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

Circulation Cardiovascular 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 System Regulatory system Central Nervous System Brain & spinal cord Peripheral Nervous System Branches out to organs Neuron Responds to electrical & chemical signals

Transmission Insert Fig. 3-6

Sending Signals Exchange of sodium & potassium concentration Neurotransmitter Secretion 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 anus Epithelial cells line the lumen Barrier to invaders Submucosal layer Taste and smell

The Mouth Mastication-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 Peristalsis Rings of contractions propelling material along the GI tract Mass movement Peristaltic 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 Kidneys Ureter Bladder Urethra Removes waste products Proper 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 function Possibly caused by altered intestinal peristalsis and decreased pain threshold Rx: 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 & prstate HTN: 10-15% salt sensitive Diabetes: type 1 & type 2 Obesity: genes regulate weight Nature vs. nurture Cardiovascular Disease (CV) 1:500  cholesterol  homocysteine (aa)

Genetic Testing? Testing will be available but very expensive Family tree!