ch.3 the human body: are we really what we eat? Flashcards
organization of the body
atoms
the smallest units of matter
atoms bond to each other to form molecules
organization of the body
molecules
groups of atoms bonded in specific configurations
ex. water is H2O
carbon dioxide is CO2
organization of the body
carbohydrates, proteins, fats, and vitamins are usually very
large molecules
organization of the body
the goals of digestion
break these large molecules down into smaller molecules
absorb the smaller molecules into the cells of the body
organization of the body
what is the organization of the body
atoms
molecules
cells
tissue
organ
organ system
organism
organization of the body
molecules are the building
blocks of cells
organization of the body
cells
the smallest unit of life
organization of the body
molecules that result from the digestion of food are used to
build the cells of the body
organization of the body
cell membrane
outer layer enclosing each cell of the body
organization of the body
cell membrane composed of
two layers of phospholipids
long lipid “tails” face each other toward the interior of the membrane
phosphate “heads” line the interior and exterior surfaces of the membrane
organization of the body
cell membrane has what embedded in the membrane
cholesterol and proteins
organization of the body
the cell membrane is selectively permeable allowing it to control the
passage of materials into and out of the cell
organization of the body
the cell membrane encloses the
cytoplasm: liquid within the cell
organelles: tiny structures that perform many different cellular functions
ex. nucleus mitochondria
organization of the body
cells join together to form
tissues
organization of the body
tissue
group of cells acting together to perform a common function
ex. muscle tissue
nervous tissue
organization of the body
different tissues combine to form
organs
organization of the body
organ
a sophisticated organization of tissues that performs a specific function
ex. stomach
heart
brain
organization of the body
organ systems
groups of organs working together for a particular function
ex. gastrointestinal system
why do we want to eat?
appetite
is a desire to eat that is stimulated by
* sight
* smell
* thought of food
why do we want to eat?
hunger
a physiologic drive to eat that occurs when our body senses that we need food
why do we want to eat?
hypothalamus region of the brain contains a
cluster of nerve cells known as the feeding center and another cluster of cells known as the satiety center
why do we want to eat?
hypothalamus functions
- nerve cells in the stomach and small intestine sense food and send message to hypothalamus
- hormones relay messgaes to the hypothalamus
- amount and type of food consumes influence satiety
why do we want to eat?
the signals that prompt us to eat include
- nerve receptors in the stomach, which send signals to the hypothalamus to indicate if the stomach is full or empty
- blood glucose levels, which trigger the release of hormones called insulin and glucagon
why do we want to eat?
hormones
chemical produced in specialized glands that travel in the bloodstream to target organs in other parts of the body
why do we want to eat?
some hormones stimulate hunger
ghrelin
why do we want to eat?
some hormones produce a feeling of satiety
cholecystokinin (CCK)
leptin
why do we want to eat?
foods have differing effects on our feelings of hunger and satiety
- proteins have the highest satiety vaule
- carbs have a lower satiety value than fats
- bulky foods provide a sense of satiety
- solid foods are more filling than semisolid foods or liquids
what happens to the food we eat?
gastrointestinal (GI) tract
series of organs arranged as a long tube through which the food passes
what happens to the food we eat?
the GI tract includes
- organs such as the stomach and intestines
- spincters
what happens to the food we eat?
