Digest S Flashcards
- Breakdown of ingested food
- Absorption of nutrients into the blood
Digestion
metabolism produces what energy
cellular energy (ATP)
- Constructive and degradative cellular activities
metabolism
ORGANS OF THE DIGESTIVE SYSTEM
Two main group:
- Alimentary canal - continuous coiled hollow tube
- Accessory digestive organs
ORGANS OF THE ALIMENTARY CANAL (7)
- Mouth
- Pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Anus
Mouth (ORAL CAVITY) Anatomy
* Lips (labia) -
* Cheeks -
* Hard palate -
* Soft palate -
* Uvula -
* Vestibule -
* Oral cavity -
* Tongue -
* Tonsils (2)
- Lips (labia) - protect the anterior opening
- Cheeks - form the lateral walls
- Hard palate - forms the anterior roof
- Soft palate - forms. the posterior roof
- Uvula - fleshy projection of the soft palate
- Vestibule - space between lips externally and teeth and gums internally
- Oral cavity - area contained by the teeth
- Tongue - attached at hyoid and styloid processes of the skull, and by the lingual frenulum
- Tonsils
- Palatine tonsils
- Lingual tonsil
processes of mouth (4)
- Mastication (chewing) of food
- Mixing masticated food with saliva
- Initiation of swallowing by the tongue
- Allowing for the sense of taste
Pharynx anatomy
* Nasopharynx -
* Oropharynx -
* Laryngopharynx -
- Nasopharynx - not part of the digestive system
- Oropharynx -posterior to oral cavity
- Laryngopharynx -below the oropharynx and connected to the esophagus
Serves as a passageway for air and food
pharynx
- Food is propelled to the esophagus by two muscle layers
- Longitudinal inner layer
- Circular outer layer
- Food movement is by alternating contractions of the
muscle layers (peristalsis)
Runs from pharynx to stomach through the diaphragm
esophagus
- Conducts food by peristalsis (slow rhythmic squeezing)
esophagus
- Passageway for food only (respiratory system branches off after the pharynx)
esophagus
Layers of Alimentary Canal Organs
mucosa
* Innermost layer
* Moist membrane
layers of moist membrane (3)
- Surface epithelium
- Small amount of connective tissue (lamina propria)
- Small smooth muscle layer
Layers of Alimentary Canal Organs (3)
- Submucosa
- Muscularis externa - smootle muscle
- Serosa
- Just beneath the mucosa
- Soft connective tissue with blood
submucosa
- Inner circular layer
- Outer longitudinal layer
Muscularis externa
- Outermost layer - visceral peritoneum
- Layer of serous fluid-producing cells
- Serosa
- Three separate networks of nerve fibers
- Submucosal nerve plexus
- Myenteric nerve plexus
- Subserous plexus
Stomach is located on the
left side of the abdominal cavity
Food enters at the
cardioesophageal sphincter
- Regions of the stomach (4)
- Cardiac region - near the heart
- Fundus
- Body
- Phylorus - funnel-shaped terminal end
- funnel-shaped terminal end
Phylorus
Food empties into the small intestine at the
pyloric sphincter
internal folds of the mucosa
Rugae
- External regions of stomach
- Lesser curvature
- Greater curvature
- Layers of peritoneum attached to the stomach (3)
- Lesser omentum - attaches the liver to
the lesser curvature - Greater omentum - attaches the greater
curvature to the posterior body wall - Contains fat to insulate, cushion, and
protect abdominal organs
attaches the liver to the lesser curvature
Lesser omentum
attaches the greater curvature to the posterior body wall
Greater omentum
Acts as a storage tank for food and site of food breakdown
stomach
Delivers____to the small intestine
chyme (processed food)
(processed food)
chyme
Specialized Mucosa of the Stomach
- Simple columnar epithelium
Simple columnar epithelium
* Mucous neck cells -
* Gastric glands -
* Chief cells -
* Parietal cells -
* Endocrine cells -
- Mucous neck cells - produce a sticky
alkaline mucus - Gastric glands - secrete gastric juice
- Chief cells - produce protein-digesting
enzymes (pepsinogens) - Parietal cells - produce hydrochloric acid
- Endocrine cells - produce gastrin
Gastric pits formed by
folded mucosa
Glands and specialized cells are in the
gastric gland region
body’s major digestive organ and
small intestine
Site of nutrient absorption into the blood
small intestine
Small intestine is a muscular tube extending form the___ to the _____
pyloric sphincter
ileocecal valve
Small intestine is suspended from the posterior abdominal wall by the
mesentery
Subdivisions of the Small Intestine (3)
- Duodenum
- Jejunum
- Ileum
- Duodenum is attached to the
- Jejunum is attached to the
- Ileum extends from __ to ___
stomach
duodenum
jejunum to large intestine
Curves around the head of the pancreas
Duodenum
- Source of enzymes that are mixed with chyme
- Intestinal cells
- Pancreas
Bile enters from the
gall bladder
- Fingerlike structures formed by the mucosa
villi of the small intestine
give the small intestine more surface area
