Name (print)___________________________________

 T.A.’s name__________________________

1. PLEASE PRINT YOUR NAME and YOUR TA’S NAME ON EVERY PAGE.

 ONLY pages with names on them will be graded.

2. Read the questions carefully.

3. Most questions require only a brief and concise answer. Length of expected answer is positively correlated with number of points the question is worth --

---DO NOT write on the back of exam-answers on back of exam are NOT graded.

4. At the end of the exam, check to see that you have answered EVERY question.

5. If you have a question during the test, raise your hand and we will come to you.

• log ₁₀ 100 = 2
• log ₁₀ 10 = 1
• log ₁₀ 1 = 0
• log ₁₀ 0.1 = -1 

1. Based on the chart below, what 2 conclusions can be made about animals in phylum W and phylum Z?

• W and Z diverged along time ago--
  Z is more closely related to X and Y than to W
  W and Z would share only a few phenotypic or genotypic features
  they shared a common ancestor along time ago
  

 2. What is the osmolarity of the Ringer’s solution that you used during the dissection of the hornworm? (looking for a concept not a number) defend your answer.

1. (2 pts.)The osmolarity of the Ringer’s solution would be the same as the osmolarity of the animal--hornworm.
   (3 pts) If there was a big difference in osmolarity than the cells of the animal would either lose or gain water and the animal’s body would become distorted during the lab.
   

 3. Cell that we have studied that does NOT have a RMP ___nodal cell (SA , AV or purkinje)____________ (RMP=resting membrane potential)

 4. The following are two traces from the nerve-muscle lab. Why is the recording jagged at 3/sec but smooth at 25 / sec? Discuss what is happening within the cell.

1. ** see picture
   
   
   (5 pts) At 3/sec the rate of Calcium reuptake is almost as fast as Calcium release from the SR, so the muscle will briefly be in a state of relaxation before the next amount of calcium is released from SR. that is -- there will be a braief period of time when the TM will block the myosin binding sites on actin.
   (5pts) At 25/sec the rate of Calcium release fromthe SR exceeds the rate of Calcium reuptake back into the SR by the Ca pumps so there is always a high free calcium level in the cytosol which keeps the TM (via TN) from blocking the myosin binding sites on actin and the muscle will continue to go through cross-bridge cycling and generating force in a smooth sustained manner.
   

 5. The following are results from two identical experiment where frequency was held constant at 25/sec and the voltage slowly increased and decreased during the nerve-muscle lab. Why is amplitude (height) of recording B greater than recording A? Give a cellular explanation.

1. 
   *** see picture
   Recroding in graph B shows a greater force production at the same frequency of stimulation. If all other things are equal (as is stated in question) then the only possible explanation is the muscle that generated recording B is bigger than the muscle that generated recording A. A big muscle has more myofibrills/cell, more myosin (force generating molecule) and actin and is capcable of producing a greater force.
   [--as stated inclass most animals in a given species has the same number of motor units in a muscle so saying more motor units is not an acceptable answer because the voltage you used in this experiment is optimized to recruit all the motor units present ]
   
   

 6. What would be the consequence to skeletal muscle function if

1. all the troponin was removed (2pts)- (why?- 3 pts)
   no Tn--no regulation by calcium release! so muscle would never contract because even if calcium is released by the SR [via AP] there is no way to move the TM from its blocking postion.
   all the tropomysoin was removed?(2 pts) (why? --3 pts)
   
   Binding site on actin for myosin would always be exposed and muscle would be in a constant state of contraction. -- conctaction could not be regulated.
   

 7. If all the calcium was removed from the extracellular fluid, how would contraction be effected (explain your answer)

1. in skeletal muscle (4 pts)
   There would be NO change to contractions. All the calcium need to skeletal muscle contraction is conatained in the SR which is an intracellualr source.
   {also will accept, No neurotransmitter released by synaptic bouton of motor neuron-- no EPP generated-- no AP in muscle--- no contraction}
   
   in cardiac muscle (6 pts)
   Force of contraction would be greatly diminished because 80% of a calcium released from SR for a normal contraction is released by Caclium induced calcium release. Calcium for caclium induced calicum release is calcium from extracellualr space that enters the cell via V-gated Ca channels during the plateau of the AP.

