Chapter 16 - Digestion Flashcards
digestion
the process of breaking down food by mechanical and enzymatic action in the alimentary canal into substances that can be used by the body
gallbladder
A small, pear-shaped organ on the right side of your abdomen, just beneath your liver. The gallbladder holds a digestive fluid called bile that’s released into your small intestine.
three parts of the small intestine
The small intestine consists of three parts.
The first part, called the duodenum, connects to the stomach.
The middle part is the jejunum.
The third part, called the ileum, attaches to the colon.
small intestine
an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place.
pancreatic duct
Also called “duct of Wirsung” or major pancreatic duct
It is a duct joining the pancreas to the common bile duct.
common bile duct (CBD)
A tube that carries bile from the liver and the gallbladder through the pancreas and into the duodenum (the upper part of the small intestine). It is formed where the ducts from the liver and gallbladder are joined.
cystic duct
a duct that connects the top of the gallbladder’s neck to the common hepatic duct
motility
(1) the quality or state of being motile (capable of movement)
(2) the ability of the muscles of the digestive tract to undergo contraction
seven mechanisms of the digestive system
ingestion of food
digestion of food
secretion of digestive juices
absorption of nutrients
movement of food through the digestive system (motility)
regulation of digestive processes
excretion of waste products (elimination)
four layers of the gastrointestinal tract
The digestive tract has been described as a tube that extends from the mouth to the anus. The wall of this digestive tube is fashioned of four layers of tissue. Although the same four tissue coats form every organ of the alimentary tract, their structure varies from organ to organ.
The four layers are:
1. Mucosa (innermost)
2. Submucosa
3. Muscularis
4. Serosa (outermost)
[The inside, or hollow space within the tube, is called the lumen.]
peristalsis
the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward
bolus
(1) a rounded mass: such as a large pill or a soft mass of chewed food
(2) a dose of a substance (such as a drug) given intravenously
segmentation (digestion)
It is what occurs when digestive reflexes cause a forward-and-backward movement within a single region of the GI tract; segmentation contractions assist in mixing food with digestive juices and helps continue the mechanical breakdown of larger food particles.
mechanics
(1) a branch of physical science that deals with energy and forces and their effect on bodies
(2) the practical application of mechanics to the design, construction, or operation of machines or tools
(3) mechanical or functional details or procedure
mechanical
- of or relating to machinery
- of or relating to artisans or machinists
- done as if by machine: seemingly uninfluenced by the mind or emotions: AUTOMATIC
- relating to, governed by, or in accordance with the principles of mechanics
- caused by, resulting from, or relating to a process that involves a purely physical as opposed to a chemical or biological change or process
- of or relating to technicalities or petty matters
mechanism
(1) a piece of machinery
(2) a process, technique, or system for achieving a result
(3) mechanical operation or action
(4) a doctrine that holds natural processes (as of life) to be mechanically determined and capable of complete explanation by the laws of physics and chemistry
(5) the fundamental processes involved in or responsible for an action, reaction, or other natural phenomenon
artisan
(1) a worker who practices a trade or handicraft: CRAFTSPERSON
(2) a person or company that produces something (such as cheese or wine) in limited quantities often using traditional methods —often used before another noun
technicality
a detail meaningful only to a specialist
handicraft
(1) manual skill
(2) an occupation requiring skill with the hands
(3) the articles fashioned by those engaged in handicraft
philtrum
the depression located between the upper lip and the nose
uvula
a fleshy extension at the back of the soft palate which hangs above the throat
frenulum (plural: frenula, frena)
a small fold of tissue that secures the motion of a mobile organ in the body (e.g. the membrane that attaches the tongue to the floor of the mouth)
diminutive
(1) one that is notably small
(2) a root word that has been modified to convey a slighter degree of its root meaning, to convey the smallness of the object or quality named, or to convey a sense of intimacy or endearment (e.g. Charlie from Charles, duckling from duck, darling from dear)
endearment
a word or an act (such as a caress) expressing affection
crown (teeth)
the portion of the tooth that is exposed and visible in the mouth
three layers of the tooth
The hard outer layer is called enamel. It is the hardest substance in the body.
The middle layer is called dentin. It is harder than bone but softer than enamel.
