Introduction to Section II - Creighton University



Biology 449 - Animal Physiology Fall 2008

Final Exam - Key

Fill in your scantron form as follows:

• Write and bubble in your name in the upper left (last name first).

• Sign your form in the upper right. By so doing you verify that you are abiding by Creighton’s policy on academic honesty.

Multiple choice: As always, choose the best answer for each multiple-choice question. Answer on your scantron form. Each question is worth 3 points.

1. Which of the following terms by itself best reflects what Claude Bernard termed the “internal environment”?

a. Blood alone

b. Cytosol

c. Extracellular fluid

d. Interstitial fluid alone

e. The air inside a room

2. If we say that the value of some aspect of an animal’s composition is physiologically regulated, we mean

a. the value changes with changes in the environment.

b. the value is actively changed by processes in the animal’s body.

c. the value doesn’t change because of a constant environment.

d. the value doesn’t change because of active processes in the animal’s body.

e. the value is incapable of change.

3. The parathyroid gland releases increasing levels of parathyroid hormone (PTH) in response to decreasing concentrations of Ca2+ in the blood. Increased PTH then leads to increased Ca2+ release from the bones into the blood (among other effects). In this system, the PTH is the

a. Afferent pathway

b. Effector

c. Efferent pathway

d. Integrating center

e. Sensor

4. If a cell membrane shows a change in potential that is in the negative direction, which of the following might have caused this change?

a. A decreased efflux of positive ions

b. An increased efflux of negative ions

c. A decreased efflux of negative ions

d. An increased influx of positive ions

e. Two of the above

5. During an action potential in a neuron, the opening of voltage-gated K+ channels

a. causes rapid depolarization of the membrane.

b. helps repolarize the membrane from its depolarized state.

c. brings the membrane back to resting potential after hyperpolarization.

d. marks the end of the refractory period.

e. Voltage-gated K+ channels do not open during action potentials.

6. Which of the following is not characteristic of metabotropic receptors on a postsynaptic neuron?

a. Slow onset of effects relative to ionotropic receptors

b. Long-lasting effects relative to ionotropic receptors

c. Potentially large number of channels opened or closed per receptor activated

d. The receptors are often associated with G-proteins.

e. All of the above are characteristic of metabotropic receptors.

7. Which of the following statements about postsynaptic potentials is true?

a. Postsynaptic potentials are an example of graded potentials.

b. One excitatory psp will never trigger an action potential, but two summed together always will.

c. An excitatory psp and an inhibitory psp will always exactly cancel each other out if they occur at the same time.

d. For a postsynaptic neuron with two presynaptic neurons, one presynaptic must be excitatory while the other is inhibitory.

e. It is not possible to have spatial summation and temporal summation occurring at the same time.

8. In the sensory system, a receptor that senses odors is an example of a

a. chemoreceptor.

b. mechanoreceptor.

c. nociceptor.

d. photoreceptor.

e. thermoreceptor.

9. An example of range fractionation in the mammalian sensory system is

a. taste receptors and odor receptors.

b. cutaneous temperature receptors and pressure receptors.

c. semicircular canals and otolith organs.

d. rod and cone photoreceptors.

e. vision and hearing.

10. Which of the following substances stimulates taste receptors by causing them to shrink?

a. Amino acids

b. Bitter compounds.

c. Hydrogen ions

d. Salt

e. Sugars

11. The sensory cells that release neurotransmitter in response to sound are known as

a. basilar cells.

b. Corti cells.

c. hair cells.

d. tympanic cells.

e. vestibular cells.

12. The vertebrate visual system is unusual in that

a. photons have to pass through several other layers of cells before reaching the photoreceptors.

b. photoreceptors are depolarized in the dark (unstimulated) and hyperpolarized in the light (stimulated).

c. the photoreceptors have photon-gated ion channels that respond directly to being hit by light.

d. Two of the above are true. (a and b)

e. All of the above are true.

13. Most hormones, particularly those released by the hypothalamus and pituitary, fall into what chemical class?

a. Amines.

b. Glycoproteins

c. Peptide hormones.

d. Prostaglandins.

e. Steroids.

14. A major function of cortisol, the stress hormone, is to

a. reduce anxiety.

b. increase appetite.

c. activate the immune system.

d. mobilize energy stores.

e. increase basal metabolic rate.

