Nutrition- digrestion and absorbtion

enzymes

Catalysts for chemical reactions in living things, - in digestive juices they are proteins that speed up or facilitate digestion to break down larger molecules into smaller units

Esophagus

A muscular tube that connects the pharynx to the stomach. i. Bolus of food is moved by rhythmic muscle contractions- peristalsis ii. Peristalsis moves food stuff through the entire GI tract

Bile

A substance produced by the liver that breaks up fat particles. a. Emulsifiers break up fat droplets to increase surface area so lipases can access molecules and complete digestion

Bolus

A term used to describe food after it has been chewed and mixed with saliva

Phagocytes

A type of white blood cell that ingests invading microbes. found in mucosa

Lymphocytes

A type of white blood cell that make antibodies to fight off infections (i. Bind to the antigen and Produce antibodies). found in mucosa

large intestine (colon)

Absorbs water, vitamins and minerals from gut content. i. Ends at the anus ii. 5 feet long iii. Peristalsis is slower (moves slower

ATP

(adenosine triphosphate) main energy source that cells use for most of their work -one reason we consume food is to obtain energy

lymphatic system

Composed of a network of vessels, ducts, nodes, and organs. Provides defense against infection. -absorbs fat- soluble nutrients - removes fluid from tissues -prodeuces ans strores immune system cells to fight infection invasion and exogenous pathogens or toxins

Osmosis

Diffusion of water through a selectively permeable membrane water

Gastrin

Digestive hormone that stimulates sustained secretion of gastric juice from the stomach begins when you smell see or think of food, the increases when food enters the stomach, then gastric juice decreases so the amount of chyme entering the small intestine is not too much

small intestine

Digestive organ where most chemical digestion and absorption of food takes place

transit time

The time between the ingestion of food and the elimination of the solid waste from that food.

ileocecal valve (sphincter)

Valve at the junction of the small and large intestines

gastric juice

a thin, clear, virtually colorless acidic fluid secreted by the stomach glands and active in promoting digestion.- includes 1. Water, Hydrochloric acid (HCL, very acidic) 3. Intrinsic factor (binds the Vitamin b12 for absorption) 4. Gastric signals (ghrelin and other)

diarrhea

a. Frequent watery stools b. Occurs when substances move too quickly through the large intestine for water to be absorbed or when water is drawn from cells into the lumen of the intestine i. Caused by- infections, irritants, medications, diseases, and consumption of hypertonic substances (ex. Certain sugar subs) ii. Symptoms and complication- pain, dehydration, malnutrition

celiac disease

a. Reaction to the protein gluten i. Found in grains such as wheat, rye, oats, and barley ii. Gluten triggers an immune response (allergic reaction) that damages the villi of the small intestine b. Symptoms- pains, cramping, diarrhea/constipations, bloating, fatigue c. Total elimination of gluten is necessary d. Diagnosis i. IgA (antibodies) ii. Endoscopy (shoes the damaged mucosa, lesions) iii. Biopsy of mucosa

elimination of waste

a. Undigested food particles via feces b. Carbon dioxide and some water via the lungs c. Minerals and nitrogen containing via the skin d. Water soluble substances and metabolic waste via urine

Local Absorption stomach

a. Water b. Alcohol c. Certain drugs (aspirin, acetaminophen)

Peristalsis

active transport so it doesnt need gravity. Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system. 1. Is lower with increasing age 2. Is higher with increasing physical activity 3. Can be decreased by medication and sedentary lifestyle

stomach muscles

crisscrossed layers create churning and mixing motions (i. The stomach has the thickest walls and strongest muscles of the GI 1. Longitudinal, circular and diagonal muscles)

saliva

digestive juice produced by salivary glands 1. Contains water, salts, mucus, and enzymes (salivary amylase) 2. Protects the teeth and the lining of the mouth esophagus and stomach

Chyme moves from the stomach into the _____.

