Chapter 24 - The Digestive System - Part1 Flashcards
What is catabolism?
the BREAKDOWN of complex molecules to simpler ones. requires oxygen and organic molecules (carbohydrates, lipids, proteins)
What is anabolism?
the synthesis of complex molecules from simpler ones
What 2 systems work together to provide the oxygen needed for catabolism?
the cardiovascular and respiratory systems
the digestive system provides both the…
fuel that keeps the cells running and building blocks needed for growth and repair
The digestive system consists of: (2 things)
-the GI tract (digestive tract or alimentary canal)
-various accessory organs
Name the structures that make up the alimentary canal/ GI tract/ digestive tract
mouth (oral cavity)
pharynx (throat)
esophagus
stomach
small intestine
large intestine
Name the accessory structures of the digestive system
teeth
tongue
glandular organs (salivary glands, liver, pancreas)
Where do glandular organs secrete their products?
into DUCTS that empty into the digestive tract
What do the secretions of glandular organs contain?
enzymes, water, buffers, other substances
Name the 6 integrated steps of the digestive system
- Integration
- Mechanical processing
- Digestion
- Secretions
- Absorption
- Excretion
Is ingestion a conscious choice?
yes
What is secretion?
the release of water, acids, enzymes, buffers by the epithelium of the digestive tract and by glandular organs
What is absorption?
the movement of organic molecules, electrolytes, vitamins, etc across the digestive epithelium and into the interstitial fluid of the digestive tract
How does the lining of the digestive tract play a protective role?
-against the corrosive effects of digestive acids and enzymes
-mechanical stresses
-bacteria that are swallowed or live in the digestive tract
the abdominopelvic cavity contains the ___ cavity
peritoneal cavtiy
describe the structure of the peritoneal cavity
lined by a serous membrane which consists of a superficial mesothelium covering a layer of areolar tissue
describe the structure of the peritoneal cavity
lined by a serous membrane which consists of a superficial mesothelium covering a layer of areolar tissue
Name and explain the 2 parts of the serous membrane lining the peritoneal cavity
visceral peritoneum (covers organs which project in the abdominopelvic cavity)
parietal peritoneum (lines inner surfaces of the body wall)
What is the term for the buildup of peritoneal fluid that creates abdominal swelling?
ascites
What is another word for the visceral peritoneum
the serosa
What is the largest serous membrane in the body
the peritoneum
what are “mesenteries”
double sheets of peritoneal membrane that suspend portions of the digestive tract within the peritoneal cavity and prevent intestines from becoming tangled during digestive movement or changes in body positio
What are the 4 major layers of the digestive tract from innermost to outermost
innermost - mucosa
submucosa
muscularis externa
outermost -serosa
Describe the structure of the mucosa, the innermost layer of the digestive tract
mucosa is a mucous membrane
consists of an epithelium moistened by glandular secretions
has a LAMINA PROPRIA of areolar tissue
Where are mechanical stresses most severe in the digestive tract and what conclusion can you draw from this?
oral cavity, pharynx, esophagus
contains stratified squamous epithelium here
stomach, small intestine, and large intestine have simple columnar
Scattered among these simple columnar cells are which 2 types of cells?
mucous cells and enteroendocrine cells
what do enteroendocrine cells do?
secrete hormones that coordinate the activities of the digestive tract and accessory organs
The secretions of gland cells by the mucosa, submucosa, or accessory glandular organs are carried to epithelial surfaces by….
ducts
what is the “lamina propria”
a layer of areolar tissue that contains blood vessels, sensory nerve endings, lymphatic vessels, smooth muscle cells, and scattered lymphoid tissue
what is the “muscularis mucosae”
the narrow sheet of smooth and elastic muscle fibers found in the lamina propria of most areas of the digestive tract
how are the smooth muscle cells in the muscularis mucosae arranged?
in 2 concentric layers
inner layer encircles the lumen
outer layer contains muscle cells parallel to the long axis of the tract (aka longitudinal layer)
contractions in the 2 layers of the muscularis mucosae do what??
alter the shape of the lumen and move the epithelial plates and folds
the submucosa is a layer of ____ ____ connective tissue that connects the ___ to the ____
DENSE IRREGULAR that connects the mucosa to the muscularis externa
describe general components of the submucosa layer
numerous blood vessels and lymphatic vessels, exocrine glands that secrete buffers and enzymes into the lumen of the digestive tract
The muscularis externa is dominated by what type of cells?
smooth muscle cells
Where is there NO serosa
there is no serosa covering the muscularis externa of the oral cavity, pharynx, esophagus, and rectum
instead, there is a dense network of collagen fibers called the ADVENTITITA
The smooth muscle along the digestive tract has rhythmatic cycles of activity due to…..
