Know the functions of the digestive system
1) Motility: this refers to the movement of food through the alimentary tract through the process of ingestion, mastication, deglutition, peristalsis, and segmentation.
2) Secretion: this includes both exocrine and endocrine secretions
3) Digestion...
Know the functions of the digestive system
1) Motility: this refers to the movement of food through the alimentary tract
through the process of ingestion, mastication, deglutition, peristalsis, and
segmentation.
2) Secretion: this includes both exocrine and endocrine secretions
3) Digestion: this refers to the breakdown of food molecules into their smaller
subunits, which can be absorbed
4) Absorption: this refers to the passage of digested end products into the blood
or lymph.
5) Storage and elimination: temporary storage and subsequent elimination of
undigested food molecules
6) Immune barrier: simple columnar epithelium with tight junctions prevents
swallowed pathogens from entering the body; immune cells in CT of the tract
promote immune responses.
What is digestion
The breakdown of food molecules into their smaller subunits, which can be
absorbed.
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6 Ways to Show Appreciation for Your Child's Teacher
Know the functions of the different organs in digestion
Alimentary organs:
-oral cavity
-pharynx
-esophagus
-stomach
-small intestine
, -large intestine
Accessory digestive: organs:
-teeth
-tongue
-salivary glands
-liver
-gallbladder
-pancreas
Know the histology of the different layers of the GI tract
Mucosa: absorptive and major secretory layer, consists of a simple columnar
supported by the lamina propria. External to lamina propria is a thin layer of
smooth muscle called the muscularis mucosae.
Submucosa: relatively thick submucosa is a highly vascular layer of CT.
Absorbed molecules enter into blood and lymphatic vessels of the submucosa.
Also contains glands and nerve plexuses
Muscularis: responsible for segmental contractions and peristaltic movement
through the alimentary tract. Has an inner circular and an outer longitudinal layer
of smooth muscle. Myenteric plexus located in between the two layers.
-Serosa: completes the wall of the alimentary tract; consists of areolar CT
covered with a layer of simple squamous
What are plicae, and what is their function?
-The mucosa and submucosa form large folds called plicae circulares.
-Absorption occurs at a rapid rate as a result of extensive foldings which increase
absorptive surface area
What are chief cells and what do they secrete?
Chief (or zymogenic) cells: which secrete pepsinogen, an inactive form of the
protein digesting enzyme pepsin;
What are G cells and what do they secrete?
G cells: a cell in the gastric gland; secrete the hormone gastrin into the blood.
What are segmentation, peristalsis, and mass movements?
-Segmentation: major contractile element of the small intestine; churning and
mixing while moving forward
-Peristalsis: wave-like, one way movement through the tract
-Mass movements??***
Know the neurological implications of the swallowing reflex
Deglutition: or swallowing is divided into three phases: oral, pharyngeal, and
esophageal. Swallowing is a complex activity that requires the coordinated
contractions of 25 pairs of muscles in the mouth, pharynx, larynx, and
esophagus. The oral phase is under voluntary control, while the pharyngeal and
esophageal phases are automatic and controlled by the swallowing center in the
brain stem.
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