The center of the tooth is called the pulp. It contains nerves and blood vessels.
cementum
A connective tissue that forms along a tooth’s root and helps solidify it by connecting to fibers that support the tooth’s place in the jawbone. It is like enamel but softer. Cementum also functions to cover the tooth’s dentin.
root (tooth)
The part of the tooth that descends below the gum line, into the upper or lower jawbones, anchoring the tooth in the mouth. Different types of teeth have a different number of roots and root formations. Typically incisors, canines and premolars will have one root whereas molars will have two or three.
neck (tooth)
The part of the tooth between the root and the crown, surrounded by the gums.
three levels of the tooth
Crown on the top, neck in the middle, root on the bottom.
gingiva
another word for the gums
gingivitis
A form of gum disease that happens when plaque builds up on teeth and causes the inflammation of the surrounding gum tissue. If left untreated it will lead to periodontitis.
plaque (teeth)
A sticky film of bacteria that constantly forms on teeth. Bacteria in plaque produce acids after you eat or drink. These acids can destroy tooth enamel and cause cavities and gingivitis (gum disease).
Plaque can also develop under the gums on tooth roots and break down the bones that support teeth.
Untreated plaque can harden into tough-to-remove tartar.
tartar
It is hardened plaque.
It forms at, underneath, and above the gumline and can irritate gum tissues. Because tartar on teeth gives plaque more surface area to grow on and a much stickier surface to adhere to, it can lead to cavities and gum disease.
periodontal ligament (PDL)
Also called the periodontal membrane.
It is the fleshy tissue between the tooth and the tooth socket that holds the tooth in place and enables it to resist the stresses of chewing. It inserts into root cementum on one side and onto alveolar bone on the other.
periodontitis
a severe form of gum disease that causes gum tissue to recede, bone to wear away, teeth to loosen, and teeth to eventually fall out
periodontium
The specialized tissues that both surround and support the teeth, maintaining them in the maxillary and mandibular bones; it consists of four principal components, namely:
- gingiva
- periodontal ligament (PDL)
- cementum
- alveolar bone proper
maxilla vs mandible
The maxilla in vertebrates is the upper fixed bone of the jaw formed from the fusion of two maxillary bones. The mandible (lower jaw or jawbone) is the largest, strongest, and lowest bone in the human face. It forms the lower jaw and holds the lower teeth in place. It is the only movable bone of the skull (discounting the ossicles of the middle ear). It is connected to the temporal bones by the temporomandibular joints.
temporomandibular joints
The two joints that connect your lower jaw to your skull. More specifically, they are the joints that slide and rotate in front of each ear, and consist of the mandible (the lower jaw) and the temporal bone (the side and base of the skull).
temporal bone
Two major bones in the skull. They help form the sides and base of the skull, where they protect the temporal lobe of the brain and surround the ear canal.
dental caries
Also called tooth decay.
It is damage to a tooth that can happen when decay-causing bacteria in your mouth make acids that attack the tooth’s surface, or enamel. This can lead to a small hole in a tooth, called a cavity. If tooth decay is not treated, it can cause pain, infection, and even tooth loss.
baby bottle tooth decay
Also called early childhood caries. It is severe tooth decay in baby teeth.
four types of teeth
- Incisors (central and lateral)
- Canines or cuspids
- Premolars or bicuspids
- Molars or tricuspids
incisors
The eight front-most teeth. There are four in the upper jaw and four in the lower jaw.
The two incisors in the middle are called central incisors. To their left and right are the lateral incisors. They are used for cutting food.
canines
Also called cuspids.
These are the slightly pointed teeth situated on one side of each of the lateral incisors. Because they resemble the fangs of a dog (canine) they acquired that name. They are your sharpest teeth, used for tearing apart food.
premolars
These are located between the canines and the molars in the back of the mouth. Premolars have two pointed cusps on their biting surface. Which is why they are sometimes referred to as bicuspids. The premolars are considered transitional teeth, guiding food from the canines to the molars in back for chewing.
molars
Molars, in the back of the mouth, are used for grinding our food. The typical adult has 12 molars, 4 of which are your wisdom teeth. Each side of the upper and lower jaw has three molars. These are our largest teeth and designed to sustain the force used for chewing, grinding and clenching.
The third molar (farthest in the back) is called the wisdom tooth.
mastication
another word for chewing
deciduous teeth
Also called primary teeth, baby teeth, milk teeth, or temporary teeth.
They are the first set of teeth in the growth and development of humans. They are usually lost and replaced by permanent teeth at between 6 and 13 years of age, but in the absence of their permanent replacements, they can remain functional for many years into adulthood.
malocclusion
imperfect positioning of the teeth when the jaws are closed
It occurs when missing teeth create wide spaces in the dentition, when teeth overlap, or when malposition of one or more teeth prevents correct alignment of the maxillary and mandibular dental arches.
dentition
the arrangement or condition of the teeth in a particular species or individual
overbite vs underbite
Overbite: a protrusion of the upper front teeth, causing them to hang over the lower front teeth
Underbite: a protrusion of the lower front teeth, causing them to stick out ahead of the upper front teeth
serous
of, relating to, or resembling serum
especially: of thin watery constitution
serum
(1) the watery, clear portion of an animal fluid
(2) a usually lightweight cosmetic preparation especially for use on the face
(3) the watery part of a plant fluid
salivary glands
The glands that produce saliva. There are three:
- (largest in size) parotid glands
- (intermediate in size) submandibular glands
- (smallest in size) sublingual glands
deglutition
the action or process of swallowing (e.g. of food)
esophagus
the muscular, mucus-lined tube that connects the pharynx with the stomach
two sphincters of the esophagus
The upper esophageal sphincter (UES) helps prevent air from entering the tube during respiration.
