chapter 3 the remarkable body nutrition: concepts & controversies, 12e sizer/whitney
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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
The Body Fluids and the The Body Fluids and the Cardiovascular SystemCardiovascular System
Extracellular fluid Intracellular fluid
All cell reactions take place
Holds cellular shape
The Body Fluids and the The Body Fluids and the Cardiovascular SystemCardiovascular System
All blood circulates to the lungs Picks up oxygen Releases carbon
dioxide
The Body Fluids and the The Body Fluids and the Cardiovascular SystemCardiovascular System
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
The Body Fluids and the The Body Fluids and the Cardiovascular SystemCardiovascular System
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
The Hormonal and Nervous The Hormonal and Nervous SystemSystem
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
The Hormonal and Nervous The Hormonal and Nervous SystemSystem
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
The Digestive SystemThe Digestive System
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
The Digestive SystemThe Digestive System
The Digestive SystemThe Digestive System
Chemical digestion Digestive juices
Salivary glands, stomach, pancreas, liver, and small intestine
MouthSaliva – starches and fatSaliva – health of teeth
StomachHydrochloric acid – protein
The Digestive SystemThe Digestive System
Chemical digestion Intestine
BilePancreatic juiceDigestive enzymes in wall of intestineFiber
Food combinations and digestion
The Digestive SystemThe Digestive System
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
The Digestive SystemThe Digestive System
Stomach Gastric juice mixes with food
Unwinds proteins
Chyme Small intestine
Bile from the liver
Pancreas Large intestine
The Digestive SystemThe Digestive System
The Digestive SystemThe Digestive System
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
The Digestive SystemThe Digestive System
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
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