duodenum

segments of small intestine

duodenum, jejunum, ileum

medium chain fatty acids

fatty acids that are six to twelve carbon atoms in length

-ase

forms names of enzymes

hormones

hormones are chemicals secreted from cells

Rectum

i. Final 8 inches of the large intestine ii. Stores feces

Probiotics

i. Food/supplement containing beneficial bacteria ii. Examples include yogurt, fermented food, beer, most natural fruits and vegetable (on the outside of food even if you wash)

Pharynx and Epiglottis

i. Swallowing- food passes from the mouth, through the pharynx, a short tube that is shared by both the digestive and respiratory systems ii. To bypass the entrance to the lungs, the epiglottis closes off the air passages to prevent choking

Digestion of the Six Nutrients

i. Water and most vitamins and minerals do not need to be digested- they are already in the absorbable form (i.e. ferric iron) ii. Carbohydrates, protein, and lipids must be digested they are too large in foods iii. They require both mechanical digestion and chemical digestion iv. Enzymes assist chemical digestions 1. -ase- word ending that denotes an enzyme e.g. lipase (cleaves lipids), protease (cleaves proteins)

mucus

i. a semi liquid secreted from mucosal cells lining the digestive tract (moistens, lubricates, and protects)

Metabolism

in the presences of oxygen, glucose, fatty acids, and amino acids can be metabolized to produce two carbon molecule (acetyl CoA) each acetyl CaA molecule enterrs a circular pathway called the citric acid cycle that produces two molecules of carbon dioxide in the final step of this metapolic pathway most of the energy relaease from the glucose fatty acids or amino acid molecules is used to produce ATP, and Oxygen combines with hydrogen to for water

digestion and absorption are...

nutrient specific processes

Prebiotics

nutrients that encourage the growth of beneficial microbes in the intestine

short chain fatty acids

part of broken down protein

mucus lining in stomach

protects organs from i. pepsin and HCL

Prancreas

releases bicarbonate to neutralize intestinal contents; produces enzymes that digest carbohydrates, protein, and fat

stomach gastric glands

secrete gastric juice into stomach for digestion

monosaccharides disaccharides

simple sugars

protein denaturation

when proteins are subject to heat, acid or other conditions that disturb their stability; protein uncoils, loses its shape, and loses its function

mouth

where digestion begins

chyme

Partially digested, semiliquid food mixed with digestive enzymes and acids in the stomach. food mass

segmentation in small intestine

Purpose of segmentation is to mix and churn not to move material along as in peristalsis

Absorbable units of macronutrients

Simple sugars (from carbohydrates) Amino acids (from protein) Fatty acids (from lipids)

stomach acid functions

Stomach acid is responsible for: - dissolving food fibers -is bactericidal (HCL kills pathogans) -cleaves pepsinogen to pepsin. -Carbohydrates are broken down to monosaccharides and disaccharides in the intestines. Intrinsic factor is secreted from parietal cells within the stomach. -denatures (uncoils) protein

gastrointestinal tract

the structures of the digestive system/tract

Stomach pH

1-2 after high protein meal, non digestive about 4-5 a. Note- antacid use (can bring it closer to 7) and foot intake can lead to digestive problems

Choking/Heimlich Maneuver

1. If food enters the airway, it can be removed by coughing or the Heimlich maneuver 2. Pushing up on the diaphragm

main involved organs

1. Mouth/Esophagus 2. Stomach 3. Small intestine 4. Large intestine

Small intestine secretions (chemical digestion)

1. Pancreas secrete pancreatic juice containing a. Sodium bicarbonate- neutralized pH of chyme b. Pancreatic amylase- polysaccharides into monosaccharides and disaccharides c. Pancreatic protease- polypeptides into amino acids d. Pancreatic lipase- triglycerides into fatty acids and glycerol 2. Also secretes digestive enzymes that multitask and act on all tree macronutrients

chemical digestion in mouth

1. Saliva is rich in enzymes to break down carbohydrates and some fats (salivary amylase and lipase) a. Starches are broken down into polysaccharides b. some Fats to glycerol and fatty acids

causes of constipation (colon)

