Chapter 3 THE REMARKABLE BODY

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Chapter 3 THE REMARKABLE BODY

• Why proper nutrition is important.

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Summary

• Organization of the human body
• Fluids and the cardiovascular system
• Hormonal and Nervous system
• Immune system
• Digestive system
• Excretory system
• Storage systems

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Organization of the Body

• Cells the smallest unit of life
• Tissues groups of similar cells working as a
  unit.
• Organs two or more tissues form a functional
  structure.
• Organ systems groups of organs working
  together.
• Organism (Body) groups of organ systems working
  together.

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Organization of the Body

• Cells trillions of self-contained, living
  entities, each with a specific job and nutrient
  requirements. Basic requirements for all cells
• Water
• Oxygen
• Essential nutrients nutrients they cannot
  make for themselves.
• Basic structure, fig 3.1

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A membrane encloses each cells contents.
These fingerlike projections are typical of cells
that absorb nutrients in the intestines.
A separate, inner membrane encloses the cells
nucleus.
Inside the nucleus is the hereditary material,
which contains the genes. The genes control the
inheritance of the cells characteristics and its
day-to-day workings. They are faithfully copied
each time the cell duplicates itself.
On these membranes, instructions from the genes
are translated into proteins that perform
functions in the body.
Many other structures are present. This is a
mitochondrion, a structure that takes in
nutrients and releases energy from them.
Fig. 3-1, p. 66
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Organization of the Body

• Genes DNA
• Blueprints for the production of proteins
• Proteins are important structural and functional
  molecules in living things.
• Genes affect nutrient utilization and nutrients
  affect gene function.

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Organization of the Body

• Tissues groups of similar cells that function
  as a unit. Ex. muscle tissue
• Organs 2 or more tissues that make up a unique
  structure. Ex. heart
• Organ systems groups of organs that perform a
  certain function. Ex. cardiovascular system.

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Organization of the Body

• Body systems groups of organ systems that work
  together to support body functions. Ex.
  cardiovascular and respiratory system.

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Body Fluids and the Cardiovascular System

• Function delivery of nutrients, including
  oxygen, to all of the cells in the body.
  Delivery of wastes to kidneys and lungs.
• Body fluids
• Extracellular fluid fluid outside cells
• Blood and lymph
• Interstitial fluid filtrate of plasma that
  bathes cells
• Intracellular fluid inside cells

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Body Fluids and the Cardiovascular System

• Body fluids contd
• Blood consists of 2 components
• Plasma liquid containing proteins and other
  molecules and
• Cells -
• RBC (red blood cells) carry oxygen to cells.
• WBC (white blood cells) our immune cells.
• Platelets fragments of cells that participate
  in blood clotting.
• Lymph milky fluid similar to plasma.

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Body Fluids and the Cardiovascular System

• Cardiovascular system, fig 3.3
• Heart a pump
• Blood vessels
• Arteries carry blood away from the heart
• Veins carry blood toward the heart and
• Capillaries connect the two and circulate blood
  to individual cells.
• Circulations
• Two loops in series
• 1) Pulmonary loop lungs ? heart ?
• 2) Systemic loop heart ? tissues ? heart
• Special Hepatic Portal Heart ? intestines ?
  liver ? heart

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Head and Arms
Lungs Oxygenate blood Remove carbon dioxide
from blood Return blood to heart
Heart Right side pumps blood to lungs Left
side pumps oxygenated blood to body
Liver Filters toxins from blood Stores,
transforms, and mobilizes nutrients
Intestines Absorb nutrients
Kidneys Filter wastes from blood Form urine
Pelvis and Legs
Fig. 3-3b, p. 69
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Lymph vessel.
Blood circulates among cells by way of
capillaries.
Blood collects into veins for return to heart.
Blood enters tissues by way of artery.
Lymph vessel.
Inside capillary.
Capillary wall has spaces between its flat
cells.
Lymph vessel.
Cells of surrounding tissue.
Fig. 3-4, p. 70
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O2
O2
AIR
CO2
CO2
body tissue
tissue capillary
lung capillary
air sac lung
Fig. 3-5, p. 71
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Hormonal and Nervous Systems