15. Which of the following cell types is found in the epiphyseal plates?

a. Chondrocytes

b. Osteoblasts

c. Osteoclasts

d. Two of the above

e. All of the above

16. Which of the following correctly lists the order of muscular components from largest to smallest?

a. muscle, sarcomere, myofiber, myofibril

b. muscle, myofiber, myofibril, sarcomere

c. sarcomere, myofibril, muscle, myofiber

d. myofibril, myofiber, sarcomere, muscle

e. muscle, myofibril, sarcomere, myofiber

17. The graph below shows the force produced by a muscle during an isometric twitch. Based on this graph, at what time after stimulation (which is at t = 0 ms) would this muscle start lifting a load of 3.0 N under isotonic conditions?

[pic]

a. t = 0 ms

b. t = 10 ms

c. t = 25 ms

d. t = 50 ms

e. t = 65 ms

18. In a living vertebrate, the motor units in a muscle are activated following a general rule to lift different amounts of weight. If the muscle is called on to lift progressively heavier weights, from very light to very heavy, the expected pattern of motor unit recruitment is

a. activate units with large numbers of slow oxidative fibers first, and units with small numbers of fast glycolytic fibers last.

b. activate units with small numbers of slow oxidative fibers first, and units with large numbers of fast glycolytic fibers last.

c. activate units with large numbers of fast glycolytic fibers first, and units with small numbers of slow oxidative fibers last.

d. activate units with small numbers of fast glycolytic fibers first, and units with large numbers of slow oxidative fibers last.

e. There is no set pattern to the activation of motor units.

19. During a normal heartbeat, the atrioventricular valves close when

a. pressure in the atria exceeds pressure in the ventricles due to ventricular relaxation.

b. pressure in the atria exceeds pressure in the ventricles due to atrial contraction.

c. pressure in the ventricles exceeds pressure in the atria due to atrial ejection of blood into the ventricle.

d. pressure in the ventricles exceeds pressure in the atria due to ventricular contraction.

e. the valve muscle contracts

20. During exercise, cardiac output may increase by five-fold. The main reason for this is

a. so that mean arterial pressure can increase by about five-fold.

b. so that mean arterial pressure can decrease by about five-fold.

c. total peripheral resistance has increased by about five-fold.

d. total peripheral resistance has decreased by about five-fold.

e. too many anabolic steroids.

21. Vasodilation can be triggered locally in tissues by the mechanism known as active hyperemia. Which of the following chemical messengers is involved in this response?

a. Acetylcholine

b. Epinephrine

c. Nitric oxide

d. Norepinephrine

e. Oxytocin

22. The main source of lymph is

a. fluid leaked from the capillaries.

b. fluid leaked from the arteries.

c. fluid leaked from the veins.

d. cytosol leaked from cells.

e. sweat reabsorbed through the skin.

23. For a person with an anatomical dead space of 250ml, a tidal volume of 750ml, and a ventilation frequency of 10 breaths/min, the alveolar ventilation rate would be

a. 75 ml/min

b. 2500 ml/min

c. 5000 ml/min

d. 7250 ml/min

e. 7500 ml/min

24. The oxygen affinity curve shown below is for hemoglobin. Based on this curve, about how much oxygen will be offloaded (in unites of %HbO2) from the hemoglobin if the PO2 at the lungs is normal and the blood arrives at tissues with a PO2 of 30 torr?

[pic]

a. 20%

b. 30%

c. 40%

d. 50%

e. 60%

25. One type of right-shift in an oxygen saturation curve is called a

a. Bohr shift.

b. Goldman shift.

c. Nernst shift.

d. Poiseuille shift.

e. Starling shift.

26. One type of peripheral chemoreceptor associated with ventilation responds to changing pH levels, rather than responding directly to a respiratory gas. The reason H+ levels are associated with changes in ventilation is

a. CO2 splits H2O into H+ and OH- when it dissolves in water.

b. CO2 combines with H2O to form H+ and HCO3- in the bloodstream.

c. O2 splits H2O into H+ and OH- when it dissolves in water.

d. O2 causes hemoglobin to shed a H+ when O2 binds to Hb.

e. O2 causes hemoglobin to shed a H+ when O2 is released from Hb.