1. The longer this process takes, the more water is removed which is the reason there is constipation and hard stools

reasoning for slow movement in colon

1. This slow movement favors the growth of bacteria called intestinal microflora (digests dietary fiber and release short- chain fatty acids and gas) a. Micro flora/ micro biome live in the colon. The release of fatty acids to the blood stream supports heart health b. If you have a working micro flora because there will be gas

Feces

1. Undigested, unabsorbed matter, dead mucosa cells (2-5 day life span), secretions from the gastrointestinal tracts, water, and bacteria 2. Is produced even in fasting i. Remember that the release of feces is voluntary (except with diarrhea and food poisoning) so not being able to access the bathroom can cause discomfort because the feces will continue to dry out

Peristalsis in colon

1. Water, nutrients and fecal matter may spend 24 hours in the colon 2. Speed has to do with the amount of food you consume and the gut mobility (older people who are less active or who perhaps take medication may take longer /expel fewer times where as a young and active person might expel more regularly and faster)

Chyme moves from the stomach to small instestine

1. enter small intestine (duodenum) through the pyloric sphincter a. Chyme amount and timing of release regulated by signals from the small intestines based on meal size and compositions (fat and protein slow it down)

active transport

1. movement of substances against the concentration gradient- requires energy (ATP) and membrane protein amino acids

long chain fatty acids

12 or more carbons (lymph)

length of small intestine

20 feet, i. and large surface are due to folds, villi, and microvilli (brush border), the total surface of a football field

protein folding

; it must be folded into the right shape to function. However, hydrogen bonds, which play a big part in folding, are rather weak and thus easily affected by heat, acidity, varying salt concentrations, and other stressors which can denature the protein -When food is cooked, some of its proteins become denatured. This is why boiled eggs become hard and cooked meat becomes firm

salivary glands

Glands of the mouth that produce saliva, a digestive secretion. Digest starches

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels fructose

Mucosa

The innermost layer of the human digestive tract; a layer of mucosal cells that line the lumen 1. They live about 2-5 days 2. New cells are formed continuously to replace those that die 3. The mucosa has high nutrient needs and is one of the first parts of the body to be affected by nutrient deficiencies

Absorption

The process by which nutrient molecules pass through the wall of the digestive system into the blood. end goal for digestion (a. safely get nutrients and water into the body while keeping out pathogens and toxins Result- transport- the ready nutrients for distribution within the body (depends on body's need for nutrients at the time when they are available))1

Gallbladder stores the bile-

bile is released into duodenum via bile duct when the stomach signals that fat is in the food

amino acids

building blocks of proteins

Mechanical digestion in the mouth

chewing, 1. The teeth crush and grind large pieces of food into smaller pieces 2. Saliva and beverages moisten the food to form semi-liquid mass

stomach

large muscular sac that continues the mechanical and chemical digestion of food i. Stomach cells produce gastric juice

Liver functions

makes bile which aids in digestion and absorption of fat

transfer of chyme from small to large intestine

most nutrients are absorbed in the small intestine but the remainder of unabsorbed portion of chyme is moved by peristalsis into the large intestine where it begins to slow down

simple diffusion

movement of a solute from an area of high concentration to an area of low concentration. 1. freely moves across membranes from areas of higher concentration to areas of lower concentration (down a concentration gradient) fatty acids

digestive system secretions

mucus, enzymes, hormones

Gallbladder

stores bile and releases it into the small intestine

accessory organs of the digestive system

teeth, tongue, salivary glands, liver, gallbladder, pancreas

the gut

the digestive system as a whole- iResponsible for digestion and absorption of nutrients

lumen

the inside of the GI tract- space within a tubular part or organ, such as the space within a blood vessel

upper esophageal sphincter

the muscular ring located at the top of the esophagus

energy-yielding nutrients

the nutrients that break down to yield energy the body can use: carbohydrate, fat, and protein. -can be broken into ATP