Digestive metacognition

how would you describe the alimentary canal?

mouth, pharynx, esophagus, stomach, small intestine, and large intestine (colon)

what are the accessory organs of the digestive system?

Teeth, tongue, gallbladder, liver, pancreas, salivary glands

what are the functions of the tongue?

-grips food and constantly reposition it between the teeth

-mixes the food w/saliva and from it into a compact mass called a bolus

-during swallowing.. the tongue moves posteriorly to push into the pharynx

-houses most of the tastebuds

-in speech, the tongue helps form some constants (K,D, T, L)

how many deciduous teeth do you have?when did they erupt? how many permanent teeth do you have?

a) Primary dentition (deciduous teeth): 20 total that erupt at intervals between 6-24 months

b) Permanent teeth: enlarge and develop causing the root of deciduous teeth to be reabsorbed and fall out between the ages of 6 and 12 years; all but the third molars (“wisdom teeth”) have erupted by the end of adolescence; there are usually 32 permanent teeth

what are incisors adapted? what are canines able to do to food? what are premolars and molars best suited for?

a) incisors: chisel-shaped teeth adapted for cutting or nipping

b) Canines: conical or fanglike teeth that tear or pierce

c) Premolars (biscuspids) and molars: have broad crowns with rounded tips and are best suited for grinding or crushing

what happens during chewing?

during chewing (mastication), upper and lower premolars and molars lock together generating crushing force

what are the functions of the salivary glands?

a) moisten, dissolves food, bind food together (bolus)

b) minds in digestion of starch

c) prevents tooth decay by neutralizing acids

d) contains bactericidal enzymes, antiviral substances, and antibodies to kill harmful oral microorganisms

e) contains proteins to help growth of beneficial bacteria

what is the difference between the intrinsic and extrinsic salivary glands?

a) Intrinsic salivary glands: scattered within mucosa of tongue, palate, lips, and cheeks mouth moist at all times

b) Extrinsic salivary glands: lie external to the mouth but have ducts that open to the mouth

what is the pharynx lined with? what are the muscle layers like?

lined with stratified squamous epithelium and mucus glands

-has two skeletal muscle layer; inner longitudinal and outer pharyngeal constrictors

what enzymes get secreted when protein digestion begins?

Protein digestion begins (secretes pepsin) functions under acidic conditions

How does the muscularis in the esopgagus change?

Muscularis changes from skeletal (superiorly) to smooth muscle (inferiorly)

what is the stomach the site of? How does acid help the stomach?

Stomach is the site where the food is churned into chyme (the liquid substance found in the stomach;= water, hydrochloric acid, and digestive enzymes). ~ 4 hours

-hydrochloric acid: a strong acid that destroys many harmful bacteria in the food

what is the small intestine site of?

site of most enzymatic digestion and absorption of nutrients (~3-6 hours)

what does the duodenum receive?

receives digestive enzymes from the pancreas and bile from the liver and gall bladder

what forms the hepatopancreatic ampulla?

main pancreatic duct and common bile duct enter the wall of the duodenum where they form a bulb called the hepatopancreatic ampulla

what do plicae circularis force the chyme to do?

-force the chyme to spiral through the intestinal lumen… slowing down its movement

describe the absorptive cells of the villi

• 1mm tall finger like projection of the muscosa that are covered by a simple columnar epithelium made up primarily of absorptive cells (enterocytes) specialized for absorbing digested nutrients.

• contain lacteals and blood capillaries.

what are the functions for the 2 hormones secreted by enteroendocrine cells?

a) cholecystokinin: signals the gallbladder to release store bile and the pancreas to secrete its digestive enzymes

b) secretin: signals the pancreatic ducts to secrete a bicarbonate-rich juice to neutralize the acidic chyme entering the duodenum

what is the main function of the large intestine?

-absorb water and electrolytes (~12-24 hours)

-digested residue contains few nutrients

-small amount of digestion by bacteria

-mass peristaltic movements force feces toward the rectum

what is the function of the ileocecal valve?

-ileocecal valve: sphincter muscle situated at the junction of the small intestine (ileum) and the large intestine

-it regulates the flow of chyme into the bowels.

what is the function of the vermiform appendix?

tube that connected to the cecum: neutralizes pathogens

describe the roles of the liver

plays a major role in metabolism, glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification

describe the gallbladder

rests in a recess on the inferior surface of the right lobe and is the storage place for bile

• thin walled, green muscular sac on the ventral surface of the liver stores and concentrated bile by absorbing its water and ions, releases bile via the cystic duct, which flows into the bile duct

what are the differences between the exocrine and endocrine function of the pancreas?

• Exocrine function: Acinar cells make, store and secrete pancreatic enzymes which are activated in the duodenum and breaks down food.

• endocrine function: produces the hormones insulin and glucagon which regulates blood sugar

what are the functions of the mesentery? where do we have more mesenteries: dorsal or ventral>

• holds organs in place

• sites of fat storage

• provides a route for circalotory vessels and nerves

- Dorsal mesenteries > ventral mesenteries

describe the tissue layers of the alimentary canal wall. which layer of the wall probably helps with peristalsis?

• mucosa, submucosa, muscularis external and serosa (adventitia)

• muscularis externa layer of the alimentary canal wall is responsible for peristalsis