27. Which of the following substances is not secreted by the stomach as either an exocrine or endocrine product?

a. Bile

b. Gastrin

c. Hydrochloric acid

d. Mucus

e. Pepsin(ogen)

28. Which of the following correctly describes what happens to most disaccharides entering the small intestine?

a. They are absorbed as disaccharides and enter the blood capillaries in the villi.

b. They are absorbed as disaccharides and enter the lymphatic lacteals in the villi.

c. They are split into monosaccharides by membrane-bound enzymes, absorbed, and enter the blood capillaries in the villi.

d. They are split into monosaccharides by membrane-bound enzymes, absorbed, and enter the lymphatic lacteals in the villi.

e. No disaccharides can be digested or absorbed in the small intestine.

29. All of the following cellular activities are promoted by insulin except

a. the storage of glycogen by the liver

b. the storage of glycogen by muscles.

c. the storage of fats by adipose tissue (fat cells).

d. the use of glucose as the major source of energy by most cells in the body.

e. the creation of glucose from amino acids.

30. An individual who is hyporesponsive to leptin would most likely

a. be underweight, have low levels of leptin in his blood, and have a weak appetite.

b. be underweight, have high levels of leptin in his blood, and have a weak appetite.

c. be overweight, have low levels of leptin in his blood, and have a strong appetite.

d. be overweight, have high levels of leptin in his blood, and have a strong appetite.

e. be overweight, have high levels of leptin in his blood, and have a weak appetite.

31. Which of the following statements about the loop of Henle is not true?

a. It maintains the concentration gradient in the renal medulla.

b. Urine increases in concentration as it descends through the tubule, and decreases in concentration as it ascends the other side.

c. The descending loop is permeable to water but not salt.

d. The thin ascending limb is permeable to NaCl but not water.

e. The thick ascending limb actively transports NaCl into the nephron.

32. The direct cause of increased release of atrial natriuretic factor is

a. increased blood Na+ concentration.

b. decreased blood Na+ concentration.

c. increased blood osmolarity.

d. decreased blood osmolarity.

e. increased stretching of the atrial muscle.

33. The juxtaglomerular apparatus of the kidney releases

a. aldosterone.

b. angiotensinogen.

c. angiotensin converting enzyme.

d. renin.

e. vasopressin.

34. In men, sperm develop from spermatocytes into mature spermatozoa

a. in about two hours, and complete maturation in the seminiferous tubules.

b. in about two days, and complete maturation in the seminiferous tubules.

c. in about two months, and complete maturation in the seminiferous tubules.

d. in about two days, and complete maturation in the epididymis.

e. in about two months, and complete maturation in the epididymis.

35. In men, the arterioles serving the erectile tissue of the penis differ from most other systemic arterioles in that

a. they are compressed by the process of erection.

b. they carry deoxygenated blood.

c. they are part of a portal system.

d. they have parasympathetic innervation.

e. they have one-way valves.

36. The bulk of the material that forms the semen is produced by the

a. bulbourethral gland.

b. prostate gland.

c. seminal vesicles.

d. testes.

e. urethra.

37. In women, oocytes complete meiosis (i.e. reach the end of meiosis II)

a. before birth.

b. during puberty.

c. about day 1 of the menstrual cycle.

d. about day 14 of the menstrual cycle.

e. when fertilization occurs.

38. The corpus luteum secretes which of the following hormones?

a. Estrogen.

b. Progesterone

c. Inhibin

d. Two of the above.

e. All of the above.

39. Menstruation itself occurs during what part of the standard menstrual cycle?

a. Days 1 through 5

b. Days 10 through 14

c. Days 15 through 20

d. Days 21 through 25

e. Days 23 through 28

40. The portion of the uterus that proliferates and dies off during each menstrual cycle is the

a. cervix.

b. endometrium.

c. fimbrae.

d. myometrium.

e. oviduct.

Short answer:

Write a concise answer to each question. Your answers should fit in the spaces provided. Diagrams may be used but must be accompanied by sufficient explanation to make the components clear. Each question is worth 8 points.

