chapter 3 the remarkable body nutrition: concepts & controversies, 12e sizer/whitney

Chapter 3Chapter 3

The Remarkable BodyThe Remarkable Body

Nutrition: Concepts & Controversies, 12e Nutrition: Concepts & Controversies, 12e Sizer/WhitneySizer/Whitney

Learning ObjectivesLearning Objectives

Describe the levels of organization in the body, and identify some basic ways in which nutrition supports them.

Compare the terms mechanical digestion and chemical digestion, and point out where these processes occur along the digestive tract.

Trace the breakdown and absorption of carbohydrate, fat, and protein from the mouth to the colon.

The Body’s CellsThe Body’s Cells

Body is composed of trillions of cells Body needs nutrients Cells are self-contained, living entities

Depend on one another Basic needs

Essential nutrients

Cells die at varying rates

A Cell (Simplified Diagram)A Cell (Simplified Diagram)

The Body’s CellsThe Body’s Cells

Genes Control function Direct production of proteins Provide instruction for structural

components of cells Affects how body handles nutrients Complete set of genes in each cell

Tissues, organs, and body systems

From DNA to Living CellsFrom DNA to Living Cells

The Body Fluids and the The Body Fluids and the Cardiovascular SystemCardiovascular System

Body fluids Supply energy, oxygen, nutrients, and water Deliver fresh supplies and pick up wastes

Types of fluids Blood

Arteries, veins, capillariesPlasma

Lymph

Blood Flow in the Cardiovascular Blood Flow in the Cardiovascular SystemSystem


Extracellular fluid Intracellular fluid

All cell reactions take place

Holds cellular shape


All blood circulates to the lungs Picks up oxygen Releases carbon

dioxide


Blood returns to heart Blood pumped to rest of body

Delivers nutrientsPicks up wastes

Blood passes through digestive system Picks up nutrients

Except for fatsFats travel via lymph

Routed directly to liver

Lymph Vessels and the Lymph Vessels and the BloodstreamBloodstream


Kidneys Fluid intake Red blood cell life

expectancy Blood is sensitive to

malnutrition

The Hormonal and Nervous The Hormonal and Nervous SystemSystem

Hormones Chemical messengers Secreted and released directly into blood by

glands Stimulate organs to take action

Glands monitor conditions in the body Pancreas

Insulin and glucagon


Nutrition affects the hormonal system Hormones affect nutrition

Appetite changes during pregnancy

Nervous system Receives and integrates information from

sensory receptors Role in hunger regulation

Cortex and hypothalamus

Cutaway Side View of the Brain Cutaway Side View of the Brain Showing the Hypothalamus & CortexShowing the Hypothalamus & Cortex


Fight-or-flight reaction (stress response) Neurotransmitters

Epinephrine and norepinephrine Metabolism speeds up Organ response

Eyes, heart, liver, stomach Heart disease

The Immune SystemThe Immune System

Cooperation among tissues to maintain defenses Physical barriers

Antigen Immune defenses

White blood cellsPhagocytesLymphocytes (T-cells and B-cells)

The Immune SystemThe Immune System

Inflammation Response to injury or irritation

Increased white blood cells, redness, heat, pain, swelling

Normal and healthy response Problem with chronic inflammation

Dietary factors

The Digestive SystemThe Digestive System

Four basic chemical tastes Sweet, sour, bitter, and salty Savory

Sweet, salty, and fatty foods Almost universally desired Can lead to drastic overeating of these

substances


Digestive tract Flexible, muscular tube

Path Total length of about 26 feet Body surrounds digestive canal

System’s job is to digest food to its components, absorb, and excrete System works at two levels


Chemical digestion Digestive juices

Salivary glands, stomach, pancreas, liver, and small intestine

MouthSaliva – starches and fatSaliva – health of teeth

StomachHydrochloric acid – protein


Chemical digestion Intestine

BilePancreatic juiceDigestive enzymes in wall of intestineFiber

Food combinations and digestion


Within 24 to 48 hours 90% of carbs, fat, and protein are digested

and absorbed Mouth

Food is crushed, mashed, and mixed with saliva

Carbohydrate digestion begins Swallowing

Peristalic waves


Stomach Gastric juice mixes with food

Unwinds proteins

Chyme Small intestine

Bile from the liver

Pancreas Large intestine


Absorption Nutrient molecules transverse intestinal

liningWater-soluble componentsFat-soluble components

Cells of small intestine are selective Folded structure

VilliMicrovilli

Details of the Small Intestine Details of the Small Intestine Lining Lining


Transport Lymph vessels

Products of fat digestionFat-soluble vitamins

Blood vesselsProducts of carbohydrate & protein digestionMost vitaminsMinerals

Nourishment of digestive tract

The Excretory SystemThe Excretory System

Organs involved in waste removal Lungs, liver, kidneys

Kidneys Waste materials are dissolved in water Working units – nephrons Urine is stored in bladder Sodium and blood pressure Work regulated by hormones Importance of water supply

Storage SystemsStorage Systems

Eating intervals of 4-6 hours Major storage sites

Liver – carbohydrates Glycogen

Muscles – carbohydrates Glycogen

Fat cells – fat and fat-related substances Variations in nutrient stores

chapter 3 the remarkable body nutrition: concepts & controversies, 12e sizer/whitney

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