Tammy's Health & Wellness Journey - What I Learned in School

datenshi

This thread is basically the notes I took in lecture from my University Nutrition class.

Do not take it as completely accurate info since some of it depended on my interpretation at the time (2005) of what I was hearing in lecture. The understood science of nutrition at the time may have changed since then. Meaning what seemed true in 2005 in regards to Nutrition may have changed since then. I may have misheard stuff or not heard some things. Also, do not take it as medical advice since my professor was not a medical doctor by any means.

Thanks,
Tammy

datenshi

These ones are in point form so may not make sense to some

Nutrition:
* The science of foods and the nutrients they contain
* Provide energy and nutrients
* Used by body for maintenance, growth, and repair

Nutrient subclasses
* Organic vs. inorganic
* Essential vs. nonessential
* Macronutrient vs. micronutrient

Energy-Yielding Nutrients
* Macronutrients (carbohydrate, fat and protein)
* Process called metabolism

The Science of Nutrition
* Help differentiate FACT from FICTION
* Study of nutrients (and other substances in food) and how the body handles them
* Hypothesis based

Epidemiological studies
* Observe health of a population and how much and what kind of food is consumed

Dietary Reference Intakes
* Define the amount of energy, nutrients and other dietary components
* EAR - Estimated Average Requirements
* RDA - Recommended Daily Allowance
* AI - Adequate Intakes
* TUL - Tolerable Upper-Intake Level

