Internal Systems and Regulation

Nutrients, Digestion and Nutrition

Organs & Organ Systems Cells

Tissues

Organs

Organ systems

Organismsp. 205, tab. 1

Monitoring Organs– X-rays electromagnetic waves…what do they do?

Bismuth and barium

– CT scan computerized axial tomography (p. 206) Many x-ray pictures, computer assimilated to give cross sectional views and

3D images Gases, solids and liquids can all be identified

– Nuclear imaging (p. 207) Information about function as radioisotopes (radionuclides) collect in target

organs and emit radiation which is translated into a picture

– NMR nuclear magnetic resonance technology Structure and function of organs NMR subcategory is MRI

– Uses the spinning motions of atomic nuclei to produce a map of the internal structures of the body and how they are functioning

Obtaining Food

Essential Nutrients– Heterotrophs – organisms that depend on

organic molecules manufactured by other living things

– Autotrophs – nourish themselves using inorganic material

Components of Digestion

Ingestion – taking in of nutrientsDigestion – breakdown of molecules by enzymesAbsorption – transport of digested nutrients to

tissues of the bodyEgestion – removal of wastes

Digestive Enzymes

Enzymatic reactions in the body are controlled by temperature and pH– Enzyme activity peaks at 37oC

pH effects on enzymatic activity– Pepsin – low pH– Amylase – neutral pH– Trypsin – basic pH

Digestion OverviewSingle celled organisms

(p. 209, fig. 3)– Hydrolytic enzymes

use water to break down molecules

Simple multi-cellular organisms (p. 209, fig. 4)– Gastrovascular cavity –

holds and digests, wastes out

Digestion Overview Complex multi-cellular

organisms (p. 209, fig. 5)– Alimentary canal specialized

regions Earthworm

– Pharynx esophagus stomach (crop) (gizzard) intestine {hydrolytic enzymes & transportation of nutrients} anus

Humans ~ 6.5 to 9m in length

Ingestion Mouth – chemical and mechanical digestion Teeth

– 3 molars, 2 premolars, 1 canine, 2 incisors on each side (4 total) of the top and bottom

– Tooth – has root and crown

• Enamel crown has Ca2+

compounds and is the hardest substance in the body

• Dentin inside the enamel and it has pulp (nerves and blood vessels)

• Decay

• Tongue (p. 211, fig. 2)• Papillae – contain the taste

buds (sweet, sour, bitter, salty)

Ingestion

Uvula – prevents food from entering the pharynx

Saliva3 pairs of salivary glands

which secrete saliva using ducts

Ingestion Esophagus

– Need to ensure trachea closes and that food passes into the esophagus

Epiglottis covers the glottis so this does not happen– Circular and longitudinal muscles (24 cm)– Bolus of food is moved along using peristalsis

Wavelike, muscular contractions and relaxations Circular muscles over food relax while longitudinal in front of

food contract Circular muscles behind food contract while the longitudinal

muscles relax p. 212, fig. 4

– Mucin helps to move food along– Regurgitation – movement of food back up to mouth

The Digestive Tract Stomach

– Muscular, J-shaped organ whose lining is covered with gastric glands

Glands secrete gastric juice– Has 3 layers of muscle (not just the 2 in the esophagus) – circular,

longitudinal and oblique– All 3 layers work to break up food in the presence of gastric juices

(mucus, HCl, pepsin) to form chyme Mucus protective layer HCl kills harmful substances and converts pepsinogen to pepsin Pepsin protein digesting enzyme

– Pyloric sphincter – controls movement of food from stomach to small intestine.

– Ulcers H. pylori bacteria Endoscope and laser treatment

The Digestive TractSmall Intestine

– Named due to small diameter (2.5 cm) not length (7m) Large intestine diameter (7.6cm), length (1.5m)

– Permanent folds to increase surface area (p. 225, fig. 2) On these folds are villi which further increases the surface

area and secrete intestinal juices Also lacteal or lymph vessels in the villi which accept larger

fat particles– Duodenum – U-shaped and is the shortest yet widest of

the 3 sections It lacks oblique muscles Pancreatic and bile ducts empty into this section

The Digestive Tract

Pancreas– Acid causes prosecretin to be converted to

secretin which travels to the pancreas and causes bicarbonate ions to be released

pH from 2.5 to 9 which inactivates pepsin– Source of enzymes that act on carbohydrates

(amylase), fats (lipases), and peptides (trypsinogen).

