Vertebrates... Organisms having a BACKBONE or SPINAL COLUMN.
                               they have a dorsal (along the back) set of nerves encased in bones
  
      members of phylum Chordata (which includes verts) are most complex animals on Earth
      some 50,000 species:  including amphibians, fishes, reptiles, birds, & humans, 
                        all with segmented spinal column & a distinct, well-differentiated head. 
                        vertebral column - a winning evolutionary design resulting in fastest runners,
                                                    highest fliers, deepest divers, most agile climbers,
                                                    and the best 150 students that ever lived...

 
'Chord'ates are characterized by a stiff (flexible) cord, notochord*, running dorsally.
             dorsal nerve cord - SPINAL CHORD - is a tube of nerve tissue, runs dorsal to notochord
  
       notochord - solid, flexible rod of cartilage,  provides internal support,
                                                                                runs from brain to tip of tail. 
            in some chordates, the  notochord  is replaced by a BONY vertebrate column... 
            making subphylum Vertebrata, a primary division of the phylum Chordata
  
       evolutionary innovations of CHORDATES:      
                           evolved 542-488 million years ago - basic body plan of most animal phyla established
               bilateral symmetry        repetition of parts on opposite sides of an axis
               cephalization                 presence of a head
               notochord & spinal cord  dorsal cords of cartilage & nerve tissue
               gill slits                         pair of opening through pharynx (vestigial in birds & mammals)
               tail                                present throughout life (vestigial in human embryos only)
               a fully lined body cavity thoracic and abdominal cavities
               a complete gut tube        coelom
               segmented development   in larva or embryo development myomeres flank notochord
                [Cambrian Explosion]             give rise to muscles & bones
  
    
          

the VERT members of chordate family have a number of similarities..... 

         all have same basic body plan & same sort of organs [liver, kidney, pancreas] including
              skeleton - with bony skull (cranium) surrounding brain    figure 49.26*
               jointed bones* - ball & socket, hinge, & pivot joints    
               vertebrate column around the dorsal nerve cord
               coelom... internal tube which runs from mouth to anus (digestive system)
                              lined with mesoderm cells.  usually there are 2 cavities: 
                                     a) thoracic cavity* -holds heart & lungs of verts
                                     b) abdominal cavity* -holds stomach, intestines, & liver   

  
      mammals... organism that maintain same body temperature regardless of environment,
                         have hair, and females that nurse their young.
      primates... vertebrate organisms with 5 grasping fingers/toes, eyes at front of head,
                        large brain, & fingernails instead of claws.
  
     model vertebrate might be ourselves - the human... , but
      
            some of our model human vertebrate's more unique characteristics include:
                 - humans have hair instead of scales & feathers, as in most verts,
                 - humans have a birthing process, instead of laying eggs,
                 - humans are  Endotherms...  warm blooded verts,      
                         - animals that regulates internal temperature at some constant value
                                  vs.  Ectotherms...  cold blooded verts,  
                         - many vert animals that use environmental energy to regulate temp
                                             [ i.e., snakes, lizards, amphibians, fish, etc...]   figure*
                 - humans have some 165 different kinds of cells in their body   [human histology]
  

  
    Major Vertebrate Tissues 
                   4 Fundamental tissues common to vertebrates: 

                                      Student Media Activity - Chapter 1d - match cell structure to function
 
       EPITHELIAL - sheets of tightly packed cells that line body cavities & organ surfaces
      -  prevents dehydration & permeability barrier (loss of H₂O)
      -  provide sensory surfaces & secretory layer ₂
     -  typed by cell SHAPE*:   squamous,  cuboidal,  columnar,  stratified  (pics)
 

    
   CONNECTIVE - mesodermal tissues that function to bind and support  pics
 
         Adipose tissue - fat cells, which pad & insulate body
   
        Blood - includes fluid matrix (not solid) for RBC & WBC's transport      (NHLBI)
                       ...plasma*  H₂O, salts, dissolved proteins
                       ...cells*     RBCs  &  WBC    (pictures = lymphocytes/leukocytes - macrophages & a clot)
 