datenshi

~~~~~~~~~~~~~~~~ Digestion, Absorption and Transport ~~~~~~~~~~~~~~~~~~

Food = Nutrients

Ingestion = Consume food

Digestion = Break down into absorbable units

Absorption = Move nutrients from gastrointestinal (GI) tract to blood

Transport = Move nutrients from blood to rest of body

Storage = Store what isn’t used for later

---

~ Digestion - Two parts: ~

Mechanical digestion
-Physical breaking of food into smaller pieces increases surface area of food

Chemical digestion
- Breakdown of food by chemicals (i.e. enzymes, acid)
- Hydrolytic reactions

---

~ Anatomy of the system ~

Basic anatomy of the GI tract:
• Mouth > esophagus > stomach > small intestine > large intestine > rectum > *kitten*
• Lumen (external to the body)
• ~GI tract is approx 9 meters in total length
• Take a bite of food takes about 20-30 hours to move from mouth to *kitten*

GI tract
• Mouth
• Pharynx
• Esophagus
• Stomach
• small intestine
• large intestine

Accessory organs to digestion
• Teeth
• Tongue
• Salivary glands
• Liver
• Gallbladder
• pancreas

---

Digestion – The Mouth
•Teeth
.......Mastication – mechanical digestion (chewing the food into smaller and smaller bits
• Tongue
.......Move food around the mouth, help with chewing and swallowing

Teeth
• Incisors – for cutting
• Canine – for tearing
• Molars – for grinding

Salivary glands
• Three pairs
• Secrete saliva
• Aids in protection, moistening/lubricating, taste, and swallowing

Saliva
• Water and salts
• enzyme (breaks down carbohydrates)
• Part of chemical digestion

---

Digestion – The Throat and Chest

Pharynx
• Does not contribute to digestion
• Passage (shared by both digestion and respiratory system)

Epiglottis
• Closes off air passage (trachea) when swallowing and directs food to esophagus

Esophagus
• Connects pharynx to stomach
• Peristalsis
.......Waves of muscular contraction
.......Part of mechanical digestion
• Sphincters
.......“Valves” found between areas of the GI
.......Control pace of food movements through GI tract
• Esophageal sphincters
.......Upper and lower
.......Prevents reflux (keeps food moving in one direction)
.......Lower esophageal sphincter also known as cardiac sphincter

Swallowing
• Food bolus (chunk of food) loaded onto tongue
• Bolus moves into pharyngeal cavity
• Epiglottis closes trachea and bolus moves past UES (upper esophageal sphincter) and into the esophagus
• UES remains open until bolus passes completely into esophagus
• Bolus moves down esophagus to LES (lower esophageal sphincter)
• LES opens and allows bolus passage into stomach

---

Digestion – The Stomach

Stomach
• Bolus is churned by muscle action (longitudinal, circular, diagonal muscles)
• Bolus now becomes chyme (pronounced kime)
• Mechanical digestion
• Stomach contains gastric glands
• Stomach contains gastric juice
.......Water
.......Hydrochloric acid
.......Enzymes (breakdown protein)
.......Kill bacteria
.......Chemical digestion
.......Water is ph7, gastric juice is approx ph2 similar to lemon juice, saliva is neutral as it is mostly water, bile and pancreatic juice is around ph8-9
• Stomache contains goblet cells
.......Secrete mucus
.......Protect lining of stomach to protect it from being digested as the muscle is made from protein as well
.......If the protective lining is removed we have problems such as ulcers which means the gastric juices are breaking down the stomach lining and muscle
• Pyloric sphincter
.......Valve between stomach and small intestine
.......Regulates chyme movement

---

Digestion – Small Intestine

• Duodenum
.......Has duct
.......Two accessory organs secrete juices (liver and pancreas)
• Liver
.......Produces bile (also serves another function)
• Gallbladder
.......Stores bile
• Bile
.......Secreted into duodenum
.......Emulsifier (increases surface area of fat droplets meaning it assists in the digestion of fat)
.......Increasing surface area vs volume which means shrinks fat cell so that ratio of volume to surface area is smaller
• Pancreas
.......Pancreatic juices secreted into duodenum
.......Enzymes that act on all 3 macronutrients (carbohydrates, fats, protein)
.......Sodium bicarbonate to neutralize acidic chyme (hydrochloric acid from stomach) which helps to increase the ph level to a neutral and prevents damage further down the GI tract

---

Absorption – The Small Intestine

• Jejunum
• Ileum
• Segmentation – where the intestines breaks the chyme into smaller parts via muscle contractions in the small intestine
• Surface area is equivalents to a tennis court (~250m2)
• Full of folds which have villi (finger like projections)
• Those projections have microvilli (microscopic hairs)
• The process of absorption is to move digested nutrients from lumen into the body via one of three methods:
.......Simple diffusion
..............Pass through membrane freely
..............Move along concentration gradient (high to low)
..............* i.e. water and small lipids
.......Facilitated diffusion
..............Molecules that are only soluble in water
..............Random association
..............Binding changes carriers shape
..............i.e. water-soluble vitamins
.......Active transport
..............Needed when concentration higher inside than outside
..............Similar to facilitated diffusion but requires energy
..............i.e. glucose and amino acids

---

Transport

• Vascular system
.......Heart
.......Arteries
.......Veins
• Hepatic portal system
.......Hepatic vein
.......Portal vein
.......Ensures liver is first to receive materials absorbed from GI tract (acting as a sort of gatekeeper)
• Lymphatic system
.......Network or vessels (going one-way unlike vascular system)
.......Lymphatic system functions
..............Return fluid to blood
..............Part of the immune system
..............Absorb fat
.......Components to remember
..............Lacteals (where big portions of fat are absorbed)
..............Thoracic duct
..............Connects to left subclavian vein (the vein located just under the left collarbone)

---

Absorption – The Large Intestine

Large intestine (colon)
• Ileocecal valve (between small and large intestine)
• Stores undigested material
• Absorbs water and some salts
• There is some bacteria found here that aid in digestion
• Consists of – ascending colon > transverse colon > descending colon > sigmoid colon > rectum > *kitten*

Nutrient storage locations
• Kidney
• Nervous tissue (brain)
• Heart
• Muscle
• Liver
• Adipose tissue
• Skeletal system

---

Regulation

• Homeostasis
.......Tendancy to maintain important variables in the face of large environmental changes
.......“Conditions have to stay about the same for an organism to survive”
.......Preservation

• Body is not constant
• Feedback – stimulus comes in which results in response to get back to what is normal or level
.......Negative feedback – the body gets cold resulting in shivering causing the body temperature to rise. If it gets to high the body may respond by stop shivering and start sweating. By stopping the shivering that is the negative feedback. It is a sort of ebb and flow loop
.......Positive feedback – you initiate stimulus which results in response that aggravates that stimulus and amplifies it. When we get to the proper level we want to cut it off right then.
• Nervous system
• Hormones – chemical messengers from one part of the body to another
.......Gastrin
.......Secretin
.......Cholecystokinin = CCK
.......Gastric-inhibitory peptide = GIP
• Factors that influence GI function and regulation
.......Immaturity (i.e. babies who spit up)
.......Aging
.......Illness
.......Nutrition

---

GI performance
• Good health = good nutrition
• Good nutrition = good health
.......Balance
.......Moderation
.......Variety
.......adequacy


***********Digestion, absorption, and transportation transforms foods into usable nutrients************

datenshi

~ Carbohydrates ~

There are good carbohydrates that create a source of energy and bad carbohydrates that are empty carbohydrates. Carbohydrates consist of sugars, starches and fibers. They have received a lot of bad press.

Chemist’s view:
Simple
...- Sugars

Complex
…-starches, fibers

datenshi

~ Simple carbohydrates ~

Hexoses (C6H12O6)

Monosaccharide
…- Glucose
……* “blood sugar”
……* Most important carbohydrate
………>One of the two sugars in disaccharides
………>Unit from which polysaccharides are made of
………>Focus of carbohydrate metabolism
…- Fructose
……* Sweet sugar
……* Found naturally in fruit and honey
……* Typically used as a high end sweetener like in corn syrup
………>Same chemical formula as glucose but structurally different
…- Galactose
……* Rarely occurs naturally
……* Again same chemical composition as glucose but with a small structural difference

Disaccharide
…- Combination of pairs of monosaccharides
…- Link two monosaccharides by condensation
…- Break up into two monosaccharides by hydrolysis
……*Hydrolysis occurs during digestion
…- Maltose
……*Two glucose units
……*These are considered the malt sugars such as the ones released during fermentation. It is typically released when starch is broken down
…- Sucrose
……*Glucose and fructose
……*Commonly known as “table sugar”
…- Lactose
……*Glucose and galactose
……* “milk sugar”, the carbohydrate found in milk
……*Lactose intolerance is the inability to break lactose into its two sub units

datenshi

~ Complex Carbohydrates ~

Polysaccharides
…- Two or more saccharides strung together
…- Glycogen
…- Starch
…- Fiber

Glycogen
…- Multiple glucose units