pacesetter cells
What is peristalsis?
the muscularis externa propels materials from one portion of the digestive tract to another by contractions
what is the term for the small rounded ball of digested contents?
a bolus
what is “segmentation”
does not follow a set pattern and does not push materials in any set direction
cycles of contraction that churn and fragment the bolus, mixing the contents with the intestinal secretions
Name 3 general things that can control digestive functions
local factors
neural mechanisms
hormonal mechanisms
What is the PRIMARY stimulus for digestive activities
local factors
respond to changes in pH, physical distortion of the wall of the digestive tract, or the presence of chemicals
Identify the organs of the digestive system
esophagus
stomach
small intestine
large intestine
accessory organs (salivary glands, liver, pancreas)
What is the importance of the mesenteries?
the mesenteries are sheets consisting of 2 layers of serous membrane connected by loose connective tissue
they support and stabilize organs in the abdominopelvic cavity and provide a route for the associated blood vessels, nerves, and lymphatic vessels
Which is more efficient in propelling intestinal contents from one place to another: peristalsis or segmentation?
peristalsis.
segmentation is basically a churning action that mixes intestinal contents with digestive fluid
Which is more efficient in propelling intestinal contents from one place to another: peristalsis or segmentation?
peristalsis.
segmentation is basically a churning action that mixes intestinal contents with digestive fluid
Name the layers of the gastrointestinal tract from superficial to deep
superficial - serosa
muscularis externalis
submucosa
mucosa
What effect would a drug that blocks parasympathetic stimulation of the digestive tract have on peristalsis?
parasympathetic stimulation increases muscle tone and activity in the digestive tract
therefore, this drug would slow down peristalsis
what is another name for the oral cavity
the buccal cavity
The oral cavity is lined by ___ mucosa which has what kind of epithelium?
oral mucosa, stratified squamous
the soft palate lies ___ to the hard palate
posterior
name the 4 structures that form the mouth
tongue, cheeks, hard palate, soft palate
How many pairs of salivary glands are there?
3
name the 3 pairs of salivary glands
parotid
sublingual
submandibular
which pair of salivary glands produces secretions that have large amounts of salivary amylase?
parotid glands
Saliva is 99.4% ______
water
What gives saliva its lubricating action?
mucins (glycoproteins)
Most of the saliva comes from which pair of glands?
the submandibular glands
______ in saliva keep the pH of the mouth near 7
buffers
saliva contains ____ and ___ which help to control the populations of oral bacteria
antibodies and lyzozyme
Salivary amylase begins digesting ______
starch (complex carbohydrates)
Where does the digestion process begin?
the oral cavity
Does any ABSORPTION take place across the lining of the oral cavity?
no
The upper and lateral surfaces of the tongue are covered with _____, some of which contain taste buds
papillae
lingual glands are found where and what do they secrete?
found on the tongue and they secrete lingual lipase to start lipid digestion
What do the extrinsic tongue muscles do? intrinsic?
extrinsic - involved in gross movements of the tongue
intrinsic - change the shape of the tongue and assist the extrinsic muscles in precise movements such as speech
what is another word for the chewing of food?
mastication
What is the part of tooth that has a mineralized matrix similar to that of bone???
dentin
How does dentin differ from bone
it DOES NOT CONTAIN CELLS
the neck of the tooth marks the boundary between the ___ and _____
root and crown
a layer of ___ covers the dentin of the crown
enamel
what does enamel consist of?
calcium phosphate in a crystalline form
Adequate amounts of ____, ____, and ___ during childhood are essential if the enamel coating is to be complete and resistant to decay
calcium, phosphate, vitamin d
what is the hardest, biologically manufactured substance
enamel
name the 4 types of teeth
incisors
cuspids (canines)
bicuspids (premolars)
molars
what are the 2 sets of teeth that form during development
deciduous teeth
secondary dentition (permanent dentition)
what are the 2 sets of teeth that form during development
deciduous teeth
secondary dentition (permanent dentition)
The deciduous teeth either….
fall out of are pushed to the side by ERUPTION
Name the structures associated with the oral cavity
tongue
salivary glands
teeth
Which type of epithelium lines the oral cavity
stratified squamous
The digestion of which nutrients would be affected by damage to the parotid salivary glands
Parotid salivary glands secrete salivary amylase so the digestion of complex carbohydrates would be affected
Which type of tooth is most useful for chopping off bits of rigid foods
incisors
Where are the fauces located?
the fauces is the dividing line between the oral cavity and the pharynx