Chapter 3: The Remarkable Body Flashcards
How many cells is the body composed of?
Trillions
Red blood cells die after about
120 days
Digestive tract cells die after about
fairly hostile working environment
3 days
self-contained, living entities, dependent on one another
Cells
- Oxygen
- Water (an essential nutrient group)
- Nutrients (especially the essential nutrients // carbs, fats, proteins, vitamins, and minerals)
- Energy (supplied by carbs, fats, proteins)
Basic Needs of Body Cells
Why are nutrients needed?
growth, development, repair, maintenance, and replacement
- direct protein production
- provide instruction for structural components of cells
- affect how body handles nutrients
- complete set of genes in each cell
- gene variations (inborn error of metabolism; influence of nutrients)
Genes Control Functions / From DNA to Living Cells
Why are cells organized into tissues?
To perform specialized tasks
Why are tissues grouped together?
To form organs
- Cardiovascular System (focus on nutrient transport)
- Lymphatic System (focus on nutrient transport)
- Endocrine (Hormonal) System
- Nervous System
- Immune System (signs and symptoms of deficiencies are seen the quickest in this system and the digestive system)
Organs that work together as part of body systems
In Nutrition, what system is most focused on?
Digestive System
- Supply energy, oxygen, nutrients, and water
- Deliver fresh supplies and pick up wasts
Body Fluids
circulate around cells
fluid outside of cells
extracellular fluid
fluid inside of cells
- all cell reactions take place here
- holds cellular shape
intracellular fluid
Sweet, sour, bitter, salty, and umami (savory)
Five basic chemical tastes
- almost universally desired
- can lead to drastic overeating of these substances
sweet, salty, and fatty foods
- flexible, muscular tube
- extends from mouth to anus / total length: est. 26 ft
- GI tract is immature at birth and matures at about 6 months of age
- extensive surface area within the small intestine for nutrient absorption
The Digestive Tract
consists of:
- mouth, esophagus, stomach, small intestines, large intestines (colon), rectum, and anus
- accessory structures: salivary glands, pancreas, liver, and gallbladder
Gastrointestinal (GI) Tract
- break apart (digest) foods into smallest components
- absorb nutrients (and other substances such as phytochemicals)
- prevent numerous (but not all) microorganisms or other harmful compounds in food from entering tissues of the body
- excrete/expel from the body any substances which are not absorbed
Main functions of the GI tract
Often thought of as a tube or a tunnel with an opening at each end
Human body surrounds digestive canal
beginning in the mouth: the altering of the texture of foods by chewing, grinding, crushing foods and adding liquids to aid swallowing, create chyme, and chemical digestive processes
The Mechanical Aspect of Digestion
includes the mixing and moving of GI tract contents from the mouth to the anus using peristalsis, segmentation, and pendular movement
The Mechanical Aspect of Digestion
the forward, rhythmic muscular contractions that move food through digestive system from the initial swallow to the anus
Peristalsis
“sloshing motion”
mixes chyme with chemical secretions; seen predominantly in the small intestine
Segmentation
(constrictive draws together, compresses) wave moving chyme backward & forward; enhances nutrient absorption in small intestine
Pendular Movement
To move foods, liquids, and other swallowed substances (such as medicines) from the mouth to the stomach
Function of the Esophagus
To allow enzyme activity to continue if the activity began in the mouth (the esophagus itself cannot start or stop any enzyme activity)
Function of the Esophagus
Once started with a swallow, peristalsis (the dominant pattern of muscle contraction and relaxation) continues all the way to the anus
Function of the Esophagus
Peristalsis begins prior to birth as we swallow small amounts of amniotic fluid and never stops until our death. It may speed up or slow down but it never stops. Digestion is an on-going process 24 hours a day
Function of the Esophagus
- Powerful muscle sets within the stomach run vertically, horizontally, and diagonally.
- These muscles make the grinding, shredding, and crushing food pieces possible.
- A heavy thick layer of mucus (often shown as a white layer) coats the interior of the stomach; protecting the stomach’s interior surface from: hydrochloric acid, digestive enzymes, other substances
The Muscular Stomach