sphincters
muscles that control the passage of material from one organ to the next
digestive system
organs of the GI tract
- mouth
- pharynx and esophagus
- stomach
- small intestine
- large intestine
- rectum
digestive system
accessory organs
- salivary glands
- liver
- gallbladder
- pancreas
organs of the GI tract
mouth
- ingestion: food enters the GI tract via the mouth
- mechanical digestion: mastication tears, shreds, and mixes food with saliva
- chemical digestion: salivary amylase begins carbohydrate breakdown
organs of the GI tract
pharynx and esophagus
propulsion: swallowing and peristalsis move food from mouth to stomach
organs of the GI tract
stomach
- mechanical digestion: mixes and churns food with gastric juice into a liquid called chyme
- chemical digestion: pepsin begins digestion of proteinds and gastric lipase begins to break lipids apart
- absorption: a few fat-soluble substances are absorbed through the stomach wall
organs of the GI tract
small intestine
- mechanical digestion and propulsion: segmentation mixes chyme with digestive juices; peristalic waves move it along tract
- chemical digestion: digestive enzymes from pancreas and brush border digest most classes of nutrients
- absorption: nutrientss are absorbes into blood and lymoh through enterocytes
organs of the GI tract
large intestine
- chemical digestion: some remaining food residues are digested by bacteria
- absorption: reabsorbs salts, water, and vitamins
- propulsion: compacts waste into feces and propels it toward the rectum
organs of the GI tract
rectum
elimination: temporarily stores feces before voluntary release through the anus
accessory organs
salivary glands
produce saliva, a mixtue of water, enzymes, mucus, and other chemicals
accessory organs
liver
produces bile to emulsify fats
accessory organs
gallbladder
stores bile before release into the small intestine through the bile duct
accessory organs
pancreas
produces digestive enzymes and bicarbonate, which are released into the small intestine via the pancreatic duct
digestion: the mouth
digestion begins in the mouth
- chewing is the mechanical digestion that breaks food into smaller pieces
- some chemical digestion takes place in the mouth
digestion: the mouth
salivary amylase
an enzyme produced by the salivary glands that begins the chemical digestion of carbohydrates
digestion: the mouth
the mouth
- chewing breaks up food and begins mechanical digestion
- salivary amylase begins chemical breakdown of carbohydrates
- minimal digestion takes place in the mouth
digestion: the mouth
enzyme
enzyme
two seperate compounds
two compounds joined together
new compound formed; enzyme left unchanged
digestion: the mouth
the esophagus propels food into the stomach
the epiglottis covers the opening to the trachea during swallowing
digestion: the mouth
esophagus
food travels from the mouth to the stomach through here
digestion: the mouth
peristalsis
is the muscular contractions moving food through the GI tract
digestion: the mouth
gastroesophageal sphincter
seperates the esophagus from the stomach
digestion: the stomach
the stomach mixes, digests, stores
food
digestion: the stomach
digestion in the stomach includes:
- extensive mechanical digestion to mix food with GASTRIC JUICE
- chemical digestion of proteins and fats
digestion: the stomach
gastric juice contains
- hydrochloric acid (HCl)
- intrinsic factor
- pepsin
- gastric lipase
what is in gastric juice
hydrochloric acid (HCl)
to denature proteins and activate pepsin
what is in gastric juice
intrinsic factor
a protein critical to the absorption of vitamin B12
what is in gastric juice
pepsin
an enzyme to digest protein
what is in gastric juice
gastric lipase
an enzyme to digest fat
digestion: stomach
chyme
semisolid product of mechanical and chemical digestion in the stomach
digestion: small intestine
from the stomach chyme is slowly released through the
pyloric sphincter to the small intestine
digestion: small intestine
chemical digestion continues in the small intestine using
pacreatic enzymes and bile
digestion: large intestine
undigested food components move through a sphincter called the
ileocecal valve to the large intestine
digestion: large intestine
in the large intestine
- very little digestion takes place
- material is stored 12-24 hr prior to elimination
- water and some nutrients are absorbed
digestion: accessory organs
surrounding the GI tract are several accessory organs
- salivary glands
- liver
- pancreas
- gallbladder
what are the accessory organs in digestion
liver
produces bile which emulsifies fats
what are the accessory organs in digestion
pancreas
- produces many digestive enzymes
- produces bicarbonate to neutralize chyme