– p. 218, table 1

Jejunum – 2.5m longContains more folds then the duodenumBreaks down remaining proteins and carbohydrates

Ileum – 3m longFewer and smaller villiContinue digestion and move food into the large intestine

Related OrganLiver

– Digestive role of producing bile salts from cholesterol Bile breaks down fats and is stored in the gall bladder

– Released into small intestine and break up fat globules into droplets

– Allows for faster processing and absorption into bloodstream

– Demolitions expert – red blood cells– Storage of monosaccharides (glucose glycogen) and

vitamins– Protein breakdown – elimination or conversion, converts

toxic N groups to urea– Detoxification – breaks down ingested poisons

The Digestive TractLarge Intestine – 1.5m, diameter is greater though

– Caecum, colon, rectum and anal canal– Caecum – blind end which leads to the appendix– Colon – water and dissolved minerals are absorbed and

bacteria break down what is left – Rectum – accepts feces and passes it along to the anal

canal (last 20 cm of large intestine)– Anus – feces pass out of body

Anal sphincters help to control

How long does it take to digest food?

Overall 24 to 72 hours depending on food and metabolic rate

Gum – is not digestible so it will pass through your digestive system the same as any other non digestible item (i.e. coins, marbles).

How to improve your digestion Tip #1: Cover the Basics

– Basic 1: Chew, Chew, Chew Take smaller bites.

– Put your fork down in between bites.

– Try using chopsticks - it forces you to slow down.

– Thoroughly chew each bite of food.

– Carbohydrate digestion begins in the mouth - chewing grains thoroughly allows amylase, the digestive enzyme present in saliva, to digest the grains.

How to improve your digestion

Basic 2: Get Enough WaterInsufficient water intake is a primary cause of constipation. Constipation then causes an imbalance in bacteria, promotes inflammation of the intestinal lining, and can even lead to the absorption of larger molecules, a condition known as intestinal permeability.

How to improve your digestion Basic 3: Increase Your Dietary Fiber

– Good sources of dietary fiber include: Dried fruit, such as dates, figs, and prunes

– Beans and legumes- if you don't have time to cook dried beans, buy canned, but make sure you rinse them thoroughly before cooking. Lentils and split peas are less gas-forming than other legumes.

– Bring an apple with you to work as a snack

– Ground flaxseeds are a gentle laxative. They can be useful for chronic constipation, damage to the intestine wall from laxative use, irritable bowel, and to soothe inflammation. Sprinkle ground flaxseeds on rice,

grains, salads, or any other meal of your choice.

How to improve your digestion Tip #2: Address Food Sensitivities and Allergies

Food sensitivities are behind many digestive disorders. For example, between 33% and 66% of IBS patients report having one or more food intolerances, resulting in bloating, gas, and pain. The most common culprits are milk and dairy (40-44%) and grains (40-60%).

A trained practitioner can supervise an elimination diet. Many foods are removed from the diet for a brief period of time, then re-introduced sequentially to isolate the body's reaction to the offending foods.

How to improve your digestion Tip #4: Increase Good Gut Bacteria

– Not all bacteria is bad. There are over 400 different kinds of bacteria and yeasts in the digestive system. Of these, the bacteria Lactobacillus acidophillus and Bifidobacterium bifidum are considered good "probiotic" bacteria because they can help to maintain intestinal health.

– Although good bacteria can be found in some yogurt, there is a wide variation in the quantity and quality. Look for good quality organic yogurt that add the active cultures after pasteurization, because this heat process destroys both good and bad bacteria.

– Supplements containing acidophilus and bifidobacteria can be found in health food stores. They are especially helpful for the following conditions: Irritable bowel syndrome

– Diarrhea– Gas, bloating, flatulence– Recurring vaginal yeast infections– Bad breath

Regulation of Secretions Nerves and hormones are in charge

– Hormone = chemical regulator that is secreted in one part of the body and transported to another part, where it causes a response.

