week 4 Flashcards
what is the difference between mechanical and chemical digestion
Mechanical: the chewing of food by the teeth before it is swallowed / the churning of food by the smooth muscles of the stomach and small intestine so that it is thoroughly mixed with digestive enzymes
Chemical: a series of catabolic reactions in which enzymes break down large food molecules (eg: carbohyrates, lipids, protein, nucleic acids) into smaller molecules that may be absorbed and used by body cells.
what are the four major layers that exist along the GI tract from the esophagaus to the anal canal (from innermost to outermost)
- mucosa 2. submucosa 3. muscularis 4. serosa
Understand the 3 MUCOSA layers of the GI tract
- what type of cells the inner layer is composed of
- what makes up the middle layer
- what is important about the outer layer
INNER LINING OF EPITHELIUM:
- nonkeratinized stratified squamous epithelium in the mouth, pharynx, esophagus, and anal canal.
- Simple columnar epithelium throughout the rest of the GI tract to assist in secretion and absorbtion
MIDDLE LAYER OF AREOLAR CONNECTIVE TISSUE (LAMINA PROPRIA)
- contains blood vessels, lymphatic vessels, and scattered lymphatic nodules
- contains most components of the mucosa-associated lymphoid tissue (MALT)
OUTER LAYER OF SMOOTH MUSCLE TISSUE (MUSCULARIS MUCOSAE)
- creates small folds in the stomach and small intestinal mucosa that increase the surface of areolar area for digestion and absorption
the mucosa is a _____ membrane that surrounds the _____.
mucus, lumen
the submucosa consists of _____ _____ tissue
areolar connective
which layer of the GI tract is highly vascular
the submucosa
what is the job of the submucosal plexus
innervates the mucosa and submucosa and plays an important role in regulating:
a. movements of the mucosa and vasoconstriction of blood vessels
b. secretions by the GI tract
the muscularis consists of _____ tissue
muscle
skeletal muscle tissue can be found in what structures and allows for ?
in the mouth, pharynx, upper and middle parts of the esophagus, and the external anal sphincter.
It produces voluntary swallowing and voluntary control of defecation
the parts of the GI tract that do not consist of skeletal muscle tissue, are composed of what kind of tissue and are divided into what two types of fibers
smooth muscle tissue
a.inner sheet of circular fibers
b.outer sheet of longitudinal fibers
what is the largest peritoneal fold
the greater omentum
what plexus primarily controls GI tract motility
myenteric plexus (plexus of Auerbach)
what kind of cells make up the serosa layer of the GI tract
simple squamous epithelium
what is the largest serous membrane of the body
the peritoneum
what is the space between the parietal and visceral peritoneum
peritoneal cavity, which contains serous fluid
ascites
a disease which is brought on by an accumulation of serous fluids
what does it mean if an organ is considered retroperitoneal
some abdominal organs, such as the kidneys and pancreas, are located on the posterior abdominal wall and are covered by peritoneum on their anterior surfaces only. These organs are said to be retroperitoneal
what are the functions of the folds of the peritoneum
a. binds organs to each other and to the walls of the abdominal cavity
b. contains blood vessels, lymphatic vessels, and nerves that supply the abdominal organs
what structure is considered a “fatty apron” and hangs in front of the abdominal viscera, extending from the stomach and duodenum downward over the small intestine, then turning upward and attaching itself to the transverse colon?
the greater omentum
what is the structure that attaches the liver to the anterior abdominal wall and diphragm
the falciform ligament
what structure suspends the stomach and duodenum from the liver and contains some lymph nodes
the lesser omentum
what structure extends from the posterior abdominal wall to wrap around the small intestine and then returns to its origin
mesentery
what structure is an outward fold of the parietal peritoneum, attaches the large intestine to the posterior abdominal wall, and carries blood and lymphatic vessels to the intestines
the mesocolon
internally, the cheeks contain what type of cells
nonkeratinized stratified squamous epithelium
what is the name of the lip muscle is covered externally by skin and internally by a mucous membrane
obicularis oris muscle
what is the labial frenulum
the midline fold of mucous membrane that attaches the inner surface of each lip to its corresponding gum
what nerves innervate the muscles of mastication
trigeminal nerves
what structure is located just underneath the skin and contains large quantities of adopose tissue and many lymph nodes?
