Digestive Part I - slides 116 through 167 Flashcards by Johnny B

Parts of the Tongue:

Fungiform papillae

Filiform papillae

Circumvallate papillae

foliate papillae

lingual tonsil

palatine tonsil

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Tongue:

Considered an accessory digestive organ

Composed of ___ ____ covered with a mucous membrane

With associated muscles forms the…

Tongue:

Considered an accessory digestive organ

Composed of skeletal muscle covered with a mucous membrane

With associated muscles forms the floor of the oral cavity

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Tongue:

Divided into symmetric lateral halves by a ___ ___ that extends entire length

Tongue:

Divided into symmetric lateral halves by a median septum that extends entire length

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Tongue:

Attached inferiorly to the ___ bone, styloid process of the ___ ___, and _____

Tongue:

Attached inferiorly to the hyoid bone, styloid process of the temporal bone, and mandible

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Tongue:

___ ___ is a fold of mucous membrane in the midline of the ventral aspect (undersurface) of the tongue

Lingual frenulum

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Functions of the lingulum frenulum?

Attaches to the floor of the mouth

- Aids in limiting the movement of the tongue posteriorly

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___ in the lamina propria of the tongue secrete Watery serous fluid which Contains lingual lipase

Lingual glands (Von Ebners glands)

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Lingual glands (Von Ebners glands) are where and secrete what?

in the lamina propria of the tongue secrete Watery serous fluid which Contains lingual lipase

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Acts on as much as 30% of dietary triglycerides

Gets secreted in the mouth, but is not activated until in the stomach

Lingual lipase

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Where is lingual lipase secreted?

Where is it activated?

Gets secreted in the mouth, but is not activated until in the stomach

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Dorsal (upper surface) and lateral surfaces of tongue are covered with

papillae

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Which parts of the tongue have papillae?

Dorsal (upper) and lateral surfaces

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

papillae

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Many contain taste buds (receptors for gustation or taste)

Some lack taste buds but have receptors for touch instead —- Helps to increase the friction between food and tongue making it easier for tongue to move food

papillae

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types of papillae?

Vallate

Fungiform

Foliate

Filiform

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Approximately 12 form an inverted “V” shaped row at the back of the tongue
Each of the 12 contain 100-300 taste buds

Vallate (circumvallate) papillae

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Mushroom shaped elevations scatter over entire tongue surface

Each contains about 5 taste buds

Fungiform papillae

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Located in small trenches on lateral margins of tongue

Most of their taste buds degeneate in childhood

Foliate papillae

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Pointed, threadlike; found on entire surface of tongue

Contain no taste buds but do have tactile receptors

These help to increase friction between tongue and food

Filiform papillae

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These help to increase friction between tongue and food

Filiform papillae

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Mechanical digestion results from mastication (chewing)

Food is reduced to a soft, flexible, easily swallowed mass called a ___

Food molecules begin to mechanically break apart in ___

This is important as ___ can only react with food in a liquid environment

Food is reduced to a soft, flexible, easily swallowed mass called a bolus

Food molecules begin to mechanically break apart in saliva

This is important as enzymes can only react with food in a liquid environment

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Two enzymes that contribute to chemical digestion are secreted in the mouth

Salivary amylase

–Initiates breakdown of carbohydrates
–Chloride ions in saliva activate this in the mouth
–Stomach acid deactivates this

Lingual lipase

–Initiates breakdown of triglycerides (lipids)
–Activated in the stomach by stomach acid

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–Initiates breakdown of carbohydrates
–Chloride ions in saliva activate this in the mouth
–Stomach acid deactivates this

Salivary amylase

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–Initiates breakdown of triglycerides (lipids)

- –Activated in the stomach by stomach acid

Lingual lipase

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When food is first swallowed, passes from mouth into pharynx

Funnel-shaped tube that extends from the internal nares to the esophagus posteriorly and to the larynx anteriorly Composed of skeletal muscle and lined with mucous membrane

Pharynx is Divided into three parts:

Nasopharynx- functions only in respiration Oropharynx- function in digestion and respiration Hypo/Laryngopharynx- function in digestion and respiration

functions only in respiration

Nasopharynx-

function in digestion and respiration

Oropharynx-

function in digestion and respiration

Hypo/Laryngopharynx-

Swallowed food passes from mouth into

oropharynx then laryngopharynx

Muscular contractions of these areas help propel food into the esophagus and then into stomach

Pharynx

Collapsible muscular tube Usually 10in long Lies posterior to the trachea

Esophagus

Esophagus Begins at inferior end of _____, passes through the inferior portion of neck, enters mediastinum, pierces the diaphragm, ends at...