• Function
• Communication systems that work together.
• Monitor and regulate body processes

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Hormonal and Nervous Systems

• Hormonal system
• Hormones (proteins) are secreted by endocrine
  glands directly into the blood.
• Regulate many functions including
• Appetite/hunger
• Satiety
• Digestion
• Nutrient utilization, ex. pancreas hormones that
  control blood glucose.

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Hormonal and Nervous Systems

• Nervous system the major communication system
• Central nervous system brain and spinal cord -
  receive information from sensory receptors,
  interprets and delivers instructions to regulate
  body functions.
• Peripheral nervous system connects brain and
  spinal cord to the rest of the body.

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Hormonal and Nervous Systems

• Brain nutrition related functions
• Hypothalamus regulates hunger/appetite.
• Cerebral cortex makes us conscious of hunger and
  causes us to eat.
• With peripheral nerves regulates digestive tract
  functions.

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Hormonal and Nervous Systems

• Both systems work together to monitor and
  regulate nutrient delivery to tissues as needed.
  
• Ex. Stress response nerves release
  neurotransmitters that stimulate endocrine glands
  that release hormones to speed up metabolism and
  provide energy.
• Both systems need nutrients to function properly.

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Immune System

• Function protect the body from invaders
  (viruses, bacteria, fungi and cancer cells).
• Organs and cells
• Skin and mucous membranes mechanical barriers.
  Proper function is sensitive to vitamin and other
  nutrient deficiencies.

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Immune System

• Organs and cells contd
• WBCs
• Phagocytes roam around our tissues seeking
  pathogens which they eat and destroy.
• T-cells Killer T-cells respond to chemicals
  from phagocytes and destroy pathogens. Helper
  T-cells stimulate the immune system.
• B-cells produce antibodies, proteins that kill or
  inactivate pathogens.

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Digestive System

• Hunger and appetite are regulated by our nervous
  and hormonal systems but our choice of foods is
  mediated in our mouths, noses and eyes.
• Taste, aroma, texture, temperature and appearance
  habits affect our choice of food.

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Digestive System

• Digestive tract muscular tube that breaks down
  food into nutrients and absorbs them into the
  blood or lymph, fig 3.78.
• Organs
• Primary mouth, pharynx, esophagus, stomach,
  small and large intestine and rectum
• Accessory salivary glands, teeth and tongue,
  pancreas, liver and gall bladder.

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Accessory Organs That Aid Digestion
Digestive Tract Organs That Contain the Food
Mouth Chews and mixes food with saliva
Salivary Glands Donate a starch-digesting
enzyme Donate a trace of fat-digesting enzyme
(important to infants)
Esophagus Passes food to stomach
Liver Manufactures bile, a detergent-like
substance that facilitates digestion of fats
Stomach Adds acid, enzymes, and fluid Churns,
mixes, and grinds food to a liquid mass
Gallbladder Stores bile until needed
Small Intestine Secretes enzymes that digest
carbo-hydrate, fat, and protein Cells lining
intestine absorb nutrients into blood and lymph
Bile Duct Conducts bile to small intestine
Large Intestine (Colon) Reabsorbs water and
minerals Passes waste (fiber, bacteria, any
unabsorbed nutrients) and some water to rectum
Pancreatic Duct Conducts pancreatic juice into
small intestine
Pancreas Manufactures enzymes to digest all
energy-yielding nutrients Releases bicarbonate to
neutralize stomach acid that enters small
intestine
Rectum Stores waste prior to elimination
Anus Holds rectum closed Opens to
allow Elimination
Fig. 3-8, p. 76
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Digestive System

• Mouth
• Taste buds on the tongue detect salty, sweet,
  bitter, sour and savory (umami).
• Mechanical digestion of food by teeth and tongue.
• Mixing of food with saliva
• Swallowing tongue and pharynx

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Digestive System

• Esophagus passes food from mouth to stomach by
  peristalsis. Peristalsis waves of muscular
  contractions from mouth to stomach, fig 3.9.

