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Biology 102 - announcments

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					  Biology 103 - Main points/Questions

      1. Why do you need to eat?
2. What does your body do with this food?
        3. What is in plant food?
What do you remember about
    human circulation?
1. Name the
   structure
2. Where is blood
   in this structure
   headed?
3. Blood in this
   structure has
   just come from
   where?
1. Aorta
2. Blood is headed
   out to the body



3. Blood here is
   returning from
   the body (this is
   the right atrium)
    Organisms’ two basic needs
Source of organic molecules
• Either build your own (autotrophs)
• Or take from other organisms (heterotrophs)
Energy source
• Either chemical (called chemotrophs)
• Or light (called phototrophs)
Most organisms are chemoheterotrophs
(Fungi, animals, many protists & bacteria) or
photoautotrophs (plants, many protists & bacteria)
    We are Chemoheterotrophs so…
• We get energy and complex carbon
  molecules (monomers) from other
  organisms
• But often we actually get polymers – what
  are these?
 Polymers are chains built of smaller
        “monomer” pieces
• These polymers are specific to the organism
  that made them but the monomers are more
  generic.
• How can we break these polymers apart to
  get access to the monomers?
Hydrolysis
Your digestive
system frees up
monomers from
food (hydrolysis).


In vertebrates
these monomers
are moved
throughout body by
circulatory system.
As always…
exchange happens
between cells and
the interstitial fluid
that surrounds
them!
  Molecules come in 4 categories… do
  you remember them? (macromolecules)
• Carbohydrates
• Nucleic acids
• Proteins
• Lipids

  Their jobs are…
  Molecules come in 4 categories… do
  you remember them? (macromolecules)
• Carbohydrates    Energy storage (short, medium,
                    long) & structure
• Nucleic acids    Information storage, short term
                    energy storage (ATP)
• Proteins         Structure, enzymes, receptors,
                    signaling
• Lipids           Long term energy storage, barriers,
                    signaling
                                           The food pyramid and
                                           other dietary
                                           guidelines...
                           sparingly

     milk, yogurt,                                meat, poultry,
     cheese                                       fish, beans, eggs,
                                                  nuts
                 2–3 servings      2–3 servings
vegetables                                            fruits




       3–5 servings                       3–5 servings
     bread, cereal,
    rice,
    pasta
 6–11 servings
Fig. 31.1
... try to make
sure people are
getting the
essential
nutrients they
need but not to
many calories.
Nutrition Labels provide
important information like...

 Number of Calories per serving

       % of various
       macromolecules

    And % of some the the key
    vitamins and minerals
So how do animals process food?
        Four stages of digestion
• Ingestion
Ingestion in a python! (chew your food!)
        Four stages of digestion
• Ingestion
• Digestion (mechanical and chemical)
  – Mechanical allows more surface area for...
  – Chemical - the actual breakdown of polymers
    into monomers (this is hydrolysis!)
        Four stages of digestion
• Ingestion
• Digestion (mechanical and chemical)

• Absorption
  – Once digested into monomers and other
    nutrients you must absorb the molecules your
    body needs
        Four stages of digestion
• Ingestion
• Digestion (mechanical and chemical)

• Absorption
• Elimination - indigestible or unwanted
  material is eliminated from the digestive
  tract... nuff said
                                  Small
                                  molecules

              Pieces
              of food

                    Chemical digestion     Nutrient
    Mechanical      (enzymatic hydrolysis) molecules
    digestion                            enter body
                                         cells

      Food                                               Undigested
                                                         material


1 Ingestion      2 Digestion           3 Absorption    4 Elimination
In simple
animals
digestion occurs
in one large
cavity and there
is only one
opening
(meaning only
one meal at a
time)
These organisms
have no
specialized
regions for
different digestion
and rely on
diffusion to
spread nutrients
around
• Complete tracts allow specialization
• Food passes each region in order
• Multiple meals at once ok
The digestive
system must also
interact with other
systems to move
nutrients from the
site of digestion to
the site of need.
These organisms
use a circulatory
system to move
fluids throughout
the organism.