…- Not a significant food source.
…- Not able to store a lot of glycogen due to its multiple branches (making it larger) and it traps water
…- The importance is not in its nutritional value, the important is that it is more efficient way to store carbohydrates in the body.
……*Muscle
……*Liver

Starch
…- Multiple glucose units (occasionally branched or unbranched)
…- Major source of carbohydrates in the diet.
…- Storage form in plants

Fibers
…- Nonstarch polysaccharides
…- Similar to starches as they are plant derived but they are considered the non-starch polysaccharide.
…- Rather than the stored form they are the structural part of plants
…- Similar to starches but indigestible
…- Fibers tend to be a composed of a variety of monosaccharides in different variations and combinations.
…- They don’t provide nutrition but provide a component to nutrition.
…- There are many different types of fibers, some categorized based on their structure
……*Cellulose
………>Plant cell walls
………>Unbranched glucose units
………>Different bonds binding glucose molecules together add to undigestibility as our body is not capable of breaking those bonds
……*Hemicellulose
………>Cereal fibers
………>Many different monosaccharides and typically are branched
……*Pectin
………>Typically found in Citrus fruit and apples
………>Many different monosaccharides and may be branched or unbranched
……*Gums and mucilages
………>Secretion where plant is cut – it oozes out typically to aid in repair.
………>One of the most common gums are guar gums
………>Made of various monosaccharides.
……*Lignin
………>Woody part of vegetables
………>Impervious to digestion
……*Resistant starches
………>Starches that escape digestion – they look like starches but act like fibers
………>Based on GI efficiency and food physical property

datenshi

~ Fibers – Physical ~

Viscous (soluable)
- gums and mucilages
- pectins
- psyllium
- some hemicelluloses

Nonviscous (insoluable)
- cellulose
- lignins
- psyllium
- resistant starches
- many hemicelluloses


~ Fibers – Daily Recommended Intake ~

Dietary fibers
- Naturally occur in food

Functional fibers
- Extracted or manufactured (such as psyllium)

Total fiber = dietary fiber + functional fiber

- Note: know the general chemical makeup of a carbohydrate as they will play a role later in metabolism. Know that starches looks an awful like cellulose but we cannot digest cellulose (meaning know there are functional differences based on structure of the component)

datenshi

Okay, that's it for tonight. I'll post more tomorrow. Sorry about the strange formatting but it doesn't allow tabs or spaces bigger than one in front of each line.

Take care,
Tammy

Learning2LoveMe

Thanks for posting all this Tammy! :flowerforyou:

Looking foward to the rest

datenshi

Thanks for posting all this Tammy! :flowerforyou:

Looking foward to the rest

No problem, I am happy to post.

It might get boring to read I am sure because it gets into chemical compounds like polysaccharides and stuff but hopefully you and others will get something out of it. Hopefully it makes sense to read since the formatting capability of posts is really lacking.

Take care,
Tammy

Phoenix_Rising

bumping into My Topics


Thanks Tammy! :flowerforyou:

datenshi

~ Digestion ~

-Breakdown carbohydrates into simplest form (a monosaccharide, which is what is absorbed and usable)
-Differ if available carbohydrates (sugars and starches) or unavailable carbohydrates (fibers)

~ Digestion of available carbohydrates ~
- Mouth and salivary glands
…* Salivary amylase
…* Breaks down starch
…… > Enzyme is a protein which in this case will hydrolyse two monosaccharides
……> Anything ending in “ase” is typically an enzyme
……>Anytime you see “lysis” that means breakdown
- Stomach
…*Acid inactivates amylase – so at that point you don’t get any further chemical breakdown
- Pancreas
…* Pancreas secretes pancreatic amylase and bicarbonate solution.
… *The bicarbonate diffuses the acid allowing the amylase to work
- Small intestines
…* Dissacharides on the surface of intestinal cells
…* Hydrolyze disaccharides by maltase, sucrase, lactase (they break down the disaccharide units they are named for)

~ Digestion of unavailable carbohydrates ~
- Mouth
…* Mechanical
- Stomach
…* Not digested
…* Delays gastric emptying
…* The fibers really hold up movement in the GI
- Small intestines
…* Not digested
…* Delays absorption
…* These fibers may be pocketing specific nutrients
…* Regulates bowel activity from the bacteria ?? via flora …as it releases small amounts of fat which can be absorbed.
…* The large intestine responds to stretch as the fiber adds volume to the intestines. This volume is what initiates the stretch response in the large intestines which speeds up movement through the intestine.

datenshi