 8. What causes (triggers) AP and what is duration (msec) of AP

1. ----in nerve
   nerve AP lasts 1-2 msec and is triggered by a graded potential (GP) [ which is a summation of both IPSPs and EPSPs] reaching a threshold value at the axon hillock of the neuron.
   
   ---in skeletal muscle
   AP lasts about 1-3 msec and is triggered by an EPP at the NMJ which is caused by release of neurotransmitter (Ach) from the motor neuron and opening of AChR channels.
   
   ---in contractile cell of left atrium
   
   AP lasts about 200 msec and is caused by flow of depolarization current through gap junction from neighboring cell.
    

9. What causes the semilunar valves to close?

1. When the ventricles relax during diastole the pressure in the ventricles falls to a valuethat is lower than the blood pressure in the aorta or pulmonary artery and the blood flows toward that low pressure region. The back flow of blood toward the low pressure ventricles is halted when the blood fills the semilunars and closes off the path.
   
   during which part of the EKG does this happen? __ T- wave__________________________

10. Describe the pressure in the left ventricule (use actual numbers) and what is causing these values

1. (5pts)---from the QRS to the beginning of the T wave?.
   The ventricles begin to contract soon after the QRS which causes the pressure in the Ventricles to rise sharply --which causes the AV valves to close. When the pressure exceeds the pressure in the arteries/aorta (80 mmHg) the blood will begin to flow out of the chambers. The ventricular contraction continues and the pressure rises to 120 mmHg. As we appproach the T-wave the ventricle begins to relax and the pressure falls due to the relaxation and the loss of blood from the chambers.
   
   (5 pts)----between T wave and next P wave?
   during this time the heart is relaxed (diastole) and the pressure in the ventricles will be very low but will increase slightly (10 mmHg) as blood fills the chambers
   

11. A blood clot forms in the veins of the right leg. Where will it get stuck and cause decreased blood flow to tissues? (just give a location)

1. arteries, arterioles or capillaries of the lung (depending on size of clot)
    

12. If the Na/K pump was blocked, what function would be lost in each of these tissues?

1. PCT (3pts)
   ThePCT would not be able to reabsorb 60% of the Na, glucose, (amino acids) --WATER!--
   
   Skeletal muscle (3 pts)
   no ion gradient-- no RMP---no AP---no muscle contraction
   
   cardiac muscle (list two functions lost) (4 pts)
   no ion gradient-- no RMP---no AP---no muscle contraction
   no sodium gradient-- no driving force for Na/Ca exchanger-- no decrease incytoplasmic Ca--no relaxation
   

13. Would you expect to find hemoglobin(or any respiratory pigment) in the hemolymph of the hornworm? defend your answer.

1. 
   You should not expect to find any hemoglobin because Hb carries oxygen (increases the oxygen carrying capacity of the blood) and in the hornworm the tracheal sytem delivers oxygen directly to the cell-- therefore the hemolymph does not function as a gas transport system.
   

14. What determines how much oxygen is in 100 ml of blood leaving the left ventricle?

1. (looking for two major factors).
   
   2 pts--the amount of hemoglobin in the 100ml of blood
   2pts.---the PO2 of the blood (which is the PO2 of the alveoli)
   ---------1 pt for PO2 of atmosphere (if you were holding your breath the PO2 of alveoli and atmosphere are different)
    

15. Three physiological variables that decrease the binding affinity of hemoglobin for oxygen.

1. select any three of these
   1. increased temperature
   2. increased PCO2
   3. increased hydrogen ions (more acidic, lower pH)
   4. decreased PO2
   5. Increased 2,3, DPG 

16. The cells in the respiratory center of the brain stem are sensitive to __hydrogen ion level

1. When this stimulus decreases the frequency of AP from these neurons ___decrease___
   Which will cause___decreased respiratory rate due to decreased excitation of diaphragm____
    

17. Draw a flow diagram that represents the basic function of the endocrine system.

1. (1 pt for each step) stimulus---sensor--integrator---release hormone to blood---target cell has a receptor---activates second messenger system in cell--- alters cell activity-- which should negate the original stimulus (negative feed back system)