– e.g. digestive glands on walls of stomach are stimulated by nerves and by gastrin. In response, individual glands secrete mucin, pepsin, HCl and lipases.

Further, chyme in duodenum stimulates ductless glands in the walls of the duodenum to secrete hormone secretin.– Secretin goes to the pancreas to stimulate duct cells there to

release alkaline fluid (sodium bicarbonate)

Knowledge is Power

How do we know what we know?– William Beaumont (1833) took a patient who had been

shot in the stomach.– Improperly healed into a fistula– Foods was put in with a string attached– Emotions linked to secretions

Homeostasis Perfect internal situation

– 37oC, 0.1% blood sugar, pH of 7.35– How do we maintain this?– Sensors coordinating centre (?) regulator– Meal blood sugar increases pancreas releases insulin insulin

allows sugar to be absorbed by cells in liver, glycogen in formed Homeostasis and Digestion

– Seeing, smelling and tasting produce gastric secretions– Secretin released when food travels from stomach to small

intestine– Speed of food movement

Large meal will cause receptors increase muscle movement of stomach to move food out of stomach

Fatty meal will be identified and cause food to stay in small intestine longer

Food EnergyUsing energy all the time

– Joules (J) or kilojoules (kJ) compared to calories– 1 cal = 4.18 J– BMR basal metabolic rate

p. 230, table 1

Metabolic Factors– Metabolism is the sum of all the chemical reactions that

occur within body cells– Differences?– Energy uses (p.232, table 2)– Dieting Dangers

Nutrients Amino acids - there are 20, we can not make 10 Fats

– Get a bad name but we need them to help us absorb vitamins, insulate, protect delicate organs, protect nerves, cell membrane

Vitamins – organic molecules that help change food into energy– Water soluble – can not be stored

C and B groups– Fat soluble – can be stored

A, D, E, K Minerals – elements that help change food into energy

– Ca, I, Fe, P, K, Na Antioxidants reduce the danger of oxygen free radicals

– FR – created by exposure to sunlight, Xrays, ozone, tobacco smoke, etc.

Damage to genetic information

Digestive DisordersSymptoms

– Bleeding– Bloating– Constipation– Diarrhea– Heartburn– Incontinence– Nausea and vomiting– Pain in the belly– Swallowing problems– Weight gain or loss

Disorder Cause Symptoms Treatment

Gallstones • Overweight, age near or above 40, female, or pre-menopausal• Caucasians • A lack of melatonin could significantly contribute to gallbladder stones

• as melatonin both inhibits cholesterol secretion from the gallbladder, enhances the conversion of cholesterol to bile

•"gallstone attack“• in which a person

may experience intense pain in the upper-right side of the abdomen, often accompanied by nausea and vomiting, that steadily increases

• Surgery or medications

Cirrhosis of liver

• In the Western World, chronic alcoholism and hepatitis C are the most common causes.

•Yellowing of the skin (jaundice) due to the accumulation of bilirubin in the blood •Fatigue •Weakness •Loss of appetite •Itching •Easy bruising from decreased production of blood clotting factors by the diseased liver.

• Liver damage from cirrhosis cannot be reversed, but treatment could stop or delay further progression and reduce complications.

Disorder Cause Symptoms Treatment

Crohn’s disease • Exact cause still unknown, a combination of environmental factors and genetic predisposition seems to cause the disease

• Abdominal pain may be the initial symptom• Diarrhea• Fecal consistency may range from solid to watery.

• In severe cases, an individual may have more than 20 bowel movements per day and may need to awaken at night to defecate

•At the present time, there is no cure for Crohn's disease and remission may not be possible or prolonged if achieved• Elemental diet, proper hydration, and smoking cessation. Smoking

Gastroesophageal reflux disease (GERD)

• Abnormal nerve or muscle function in the stomach which, in turn, causes food and stomach acid to be digested too slowly.

• Heartburn • Regurgitation • Trouble swallowing (dysphagia) • Less-common symptoms include:

• Pain with swallowing (odynophagia)

• Increased salivation (also known as water brash)

• Nausea• Chest pain

• Only weight loss and elevating the head of the bed were supported by evidence• Medication• Surgery