        Cartilage* - strong, but flexible skeletal material at end of bones
                          - collagen & elastin fibers embedded in rubbery matrix chondroitin
 
        Bone - mineralized rigid connective tissue [NIH bone diseases site]
                          - collagen fibers embedded with Ca⁺salts for hardness
 
        Fibrous connective tissue - dense matrix of collagen fibers... 
                  forms   ...tendons - connects muscles to bone
                               ...ligaments - join bones to bones and together at joints
 
        Loose connective* - loose weave of fibrous proteins
                               ...binding & packing material holds organs & tissue in place
        

   
 Muscle & Nerve Tissue
   
    MUSCLE... contractile tissue derived from mesodermal origins
                      contains proteins actin & myosin = in filament (thread-like) form
                      multi-nucleate cells that assemble into fibers called myofibrils
  
         3 kinds:     a)  skeletal...  striated appearance in microscopy - voluntary control
                           b)  cardiac....  striated, but branched, in heart - involuntary control
            all*         c)  smooth....   in organ walls, non-striated - involuntary    micrographs   [chimp]

                                     role of skeletal muscles of the human body  
 
      
    NERVE...  tissues made of cells that conduct electrical impulses for communication
 
         2 kinds    a)  neurons* - electrically excitable cells of nervous system
                         b)  glial cells (astrocytes)-  non-conducting cells that
                                                 surround, support, insulate, & protect neurons
  
                                                                       summary figure of vertebrate tissues*
 

ORGANS - systems made of the 4 tissue  types above (& some others), 
                        which catalyze a physiological process (some specific function)

                 The eleven main vertebrate animal ORGAN SYSTEMS..... Table*

 VERTEBRATE  PHYSIOLOGY... study of vertebrate function often measures:
              Metabolic Rate - total energy used by organisms per unit time,
                                                          in doing biological work.

Animal Bioenergetics...                                        energy costs.... to do vertebrate physiology                                                                 to walk, run, swim, or just to be...

How to measure METABOLIC RATE [MR]...             measured in calories - amt of heat energy --> raise 1g H2O 1oC  [14.5o to 15.5o C]                       ?   minimal  Cal  -->  that required for basic functions of life                       ?   maximal Cal  -->  peak metabolic activity --> Olympic swimmer               linked to Krebs Cycle - MR is often determined by O2 consumption reported as  VO2max

VO2max 'stress' measuring equipment...                     respirometer*,    oxygen meters,    a cycle ergometer*,                 tread-mill* bike   or  swimming flume*  to measure VO2 max.

  
  Vertebrate Physiology  &  Metabolic Rates is...
  
     influenced by  variables  [which make up the science of Physiology]
                                    age,  sex,  body size,  temp,  food levels,  time of day,
                                    size of organism,  hormonal balance,  available O₂
  
    BMR - basal metabolic rate - calories used @ rest w/o stress by endotherms  
                    an animal that derives its body heat from its own metabolism 
                    ex : humans -     males    1,600 - 1,800 Kc/d
                                           females    1,300 - 1,500 Kc/d
                             Lance Armstrong - 6,500Kc/d & 10,000Kc/d for mountains
                                                                (3,500 cal = 1 pound body mass)
                                  his heart is 1/3 larger,
                                       @ rest = 32 bpm & @ max = 200 bpm w stroke volume of 200ml (2x avg)
    
    SMR - standard metabolic rate - ectotherms @ given temp
                      animal warms itself by absorbing heat from its surroundings

    HOMEOSTASIS...  How Animals regulate their internal environment
                                 ... maintenance of a steady state internal environment (constancy)
                                     in face of a changing external environment [ figure*]

        PHYSIOLOGICAL COMPENSATION...  short term physiological adjustments 
              or adaptations to environmental changes, i.e., homeostatic compensation

        Internal "Milieu" - (Claude Bernard - Fr. 1880's)... the interstitial fluids 
              filling spaces between cells exchanging nutrients with the blood are stable:
 