Although cells still
use diffusion over
short distance (the
local environment)
 The human
 digestive system
 has several
 specialized
 regions
Each one with a
specialized
function
                        We will look at several specialized
Mouth                   regions of the digestive tract in
                        humans including:
Esophagus

                        1. Mouth
                        2. Esophagus
            Stomach
                        3. Stomach
            Small
            intestine   4. Small & Large Intestine

            Large
            intestine

            Rectum
            Anus
            Salivary    We will also look at several
            glands
Mouth                   specialized “helper”
                        organs/structures:
Esophagus

                        1. Salivary glands

Gall-
                        2. Liver
bladder     Stomach
                        3. Pancreas
            Small
Liver       intestine   4. Gall bladder
 Pancreas   Large
            intestine

            Rectum
            Anus
    Tour of the Digestive system:
Start in the mouth
Fig. 31.8 Diagram of generalized vertebrate dentition
    Tour of the Digestive system:
Start in the mouth
• Lots of mechanical digestion (chewing)
• Add saliva – moisten/dissolve food
• Saliva includes amylase – what is this?
• Starts carbohydrate digestion
• What happens when you swallow?
   We us the same tube for
   breathing and eating at first
   (the pharynx).
  Food we swallow must pass
  over the opening to the
  trachea (the glottis)
A flap of tissue (the epiglottis)
covers the glottis as we
swallow to prevent choking.
                      food
                                pharynx




                             epiglottis


glottis                      esophagus

                             larynx




          (a) Before swallowing
                        epiglottis
                        (folds over)

                        food
                        (enters
                        esophagus)



                        larynx
                        (moves up)


(b) During swallowing
    Tour of the Digestive system:
Next stop is the esophagus
• Muscular tube that transports food to
  stomach
• What kind of muscle do you think?
Contraction of the
muscle lining (called
peristalsis!) pushes
food down the tube




      Figure 31.12 The
  esophagus and peristalsis
    Tour of the Digestive system:
Next stop is the stomach
                          More smooth muscle
                          causes stomach to
                          “churn” food (more
                          mechanical digestion)




• Food is converted to an acidic soup called
  chyme by the churning and the addition of
  gastric juice from cells that line the stomach
• Protein digestion starts here as enzymes
  secreted into the chyme start hydrolyzing
  the proteins you eat
    Tour of the Digestive system:
Next stop is the small intestine
• Controlled by a sphincter
• First part is called the duodenum
  – Mixes chyme with other secretions from:
  – Pancreas, Liver, Gall bladder and the intestine
    itself
Digestion in the Small Intestine
• The small intestine is the longest section
  of the digestive system
• It is the major organ of both chemical
  digestion and absorption
• Each class of macromolecule needs
  different digestive enzymes
Digestion takes place
 in several different
places depending on
the type of molecule.
                Carbohydrate digestion
               Polymers             Disaccharides
               (starch, glycogen)   (sucrose, lactose)
Oral cavity,
pharynx,           Salivary amylase                          For example:
esophagus
                Smaller polysaccharides,
                maltose
                                                             Carbohydrate
Stomach                                                    digestion starts in
                Polymers                                  the mouth, stops in
Lumen of
small
intestine
                   Pancreatic amylases
                                                         the stomach (why?)
                Maltose and other
                disaccharides                              then continues in
                       Disaccharidases
                                                          the small intestine.
Epithelium
of small
intestine
(brush
border)
                      Monosaccharides
   Absorption in the Small Intestine
• Has a huge surface area - Why?
• The enormous surface greatly increases
  the rate of nutrient absorption
• The sm. intestine also contains a large
  network of blood vessels and small
  lymphatic vessels
  The large blood flow allows
 your body to constantly flush
newly absorbed nutrients out of
 the intestine to the rest of the
              body.