the greater omentum
the recess that is bounded externally by the lips and cheeks and internally by the gums and teeth is called the_
oral vestibule
the area that lies within the teeth and gums is called the _
oral cavity
the space that extends from the gums and teeth to the fauces that connects the oral cavity to the pharynx is called the_
oral cavity proper
the hard palate forms the _____ portion of the roof of the mouth and consists of the _____ and ____ bones covered by mucous membrane
anterior, maxillae, palatine
the hard palate separates what two structures
the oral cavity from the nasal cavity
the soft palate forms the _____ portion of the roof of the mouth and lies between the _____ and the _____.
posterior, oropharynx and nasopharynx
projecting downward from the free edge of the soft palate is the fingerlike _
uvula
on either side of the base of the uvula are two muscular folds.
_____, the palatoglossal arch extends to the side of the base of the _____.
_____, the palatopharyngeal arch extends to the side of the _____,
anteriorly, tongue
posteriorly, pharynx
where are the palatine tonsils located?
the lingual?
palatine tonsils are located between the palatoglossal arch and palatopharyngeal arch.
Lingual tonsils are located on the base of the tongue
what are the three major types of salivary glands and what are their locations
a. parotid glands; located inferior and anterior to the ears btw the skin and masseter muscle
b. submandibular glands; located beneath the base of the tongue
c. sublingual glands; located in the floor of the mouth superior to the submandibular glands
all salivary glands are made up of what type of cells
simple cuboidal
T/F_the salivary glands are innervated by BOTH sympathetic and parasympathetic fibers
TRUE
saliva is ?% water and ?% solutes?
What are these solutes?
99.5%, .5%
a.bacteriolytic lysozyme
b.salivary amylase, which initiates starch digestion
c.lingual lipase (secreted by lingual glands on the dorsum of the tongue), which initiates triglyceride digestion
what nerves stimulate the secretion of saliva
facial and glossopharyngeal.
*this is different from when saliva is secreted due to the sight, smell, sound, or thought of food.
T/F_the tongue is composed of smooth muscle tissue covered by mucous membrane
False_it is composed of skeletal muscles covered by mucous membrane
the tongue is divided into symmetrical lateral halves by a _____ _____ that is attached inferiorly to the _____ bone, _____ _____ of the temporal bone, and _____.
median septum, hyoid, styloid process, mandible
what is the difference between extrinsic and intrinsic muscles of the tongue
Extrinsic:
a. originate outside the tongue and insert into it.
B. they move the tongue for food manipulation during chewing and swallowing
c. they form the floor of the mouth and hold the tongue in position
Intrinsic:
a. they alter the shape and size of the tongue for speech and swallowing
what is the lingual frenulum
the fold of mucous membrane that attaches the midline of the inferior sufrace of the tongue to the floor of the mouth. It limits the movemebt of the tongue posteriorly
children born with an extremely short lingual frenulum are often referred to as “tongue tied” because restricted tongue movemebt distorts speech. This congenital condition is called:
ankyloglossia
the superior and lateral surfaces of the tongue are covered with _____. Which are projections of the lamina propria covered with epithelium
papillae
what kind of papillae are mushroom-like projections distributed among the filiform papillae and are more numerous near the tip of the tongue
fungiform papillae
what kind of papillae are arranged in the form of an inverted “v” on the posterior surface of the tongue
vallate (circumvallate) papillae
what kind of papillae are on a tongue’s lateral margins, and have few taste buds in adults
foliate papillae
what kind of papillae are cone-shaped projections diustributed in parallel rows over the anterior two-thirds of the tongue
filiform papillae