hypo/laryngopharynx ....superior portion of stomach

Pierces diaphragm through esophageal hiatus Sometimes part of the stomach herniates through this opening (called hiatal hernia)

Esophagus

Sometimes part of the stomach herniates through this opening called....

hiatal hernia

Esophagus- Histology Superficial surface to lumen:

Adventitia Muscularis Submucosa Mucosa

Superficial surface to lumen Attaches esophagus to surrounding structures Muscularis Superior 1/3 esophagus is skeletal muscle Middle 1/3 esophagus is skeletal transitioning to smooth muscle Inferior 1/3 esophagus is smooth muscle Submucosa Contains areolar connective tissue, blood vessels, mucous glands

Adventitia

Esophagus: Superior 1/3 esophagus is skeletal muscle Middle 1/3 esophagus is skeletal transitioning to smooth muscle Inferior 1/3 esophagus is smooth muscle

Muscularis

Esophagus: Contains areolar connective tissue, blood vessels, mucous glands

Submucosa

Esophagus: Superior 1/3 esophagus is __ ____ Middle 1/3 esophagus is skeletal transitioning to ___ ____ Inferior 1/3 esophagus is ___ _____

Esophagus: Superior 1/3 esophagus is skeletal muscle Middle 1/3 esophagus is skeletal transitioning to smooth muscle Inferior 1/3 esophagus is smooth muscle

Esophagus Mucosa (3 layers)

Muscularis mucosae (smooth muscle) Lamina propria (areolar connective tissue) Nonkeratinized stratified squamous epithelium Affords considerable protection against abrasion from food particles

At either end of the esophagus, muscularis layer thickens forming sphincters

Upper esophageal sphincter (UES) Lower esophageal sphincter (LES)

which is skeletal muscle | Regulates movement of food from hypopharynx to esophagus

Upper esophageal sphincter (UES)

which is smooth muscle | Regulates movement of food from esophagus to stomach

Lower esophageal sphincter (LES)

Secretes mucous (protective function) Transports food to the stomach Does NOT produce digestive enzymes Does NOT participate in absorption

Esophagus

Act of swallowing

Deglutition

Movement of food from the mouth into the stomach Facilitated by the secretion of saliva and mucous and involves the mouth, pharynx, esophagus Assisted by swallowing which is completed in three phases?

Deglutition 1. The voluntary stage 2. The pharyngeal stage 3. The esophageal stage

Swallowing starts when bolus is forced to back of the oral cavity Bolus begins to travel backward toward the oropharynx by the movement of the tongue upward and backward against the palate

The Voluntary Stage

The Pharyngeal Stage (continued later) Passage of bolus into oropharynx through.... Bolus stimulates receptors here which send impulses to deglutition center in the...

The Pharyngeal Stage ...hypo/laryngopharynx and eventually into esophagus ....medulla oblongata and lower pons of brain stem

The Pharyngeal Stage (continued) The returning impulses cause the soft palate and uvula to move upwards to... This prevents swallowed food and liquids from entering the nasal cavity Impulses also cause the epiglottis to.... This prevents the bolus from entering the respiratory tract The bolus moves through the oropharynx and hypo/laryngopharynx At this point the _________ relaxes

...close off the nasopharynx ... move to cover the opening to the larynx upper esophageal sphincter

The Esophageal Stage begins when?

Begins once the bolus has entered the esophagus

The Esophageal Stage During this phase, peristalsis pushes the bolus onward As the bolus is moved down the esophagus, the ________relaxes allowing food into the stomach

lower sphincter

is a progression of coordinated contractions and relaxations of the circular and longitudinal layers of the muscularis

Peristalsis

Passage of solid or semisolid food from mouth to stomach takes 4-8 seconds Passage of very soft foods or liquids takes about 1 second

The Esophageal Stage

J-shaped enlargement of the GI tract directly inferior to diaphragm

Stomach -

stomach connects the

esophagus to the duodenum (first part of the small intestine)

Stomach serves as a mixing chamber and holding reservoir When food mixes with gastric juices, this becomes

chyme

Position and size of stomach vary continually as it moves with breathing, and shrinks or expands in response to food or lack there of

cool dude

Most distensible part of the GI tract

stomach

Most distensible part of the GI tract, can expand and accommodate a large quantity of food... why?

Because the mucosa lies in rugae (folds)

picture on slide 147

check it out slacker

Stomach Has four main regions... name them all

Cardia Fundus Body Plyoric part (three parts of this)

Surrounds the superior opening of the stomach

cardia

Rounded portion superior to and left of the cardia

The fundus

Inferior to the fundus, large central portion

The body

The pyloric part (divided into three parts)

Pyloric antrum connects to the body of the stomach Pyloric canal leads to the third region Pylorus- connects to the duodenum via pyloric sphincter

connects to the body of the stomach

Pyloric antrum

leads to the third region

Pyloric canal

connects to the duodenum via pyloric sphincter

Pylorus

Stomach-Histology Superficial to lumen 4 layers?