                     Figure 31.14 The
                      small intestine
Absorption in the Large Intestine
• A major function of the colon is to recover
  water that has entered the alimentary canal
• Wastes of the digestive tract, the feces,
  become more solid as they move through
  the colon
• Feces pass through the rectum and exit via
  the anus
        Lactose Intolerance
• As humans age many lose the ability to
  digest the milk sugar lactose
• Lactose is a disaccharide formed from a
  glucose and a galactose
Symptoms of Lactose Intolerance
Present after a meal high in lactose:
• Lactose present in stool
• Diarrhea
• Abdominal pain and cramping
Questions about Lactose Intolerance
1. Where is lactose normally digested?
2. Why is lactose uncommon in the stool of
   people that are not intolerant – where does
   it go?
3. Diarrhea is a condition where excess water
   is mixed with undigested food. What part of
   the digestive system is normally
   responsible for removing excess water?
4. Pain and cramping can result from
   bacterial digestion of lactose – where are
   bacterial located in your digestive tract?
                Carbohydrate digestion
               Polysaccharides      Disaccharides
Oral cavity,
               (starch, glycogen)
                   Salivary amylase
                                    (sucrose, lactose)
                                                         • Lactose usually
pharynx,
esophagus
                Smaller polysaccharides,
                                                           digested in small
                maltose
                                                           intestine
Stomach
                                                         • If not it stays in &
                Polysaccharides
Lumen of           Pancreatic amylases
                                                           – Bacteria eat &
small
intestine
                Maltose and other                          – draws water…
                disaccharides



                       Disaccharidases
Epithelium
of small
intestine

                      Monosaccharides
 Incisors                        Natural selection has
                                 adapted the
                        Molars
 Canines
            Premolars            digestive system to
(a) Carnivore
                                 different diets

                                 But notice that the
                                 basic pattern of
(b) Herbivore                    teeth is the same –
                                 Homology!



(c) Omnivore
Fungi – the other chemoheterotrophs
• all fungi perform external digestion
• they secrete digestive enzymes into their
  surroundings and then absorb back into their
  bodies any organic molecules
• many fungi are able to break down the
  cellulose in wood
• some fungi are carnivores
  – for example, oyster fungus attracts nematode
    worms and then feeds upon them
• Fungal hyphae spread
  throughout their food
  source by growing
• The resulting mat is
  called a mycellium
• Because hyphae are so
  thin they have very
  large surface area
             Photoautotrphs
• Generate their own organic molecules from
  carbon dioxide & light energy
• Use photosynthesis to capture light energy
  and CO2 – this builds complex molecules
• Still need a source of nutrient atoms
Magnesium deficiency in a tomato plant
Nutrient         Source             Major function
Carbon       CO2 in              Build organic
             atmosphere          compounds
Oxygen       CO2 in              Build organic
             atmosphere          compounds
Hydrogen     H2O in soil         Build organic
                                 compounds
Nitrogen     Nitrogen            Build Proteins &
             compounds in soil   Nucleic acids
Phosphorus   Phosphate in soil Build nucleic acids &
                               phospholipids
Potassium    Potassium in soil Water balance,
                               stomatal opening
So a nutrition label
for a plant might look
like this.
With information on
amounts of
  • CD28020.GIF
commonly needed
nutrients.

Where is the
information on
calorie content?
 Where do plants get nutrients?
• Plant roots absorb water that has nutrients
  dissolved in it
• High surface area in the root helps absorb
• Plants can control what makes it into the
  stele.
root
hairs
                epidermis
root hair        cortex

               endodermis
               of cortex
                pericycle

                 xylem
                phloem




            vascular
            cylinder




             apical
            meristem
              root
              cap
• Plant root cross
  section
• Zoom in on the
  cylinder
  cortex


endodermis


  xylem


 phloem
• Endodermis is key
  region that controls
  access to the xylem
• Wax in the cell wall
  creates a barrier called
  the Casparian strip
• Forces fluid through
  endodermal cells
Absorption rates depend on
  surface area - so areas
adapted for high absorption
   • 30
 have high surface areas.
   • CD280931.JPG
   • Copyright Biological Photo Service
Some roots
are covered
with fungal
  hyphea.
                Mycorrhizal
                Fungi can
                drastically
                increase a plant
• CD28100.GIF   roots surface
                area and access
                to nutrients!

				
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posted:2/25/2013
language:English
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