Digestive Part I - slides 116 through 167 Flashcards
Parts of the Tongue:
Fungiform papillae
Filiform papillae
Circumvallate papillae
foliate papillae
lingual tonsil
palatine tonsil
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
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
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
Tongue:
___ ___ is a fold of mucous membrane in the midline of the ventral aspect (undersurface) of the tongue
Lingual frenulum
Functions of the lingulum frenulum?
- Attaches to the floor of the mouth
- Aids in limiting the movement of the tongue posteriorly
___ in the lamina propria of the tongue secrete Watery serous fluid which Contains lingual lipase
Lingual glands (Von Ebners glands)
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
Acts on as much as 30% of dietary triglycerides
Gets secreted in the mouth, but is not activated until in the stomach
Lingual lipase
Where is lingual lipase secreted?
Where is it activated?
Gets secreted in the mouth, but is not activated until in the stomach
Dorsal (upper surface) and lateral surfaces of tongue are covered with
papillae
Which parts of the tongue have papillae?
Dorsal (upper) and lateral surfaces
Nipple shaped projections of the lamina propria covered with stratified squamous epithelium
papillae
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
types of papillae?
Vallate
Fungiform
Foliate
Filiform
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
Mushroom shaped elevations scatter over entire tongue surface
Each contains about 5 taste buds
Fungiform papillae
Located in small trenches on lateral margins of tongue
Most of their taste buds degeneate in childhood
Foliate papillae
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
These help to increase friction between tongue and food
Filiform papillae
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
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
- –Initiates breakdown of carbohydrates
- –Chloride ions in saliva activate this in the mouth
- –Stomach acid deactivates this
Salivary amylase
- –Initiates breakdown of triglycerides (lipids)
- –Activated in the stomach by stomach acid
Lingual lipase
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
- The voluntary stage
- The pharyngeal stage
- 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?
- Serosa
- Muscularis (three layers of smooth muscle)
- Submucosa (connective areolar tissue)
- 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
- The hepatic ducts, which carry bile from the liver lobes, combine to form the common hepatic duct
- The common hepatic duct combines with the cystic duct from the gallbladder to form the common bile duct
- The common bile duct and the pancreatic duct combine to form the hepatopancreatic ampulla
- The hepatopancreatic ampulla empties bile and pancreatic secretions into the duodenum at the major duodenal papilla
- 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
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 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)
