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
what is the fifth and final sphincter, where is located and what is its function
anal sphincters (internal and external)
at the end of the anus to the outside of the body
prevents defecation until person desires to do so
(external is controlled voluntarily & internal is involuntarily controlled)
what condition can result if the lower esophageal sphincter relaxes/malfunctions?
GERD (gastroesophegeal reflux disease)
where the contents of the stomach flow back into the esophagus AKA heartburn
can happen from large meals, caffeinated drinks, fatty and fried foods, garlic, spicy foods and tomato based foods
what are the 3 GI motilities
peristalsis
mass movements
segmentation
what is peristalsis and what does it do
coordinated waves of contraction and relaxation of the muscles in the lining of the GI tract
it propels food through
most frequent in the small intestine
what is mass movement
large peristaltic waves
occur a few times a day
the feelings we get when you have to fart. you feel it moving in your stomach
what is segmentation and where does it occur
back and forth movements for mixing like “kneading”
occurs in the small intestine
what is olfactory and why is it important in digestion
the sense of smell
important in digestion because it stimulates salivary glands and other digestive processes
what is saliva
watery substance made by salivary glands in the mouth
contains lubricants, enzymes, and lysozymes
what is mucus
thick substance made by mucous glands throughout the GI tract
what reactions are most digestion reactions
hydrolysis reactions
what are the bodies 7 secretions
- saliva
- mucus
- enzymes (lipase, protease, amylase)
- acid (HCL)
- bile
- bicarbonate
- hormones
what ENZYMES play a role in digestion and absorption, where is their site of production, and what is their function
amylase - mouth, S.I, pancreas - break down carbohydrates enough for absorption
lipase - mouth, S.I, pancreas - break down fats
protease - stomach, S.I, pancreas - breaks down proteins
where is the secretion saliva produced and what is its function
in the mouth
dissolves taste forming compounds; contains many compounds that aid swallowing, digestion, and protection of teeth
where is the secretion mucus produced and what is its function
mouth, stomach, S.I., & L.I.
protects GI tract cells, lubricates digesting food
where is the secretion acid HCL produced and what is its function
stomach
promotes digestion of protein, destroys microorganisms, increases solubility of minerals
where is the secretion bile produced and what is its function
liver (stored in the gallbladder)
aids in fat digestion (emulsifies fat)
where is the secretion bicarbonate produced and what is its function
pancreas, S.I
neutralizes stomach acid when it reaches small intestine
where is the secretion hormones produced and what is its function
stomach, S.I, pancreas
regular food intake, digestion, and absorption
what is trypsin
a digestive enzyme that breaks down proteins in the small intestine. it is secreted by the pancreas
HCL and pepsin both do what
denature proteins
what are the 5 GI hormones that control digestion
- gastrin
- secretin
- cholecystokinin (CCK)
- somatostatin
- glucose-dependent insulinotropic peptide
what is the function of the gastrin hormone
stimulates HCL and pepsinogen
stimulates gastric and intestinal motility
what is pepsinogen
a substance which is secreted by the stomach wall and converted into the enzyme PEPSIN by gastric acid
what is the function of the secretin hormone
stimulates release of pancreatic bicarbonate in response to acidic chyme in the small intestine
what is the function of the hormone cholecystokinin
stimulates release of pancreatic enzymes and bile from the gallbladder in response to fat in the chyme
what is the function of the hormone somatostatin
inhibits release of GI hormones (growth hormone, insulin, and gastrin)
slows gastric emptying, GI motility, and blood flow to the intestine
what is the function of glucose-dependent insulinotropic peptide
inhibits gastric acid secretion
stimulates insulin release
what are the 3 accessory organs
liver
gallbladder
pancreas
where does the majority of digestion take place
small intestine because the pancreas and small intestine produce most of the digestive enzymes used in the body
what does flavor consist of?
taste, smell and texture
what are the 5 taste sensations
sweet
salty
sour
butter
umami = savory & rich (bbq sauce)
what is intrinsic factor
a substance secreted by the STOMACH which enables the body to absorb vitamin B12
vitamin B12 is ONLY found in animal products so vegans should be taking a B12 supplement
what are enterocytes and how long do they live
a cell of the intestinal lining
the entire supply is replaced every 2-5 days
what are villi and microvilli and their function
small finger like projections located in the walls of the small intestine
to increase the surface area in order to maximize the absorption of digested food
why are enterocytes affected by chemotherapy
what are the 3 segments of the small intestine and where does bile and pancreatic enzymes enter the S.I?
1st = duodenum also where bile and P.E enter
2nd = jejunum
3rd = ileum
what are prebiotics and examples
a NON digestible carbohydrate that promotes growth of beneficial microorganisms in the large intestine
they act as food for probiotics
examples: wheat, onions, garlic, asparagus and bananas
what are probiotics
a microorganism introduced into the body for its beneficial qualities
beneficial bacteria
what are the top 8 common food allergies
- milk
- wheat
- soy
- eggs
- fish
- shellfish
- peanuts
- tree nuts
what is heartburn
has nothing to do with the heart
occasional reflux
what is GERD
heartburn twice a week or more
occurs when the lower esophageal sphincter relaxes or malfunctions and lets contents of the stomach flow back into the esophagus
what are ulcers and it’s symptoms
erosion of the top layer of cells in the lining of the GI tract
can cause bleeding and even death
symptoms = burning pain the stomach
most often happens between meals or during the night
what are gallstones
abnormal stone like mass usually of undissolved cholesterol formed in the gallbladder
can be small as a grain of sand or as big as a golf ball
what are food intolerances
the inability to DIGEST a food
mainly caused by a deficiency in a digestive enzyme
associated with the GI tract
what are food allergies
an IMMUNE response, often in small amounts and can be quite severe
rash, loose stools
what is celiac disease
immune response to ingested gluten
propel with this disease that consume gluten damages the intestinal villi
what is IBS?
irritable bowel SYNDROME
irregular bowel function (diarrhea, constipation, abdominal pain)
cause is unknown - can be stress or dietary intolerances
what is IBD and what other diseases does it associate with
irritable bowel disease
group of serious chronic intestinal diseases
- ulcerative colitis = the inflammation and ulceration in the innermost layer of the large intestine
- Crohn’s disease = can affect ANY part of the GI tract. the inflammation and ulceration that extends through ALL layers and not just the innermost (like ulcerative colitis)
what are hemorrhoids
AKA piles
swollen veins in the rectum and anus
often associated with obesity and constipation
what is gluten
a substance responsible for the elastic texture of dough
a mixture of 2 proteins
what is the difference between celiac disease and gluten intolerance
celiac disease is an autoimmune disorder and gluten intolerance is a sensitivity