villi
Small projections of the plasma membrane
Microvilli of the Small Intestine
- Found on absorptive cells
Microvilli of the Small Intestine
Structures Involved in Absorption of Nutrients (3)
- Absorptive cells
- Blood capillaries
- Lacteals (specialized lymphatic capillaries)
Folds of the Small Intestine are called (2)
circular folds or plicae circulares
Deep folds of the mucosa and submucosa
Folds of the Small Intestine
Do not disappear when filled with food
Folds of the Small Intestine
The submucosa of the Folds of Small Intestine has
Peyer’s patches (collections of lymphatic tissue)
(collections of lymphatic tissue)
Peyer’s patches
Larger in diameter, but shorter than the small intestine
large intestine
Frames the internal abdomen
large intestine
Functions of the Large Intestine (4)
- Absorption of water
- Eliminates indigestible food from the body as
feces - Does not participate in digestion of food
- Goblet cells produce mucus to act as a lubricant
- Does not participate in digestion of food
large Intestine
produce mucus to act as a lubricant
Goblet cells
saclike first part of the large intestine
- Cecum -
Accumulation of lymphatic tissue that
sometimes becomes inflamed
(appendicitis)
Hangs from the cecum
appendix
Accumulation of lymphatic tissue
appendix
- Colon (4)
- Ascending
- Transverse
- Descending
- S-shaped sigmoidal
Structures of the Large Intestine (3)
- Colon
- Rectum
- Anus - external body opening
external body opening=
Anus
Smooth muscle is reduced to
three bands (teniae coli)
- Walls are formed into pocketlike sacs called
haustra
ACCESSORY DIGESTIVE ORGANS (5)
- Salivary glands
- Teeth
- Pancreas
- Liver
- Gall bladder
Saliva-producing glands
SALIVARY GLANDS
- Saliva-producing glands (3)
- Parotid glands - located anterior to ears
- Submandibular glands
- Sublingual glands
- Saliva-producing glands located anterior to ears
Parotid glands
saliva is mixture of
mucus and serous fluids
Saliva helps to form a
food bolus
saliva contains ____ to begin starch digestion
salivary amylase
Dissolves chemicals so they can be tasted
saliva
The role is to masticate (chew) food
teeth
how many sets of teeth does human have?
2
- ___(baby or milk) teeth
- 20 teeth are fully formed by age___
Deciduous
two
Replace deciduous teeth beginning
between the ages of 6 to 12
Permanent teeth
Permanent teeth replace deciduous teeth beginning between the ages of
6 to 12
- A full set is ___teeth, but some people
do not have __
32
wisdom teeth
Classification of Teeth (4)
- Incisors
- Canines
- Premolars
- Molars
Regions of a Tooth
crown
neck
root
- exposed part of teeth
crown
- Outer enamel
- Dentin
- Pulp cavity
Crown
- Region in contact with the gum
- Connects crown to root
neck
Periodontal membrane attached to the bone
* Root canal carrying blood vessels and
nerves
root
Produces a wide spectrum of digestive enzymes that break down all categories of food
pancreas
Enzymes are secreted into the
duodenum
Alkaline fluid introduced with enzymic
neutralizes
acidic chyme
- Endocrine products of pancreas (2)
- Insulin
- Glucagons
Largest gland in the body
liver
Located on the right side of the body under the diaphragm
liver
Liver consists of _____ suspended from the
____and ____ by the ___
four lobes
diaphragm
abdominal wall
falciform ligament
liver is connected to the gall bladder via the common
hepatic duct
Produced by cells in the liver
bile
bile is composed of (5)
- Bile salts
- Bile pigment
- Cholesterol
- Phospholipids
- Electrolytes
(mostly bilirubin from the breakdown of hemoglobin)
Bile pigment
- Sac found in hollow fossa of liver
gall bladder
liver stores bile from the liv by way of the
cystic duct
Bile is introduced into the duodenum in the
presence of
fatty food
can cause blockages
Gallstones
Processes of the Digestive System
* Ingestion -
* Propulsion -
* Peristalsis -
* Segmentation -
- Ingestion - getting food into the mouth
- Propulsion - moving foods from one region of the digestive system to another
- Peristalsis - alternating waves of contraction
- Segmentation - moving materials back and forth to aid in mixing
Mechanical digestion (3)
- Mixing of food in the mouth by the
tongue - Churning of food in the stomach
- Segmentation in the small intestine
chemical digestion (2)
- Enzymes break down food molecules
into their building blocks - Each major food group uses different
enzymes
Carbohydrates are broken to
Proteins are broken to
Fats are broken to (2)
simple sugars
amino acids
fatty acids and alcohols
End products of digestion are absorbed
in the
blood or lymph
Food must enter___ and then into ____
mucosal cells
blood or lymph capillaries
- Elimination of indigestible substances as
feces
Defecation
Digestive activity is mostly controlled by reflexes via the
parasympathetic division