The lower esophageal sphincter (LES), or cardiac sphincter, normally prevents backflow of acidic stomach contents.
stomach
A pouch that food enters after it has been chewed, swallowed, and passed through the esophagus; it performs a chemical breakdown of food by means of enzymes and hydrochloric acid.
three divisions of the stomach
The fundus is the enlarged, curving base to the left of and above the opening of the esophagus into the stomach.
The body is the central part of the stomach.
The pylorus is its lower narrow apex section, which joins the first part of the small intestine.
apex (general definition)
- the uppermost point
- the narrowed or pointed end
- the highest or culminating point
- the point of sharpest curvature in a path (such as that followed by a turning vehicle)
culminate
- (of a celestial body) to reach its highest altitude
- to rise to or form a summit
- to reach the highest or a climactic or decisive point
summit
(1) the highest point of a hill or mountain
(2) a conference of highest-level officials (such as heads of government)
(3) the highest level of officials
(4) the topmost level attainable
gastric glands
A set of three glands in the stomach.
The cardiac glands are found in the cardia of the stomach which is the part nearest to the heart, enclosing the opening where the esophagus joins to the stomach; they primarily secrete mucus.
The fundic glands (or oxyntic glands) are found in the fundus and body of the stomach; they secrete hydrochloric acid (HCl) and intrinsic factor.
The pyloric glands are located in the antrum of the pylorus; they secrete gastrin.
gastrin
a hormone which stimulates secretion of gastric juice and is secreted into the bloodstream by the stomach wall in response to the presence of food
hydrochloric acid (HCI)
the main component of gastric acid, an acid produced naturally in the human stomach to help digest food
intrinsic factor
A protein that helps your intestines absorb vitamin B12. It is made by cells in the stomach lining.
mucus
A normal, slippery and stringy fluid substance produced by many lining tissues in the body. It is essential for body function and acts as a protective and moisturizing layer to keep critical organs from drying out. Mucus also acts as a trap for irritants like dust, smoke, or bacteria.
antrum
A general term for a cavity or chamber, which may have specific meaning in reference to certain organs or sites in the body. One good example below:
pyloric antrum: the lower portion of the stomach. This is what is usually referred to as “antrum” in stomach-related topics
hiatal hernia
A condition in which part of the stomach pushes up through the diaphragm muscle.
hernia
a condition in which part of an organ is displaced and protrudes through the wall of the cavity containing it (often involving the intestine at a weak point in the abdominal wall)
gastroesophageal reflux disease (GERD)
A chronic disease that occurs when stomach acid or bile flows into the food pipe and irritates the lining. The backward flow of stomach acid up into the esophagus causes symptoms (often referred to as heartburn), which typically include burning and pressure behind the breastbone.
bile
a dark-green-to-yellowish-brown fluid produced by the liver of most vertebrates that aids the digestion of lipids in the small intestine
liver
The largest solid organ in the body, situated in the upper part of the abdomen on the right side.
The liver’s main job is to filter the blood coming from the digestive tract, before passing it to the rest of the body. The liver also detoxifies chemicals and metabolizes drugs. As it does so, the liver secretes bile that ends up back in the intestines. The liver also makes proteins important for blood clotting and other functions.
pyloric sphincter
A ring of smooth muscle that connects the stomach and small intestine. It opens and closes to control the passage of partially digested food and stomach juices from the pylorus to the duodenum.
stricture
(1) an abnormal narrowing of a bodily passage
(2) a constriction of the breath passage in the production of a speech sound
(3) something that closely restrains or limits: RESTRICTION
(4) an adverse criticism: CENSURE
censure vs censor
Censure: a judgment involving condemnation
Censure: the act of blaming or condemning sternly
Censure: an official reprimand
vs.