what kind of papillae appear whitish and lack taste buds, and increase friction between the tongue and food, making it easier for the tongue to move food
filiform papillae
the sockets are lined by the _____ _____ or membrane, which anchors the teeth in position and acts as a shock absorber during chewing
periodontal ligament
what forms most of the mass of a tooth
dentin
swallowing aka_
deglutition
layers of the wall of the esophagus (innermost to outermost)
- mucosa 2. submucosa 3. muscularis 4. adventitia
the entry of food into the esophagus is regulated by the _
upper esophageal sphincter or valve
what are the two functions of the esophagus
- secrete mucus to lubricate the bolus and reduce friction
- transport food to the stomach
food is pushed through the esophagus by involuntary waves of muscular contractions called_
peristalsis (this is the function of the muscularis)
just above the diaphragm is the _____ _____ sphincter or valve, which briefly relaxes to permit passage of the bolus from the esophagus into the stomach
lower esophageal
location of the stomach
directly under the diaphragm in the upper left portion of the adbominal cavity
4 major areas of the stomach
- cardia: surrounds the superior opening of the stomach
- fundus: the rounded portion above and to the left of the cardia
- body: the large, central portion
- pylorus: the inferior portion that connects to the duodenum and has two regions:
a.pyloric antrum, which connects to the stomach’s body
b.pyloric canal, which leads into the duodenum
when the stomach is empty, its mucosa lies in large folds called
rugae
4 standard layers of the stomach
- mucosa 2. submucosa 3. muscularis 4. serosa
what type of cells can be found in the gastric pits of the mucosa layer in the stomach
epithelial columnar cells
what are the 4 types of secretory cells pertaining to gastric glands of the stomach
a.mucus neck cells, which secrete mucus
b.chief (zymogenic) cells, which secrete pepsinogen and gastric lipase
c.parietal cells, which secrete HCl (which converts pepsinogen into the active pepsin and kills microbes in food) and intrinsic factor (which is essential for the absorption of vitamin B12)
d.G cells, which are located primarily in the pyloric antrum and secrete the hormone gastrin into the blood
mucus neck cells, chief zymogenic cells, and parietal cells collectively form ? through their secretions into the stomach lumen
gastric juice
what are the three layers of the muscularis layer in the stomach wall
- the outer longitudinal layer
- the middle circular layer
3.the inner oblique layer, found primarily in the body of the stomach
functions of the stomach
- mixing waves that macerate food, mix it with gastric juice, and reduce it to a soupy liquid called chyme
- propelling small quantities of chyme through the slightly open pyloric sphincter into the duodenum
3.digest proteins by pepsin into peptides - limited digestion of triglicerides by gastric lipase
- empties food/drink contents into the duodenum about 2-4 hours after ingestion
what are the only substances absorbed into the stomach wall
some water, electrolytes, certain drugs (notably asprin), alcohol
what organ is considered the “home of all digestion”
the pancreas
location of the pancreas
retroperitoneal and is located posterior to the greater curvature of the stomach
what are the three major regions of the pancreas and their locations
- the medial head, located near the curve of the duodenum
- a central body, located superior and to the left of the head
- a lateral, tapering tail
in most people, the pancreatic duct joins the common bile duct from the _____ and _____ to form the _____ _____.
liver, gall bladder, hepatopancreatic ampulla
about 1% of the glandular epithelial cells of the pancreas are organized into clusters called _____ _____. What is their function?
pancreatic islets; they form the endocrine portion of the pancreas and secrete the following hormones: glucagon, insulin, somatostatin, pancreatic polypeptide
99% of the glandular epithelial cells of the pancreas are arranged in clusters called _____. What is their function?
