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					    The Digestive and Excretory
            Systems
Nutrition
• Nutrition is the science or study of how our
  bodies obtain energy, build tissue, and control
  body functions using materials supplied in the
  food we eat
• Food contains nutrients (molecules that provide
  energy and material for growth and repair)
• Humans are heterotrophs-obtain their food
• Autotrophs (i.e. Plants) are capable of producing
  their own food
           Types of Nutrients

• Organic nutrients include carbohydrates,
  proteins, lipids , and vitamins
• Inorganic nutrients include water and minerals
• Scientists refer to the energy stored in food as
  dietary calories
• Adolescent females require about 2200 calories
  per day and males require about 2800 per day
• A balanced diet includes foods from the four
  basic food groups: vegetables and fruit, grain
  products, dairy products, and protein-rich foods
        Nutrients Continued
Carbohydrates-
most of the energy
made up of Carbon, Hydrogen, and
 Oxygen (1:2:1 ratio)
sugars and starches
monosaccharides, disaccharides, and
 polysaccharides
         Nutrients Continued
Proteins-
Provides the body with material necessary for
  growth and repair
Made up of amino acids

Lipids or Fats
Your body does need a certain amount of fat in
  order to be healthy
Three fatty acids joined to a Glycerol molecule
Saturated fats or Unsaturated fats
         Nutrients continued
Vitamins-
Do not contain energy
Water -soluble and fat- soluble
Needed by the body in very small amounts that
  serve as coenzymes
Play a role in cellular reactions
When the body does not receive a sufficient
  supply , it can develop a vitamin deficiency
Minerals –
Inorganic substances required by the body for
  normal functions
          Nutrients continued
A balanced diet usually provides all the necessary
 minerals

Water-
Essential nutrient and most important
Most of our bodies weight is water
Solvent
We lose between 3-5 L of water through sweat,
 urine, and exhaled air
Dehydration
                  Digestion

• The Digestive System includes: the mouth, the
  pharynx, esophagus, stomach, small intestines,
  and large intestines
• Several major accessory structures include
  salivary glands , the Pancreas, and the Liver all
  add secretions to the digestive system
• The function of each organ of the digestive
  system is to help convert foods into simpler
  molecules that can be absorbed and used by the
  cells of the body
            Path of Digestion
Food is ingested through the mouth. It is here where
  food is broken down into chewable and swallow
  able chunks by the teeth and the tongue
  (mechanical digestion). The teeth do much of the
  mechanical digestion by cutting, tearing, and
  crushing food into smaller fragments. The
  salivary glands secrete saliva, which helps to
  moisten food and make it easier to chew.
  Amylase is an enzyme that breaks down chemical
  bonds between the sugar monomers and the
  starches.
• Pharynx-the food then passes from the mouth or
  oral cavity into the pharynx. As the tongue moves
  food into the pharynx, it presses down on a small
  flap of cartilage called the Epiglottis. Once in the
  Pharynx swallowing becomes involuntary and
  the medulla is the part of the Brain the controls
  swallowing.
• Esophagus-food is then passed through the food
  tube or esophagus and into the stomach. The food
  moves down the esophagus by involuntary
  muscle contractions known as peristalsis.
            Path of Digestion
• The sphincter closes the esophagus after food
  passes into the stomach and prevents contents
  from moving back up.
• Reverse peristalsis
• Stomach-food enters the stomach from the
  esophagus. The stomach contains microscopic
  gastric glands that release mucus, hydrochloric
  acid, and gastric juices. Pepsin is also produced ,
  especially useful for protein digestion.
• Ulcers are lesions of the digestive tract lining
           Path of Digestion
• The semi-liquid mass of partially digested food
  known as Chyme enters the duodenum and into
  the small intestines.
• Pancreas-the presence of chyme in the duodenum
  causes the release of pancreatic fluid from the
  pancreas. The pancreas is a gland that formed by
  the duodenum and under the surface of the
  stomach. The pancreas produced hormones that
  regulate blood sugar levels, produces enzymes
  that break down carbohydrates, proteins, lipids,
  and nucleic acid.
            Path of Digestion
• Liver- assists the pancreas and produces bile.
  Bile helps to neutralize the chyme from the
  stomach and emulsifying fats. Bile is stored in
  the gall bladder.
• Small Intestines- made up of the duodenum,
  jejunum, and the ileum, specially adapted to
  absorb nutrients because it is covered with villi.
• The Large Intestines-main job is to reabsorb
  water and electrolytes. Diarrhea occurs when
  there is interference with water absorption.
           Today’s Agenda

• Aim: What is the job of the excretory
  system?
• Do Now
• Class Discussion
• Group work
• Closing
       The Excretory System
DO NOW
How is the process of preparing a pot of
 coffee using a coffee filter, ground coffee,
 and boiling water similar to the processes
 involved in human excretion?
 The Human Excretory System

The excretory system plays a major role in
 maintaining homeostasis
The organs of excretion are the skin, lungs,
 and kidneys
The liver may also be considered an organ
 of excretion
Carbon dioxide, urea, water, and salts are
 all metabolic wastes produced by humans
                The Skin
 Epidermis (outer layer) protects dermis
Dermis (inner layer)
Sebaceous glands-produce oils
Sweat glands-produce sweat that is
 released through holes called pores
Helps to remove excess heat because
 evaporation of sweat cools the body
               The Lungs

• Upon exhaling the lungs rid the body of
  carbon dioxide and water vapor
                The Kidneys

• Main organ of the excretory system
• 2 kidney’s located on either side of the spinal
  column near the lower back
• Play a role in maintaining homeostasis by
  regulating the water content of the blood, and,
  therefore, blood volume, maintains blood pH,
  and removes waste products from the blood
• Urine (urea, water, salts, and other waste
  products)
• Filtration and reabsorbtion
         The Urinary System
• The kidneys, ureters, the bladder, and the
  urethra
• Urine passes from each kidney through the
  ureter to the urinary bladder where it is
  stored
• During urination, the urine travels from the
  bladder to the outside of the body through
  the urethra during urination
       Structure of the Kidney
• 3 main parts of the kidney: cortex ( the outer
  part), the medulla ( the middle part) , and the
  pelvis ( inner region)
• Renal artery and renal vein supply kidneys with
  blood
• Over 1 million nephrons
• Each nephron is made up of a glomerulus,
  Bowman’s capsule, and a renal tubule
• The glomerulus is a network of capillaries
• Bowman’s capsule is a double walled chamber
  that surrounds the glomerulus
          Structure of Kidney
• Proximal tubule is a segment of the nephron
  tubule where water, sodium ions, glucose, and
  amino acids are absorbed
• Loop of Henle is where the proximal tubule
  leads, and it is here that sodium ions are actively
  transported out
• Distal tubule is where additional sodium and
  water can be reabsorbed
• Collecting tubule receives urine from smaller
  tubules
               The Liver
• Detoxification –removes harmful waste
  from the blood
• Overloading the liver with alcohol can lead
  to cirrhosis and the liver becomes
  overgrown with extra tissue
• Cirrhosis limits the function of the liver
  and can lead to death
                Interference
•  Kidney stones- substances in urine crystallize in
   the urinary tract or kidney
• Gout is a disorder where uric acid builds up and
   is stored in the body, usually the joints or big
   toe
• Humans can survive with one kidney , but if
   both are damaged by disease or injury there are
   two ways to keep the person alive
1. Kidney transplant from a compatible donor
2. Dialysis
         Partner Discussion
• What is the purpose of a urine test?
• What can a urine test possibly detect?

				
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posted:4/18/2011
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