Censor: a person who supervises conduct and morals
Censor: one of two magistrates of early Rome acting as census takers, assessors, and inspectors of morals and conduct
Censor: to examine in order to suppress or delete anything considered objectionable
Censor: to suppress or delete as objectionable
ulcer
- an open sore on an external or internal surface of the body, caused by a break in the skin or mucous membrane that fails to heal
- (stomach ulcer) a sore that develops on the lining of the esophagus, stomach, or small intestine
sore (noun) (on the body)
an area of the body with the tissues ruptured or abraded
Helicobacter pylori (H. pylori)
bacteria that can cause an infection in the stomach or duodenum
rugae
A series of ridges produced by folding of the wall of an organ. Most commonly rugae refers to the gastric rugae of the internal surface of the stomach.
plica
(1) a fold of synovial tissue found in the lining of a joint
(2) Plica circularis: numerous folds of mucous membrane that line the inner wall of the small intestine
villus (plural: villa)
any of the fingerlike or threadlike projections from the surface of certain membranous structures, typically serving to increase surface area and facilitate the passage of fluid or nutrients
cholecystokinin (CCK)
a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein
gallstones
Solid clumps of material (mostly cholesterol) that form in the gallbladder.
Some gallstones never cause problems and are called silent gallstones, whereas others produce painful symptoms or other medical complications and are called symptomatic gallstones.
cholecystectomy
the surgical removal of the gallbladder
ursodeoxycholic acid
a bile acid used for the treatment of primary biliary cirrhosis (PBC)
primary biliary cirrhosis (PBC)
a chronic disease in which the bile ducts in your liver are slowly destroyed
biliary
(1) of, relating to, or conveying bile
(2) affecting the bile-conveying structures
cirrhosis
also known as liver cirrhosis, hepatic cirrhosis, and end-stage liver disease
it is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease
fibrosis
also known as fibrotic scarring
it is pathological wound healing leading to the creation of permanent scar tissue
ileocecal valve
the valve formed by two folds of mucous membrane at the opening of the ileum into the large intestine
large intestine
The long, tube-like organ that is connected to the small intestine at one end and the anus at the other.
four parts of the large intestine
- cecum: a pouch that forms the first part of the large intestine
- colon: the longest part of the large intestine; removes water and some nutrients and electrolytes from partially digested food
- rectum: the last several inches of the large intestine closest to the anus.
- anal canal: the terminal segment of the large intestine, between the rectum and anus
anus
The opening of the rectum to the outside of the body.
four parts of the colon
- Ascending colon: This is the first part of the colon, on the right side of the abdomen.
- Transverse colon: This is the middle part of the colon, going from the right to the left side of the abdomen.
- Descending colon: This is the third part of the colon, on the left side of the abdomen.
- Sigmoid colon: This is the last part of the colon, ending with the rectum.
microbiota
Ecological communities of commensal, symbiotic and pathogenic microorganisms found in and on all multicellular organisms studied to date from plants to animals. Microbiota include bacteria, archaea, protists, fungi and viruses.
ecology
adj. ecological
the branch of biology that deals with the relations of organisms to one another and to their physical surroundings
symbiosis
any type of a close and long-term biological interaction between two different biological organisms
obligatory symbiosis vs facultative symbiosis
Symbiosis can be obligatory, which means that one or more of the symbionts depend on each other for survival, or facultative (optional), when they can generally live independently.
ectosymbiosis vs endosymbiosis
When one organism lives on the surface of another, such as head lice on humans, it is called ectosymbiosis; when one partner lives inside the tissues of another, such as Symbiodinium within coral, it is termed endosymbiosis.
symbiont
an organism living in symbiosis with another
six types of symbiosis
- commensalism: a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed.
- mutualism: both organisms benefit from each other
- amensalism: one is harmed while the other is unaffected
- parasitism: one is harmed and the other benefits; distinct from predation in that the parasite lives off the host organism for a period of time instead of eating it directly
- predation: one species (the predator) hunts and kills another species (the prey)
6: competition: species compete for limited resources in the same environment
feces
The solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contains a relatively small amount of metabolic waste products such as bacterially altered bilirubin, and dead epithelial cells from the lining of the gut.
colostomy
a surgical operation in which a piece of the colon is diverted to an artificial opening in the abdominal wall (stoma) so as to bypass a damaged part of the colon
colostomy bag
A plastic bag that collects fecal matter from the digestive tract through an opening in the abdominal wall called a stoma. Doctors attach a bag to the stoma following a colostomy operation.
vermiform appendix
also called the appendix
It is a wormlike, tubular structure directly attached to the back of the cecum.
The appendix serves as a sort of incubator or “breeding ground” for the nonpathogenic intestinal bacteria found throughout the colon. When the normal microbiome of the gut is disrupted by infection or antibiotics, for example, beneficial bacteria hidden away in the appendix can migrate into the colon to restore the normal ecological balance.
appendicitis
inflammation of the appendix
movement of food through the GI tract
From entrance to exit:
- Mouth
- Esophagus
- Stomach
- Small intestine
- Large Intestine
- Anus