                          the Constancy of Human milieu
                                    pH of blood           7.4      +   0.1
                                    blood sugar            0.1%        [mg% - 100 mg/100ml blood]
                                    body temp            37^o C   +   1^o C

Homeostatic Regulation:
        we've observed the process, now let's look at
                                     the mechanisms that cells have evolved to maintain constancy
  
        a Homeostatic Regulator mechanism has 3 parts...      (example: a heating system)
                  receptor ....     detects a change...             thermometer
                  controller ...    processes info...                 thermostat responds 
                  effector .....    produces the response...    heater       (not unlike signal transduction)

  Examples of Homeostatic Regulation

        1.  Temperature         
                  Room temperature controllers - see model* -
 
                  How a body warms - heat transfers from warmer body --> cooler
     
                  hypothalmus regulates body temperature                  
                                            via homeostatic thermoregulation...    figure*
 

     2. pH regulation of the blood 
               pH 7.4  +  0.1      a shift of 0.4 pH unit = death
                 'Andromeda Strain' - virulent space microbe infects town's people...
                      - all die by blood clotting; growth curve of microbe = narrow pH range
                      - only 2 survived the microbe...  why? 
                                 a crying baby - blows off CO₂ - lowers blood acidity = alkalosis
                              & a drunk (Sterno) - bleeding stomach ulcers - favors = acidosis
   
         carbonic anhydrase
                             CO₂ + H₂O   <--CA-->   H₂CO₃    <--->   H⁺ + HCO₃^-     Fig 42.30*
 
              Hb pick up H⁺ ions...   buffering blood cell...
                               buffer: a substance, as HB & other proteins, that in solution tends to stabilize the
                                                       hydrogen-ion concentration by neutralizing, within limits, both acids and bases
                   if pH in blood cells drop [H+ ^] then carbonic anhydrase
                            HCO₃^-  +  H⁺ shifts ---> to   H₂CO₃  which dissociates & vice versa
                    

  
     3.  Calcium homeostasis   (in blood - normal range is 9 to 11 mg%)
              Ca⁺² is needed for nerve function, muscle contraction, blood clotting, etc. 
                      calcium regulation functions via antagonistic hormones*,
                      a common approach in homeostatic regulations
   
                                thyroid makes --> calcitonin hormone - lowers Ca levels
                                           causes Ca to be deposited into bone
                                           reduces intestinal absorption of Ca
                                           reduces Ca uptake by kidney
  
                                 parathyroid --> parathyroid hormone - raises Ca levels
                                          stimulates release Ca from bone
                                          increase Ca uptake by intestine & kidney       

   More examples of homeostatic regulations...

      4. Blood Glucose balance   (80-120mg/100ml)
                   pancreas makes insulin and glucagon, which are antagonistic hormones
                   (Am. Diabetes Assoc. & its diseases):               How glucose homeostasis works*        

       5. Osmoregulation - water balance of organism
                       osmosis - net movement of water...     hypotonic to hypertonic
  
                 terrestrial animals...
                       gain water from food & drink
                       lose water by urinating, defecating, & evaporation
                 aquatic animals...   (FW vs. SW)
                       osmoconformer*...  internal [solute] same as environment
                       osmoregulator.....    internal [solute] maintain constant level
                                                                                                    

Osmoregulation ...    fresh water fish   vs.   seawater fish  
  
              FW fish - internal [solutes] greater ... thus constantly GAINS water 
                                   thru its body surface, its gills, and food it eats
                         compensates - does not drink water
                         excretes large amounts dilute urine     (retains salts, excretes water)
                         regains most ions that are lost in urine [Na, Cl, K] via food & gills
  FIGURE*                                                                                                                                                      
              SW fish - often internal [solutes] less ... thus constantly LOSES water
                         compensates - drinks SW
                         urine very concentrated...   (retains water, excretes salts)
                         pumps ions gained via drinking [Na, Cl, K] out via gills                

   Other marine vertebrates -  birds  possess...  nasal gland*  to eliminate excess salts
                                                 sharks  possess...  rectal  gland* get rid of salts gained
              osmoregulation summary*
   next                                                                                     Key Concepts*