1. Serosa 2. Muscularis (three layers of smooth muscle) 3. Submucosa (connective areolar tissue) 4. Mucosa (lamina propria and muscularis mucosae) - ---Contains gastric glands/pits - ----Contains specialized exocrine gland cells - ---Contains an enteroendocrine cell type

Greater curvature of stomach serosa continues as the greater omentum Lesser curvature of stomach projects upward towards liver as the lesser omentum

serosa of stomach

of stomach serosa continues as the greater omentum

Greater curvature

of stomach projects upward towards liver as the lesser omentum

Lesser curvature

Contains Auerbach’s plexus (myenteric plexus)

Muscularis (three layers of smooth muscle)

Auerbach's plexus AKA

myenteric plexus

Contains Meissner’s plexus (submucosal plexus)

Submucosa (connective areolar tissue)

Submucosa AKA

(connective areolar tissue)

Meissner’s plexus AKA

(submucosal plexus)

Stomach histology: Mucosal layer (3 layers external to internal) NAME THEM

Muscularis mucosae (smooth muscle) Lamina propria (connective areolar tissue) Mucosa

Mucosa Form columns of secretory cells called _____ that open into the lumen surface (gastric pits) Gastric glands contain three types of exocrine gland cells that..... Gastric glands also contain

gastric glands .....secrete their product into stomach lumen enteroendocrine cells

Mucosa: Gastric glands contain three types of exocrine gland cells that secrete their product into stomach lumen

Mucous neck cells Chief cells Parietal cells

Mucosa: Gastric glands also contain enteroendocrine cells

G-Cell – secretes a hormone into the BLOODSTREAM, not stomach lumen Enterochromaffin-like cells – secretes hormone into bloodstream

secretes a hormone into the BLOODSTREAM, not stomach lumen (of the mucosa of stomach)

G-Cell

– secretes hormone into bloodstream (of the mucosa of stomach)

Enterochromaffin-like cells

Exocrine cells of the stomach:

Mucous cells/neck cells Chief cells (zymogenic) Parietal cells (oxyntic)

Exocrine cells of the stomach: Chief cells (zymogenic) Secrete what two things?

Secretes pepsinogen (inactive precursor enzyme) Secretes gastric lipase (of little importance here)

Exocrine cells of the stomach: Parietal cells (oxyntic) Secretes what THREE things?

Parietal cells (oxyntic): Secretes hydrochloric acid (HCl) Secretes intrinsic factor (IF) Secretes bicarbonate

Deactivates salivary amylase Activates lingual lipase

hydrochloric acid (HCl) | secreted by Parietal cells (oxyntic)

is needed to aid in absorption of vitamin B12/cyanocobalamin If B12 is not absorbed, ______- can occur

Intrinsic factor (Parietal cells (oxyntic) secrete this) pernicious anemia

parietal cells AKA

oxyntic

This gets formed inside the cell and is secrete into the blood stream (secreted by parietal cells of the stomach)

bicarbonate

Found in the pyloric antrum Secretes hormone Gastrin into bloodstream

G-Cells

Enteroendocrine Cells

G-Cells Enterochromaffin-like Cells

Secretes histamine

Enterochromaffin-like Cells

activates parietal cells to produce HCl

histamine (secreted by Enterochromaffin-like Cells)

Stimulates HCl acid production (with histamine) Stimulates gastric motility Stimulates Chief cells to produce more pepsin

Gastrin in bloodstream (secreted by G-cells)

Gastrin in bloodstream (secreted by G-cells) stimulates what three things?

Stimulates HCl acid production (with histamine) Stimulates gastric motility Stimulates Chief cells to produce more pepsin

SLide 156 image looks cool

good nerd

Mechanical Digestion _____- peristaltic waves in the stomach occurring every 15-20 seconds

Mixing waves

Mixing waves- Help ___ food, mix it with gastric secretions, and reduce it to a soupy liquid At this point, the substance formed in the stomach is called ____ These waves ____ as the chyme is moved towards the pylorus

macerate chyme intensify

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

Gastric emptying-

Gastric emptying- approximately 3mL of chyme is ejected into the duodenum each wave The remainder is....

pushed back into body of stomach where mixing continues

Chemical digestion in the stomach think of these two....

Pepsin Gastric Lipase

the only proteolytic (protein digesting) enzyme in the stomach

Pepsin

Released in very small quantities (usually only in the face of pancreatic insufficiency)

Gastric Lipase-

If active, digests small quantity of triglycerides

Gastric Lipase-

Gastric Lipase- The majority of lipid digestion occurs in the ___ from ___

small intestines from pancreatic juices

Pepsin Prepared as pepsinogen (inactive form) in the...