acini; they form the exocrine portion of the pancreas and secrete a mixture of fluid and digestive enzymes called pancreatic juice
the major exocrine function of the pancreas is to secrete pancreatic juice, which includes what components:
water, some salts, sodium bicarbonate, several digestive enzymes
what is the main function of digestive enzymes: trypsin, chymotrypsin, and carboxypeptidase
digest proteins
what is the heaviest gland of the body and also the second largest organ of the body
liver
location of the liver
under the diaphragm in the upper right portion of the abdominal cavity
the larger right and smaller left lobes of the liver are separated by what
the falciform ligament
what are hepatocytes
liver cells, whose function inculdes the secretion of bile
the portal triad of the liver is composed of:
~a branch of he hepatic portal vein
~a branch of the hepatic artery
~a bile duct
what is the difference between the hepatic artery and the hepatic portal vein
the artery provides oxygenated blood, the vein delivers deoxygenated blood containing newly absorbed nutrients from the GI tract
what are some functions of the liver, aside from secreting bile
carbohydrate metabolis; lipid metabolism; processing of drugs and hormones; excretion of bilirubin; synthesis of bile salts; storage of substances like glycogen, vitamins, minerals; phagocytosis; activation of vitamin D
what are the three regions that make up the sm. Intestine
- the duodenum (25 cm long; retroperitoneal)
- the jejunum (1 m long)
- the ileum (2 m long; meets the large intestine at the ileocecal sphincter)
the mucosa layer of the sm. Intestine has numerous _____, which greatly increase the surface area available for digestion and absorption
villi
the mucosal epithelium of the sm. Intestine consists of what kind of cells
simple columnar epithelium
goblet cells, which secrete mucus
absorptive cells, which help digest and also absorb digested nutrients
what kind of cells exist in the deepest part of the sm. Intestinal layer
paneth cells, which secrete lysozyme and are capable of phagocytosis
what three types of enteroendocrine cells are found in the small intestine
~S cells, which secrete secretin
~CCK cells, which secrete cholecystokinin, or CCK
~K cells, which secrete glucose-dependent insulinotropic peptide, or GIP
what is the collection of white blood cells in the small intestines called
aggregated lymphatic follicles (peyer’s patches)
what are the glands that secrete an alkaline mucus that helps neutralize gastric acid in the chyme
duodenal (brunner’s) glands
the completion of digestion is in what organ
small intestine
the surfaces of microvilli have _____-_____ enzymes that help break down sugars
brush-border
what are segmentations
move chyme back and fourth to thoroughly mix the chyme with digestive juices and bring nutrients into contact with the mucosa for absorption
where does the lg. intestine extend from
the ileum to the anus
the large intestine is attached to the posterior abdominal wall by the _____
mesocolon
the digestion of carbohydrates, proteins, and lipids is completed in what organ
the small intestine
what are the 4 major regions of the large intestine
- cesum; a blind porch in the lower right portion of the abdominal cavity
- colon
- rectum, which descends anterior to the sacrum and coccyx
- anal canal, which is the terminal 2 to 3 cm of the rectum
what are the 4 segments of the colon
- the ascending colon; ascends on the right side of the abdominal cavity to the right colic (hepatic) flexure (hooks up to the LV)
- the transverse colon; travels across to the left side to the left (splenic) flexure (hooks up to the SP)
- the retroperitoneal descending colon; descends on the left side of the abdominal cavity to the level of the iliac crest
- the sigmoid colon; travels medially from the left iliac crest to the level of the third sacral vertebra
attached to the cecum is the _____
appendix
chyme from the ileum enters the cecum via the ?
ileocecal sphincter or valve
what structure attaches the appendix to the inferior part of the mesentery of the ileum
the mesentery of the appendix (mesoappendix)
what are the two kinds of cells found in the mucosa layer of the large intestine
absorptive cells, whose main fxn is water reabsorption, & goblet cells, which secrete mucus
*note that NO enzymes are secreted
describe the two characteristics of the muscularis layer of the large intestine
it is composed of 2 layers of smooth muscle tissue:
- an inner circular layer and an outer longitudinal layer; the latter has three thickened longitudinal bands called TENIAE COLI
- tonic contractions of these bands crease a series of pouches called HAUSTRA in the colon.
what are the 3 types of movement that happen in the large intestine
- haustral churning
- peristalsis
- mass peristalsis
the parasympathetic nervous system influences digestion by…
stimulating peristalsis and secretory activity
the sphincter between the stomach and duodenum is called
the pyloric sphincter
