose of water in saliva

Medium for dissolving foods, allows digestion reactions to begin

Purpose of Chloride ions in saliva

Activate salivary amylase, breaking down starches into maltose, maltotriose and a-dextrin

Ph of saliva

6.3-6.85 acidic

What wastes are secreted through saliva

Urea and uric acid

Function of mucous in saliva

Lubricates it so it can be moved around in mouth, formed into ball, and swallowed

What controlls salivation

Autonomic nervous system

Xerostomia?

Dry mouth due to sympathetic stimulation

Two salivary nuclei

Superior and inferior

Two nerves involved in parasympathetic impulses

Facial and glossopharyngeal

Salivas purpose after eating

Washes, dilutes and buffers

What is the attachment of the tongue

Inferiorly to hyoid, styloid process, mandible

Extrinsic muscles of the tongue

Hyoglossus Genioglossus Styloglossus

Fold of mucous membrane in the midline of the ventral aspect

Lingual frenulum

Lingual glands (von ebners) secrete

Mucous and watery serous fluid containing lingual lipase

Acts on dietary triglycerides

Lingual lipase, not activated until in the stomach

Nipple shaped projections of the lamina propria covered with stratified squamous epithelium

Papillae

Function of papillae

Taste buds, receptors for gustation or taste

Approximately 12 form an inverted V shaped row at the back of the tongue Contain 100-300 taste buds

Vallate

Mushroom shaped elevations scatter over entire tongue | 5 taste buds

Fungiform

Located in small trenches on lateral margins of tongue | Most taste buds gone after childhood

Foliate

Pointed, threadlike, found on entire surface of tongue | No taste buds

Filiform

A soft, flexible, easily swallowed mass

Bolus

Two enzymes involved in chemical digestion in the mouth

Salivary amylase | Lingual lipase

Initiates breakdown of triglycerides

Lingual lipase

Initiates breakdown of starches

Salivary amylase

Funnel shaped tube that extends from the internal nares to the esophagus posteriorly and to the larynx anteriorly

Pharynx

Three parts of the pharynx

Nasopharynx Oropharynx Hypo/laryngopharynx

Collapsible muscular tube that lies posterior to trachea

Esophagus

Where does the esophagus pass through the diaphragm

Esophageal hiatus

Three layers of the esophagus

Adventitia Muscularis Submucosa

Two sphincters of esophagus

Upper esophageal | Lower esophageal

What two things does the esophagus NOT do

Produce digestive enzymes or particpate in reabsorption

Act of swallowing

Deglutition

Three stages of swalloing

Voluntary Pharyngeal Esophageal

Bolus stimulates receptors here which send impulses to deglutition center in the medulla oblongata and lower pons of brain stem

Pharyngeal stage

What closes during the pharyngeal phase

Soft palate and uvula block nasopharynx | Epiglottis closes larynx

Progression of coordinated contractions and relaxation of the circular and longitudinal layers of the muscularis

Peristalsis

Large folds

Rugae

What is the most distensible portion of the GI

Stomach

What happens to food in the stomach

Starches and triglycerides continue to break down Proteins begin digestion Semisolid bolus converted to liquid Certain substances absorbed

Four main regions of stomach

Cardia Fundus Body Pyloric part

Surrounds the superior opening of the stomach

Cardia

Rounded portion superior and left of the cardia

Fundus

Inferior to the fundus, large central part

Body

Three parts of the pyloric part of stomach

Pyloric antrum Pyloric canal Pylorus

Pyloric antrum

Connects to the body of the stomach

Pyloric canal

Leads to the third region of pyloric part

Pylorus

Connects to the duodenum via pyloric sphincter

Four layers of stomach

Serosa Muscularis Submucosa Mucosa

What does the mucosa of the stomach contain

Gastric glands/pits Specialized exocrine gland Enteroendocrine cell type

Greater curvature of stomach serosa continues as what

Greater omentum

Lesser curvature of stomach serosa projects up toward liver as

Lesser omentum

Three layers of. Muscularis

Outer longitudinal Middle circular Inner oblique

Three types of exocrine glands in the mucosa of stomach

Mucous neck cells Chief Parietal

Function of mucous/neck cells

Secrete mucous

Purpose of chief cells

Secrete pepsinogen and gastric lipase

Function of parietal cells

Secrete hydrochloric acid and intrinsic factor

Function of intrinsic factor

Aid in absorption of B12 and cyanobalamin

What are G cells

Gastric glands found only in pyloric antrum and secrete gastrin into bloodstream

Macronutrients?

Carbs, protein, lipidds

Micronutrients

Vitamins minerals essential fatty acids amino acids

Mixing waves?

Peristaltic waves in the stomach occuring every 15-20 seconds

Substance formed in the stomach is called

Chyme

Approximately 3mL of chyme is ejected into the duodenum each wave

Gastric emptying

Cells integral for hydrochloric acid secretion

Parietal cells

Actively transports a H+ into lumen while bringing a K+ into the cell

Proton pumps

Function of carbonic anhydrase

Catalyzes formation of carbonic acid from waater and carbon dioxide

What happens to bicar made from the disassociation of carbonic acid

Enters the bloodstream

Methods of stimulation of hydrochloric acid

Acetylcholine Gastrin Histamine

Where are the receptros for gastrin, acetylcholine, and histamine

Plasma membranes of parietal cells

The only proteolytic enzyme in the stomach

Pepsin

What is the inactive form of pepsin

Pepsinogen, made in chief cells

What activates pepsinogen

Hydrochloric acid in the stomach or active pepsin molecules

What protects stomach epithelial cells

1-3mm thick layer of alkaline mucous

What pH does gastric lipase function in

5-6

What's absorbed in the stomach

Water, ions, short chain fatty acids, and some drugs

Other name of pancreatic duct

Duct of wirsung

Joins common bile duct from liver and gallbladder then enters duodenum as the HEPATOPANCREATIC AMPULLA (ampulla of Vater)

Pancreatic duct (duct of Wirsung)

Where does the ampulla of Vater open

Approx 4in inferior to pyloric sphincter

What regulates the ampulla of Vater

Mass of smooth muscle surrounding sphincter of the hepatopancreatic ampulla (sphincter of Oddi)

Acceessory duct of pancreas also known as

Duct of santorini

Where does the duct of santorini empty

Duodenum, approx 1 in superior to the hepatopancreatic ampulla (ampulla of Vater

What are Acini

Exocrine portion of pancreatic glands

What do acini cluster cells secrete

Pancreatic juice

What is the endocrine portion of the pancreas

Islets of Laangerhans

What does the pancreas secrete

Sodium bicarb, salt, water, enzymees

Function of pancreatic sodium bicarb

Creates proper pH for the action of digestive enzymes in small intestine

Pancreatic amylase

Starch digestion

Trypsin

Protein digestion

Chymotrypsin

Protein digestions

Carboxypeptidase

Protein digestion

Elastase

Protein digestion

Pancreatic lipase

Principle triglyceride digestion

Ribonuclease

Digests RNA

Deoxyribonuclease

Digests DNA

What divides the liver

Falciform ligament

Test 4 Flashcards

(171 cards)