Chemical and mechanical receptors are located in organ walls that
trigger reflexes
Stimuli include: (3)
Reflexes include: (2)
- Stretch of the organ
- PH of the contents
- Presence of breakdown products
- Activation or inhibition of glandular secretions
- Smooth muscle activity
Food is physically broken down by chewing
Mechanical breakdown
- Food is mixed with saliva
- Breaking of starch into maltose by
salivary amylase
chemical digestion
Breaking of starch into ____ by salivary amylase
maltose
(Swallowing)
Deglutition
Deglutition (Swallowing)
- Buccal phase
- Voluntary
- Occurs in the mouth
- Food is formed into a bolus
- The bolus is forced into the pharynx by
the tongue
The bolus is forced into the pharynx by
the
tongue
- Involuntary transport of the bolus
Pharyngeal-esophageal phase
- All passageways except to the stomach
are blocked
Pharyngeal-esophageal phase
- Tongue blocks off the
- Soft palate (uvula) blocks the
- Epiglottis blocks the
- Tongue blocks off the mouth
- Soft palate (uvula) blocks the
nasopharynx - Epiglottis blocks the larynx
- Peristalsis moves the bolus toward the
- The ____ is opened when food presses against it
stomach
cardioesophageal sphincter
Gastric juice is regulated by (2)
neural and hormonal factors
Presence of food or falling pH causes the release of
gastrin
causes stomach glands to produce
protein-digesting enzymes
Gastrin
makes the stomach contents very acidic
Hydrocholoric acid
Necessity of an Extremely Acid Environment in the Stomach
- Activates pepsinogen to pepsin for protein digestion
- Provides a hostile environment for
microorganisms
Extremely acid environment in the stomach activates ____ to___ for protein
digestion
pepsinogen
pepsin
- Protein digestion enzymes (2)
- Pepsin - an active protein digesting
enzyme - Rennin - works on digesting milk protein
- an active protein digesting enzyme
- works on digesting milk protein
- Pepsin - an active protein digesting
enzyme - Rennin - works on digesting milk protein
The only absorption that occurs in the stomach is of (2)
alcohol and aspirin
Food must first be well ___
____occurs in the lower stomach
mixed
Rippling peristalsis
meters out chyme into the small intestine (30 ml at a time)
pylorus
The stomach empties in
four to six hours
Enzymes from the brush border
* Break double sugars into ____
* Complete some ____
- Break double sugars into simple sugars
- Complete some protein digestion
play the major digestive function
Pancreatic enzymes
- Help complete digestion of starch
___ - Carry out about half of all protein
digestion ___
(pancreatic amylase)
(trypsin, etc.)
Water is absorbed along the length of the
small intestine
- Most substances are absorbed by ____ through cell membranes
- Lipids are absorbed by __
active transport
diffusion
Substances are transported to the___ by the _____
liver
hepatic portal vein or lymph
major means of moving food
Peristalsis
- Segmental movements
- Mix chyme with ___
- Aid in propelling food
digestive juices
in large intestine ___ enzymes are produced
no digestive
Absorbed in large intestine (3)
Water
Vit K
Vit B
Propulsion in the Large Intestine
- Sluggish peristalsis
- Mass movements
- Presence of feces in the rectum causes a
defecation reflex
- Slow, powerful movements
- Occur three to four times per day
mass movements
Presence of feces in the rectum causes a
defecation reflex
Defecation occurs with relaxation of the
voluntary (external) anal sphincter
Regulation of Food Intake (1)
- Body weight is usually relatively stable
- Mechanisms that may regulate food intake (4)
- Levels of nutrients in the blood
- Hormones
- Body temperature
- Psychological factors
- amount of heat produced by the body per unit of time at rest
Basic metabolic rate (BMR)
- Factors that influence BMR (4)
- Surface area
- Gender
- Age
- thyroxine produced
- small body usually has higher BMR
- Surface area
- males tend to have higher BMR
Gender
Age- ___ and ___ have a higher BMR
children and adolescents
High thyroxine=
higher metabolic rate
Total amount of kilocalories the body must
consume to fuel ongoing activities
total metabolic rate (TMR)
TMR must equal ___consumed to maintain
homeostasis and maintain a constant weight
calories
The alimentary canal is a continuous tube by the __ of development
fifth week
___ from the mucosa of the alimentary tube
Digestive glands bud
The developing fetus receives all nutrients
through the
placenta
In newborns, feeding must be___,
peristalsis is ___, and vomiting is ___
frequent
inefficient
common
Teething begins around age
six months
Metabolism decreases with
old age
Middle age digestive problems (2)
- Ulcers
- Gall bladder problems
- Activity of digestive tract in old age
-Digestive Juices
-Peristalsis
-Common disease (2)
- Fewer digestive juices
- Peristalsis slows
- Diverticulosis and cancer are more common