Lesson 12: Nutrition Flashcards
How do we obtain energy via nutrition?
From ingested food that has been mechanically and chemically processed by the body so it can pass through the gastrointestinal tract and enter the bloodstream.
Where does the vascular system carry food molecules through and to before distributing them around the body?
Through the hepatic portal vein and to the liver.
What are food molecules broken down in to after entering the cells?
Carbohydrates, fats and proteins or further used for energy production during exercise.
What is the simplified journey of food through the body? (6)
- First enters via ingestion of food in to the mouth
- Food is then moved along the digestive tract
- Molecules are mechanically prepped for digestion
- It is then chemically digested
- Now ready for absorption into the lymphatic and circulatory systems
- Indigestible/waste products are eliminated via defecation
What does the lymphatic system generally do?
Returns interstitial fluid (excess fluid between cells) back to the bloodstream as to prevent swelling of interstellar spaces.
what is the lymphatic system composed of? (4)
capillaries
collecting vessels
lymph nodes
lymphoid organs
how is lymph fluid different from blood?
it does not carry red blood cells or platelets as these cannot escape via blood-vessel walls
after entering the blood via lymphatic capillaries, where does lymph then circulate?
through the arteries, blood capillaries and veins
what are the 4 functions of the lymphatic system?
- to destroy bacteria and foreign substances
- aid in creation antibodies to destroy bacteria and foreign substances as a specific immune response
- return interstitial fluid to the bloodstream
- prevent excessive accumulation of tissue fluid and filtered proteins by draining them in to highly permeable lymphatic capillaries in the connective tissue
For food to be absorbed by the body, what must it do?
cross cells that line the walls of the gastrointestinal tract as opposed to just passing through
What is the gastrointestinal tract composed of?
mouth pharynx esophagus stomach small intestine large intestine
After entering the mouth, what mechanical process next helps break down the food in to smaller pieces?
chewing
How does saliva ease swallowing?
by blending in to the food and dissolving some of it during chewing.
What does saliva initiate?
carbohydrate digestion
where does swallowed food pass to and via from the mouth?
To the stomach via the pharynx and then esophagus
What is swallowed food first called?
bolus
what is bolus?
ball-like mix of food and saliva
what helps bolus reach the stomach from the esophagus?
waves of peristalses
what are peristalses?
rhythmic contractions of the longitudinal muscles in GI tract that help bolus reach the stomach
after the esophagus, where does bolus go at the top of the stomach?
cardiac sphincter
what does the stomach do to prepare food for entry in to the small intestine?
mechanically grinds the food into chyme and chemically uses specialized stomach cells that produce secretions to break down food particles.
why does the stomach wait for optimal absorption and digestion time before allowing chyme to enter the small intestine?
because the small intestine is the primary site for digestion and absorption, the body has to be careful as to not overwhelm it so that it can do its job well
what energy providing nutrients are absorbed and digested in the small intestine? (6)
carbohydrates fats proteins vitamins minerals water
what is the small intestine further divided in to?
duodenum
jejunum
ileum
when passed in to the duodenum, what is chyme exposed to?
bile and pancreatic ezymes
where does bile come from and what does it aid in?
comes from the liver and gallbladder
aids in the digestion of fats
what do pancreatic enzymes aid the digestion of
carbohydrates, fats and proteins
what does segmentation do with chyme whilst in the small intestine?
helps to push it along as well as momentarily squeezing its contents so that it is forced backwards a couple inches as to allow the digestive juices and absorbing cells to better connect with the nutrients
what is segmentation
contractions of the circular muscles in the digestive tract
where is food most absorbed in the small intestine divisions?
duodenum and jejunum
what are the hair-like projections called in the duodenum and jejunum?
villi and microvilli
why does each projection (villi and microvilli) in the duodenum and jejunum have their own capillary network and lymphatic vessel?
to allow nutrients to immediately pass in to the bloodstream and body fluids.
what final absorption occurs in the large intestine?
water and salt
where are the kidneys located?
at either side of the vertebral column in the posterior abdominal cavity
what are the main excretory organs?
kidneys
what organs make the urinary system?
kidneys
what are the kidneys critical for?
maintaining the body’s internal environment for survival of its cells
what do the kidneys eliminate and excrete/conserve?
they eliminate metabolic products such as urea, uric acid, creatinine and conserve/excrete water and electrolytes
what are electrolytes?
minerals that carry an electrical charge.
what substances are reabsorbed to the blood via the flowing filtrate in the kidneys? (4)
water
glucose
amino acids
electrolytes
what do hormones control in the kidney?
regulate absorption and secretion processes and control which materials will be excreted or reabsorbed.
once reabsorption and secretion are complete, what happens to the remaining fluid in the kidneys?
it is moved to the bladder to be excreted as urine.
what is the epiglottis?
a flap of tissue that sits beneath the tongue at the back of the throat
what is the main function of the epiglottis?
to close over the windpipe (trachea) while you’re eating to prevent food entering your airway.
what is gastric processing?
the process by which the contents of the stomach are moved into the duodenum.
what does the amount of time for gastric processing to occur depend on? (2)
- the type of food - carbohydrates will empty first, then proteins, then fat
- amount of muscle action of the stomach and in the receiving small intestine
how long will the small intestine spend digesting food?
1-4 hours
when the small intestine finally digests food in to chyme and absorbs its nutrients/energy in to the blood, where does this blood go?