.... chief cells

inactive form of pepsin

pepsinogen

activates the pepsinogen in the lumen

HCl or pepsin

Most efficient in acidic environment

Pepsin

Stomach epithelial cells are protected by a 1-3mm thick layer of alkaline mucous This helps to prevent the pepsin from....

digesting the proteins found in the structure of the epithelial cells

Absorption in the stomach

Very little occurs as the epithelial cells are impermeable to most substances, However, water, ions, short-chain fatty acids and some drugs (like aspirin and alcohol) can be absorbed

what can be absorbed in the stomach?

water, ions, short-chain fatty acids and some drugs (like aspirin and alcohol) can be absorbed ALTHOUGH... Very little occurs as the epithelial cells are impermeable to most substances

Within 2-4 hours of ingesting a meal, the stomach has emptied its contents into

duodenum

In the stomach: ____ spend least amount of time in stomach h

Carbohydrates

In the stomach: ____remain somewhat longer

High-protein foods

In the stomach: ______ remain the longest in stomach

Fat-laden meals

Accessory digestive organ A retroperitoneal gland - --Approximately 5-6in long and 1in thick - --Lies posterior to the greater curvature of the stomach

Pancreas

Pancreas exocrine functions?

Acini – clusters of glandular cells that produce digestive enzymes/fluids

– clusters of glandular cells that produce digestive enzymes/fluids (pancreatic exocrine function)

Acini

Pancreas endocrine functions?

Pancreatic islets –produce hormones

–produce hormones | pancreatic endocrine function

Pancreatic islets

Fluid and digestive enzymes secreted by exocrine cells (pancreas)

Pancreatic juices-

Primary duct in pancreas

Pancreatic duct (duct of Wirsung)

Pancreatic duct AKA

(duct of Wirsung)

Pancreatic duct Merges with the

common bile duct

After the Pancreatic duct Merges with the common bile duct

Hepatopancreatic ampulla (ampulla of Vater) is formed Sphincter of Oddi surrounds this ampulla controlling flow of fluids

This opens into the duodenum

Pancreatic duct (duct of Wirsung)

Accessory duct AKA

(duct of Santorini)

Smaller duct branching off of pancreatic duct Drains into duodenum, just proximal to the ampulla of Vater

Accessory duct (duct of Santorini)

Accessory duct (duct of Santorini) Smaller duct branching off of _____ Drains into duodenum, just proximal to the ...

pancreatic duct .....ampulla of Vater

Draw out the route from the hepatic duct to the minor duodenal papilla

1. The hepatic ducts, which carry bile from the liver lobes, combine to form the common hepatic duct 2. The common hepatic duct combines with the cystic duct from the gallbladder to form the common bile duct 3. The common bile duct and the pancreatic duct combine to form the hepatopancreatic ampulla 4. The hepatopancreatic ampulla empties bile and pancreatic secretions into the duodenum at the major duodenal papilla 5. The accessory pancreatic duct empties pancreatic secretions into the duodenum at the minor duodenal papilla

Everyday pancreas produces ____ of pancreatic juice

1200-1500mL

pancreatic juice: A clear, colorless liquid consisting mostly of ....

....water, some salts, sodium bicarbonate, several enzymes

Sodium Bicarbonate (NaHCO3--) gives pancreatic juice slightly

alkaline pH (7.1-8.2)

Buffers acidic gastric juices in chyme Stops the action of pepsin from the stomach Creates proper pH for the action of digestive enzymes in small intestine

Sodium Bicarbonate (NaHCO3--) in bicarbonate juices

Trypsin* – protein digestion Chymotrypsin* – protein digestion Carboxypeptidase* – protein digestion Elastase*- protein digestion Pancreatic amylase- carbohydrate digestion Pancreatic lipase – principle triglyceride digestion Phospholipase – phospholipid digestion Cholesterol esterase – aids in cholesterol digestion

Pancreatic Juice- Enzymes

``` Trypsin* – ? digestion Chymotrypsin* – ? digestion Carboxypeptidase* – ? digestion Elastase*- ? digestion Pancreatic amylase- ? digestion Pancreatic lipase – ? digestion Phospholipase – ? digestion Cholesterol esterase – aids in ? digestion ```

pancreatic enzymes: Protein digesting enzymes are produced in inactive forms (zymogenic)

Trypsinogen (inactive) – Trypsin (active) Chymotrypsinogen (inactive) – Chymotrypsin (active) Procarboxypeptidase (inactive) – Carboxypeptidase (active) Prolastase (inactive) – Elastase (active)