Digestive system Flashcards
What is the purpose of the digestive system?
provides fuel to keep all the body’s cell functioning
supplies building blocks needed for cell growth and repair
What are two groups of the organs compose the digestive system
the digestive canal and the accessory digestive organs
What is a digestive canal
It is a continuous tube that extends through thoracic and abdominal cavities from the esophagus to the anus
What organs includes in GI tract?
esophagus
stomach
small intestine
large intestine
anal canal
The accessory organs include:
mouth
teeth
tongue
salivary glands
pharynx,
liver,
gallbladder
pancrease
ingestion
the process involve taking food and liquids into the mouth
secretion
cells with walls of the digestive canal and accessory digestive organs secret about 7 l of water, acid, buffers and enzymes into the lumen
digestion
a process of breaking down ingested food into small molecules that can be used by body cells
mechanical digestion
the teeth cut and grind before it is swallowed
smooth muscles of the stomach and intestine churn the food to further assist the process
chemical digestion
the large carbohydrate, lipid, protein and nucleic acid molecules in food are split into smaller molecules by hydrolysis
Motility
alternating contractions and relaxations of smooth muscle in the walls of the digestive canal mix food and secretions and move them toward the anus
Absorption
The movement of the products of digestion from the lumen of the digestive canal into blood plasma or lymph. Once absorbed these substances circulate to cells through the body
Defecation
Waste, indigestible substances, bacteria cells sloughed from the digestive canal and digested material that was not absorbed that was not absorbed in their journey through the digestive canal leave the body through the anus a process called defecation
what are layers of the digestive canal
mucosa
submucosa
musclaris
serosa or adventitive
Mucosa
nonkeratinized stratified squamous epithelium = mouth
pharynx
esophagus
anal canal
PROTECTIVE FUNCTION
simple columnar epithelium=
stomach
small intestines
DECRETION AND ABSORPTION
what kind of the glands located among the epithelium cells
exocrine gland= secret mucus and fluid into the lumen of the digestive canal
endocrine glands=enteroendocrine glands =secrets hormones
What is mucosa composed of?
epithelium
lamina propira
muscularis mucosae
Lamina propria of mucosa
Areolar CT contains many blood vessels and lymphatic vessels which are the routes by which nutrients absorbed into the digestive canal reach the other tissues of the body.
what kind of the cells lamina proper contains
mucosa-associated lymphoid tissue MALT
WHERE YOU CAN FIND malt?
Tonsils
small intestine
appendix
large intestine
What is the muscularis mucosae of mucosa?
A thin layer of smooth muscles fibre that throws the mucous membrane of the stomach and small intestine into may fold which increases the surface area for digestion and absorption
Submucosa
consist of areolar connective tissue that binds mucosa to muscularis
What is located in the submucosa layer
an extensive network of neurons known as submucosal neural plexuses
What is submucosal neural plexuses?
The plexuses of the ENS consist of motor neurons, interneurons, and sensory neurons
what does the motor neuron supply of the submucosal neural plexus
the secretory cells of the mucosal epithelium controlling the secretions of the organs of digestive canals
hat does interneurons of the ENS do?
connect the neurons of the myenteric and submucosal neural plexuses
What does the sensory neurons of the ENS supply?
supply the mucosal epithelium and contain receptors that detect stimuli in the lumen of the digestive tract
what are 2 major types of sensory receptor in the wall of digestive canal
chemoreceptors respond to certain chemicals in the food
mechanoreceptors= such as stretch receptors that are activated when food distends the wall of the digestive canal organ
Muscularis layer of the mouth
pharynx
superior and middle parts of the esophagus
external anal sphincter contains what kind of muscles?
Skeletal muscles and their voluntary action
Throughout the rest of digestive canaal muscular layer consist:
smooth muscles
found in two sheets
inner shhet=circular fibers
outer sheet=longitudinal fibers
what is found between layers of the muscular layer?
second plexus of neurons called myenteric neural plexus
What do motor neurons of the myenteric neural plexus supply?
They supply longitudinal and circular smooth muscles layer of the muscular layer and this plexus controls digestive canal motility particularly the frequency and the strength of the contraction of the muscular layer
what is serosa
a serous membrane composed of areolar connect tissue and simple squamous epithelium (mesothelium)
who lacks serosa?
Esophagus laks serosa instead only a single layer of areolar connective tissue called adventitia
peritoneum
largest serous membrane of the body
what is composed peritoneum of?
a layer of simple squamous epithelium mesothelium
supporting layer of areolar connective tissue
how is peritoneum divided
parietal peritonemu
visceral peritonemu
what is parietal peritonemu
lines the wall of the abdominal cavity
visceral peritoneum
covers some of the organs in the cavity and their serosa
what is the name of the slim space containing lubricating serous fluid that is between the parietal and visceral portion of the peritoneum
peritoneall cavity
which organs are retroperitoneal
kidneys
ascending and descending colons of the large intestine
duodenum of the small intestine
pancrease
what does reroperitoneal mean
organs that lie on the posterior abdominal wall and covered by peritoneum only ob their anterior surface
What are 5 major peritoneal fold
the greater omenutm
falciform ligament
lesser omentum
mesentery
mesocolon
greater omenutm
longest peritoneal fold
drapes over transverse colon and coils of small intestine like fatty apron”
contains considerable amount of adipose tissue
many lymph nodes of the greater omentum contribute to macrophages and antibody-producing plasmocytes that help combat and contain infections of the digestive canal
falcifrom ligament
attaches the liver to the anterior abdominal wall and diaphragm
the liver is the only digestive organ that is attached to the anterior abdominal wall
lesser omentum
suspends stomach and dudodenum from liver
mesenteries
helps stabilize position of the abdominal organs
prevents intestines from becoming entangled
mesocolon
binds transerse and sigmoid colon to posterior abdominal wall
