Chapter 3: The Human Body: A Nutritional Perspective

Chapter 3: The Human Body: A

Nutritional Perspective

Body Cells

Form tissues

Tissues form Organs

Organs form Systems (e.g., digestive)

Cell membranes allow passage of substances in & out of cells

DNA in nucleus

Four Types of Tissues

Epithelial Covers surfaces inside & outside of the body

Connective Supports & protects the body, stores fat

Muscle Able to contract & relax are designed for movement

Nervous Brain & spinal column, communicate by transporting

nerve impulses

Nutrition & systems

Each type of organ system is impacted by nutrient intake & simultaneously determines how each nutrient is used

Genetic influence is significant in that DNA controls what happens next

CirculationCardiovascular System Heart and blood vessels Systemic circulation Pulmonary circulation Portal circulation

Lymphatic system Lymph vessels & fluid Immune function Drains excess fluids Carries large fat compounds

Portal Circulation

Transports nutrients

From the small intestine

Delivers to the liver

Allow liver to process nutrients before returning it to the bloodstream

Exchange of Nutrients

Insert Fig. 3-4

Blood Circulation

Nervous SystemRegulatory system

Central Nervous SystemBrain & spinal cord

Peripheral Nervous SystemBranches out to organs

NeuronResponds to electrical & chemical signals

Transmission

Insert Fig. 3-6

Sending Signals

Exchange of sodium & potassium concentration

NeurotransmitterSecretion of dopamine, epinephrine and

norepinephrine

Transmission is dependent on nutrients supply

Endocrine System

Secretes regulatory substances (hormones)

Body’s messenger

Insulin

Thyroid hormones

Immune System

Defense against invading pathogens

Skin, intestinal cells, WBC

Sensitive indicator of the body’s nutritional status

The Digestive System

Digestive System

Mouth to anusEpithelial cells line the lumenBarrier to invadersSubmucosal layer

Taste and smell

The MouthMastication-chewing

Saliva Salivary amylase begins the breakdown of starch Mucus to lubricate the food for easier swallowing Lysozyme to kill bacteria

Tongue Taste receptors

The Esophagus

Long tube

Connects pharynx to the stomach

Epiglottis prevents choking

Peristalsis, muscle contraction

Lower esophageal sphincter

Heartburn

The Stomach

Lower esophageal sphincter & pyloric sphincter

Capacity of ~4 cups

Secretion of acid & enzymes

Holds food for 2-4 hours

Formation of chyme

Mucus layer prevents autodigestion

Physiology of the Stomach

The Small Intestine

The walls are folded

Villi projections are located on the folds

Absorptive cells are located on the villi

Increases intestinal surface area by 600x

Rapid cell turnover

The Small Intestine

The Large Intestine

~3 1/2 feet in length

No villi or enzymes present

Little digestion occurs

Indigestible food stuff

Absorption of water, some minerals, vitamins

Contains bacteria

Formation of feces for elimination

Rectum

Stool remains

Stimulates elimination

Muscle contraction

Anal sphincters

Movement Along the Intestine

PeristalsisRings of contractions propelling material

along the GI tract

Mass movementPeristaltic wave that contracts over a large

area of the large intestine to help eliminate waste

Movement

Accessory Organs

Pancreas enzymes

Liver bile

Gallbladder storage

The Pancreas

Manufactures digestive enzymes

Produces glucagon & insulin

Secretes pancreatic juices

Bicarbonate needed to neutralize chyme

The Urinary System

KidneysUreterBladderUrethraRemoves waste productsProper function determined by cardiovascular system, fluid intake & drug use

Ulcers

Helicobacter pylori

Excessive use of aspirin

Excessive acid production

Stress

Stomach looses its mucus protection

S/S: pain in ~2 hrs after eating

Rx: Antibiotics, antacid, refrain from smoking, limit use of aspirin and aspirin like meds.

Heartburn

S/S: Gnawing pain in the upper chest

Movement of acid from the stomach into the esophagus

Gastroesophageal reflux disease (GERD)

Rx: smaller, more frequent meals, low fat, wait 2 hours before lying down, refrain from smoking, low excess weight, limit spicy foods, medication

Constipation

Difficult or infrequent bowel movement

Caused by slow motility, medication &/or supplements of calcium/iron

Feces stay in the large intestine longer

Ignore normal urges to defecate

Rx: Eat plenty of dietary fiber, drink more fluids, regular physical activity

Laxatives

Irritate the intestinal nerve to stimulate peristaltic muscles or

Draws water into the intestine

Regular use can decrease muscle action in the large intestine

GI tract becomes dependent on laxatives

Hemorrhoids

Swollen veins of the rectum & anus

Intense pressure and straining

S/S: pain, itching, bleeding

Rx: eat plenty of fiber and fluid

Irritable Bowel Syndrome

S/S: Cramps, gassiness, bloating, irregular bowel functionPossibly caused by altered intestinal peristalsis and decreased pain thresholdRx: individualized, elimination diet, moderate caffeine, low fat, small meals, stress reduction

Diarrhea

Increased fluidity, frequency or amount of bowel movement

Usually caused by an infection in the intestine

Bacteria & viruses cause the intestinal cells to secrete fluid

Rx: plenty of fluid

Genetics

Entire organism is controlled by genes in cells

Human Genome Project (2003) Cookbook of recipes

Traits Risk for diseases

Genetic Screening Treatment Gene therapy

Nutrigenomics

The study of how food impacts health through its interactions with genes & its subsequent effect on gene expression

Your specific nutritional requirements that will effect diseases & their progression

Nutritional Diseases

Cancer: Colon, breast & prstateHTN: 10-15% salt sensitiveDiabetes: type 1 & type 2Obesity: genes regulate weight

Nature vs. nurture

Cardiovascular Disease (CV)1:500cholesterol homocysteine (aa)

Genetic Testing?

Testing will be available but very expensive

Family tree!