41. For each of the following scenarios, indicate which way water and any solutes would move (if at all), and provide a brief (one or two sentence) explanation as to why. All scenarios feature two volumes of water or water-based solution, A and B, separated by a membrane.

|Case |            A             |            B             |                Membrane                 |

|a |Water only |1.0 M glucose |Permeable to water only |

Result:

Water would move from A to B, drawn by the difference in osmotic concentration.

|Case |            A             |            B             |                Membrane                 |

|b |1.0 M glucose |1.0 M sucrose |Permeable to water and glucose only |

Result:

Glucose would move from A to B, down its concentration gradient (since there is no glucose on side B). This would change the osmotic gradient from isosmotic to hyperosmotic on side B, so water would then move from A to B.

|Case |            A             |            B             |                Membrane                 |

|c |1.0 M sucrose |Same as A |Freely permeable to water and glucose only. Sucrose is |

| |1.0 M glucose | |actively transported from B to A. |

| |(i.e. 1.0 mole of each per | | |

| |liter of water) | | |

Result:

The active transport of sucrose from B to A would cause A to become hyperosmotic, so water would then move from B to A. As water leaves B, the glucose on that side becomes more concentrated, so the glucose too would begin moving from B to A, down its concentration gradient. [This is analogous to the pattern in the proximal tubule of the nephron witn NaCl, water, and urea.]

42. Describe the process of action potential propagation in a myelinated axon.

A myelinated axon consists of relatively long stretches wrapped in glial cells that serve as an insulator, alternating with short uncovered regions known as nodes of Ranvier. AP’s can occur at the nodes but not the myelinated regions. When an initial region of the axon experiences an AP, the depolarization that occurs spreads to adjacent regions of the membrane. The magnitude of the depolarization decreases with distance, but spreads much further in the myelinated axon than it would in an unmyelinated axon (i.e. the myelin provides better cable properties). The depolarization spreads far enough to bring the axon at the next node above threshold, triggering an AP there, which then depolarizes the membrane along to the next node, etc. The refractory period keeps the AP’s from moving back they way they came. The resulting AP’s appear to “jump” from one node to the next, hence the name saltatory conduction. The rate of propagation is much higher than in an unmyelinated axon.

43. Complete the following table for the hypothalamic-pituitary system by filling in the blanks with the appropriate hormones. Be sure to provide the full name of each hormone, not the abbreviation. (You may, however, use “h.” for “hormone.”)

| | | | |Target Organ or Tissue |

|Hypothalamus | |Anterior Pituitary | |and Effects |

|Thyrotropin releasing h. |→ |Thyroid stimulating h. |→ |Thyroid hormone |

| | | | |T3/T4 release |

|Prolaction releasing h. or |→ |Prolactin |→ |Breasts |

|TRH | | | |Development, milk production |

|Corticotropin releasing h. |→ |Adrenocorticotropic h. |→ |Adrenal cortex |

| |→ | | |Cortisol release |

|Growth h. releasing h. |→ |Growth h. |→ |General body tissues |

| | | | |Growth and repair |

| | | |( |Liver |

| | | | |IGF-1 release |

44. Explain how the release of Ca2+ from the sarcoplasmic reticulum controls cross-bridge cycling in muscles.

The thin filaments of the myofibrils have wrapped around them a strand-like protein called tropomyosin, which blocks the binding sites for myosin on the actin when the muscle is at rest. The position of tropomyosin is controlled by another molecule, troponin, which is bound to both the tropomyosin and the actin. When Ca2+ is released from the SR, it diffuses into the myofibrils and binds to the troponin, causing it to change conformation and move the tropomyosin away from the myosin binding sites. Cross-bridge cycling can then occur. When the SR stops releasing Ca2+ and levels decline again, the process reverses, ending contraction.

45. These two questions relate to electrical activity in the human heart:

a. Where are action potentials in the heart initiated, and what pattern and pathway do they follow as they spread through the heart?

AP’s are iniated myogenically by the pacemaker cells in the sinoatrial node, located atop the right atrium. From here they spread throughout the atrial muscles via the gap junctions that electrically connect the myocardium. They do not reach the venricular muscle directly, however. Instead the AP’s reach the atrioventricular node (which also includes secondary pacemaker cells), where a delay of about 1/10 second is introduced before the AP’s are passed to the bundle of His, which carries them down he ventricular septum to the Purkinje fibers, which then transmit them to the ventricular myocardium. AP’s then spread through the ventricle.

b. What extrinsic (external) factors control the rate of the heart’s beating?