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As the circular and longitudinal muscles tighten
and relax, the food moves ahead of the
constriction
Swallowed food
Fig. 3-9b, p. 77
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Digestive System

• Stomach mechanical and chemical digestion of
  food forming a liquid mass chyme.
• Small intestine
• Chemical digestion of food into primary nutrients
• Absorption of nutrients into the blood/lymph.

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Digestive System

• Large intestine
• Absorbs water and some minerals
• Compacts undigested components into feces.
• Rectum stores feces for elimination, opening
  held closed by anus (sphincter composed if
  muscles).

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Digestive System

• Chemical Digestion, Table 3.1
• Mouth some partial digestion of starch by
  amylase, an enzyme in saliva.
• Stomach acid (HCl) and pepsin begin digestion
  of proteins into peptides.

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Digestive System

• Chemical digestion
• Small intestine
• Receives bicarbonate from pancreas to neutralize
  acid from the stomach.
• Receives bile from the gall bladder to emulsify
  fats. Bile works like soap to break fats into
  small droplets.

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Digestive System

• Chemical digestion
• Small intestine
• Receives enzymes from pancreas that breakdown
  starches to disaccharides, peptides to amino
  acids and fats into glycerol and fatty acid
  chains.
• Also produces enzymes that breakdown
  disaccharides to monosaccharides and peptides to
  amino acids.

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Digestive System

• Chemical Digestion
• Release of enzymes is controlled by the foods
  eaten.
• Absorption of nutrients
• Primarily in small intestine
• Walls have finger-like projections villi, with
  smaller hair-like projections microvilli.
  These increase the surface area for absorption of
  nutrients.

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stomach
small intestine
folds with villi on them
If you have ever watched a sea anemone with its
fingerlike projections in constant motion, you
have a good picture of how the intestinal villi
move.
The wall of the small intestine is wrinkled into
thousands of folds and is carpeted with villi.
muscle layers beneath folds
a villus
Between the villi are tubular glands that secrete
enzyme- containing intestinal juice.
capillaries
lymphatic vessel
artery
vein
lymphatic vessel
microvilli
This is a photograph of part of an actual human
intestinal cell with microvilli.
Each villus, in turn is covered with even smaller
projections, the microvilli.
Fig. 3-12, p. 84
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Digestive System

• Absorption contd
• Nutrients pass into villi
• Water soluble nutrients pass into the blood and
  are delivered to the liver.
• Fat soluble nutrients pass into the lymph and
  enter the blood near the heart.
• Malnutrition destroys many villi and absorption
  decreases. Malnutrition also weakens muscles
  that control the movement of food through the
  tract.

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Digestive System

• OYO (On Your Own) read A letter from your
  digestive system, pp 83-87.

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Excretory System

• Cells produce CO2 as they work. CO2 is
  transported in the blood to the lungs for
  elimination.
• The liver filters toxins and other wastes and
  delivers them, via the blood, to the kidneys or
  digestive tract for elimination.

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Excretory System

• Kidneys are composed of smaller units called
  nephrons that filter blood, decide what nutrients
  to keep and eliminates the rest in the urine.

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Storage Systems

• Hold nutrients for period between meals.
• Liver and muscle store glucose in the form of
  glycogen. Between meals the glycogen is broken
  down to glucose and delivered to cells via the
  blood. Limited storage!

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Storage Systems

• Fat cells (adipose tissue) store excess nutrients
  as fat and releases it when glucose stores are
  depleted. Unlimited storage!!

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Alcohol is it good for you?

• Source of energy but a non-nutrient.
• Beneficial and adverse effects OYO read the
  Controversy, pp 91-98.