what are the accessory organs in digestion
gallbladder
stores bile
absorption
absorption
the process of taking molecules across a cell membrane and into cell of the body
absorption
a small amount of absorption occurs in the
stomach
absorption
most absorption of nutrients occurs in the 3 sections of the small intestine
- duodenum
- jejenum
- ileum
absorption
the lining of the GI tract has special structures to facilitate absorption
- villi
- brush border
special structures of lining of the GI tract to facilitate absorption
villi
folds in the lining that are in close contact with nutrient molecules
special structures of lining of the GI tract to facilitate absorption
brush border
composed of microvilli that greatly increase the surface area
absorption
water-soluble nutrients
(carb, protein, minerals, some vitamins)
enter the
portal vein
absorption
the portal vein transports these nutrients to the
liver
absorption
fat-soluble nutrients
(lipids, some vitamins)
enter the
lymphatic vessels
absorption
lymphatic vessels transport these nutrients directly to the
bloodstream
absorption
nutrients are absorbed across the mucosal membrane and into the bloodstream or lymph
- passive diffusion
- facilitated diffusion
- active transport
- endocytosis
the role of the neuromuscular system
2 components of the neuromuscular system regulate the activities of the GI tract
- the muscles of the GI tract mix and move food—-both voluntary and involuntary muscles
- nerves control the contractions and secretions of the GI tracts— the enteric nervous system (ENS)–other branches of the autonomic nervous system—the central nervous system (CNS)
GI tract disorders
the lining of the stomach is designed to cope with hydrochloric acid but other regions of the
GI tract are not
GI tract disorders
heartburn is caused by
hydrochloric acid in the esophagus
GI tract disorders
gastroesophageal reflux disease
(GERD) is a
chronic disease for which painful
persistent heartburn is the most common symptom
GI tract disorders
peptic ulcers
regions of the GI tract that have been eroded by HCl and pepsin
GI tract disorders
what is the bacteria that contributes to the production of both gastric and duodenal ulcers
helicobacter pylori
GI tract disorders
vomiting often accompanies a gastrointestinal infection such as
norovirus
GI tract disorders
cyclic vomiting syndrome
(CVS)
a chronic condition involving severe nausea and vomiting that can last for HOURS OR DAYS
GI tract disorders
diarrhea can be caused by
- food intolrances
- infection of the GI tract
- stress
- bowel disorders
can lead to severe dehydration
is more dangerous for CHILDREN AND ELDERLY
GI tract disorders
constipation
no stool passed for 2 or more days
GI tract disorders
irritable bowel syndrome (IBS)
is a disorder that interferes with normal colon function
more common in women than in men
GI tract disorders: IBS
symptoms of IBS include
- abdominal cramps
- either diarrhea or constipation
GI tract disorders
cancer can develop in any region of the
GI tract
GI tract disorders
the most common cancer forms are
- oral cancer
- pancreatic cancer
- colorectal cancer
in depth: disorders related to foods
food tolerance
a particular food causes numerous unpleasant symptoms
in depth: disorders related to foods
food intolerance symptoms include
- gas
- pain
- diarrhea
in depth: disorders related to foods
food allergy
hypersensitivity reaction of the immune system to a componenet in a food
the immune system is not involved
in depth: disorders related to foods
celiac disease
an autoimmune disease that is also considered a genetic disorders
in depth: disorders related to foods
celiac disease diet
- complete intolerance for gluten, a protein found in wheat, rye, barley, and triticale
- can damage the small intestine leading to poor absorption of nutrients
- requires a diet lacking wheat, rye, barley and tritcale
non-celiac gluten sensitivity
some individuals may have a negative GI reaction when consuming gluten but do NOT have celiac disease
- bloating
- abdominal pain
- diarrhea
- possible joint pain
smyptoms improve by following a gluten free diet
signs and symptoms of dehydration
symptoms in adults
- thirst
- light-headness
- less frequent urination
- dark-colored urine
- fatigue
- dry skin
sympotoms of dehydration
symptoms in children
- dry mouth and tongue
- no tears while crying
- no wet diapers for 3 hrs or more
- high fever
- sunken abdomen eyes or cheeks
- irritable or listless
- skin does not rebound when pinched adn releases
heartburn
gastric juice seeping backward through the
gastroesophageal sphinter is not cleared quickly or completely enough from the lower esophagus, an burns the lining