Sympathetic nervous system activity increases heart rate, while parasympathetic activity decreases it. The hormone epinephrine can also increase heart rate.

46. In the figures below, draw in the general patterns for the changes in pressure in the intrapleural fluid and the alveoli during ventilation in a resting person. Indicate the approximate values for your curves on the Y axis.

The intrapleural pressure drops from about -4 to -6 torr from the start to the end of inhalation; the pattern then reverses during exhalation.

Alveolar pressure is zero just before inhalation begins; it then drops to -1 torr during mid-inhalation, returning to zero as inhalation ends. During exhalation, the pressure climbs to +1 torr at mid exhalation, then drops to zero again as exhalation ends.

47. Diagram or describe the control of the exocrine functions of the pancreas by two different hormones, including any feedback loops. (Exocrine functions are those that involve secretion of substances into the GI tract rather than the secretion of hormones into the blood.)

One hormone controlling the pancreas is secretin. In response to low pH in the small intestinal lumen, the SI releases secretin. One of its effects is to promote the release of bicarbonate from the pancreas, which helps to neutralize the acid and thus regulate intestinal pH.

The other hormone we discussed in cholecystokinin. CCK is released in response to the presence of fats and proteins in the SI. It triggers the release of digestive enzymes (lipases, proteases and amylases) from the pancreas. These enzymes help the digestion and absorption of the nutrients in the SI, thus helping eliminate the stimulus for CCK release.

48. Diagram or describe the pathways and feedback loop associated with anti-diuretic hormone. Provide a clear explanation of the effects of ADH on the kidney.

Low levels of water in the extracellular fluid cause an increase in osmolarity as well as a drop in blood pressure (due to low blood volume). The high osmolarity is sensed directly by the hypothalamus, while the BP is sensed by carotid baroreceptors that pass information to the hypothalamus. In response, the hypothalamus triggers the release of ADH from the posterior pituitary. ADH can cause vasoconstriction (which will improve BP), but its main effect is to cause an increase in the permeability of the collecting ducts (by causing the insertion of aquaporins into the epithelial membranes), which causes more water to be reabsorbed from the urine. This helps reduce further water loss, helping to counteract the low body water. (The hypothalamus also promotes increased thirst, with drinking directly improving body water levels.)

49. Diagram or describe the hormonal pathways that promote spermatogenesis in men, including any feedback loops. You do not need to describe the process of spermatogenesis itself.

The hypothalamus releases gonadotropin releasing hormone, which promotes release of follicle stimulating hormone and luteinizing hormone from the anterior pituitary. The LH promotes the release of testosterone by the Leydig cells. This testosterone, along with the FSH, promotes the Sertoli cells to promote spermatogenesis by the spermatogonia and also to release inhibin. Levels of the hormones are controlled by the fact that increasing levels of testosterone tend to decrease the release of GnRH and LH, while increasing inhibin decreases the release of FSH.

50. On the graph below, draw in lines representing the approximate levels of estrogen and luteinizing hormone during the follicular phase of the human menstrual cycle. Also, either on the graph or in the space below, indicate what events are occurring in the ovary during this period and on what day(s) they are occurring. You do not need to diagram any hormonal pathways or feedback loops.

Estrogen levels are very low at Day 1 and stay low until about Day 5, when then begin to rise, and do so at an increasing rate. At Day 11 or so they rise rapidly (due to the positive feedback loop), peaking for a day or two before dropping somewhat just before Day 14.

LH levels are low on Day 1 but are rising, and continue to rise for a few days to a moderate level. At this point they start to fall slightly for the next week or so before rising very rapidly starting at about Day 11 to a peak at day 14 (due to the positive feedback loop).

The ovary contains many immature follicles, each consisting of an oocyte surrounded by granulosa cells. On Day 1 about one to two dozen follicles begin developing. This means that the granulosa cells begin proliferating, with some differentiating to theca cells a few days later. Around Day 7, all but one follicle (the dominant follicle) die off. The oocyte in the remaining follicle continues maturing until it is ready to be released; this occurs on Day 14 as ovulation.

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