~~~~ Absorption ~~~~
- Small intestine
- 99% of absorption takes place in the small intestine
- Glucose and galactose absorbed through active transport
…* We are expending energy to absorb these
…* glucose is the key unit
- Fructose absorbed through facilitated diffusion

~~~~ Preview of metabolism ~~~~
- Glucose plays central role
…* Preferred source for nervous tissue and developing erythrocytes (red blood cells). The brain functions solely on glucose
…* Glycolysis is the breakdown of glucose and converting it into energy
…* We can store it in our body and contains glycogen which can be broken down into individual glucose units to be used when we need them.
…* Glycogenolysis breaking down the glycogen into glucose
…* Gluconeogenesis is making new glucose from protein – the protein is often from muscle tissue but it isn’t the ideal situation to use that for fuel.
…* We cannot turn fat into glucose although glucose can be turned into fat

~~~~ Carbohydrate storage ~~~~
- Glycogen
…* Main storage form of glucose
…* 1/3 storage of glycogen in liver, 2/3 in muscle
…* Limited storage as it is bulky due to branches and water retention.
…* Excess carbohydrates stored as fat (energetically expensive) meaning it takes considerable energy to turn carbohydrates into fat as opposed to fat being turned into body fat.

datenshi

~~~~ Glucose homeostasis ~~~~

- Maintain ~90 mg/dL or 5mM
- This is just a number that we can use to measure as this is what the body tries to store.
- Regulated primarily by 2 hormones (hormones are chemical messengers that tell the body what to do) secreted by the pancreas
…* Insulin (promotes glucose storage)
……> The pancreas releases insulin which tells the liver and muscles (via receptors) to take up the extra glucose and store it.
…* Glucagon (promotes glucose release)
……> Reaches receptors on the liver from the pancreas which secretes this hormone when it detects low glucose and it tells the liver to break down the glycogen into glucose and release it into the blood stream

~~~~ Out of control ~~~~

- Hyperglycemia
…* High blood glucose
…* Typical sign of diabetes

- Hypoglycemia
…* Low blood glucose (can result in lightheadedness)

- Manage through healthy or alternative diets

~~~~ How do we control this? With Consistency ~~~~~

- Glycemic response
…* Glucose absorption after a meal
- Glycemic index
…* Potential to raise blood glucose
…* Is lower better?

- Glycemic index
Pros
…* Improves glucose control
…* Improve lipid metabolism

Cons
…* not enough scientific information
…* available on glycemic index
…* Not on food labels
…* Not intuitively apparent what the benefits are

datenshi

~~~~ Health Canada Recommends ~~~~
- Average person on 2000 kcal/day
…* 900-1300 kcal total carbohydrates (45% - 65%)
…* Of that they recommend minimum 130 g/day (520 kcal) digestible carbohydrates (sugars and starches)
…* 30 g/day total fiber (too much can be detrimental though as can too little)
…* Limit added sugars (no more than 25% of that carbohydrate intake - lower is better)

~~~~ Total Carbohydrates ~~~~
- Major source of energy (starch and sugars)
- Prefer fuel used by the brain
- Look to variety

~~~~ Fiber ~~~~
- Balance (soluable and insoluable), moderation, and variety
- Each type of fiber has its own important purpose

~~~~ Limit added sugars ~~~~
- Enhance flavour
- Fuel for fermentation
- But they are empty calories (have no vitamins, water and have little carbohydrates)
- Contribute to tooth decay

~~~~ Sugar alternatives ~~~~
- Controls kcals and limit added sugars intake
- Two types
….* Artificial sweeteners
…* Sugar replacers or nutritive sweeteners

~~~~ Aspartame ~~~~
- General purpose
…* Coffee, etc
- 4 kcal/g but not in form of carbohydrates but rather protein
- Limit to 50mg/kg body weight daily
- Warning issued for people with phenylketonuria (PKU) which means the person cannot deal with one of the amino acids in it.

~~~~ Sucralose ~~~~
- General purpose sweetener (such as Splenda)
- Can be used in cooking and replace sugar
- Formed from sucrose but is chemically altered so that the body doesn’t recognize it and doesn’t metabolize or absorb it.

~~~~ Acceptable Daily Intake ~~~~

- Consumption considered safe, if maintain daily throughout life
- 50/mg/kg body weight (3500 mg) aka 100 packets of sweetener a day

~~~~ Sugar replacers ~~~~

- Sugar alcohols
- “sugar free” but not “calorie free”
- Low glycemic response – slow to diffuse into the system
- Sorbitol, mannitol, maltitol, lactitol, isomalt, xylitol are some common ones and quite often found in gum as the acids in the mouth can’t break them down which helps prevent tooth decay.


**********End message: Balance, moderation, and variety are the keys to good carbohydrate nutrition.**********

datenshi

Okeedoke, that's it for tonight.... more to come tomorrow.

Take care,
Tammy