Directly to the liver for process and distribution to the rest of the body.
where do the indigestibles and waste products (such as fiber) move to the large intestine through?
ileocecal valve
what happens with waste products as water is reabsorbed in the large intestine?
the waste becomes harder until it is excreted from the body via the rectum/anus
how long does it take for waste to typically pass through and leave the large intestine/rectum?
typically 18 to 72 hours
what is absorbed through the walls of the small intestine?
carbohydrates proteins lipids vitamins minerals
what are lipids?
molecules that contain hydrocarbons and make up the building blocks of the structure and function of living cells
what do villi and microvilli form and what takes place here?
they form a brush border where nutrient absorption takes place
what differences constitute to the difference in absorption of nutrients?
their size, solubility and relative concentration
where does sugar, amino acids, water-soluble vitamins and minerals enter after passing from the membrane of the small intestine in to the blood?
the portal circulation
what does the portal circulation do?
takes nutrients through the bloodstream to the liver
what does the liver do with harmful substances?
detoxifies any harmful substances before sending them to the brain or heart
where do fat and fat-soluble vitamins transfer to as a result of being too large to enter capillaries?
they transfer in to the lymphatic system and are added to the bloodstream via the thoracic duct
what is the thoracic duct?
a large lymphatic vein that drains in to the heart
what are chylomicrons and what do they travel?
A small fat globule composed of protein and lipid (fat) that transports fat
what are macronutrients the body’s source of?
calories and energy to fuel life.
what are the 3 macronutrients?
carbohydrates
proteins
fats
how many calories are there per gram of carbohydrates?
4 calories
what are monosaccharides and what are the 3 main ones?
they are the most basic unit of carbs
- glucose
- fructose
- galactose
what is glucose?
the predominant sugar and building ground for most carbs
where is fructose found?
fruit
what does galactose form with and to create what?
forms with glucose to form the disaccharide, lactose.
what are disaccharides?
sugar formed by the joining of two monosaccharides
are mono/disaccharides water or fat soluble?
water
what are 2 other disaccharides other than lactose and what monosaccharides are they the combination of?
maltose - x2 glucose molecules
sucrose - glucose and fructose
what is oligosaccharide?
chain of 3-10 simple sugars
what is a polysaccharide?
a long chain of sugar molecules
what 2 polysaccharides are the only ones fully digestible by humans?
glycogen and starch
where is glycogen found?
in meat/seafood
where is starch found?
in grains and vegetables
what is a complex carbohydrate?
a long, complex chain of sugar molecules
what is a simple carbohydrate?
a short chain of sugar molecules
what happens with carbohydrates that are not immediatly used for energy after consumption?
they are stored as glycogen
where is glycogen stored?
liver and muscle cells
why would glycogen be broken down into single molecules?
to be used as a rapid source of energy
what will increase glycogen stores?
carb loading
what are carbohydrates converted to if the body consumes more than it can use and store?
it is converted in to fat for long-term storage
how many calories are there per gram of protein?
4 calories
what 6 things does protein function to help form?
brain nervous system blood muscle skin hair
what is protein the transport mechanism for? (5)
iron, vitamins, minerals, fats and oxygen
what is protein key for?
acid-base and fluid balance
what does protein form and what does each do?
enzymes - speed up chemical reactions
antibodies - used to fight infections
When in desperate need of energy, will the body turn to carbohydrates, fats or proteins as a last resort?
proteins
what are proteins build from?
amino acids
what are amino-acids?
carbohydrates with the nitro-containing amino group and sometimes attached to sulfur
how do amino acids form protein?
the amino acids join together through peptide bonds to form protein
how many essential amino acids cannot be formed by the body and must be consumed via the diet?
8-10
what is the protein quality in food determined by?
the composition, bioavailability and digestibility of the essential amino acids
what constitutes as a complete protein?
one that contains all 9 essential amino acids required for the body’s repair and build
how can you boost plant protein quality?
by combining complementary plant proteins that (when combined) will provide all 9 of the essential amino acids
what are 3 great plant combinations (of food sources) to get a complete protein?
- grains and legumes
- grains and dairy
- legumes and seeds
how many calories does fat have per gram?
9 calories
what are the functions of fat in the body? (5)
insulation cell structure nerve transmission vitamin absorption hormone production
what is adipose tissue/fat stored as?
triglycerides
why do unsaturated fats have a shorter shelf life?
because they are susceptible to oxidative damage
how many double bonds does unsaturated fat contain?
1 or more between carbon atoms
how many double bonds does monounsaturated fats contain?
1 double bond between 2 carbon atoms
what are some positives of monounsaturated fats?
aids weight loss, decreases inflammation and risk of heart disease
what are some examples of monounsaturated fats?
avocado, olive oil, canola oil, peanut oil, nuts
how many double bonds does polyunsaturated fats cotain?
1 double bond between 2 or more sets of carbons
what are somes source of polyunsaturated fats?
soybean oils, corn oil, safflower oil and cold water fish
what is a type of polyunsaturated fat that MUST be consumed in the diet?
essential fatty acids
What are the 3 forms of Omega-3?
- Alpha linolenic acid (ALA)
- Eicosapentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
where is alpha linolenic acid found and what is it converted in to?
found in plants and converted to EPA and DHA - the 2 other omega-3s
where are eicosapentaenoic acid and docosahexaenoic acids found?
egg yolk, cold water fish and shellfish
what are 6 functions of omega-3s?
- reduce blood clotting
- dilate blood vessels
- reduce inflammation
- eye and brain development - particularly in late stages of pregnancy
- reduce cholesterol and triglyceride levels
- preserve brain function, reducing risk of mental illness and ADHD
are omega 3s and omega 6s produced or not produced by the body?
not produced, must be consumed via diet
what is the recommended dose of omega 3/6s daily?
250-500mg a day