digestive system review
in order walls of alimentary canal form inside out
1. lumen is where nutrients and water are mixed with secretions 2. the mucosa contains the surface epithelium that allows for absorption of nutrients, as well as glands for secretion 3. the submucosa is composed mostly of connective tissue, nerves, and vessels, which help to nourish surrounding tissues 4. the muscular layer is responsible for the moevement of substances through the alimentary canal 5. the serosa is composed of epithelia and connective tissues thatt reduce friction between organs in the abdominal cavity
IN ordeR
1. the first sphincter of the digestive system is called the orbicularis oris muscle, surrounds the entrance to the oral cavity 2. the inferior constrictor muscles act as a sphincter, preventing air from entering the esophagus but relaxing to allow the entrance of food into the stomach 3. the terminal end of the esophagus is the lower esophageal sphincter which controls the entrance of food into the stomach 4. the pyloric sphincter regulates the movement of food from the stomach to the small intestine 5. the junction of the small and large intestine is the loaction of the ileocecal sphincter, which regulates the movement of intestinal contents into large intestine 6. the involuntary controlled internal anal sphincter is composed of smooth muscle that relaxes at onset of defecation 7. the voluntary relaxation of the external anal sphincter which is composed of skeletal muscle, is the final step in defecation
IN order:
1. the oral cavity provides mechanical digestion of chewing which is called mastication 2. the esophagus moves food fro the pharynx to the stomach with wave like contractions called peristaltic waves 3. the stomach is a hollow storage vat that initiates digestion of proteins 4. the small intestines is where most absorption of nutrients takes place 5. large intestines absorbs a little water and electrolytes, but is mostly for a storing feces.
walls of digestive tract four layers
inner mucosa, submucosa, muscular layer, outer serosa
accessory organs of the GI tract
liver, gallbladder, pancreas, salivary glands, teeth
organs of alimentary tract
mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus
GI tract in order
oral cavity, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum) large intestine (ascending colon, transverse colon, descending colon, sigmoid colon), rectum, anus
sublingual gland
produces 3-5% of saliva
submandibular gland
produces 60-70% of saliva
liver
produces and secretes bile stores glycogen, minerals, and vitamins
pancreas
produces and secretes digestive enzyme, releases insulin into the blood
parotid gland
products 25-30% of saliva
gallbladder
stores and concentrates bile