What are the 6 major organs of the GIT?
What are the 6 accessory organs of the GIT?
What are the 6 key steps (or processes) of the GIT?
What are the layers of the GI?
(Inner to Outer)
Lumen (inner cavity)
Mucosa
Submucosa
Muscularis Externa
Serosa
Body wall
What are the 2 layers of the Muscularis Externa and their functions?
Responsible for peristalsis and segmentation.
What are the 3 layers of the Mucosa and their functions?
Responsible for Protection, absorption and secretion
What does the Submucosa contain?
Submucosal plexuses
Capillaries and lymph
Responsible for transport and regulation
Which areas of the GI feature Stratified squamous epithelium for protective purposes?
Oral cavity, pharynx, esophagus and anal canal.
Which area of the GI features columnar epithelium upon villi to increase surface area for absorption?
Small Intestine.
Which area of the GI features both Columnar epithelium and tubular glands for further absorption and protection?
Large Intestine
Which area of the GI features gastric glands mainly focusing on secretion?
Stomach
What is bolus?
Small rounded mass of chewed food substance.
What are the 3 steps in peristalsis?
Where does peristalsis occur?
Esophagus, stomach, small/large intestines.
What is peristalsis?
contraction and relaxation of adjacent sections to propel food forward.
What is segmentation?
Contraction and relaxation of non-adjacent sections to move food forward and backward as a form of mechanical digestion (food is churned and mixed)
What is the purpose of segmentation?
Mixes chyme with digestive secretion and increases exposure to epithelium for absorption.
Where does segmentation occur?
Small and large intestines
Where can the submucosal plexus be found and what is its purpose?
Submucosal layer.
Control local blood flow, gastrointestinal secretion and absorption from GIT into blood/lymph vessels.
Where can the Myenteric plexus be found and what is its purpose?
Between the circular and longitudinal muscles.
Regulates gastric motility and contractility.
What is enteric plexus?
Nerve plexuses relating to the intestines.
Myenteric and submucosal plexuses.
What nervous system controls the GIT?
Autonomic
- Parasympathetic nervous system via the vagus nerve. (CN X)
- Sympathetic nervous system via splanchic nerves.
What happens to the GIT when PNS activates?
Acetylcholine released
Promoting vasodilation to GIT, increasing secretion, motility and relaxation of sphincters.
What happens to the GIT when SNS activates?
Norepinephrine is released
Ceases digestive activities.