HUMAN SYSTEMS QUESTION 1993:               L. PETERSON/AP BIOLOGY

	Many physiological changes occur during exercise.

	(a)  Design a controlled experiment to test the hypothesis that an exercise 
	        session causes short-term increases in heart rate and breathing rate
	        in humans.

	(b)  Explain how at least three organ systems are affected by this increased
	        physical activity and discuss interactions among these systems.
  

  
  STANDARDS:
  
  This question was composed of two discrete parts.
       In part (a) students needed to demonstrate an undertanding of basic experimental
       protocol. A maximum of 6 points was set for this section to be determined from
       four protocol points, and single points for verification, understanding of a control,
       and the understanding of what short-term increase means in relation to exercise.
       In part (b) students were expected to utilize broader conceptual tehemes. Points were
       awarded for an effect that was clearly the result of exercise. Points were given for an
       interaction if the student demonstrated proper effects in each system under 
       consideration and a mechanism (how) to connect each system. (See model at the end
       of the standard list). A maximum of 6 points was set for this section.
  
  (a) Experiment                        (Maximum of 6 points)
  1 + 1 - How to measure heart rate (i.e. pulse rate) and/or breathing rate 
               (i.e. breaths/minute) 
  
  __ What exercise (mode, intensity, duration)
  __ When measured (before, during, after) or how long - time function
  __ Repeatibility - Verification (i.e. large group size, repeated test)
  __ Description of control vs. experimental group (2 groups only if variables controlled
        (or same subjects)
  __ Understanding of Short-term - return to homeostatic conditions.
  
   (b)  Discussion of at least three organ systems affected and their associated interactions
                                   (Maximum of 6 points)
  
  SYSTEM  EFFECT (one/system)      INTERACTIONS
  
  Muscular   Decrease intracellular ATP,        Effects of PCO2, H+ concentration,
             glycogen and O2 stores             PO2 on receptors in Medulla, Pons,
             Increase ATP, nutrient, O2         Aortic, Carotid bodies and  
             demands / use                      subsequent effects on circulatory
             Increase production CO2            and respiratory activity.
             Lactic acid                        Capillary beds dilated - muscles.
             Increased heat                     Capillary beds dilated - skin, heat                                     loss, etc.
 
 Respiratory    Increased gas exchange          Receptors (aortic, carotid, medulla,
                Tidal volume, ventilation,      pons, stretch).
                diffusion capacity              O2 to cells.
  
  Circulatory  Stroke volume increased       Blood travels faster/volume to     
               Flow rate increased           deliver O2 - nutrients.
               Cardiac output increased      Capillary beds to muscles dilate,
               Blood pressure increased      those to splanchnic, renal areas
                                             constricted.
                                             Capillary beds to skin dilate -
                                             heat loss.
  
  Nervous Medulla - Pons                Impulses sent to diaphragm -
            (pneumotaxic)               intercostal, etc.
          Stretch receptors             Sympathetic system stimulated.
          Increased neurotransmitters   Parasympathetic - return to
                                        homeostasis.
                                        Neuromuscular junction.
  
  Endocrine    Increased ACTH (ant pit)    Stimulates adrenal cortex
               Increased Adrenaline        -steroid production.
               (adrenal medulla)           Stimulates circulatory 
               Increased glucagon          (heart, caps, liver).
               (pancreas)                  Stimulates glycogenolysis - 
                                           liver.
  
  Excretory    Decreased urine output        Decreased blood flow to kidneys.
  
  Digestive    Increased rate of glycogenolysis   Provides fuel for activity.
               Blood diverted away from
               splanchnic renal areas
  
  Integument   Increased sweat/glow/flush         Capillary beds - heat loss - cooling.
  
  
   	System A			(How)		System B
	Valid effect	    ->	   carries O2 to muscle ->  Valid effect

i.e.   Stroke volume up		(etc.)		i.e. materials for muscular function
     Thus for a valid interaction an explanation needs proper effect in both systems.