phosis IS: lecholamine, d. Calcitonin. romotes pregnancy by retaining the thick

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phosis IS: lecholamine, d. Calcitonin. romotes pregnancy by retaining the thick endometriu preventing menses is LH and a.FSH,b. ICSH, c. Estrogen, d. Progesterone. 39.The ovum is usually fertilized in the: a. Uterus,b. Cervix, c. Oviducts, d. Fundus. 40. Th brane immediately surrounding the embryo is the: e extraembryonic mem a. Amnion, b. Chorion, c. Allantois, d. Placenta. TRUE (T) or FALSE (F) e heart beat begins at the pacemaker, which is the AV Node. proteins which prevent atherosclerosis are the High Density Li 42. The lipo 43. Histamine increases inflammation and vasoconstri irds manifest double respiration while we mammals show single respiration. 45. Countercurrent exchange occurs both in gills and kidneys. 46. The diaphragm and external intercostals contract in forced expiration. he last bronchioles before the alveoli are the terminal bronchioles. 48. A vaccination is an example of passive immunity 49. Insects use both Malpighian tubules and the rectum to excrete dry uric acid. 50. The afferent arteriole exerts greater blood pressure than the efferent arteriole. 51. Most hormones work by negative feedback. 52. Insulin deficiency causes Diabetes Insipidus. 53. Sex attractants are called pheromones. 54. The common opening for the digestive, reproductive and excretory systems in many vertebrates is the vulva. 55. The extraembryonic membranes evolved to protect embryos against dehydration and are found in amniotes. FILL-INS 56. A brain inhibitory neurotransmitter is and an excitatory neurotransmitter is -57. The neuron's action potential occurs when it's while its refractory period occurs when it's 58. Saltatory conduction occurs in the of the 59. The intensifies your emotions while the helps you to remember. 50. The deepest part of the ocean is the and the shallowest is the

Explanation / Answer

41.

The given statement is false. Heart contains autorhythmic tissues that are composed of specialized noncontractile cardiac cells and include sinoatrial node (SA node), atrioventricular node (AV node), bundle of His and Purkinje fibers. The right atrial wall contains a small and specialized region located in at the opening of superior vena cava is called SA node. The SA node is also known as pacemaker and generates about 70 – 80 action potentials/min. A small bundle of specialized cardiac muscle cells found at the base of right atrium near the septum and above the junction of atria and ventricles is called the AV node. The AV node generates about 40 – 60 action potentials/min.

42. The given statement is True. High density lipoproteins remove fat from cells that export fat. Increased HDL levels in cells export more fat and remove fat deposition from cells and prevent atherosclerosis.

43.  The given statement is True. Histamine is produced during allergic response. Mast cells release the histamine that triggers the inflammation in the body. Usually histamine increases the permeability of blood vessels causing vasdopermeability. Histamine has 4 receptors called H1, H2, H3 and H4. Histamine binding H1 receptor innervating samooth muscle causes vasoconstriction.

44. The given statement is False. In mammals, the pulmonary capillary blood exposed to air on both the sides of intra-alveolar septum and this arrangement of blood capillaries is called single capillary system but the airflow in lungs is bidirectional. In birds, the lung volume is small and do not inflate and deflate but maintain a constant volume. The lungs are unidirectionally ventilated and the supporting air sacs inflate and deflate. Thus, unidirectional airflow enables to completely ventilate the birds' lungs and enable them to fly.

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