Chapter 4 Flashcards
what are the 4 main tissue types in the body
- epithelial
- connective
- nervous
- muscular
what tissue lines the digestive tract
epithelial
what is digestion (mechanical and chemical)
the mechanical or chemical breakdown of large ingested molecules into small (microscopic) absorbable molecules
mechanical = chewing, muscle movements of the tract
chemical = hydrolysis, enzyme breakdown
what is absorption
the passage of digested molecules across the digestive tract into the inside of the body
what is the difference between digestion and absorption
digestion is the PROCESS of breaking foods into their building blocks by mechanical or chemical processes while absorption is the ASSIMILATION of nutrients into the bloodstream
why is the GI tract an important rule in immunity?
and where do digestion and absorption occur?
the tube from the mouth to the anus is EXTERNAL to the human body UNTIL it is absorbed
think of the body as a DONUT
it is important from an immune perspective as pathogens (bacteria, viruses, and fungi) are kept “outside” while traveling through the GI tract
digestion occurs WITHIN the tube
absorption occurs ACROSS the tube
what is the flow of digestion
- pre-ingestion (marinating, tenderizing, etc)
- mouth
- esophagus
- stomach
- small intestine and accessory organs (liver, gallbladder, pancreas)
- large intestine
- rectum
what are the functions of the mouth and salivary glands
- prepare food for swallowing: chewing, moistening with saliva
- detect taste molecules
- START digestion of starch with AMYLASE enzyme
- START digestion of fat with LIPASE
what are the functions of the esophagus
moves food to stomach by peristaltic waves initiated by swallowing
what are the functions of the stomach
- secrets gastric juice containing acid, enzymes, hormones
- mixes food with gastric juice, converting it to liquid chyme
- STARTS digestion of PROTEIN and FAT
- kills microorganisms with acid
- secretes intrinsic factor, a protein required for vitamin B12 absorption
- slowly releases chyme into small intestine
what is the function of the liver
produces bile to aid FAT digestion AND absorption
what is the function of the gallbladder
stores and concentrates bile and releases it into the small intestine
what is the function of the pancreas
secretes pancreatic juice containing digestive enzymes and bicarbonate into the small intestine
what are the functions of the small intestine
- mixes chyme with bile and pancreatic juice to COMPLETE digestion
- secretes hormones that help regulate digestive processes
- secretes digestive enzymes
- absorbs nutrients and other compounds in foods
- transports remaining residue to large intestine
what are the functions of the large intestine (colon)
- absorbs water and electrolytes (sodium and potassium)
- forms and stores feces
- houses most of the gut microbiota
what is the function of the rectum
holds and expels feces via the anus
where are carbs digested
the mouth
where are carbs absorbed
small intestine
what enzyme digests carbs
amylase
where are fats digested and by what enzyme
small intestine and by lipase
where are proteins digested and by what enzyme
stomach and by pepsin
what is the difference between mechanical and chemical digestion
mechanic digestion refers to the process of PHYSICAL breakdown of foods into smaller particles
chemical digestion refers to the process of CHEMICAL BREAKDOWN of foods especially by the enzymes into smaller substances that can be absorbed
where do we see chemical digestion
in the mouth (salivary enzymes and water)
in the stomach (stomach enzymes and water)
small intestine (intestinal enzymes, accessory organ enzymes and water)
where do we see mechanical digestion
the mouth (chewing)
esophagus (minimal, via peristalsis)
in the stomach (mixing)
small intestine (mixing and peristalsis)
what is bolus and where is it formed
bolus is the food chewed up, and is formed in the mouth then is swallowed
what is chyme and where is it formed
food after it becomes a liquid substance in the stomach
why do secretions need to be tightly regulated
stomach acid (HCL) will digest the stomach lining
protein digesting enzyme could target body proteins if not controlled
basically to prevent the body from degrading the useful and necessary parts of itself
why do enzymes need to be tightly controlled?
enzymes break down fats and some proteins and human cell walls are made of fats and proteins
basically to protect the body’s necessary parts
what is an enzyme
a protein that helps speed up chemical reactions
what is the first sphincter, where is it located, and what is it’s function
lower esophageal sphincter
at the end of the esophagus and into the stomach
prevents back flow (reflux) of stomach contents back into esophagus
what is the second sphincter, where is it located, and what is its function
pyloric sphincter
at the end of the stomach into the small intestine
controls the flow of stomach contents into the small intestine
what is the third sphincter, where is it located, and what is its function
hepatopancreatic sphincter (aka sphincter of Oddi)
controls where accessory organs dump into the small intestine
from told the flow i’d bile abs pancreatic juice from the common bile and pancreatic ducts into the small intestine
what is the fourth sphincter, where is it located, and what is its function
illeocecal sphincter
at the end of the small intestine into the large intestine
prevents the contents of the large intestine from reentering the small intestine