Question

In cardiac muscle, which of the following work to remove calcium from the intracellular fluid? Select one: a. Only the L-type Ca++ channel in the T tubules b. Only the Ca++ pump on the sarcoplasmic reticulum c. Only the Na+, Ca++ exchangers on the cell membrane d. Both the Ca+ pump and Ca++, Na+ exchanger.

Chronic stress in adolescents may result in decreased stature. Select one: True False

The presence of food in the stomach is a stimulus for acid secretion. Select one: True False

The name for a chemical, released by an immune cell which attracts other leukocytes to the area. Select one: a. interferons. b. opsonins. c. antigens. d. lysozymes. e. chemotaxins

A feed forward mechanism is an anticipatory response to stimulus. Select one: True False

Answer 1

1.In cardiac muscle, which of the following work to remove calcium from the intracellular fluid?

Answer -d.Both the Ca+ pump and Ca++, Na+ exchanger

Explanation-

In cardiac muscle,the L type of the Ca++ channel in T tubules allows the influx of calcium at the sarcolemma when action potential is at plateau .Then intracellular calcium interact with the troponin and then configurational chnage in troponin/tropomyosin occurs that results into actin myosin interaction and muscle contraction.In cardiac muscle,during the repolarisation phase the intracellular calcium decreases and therfore it get dissociated from the troponin and results into muscle relaxation.The process of muscle relaxation is ATP-dependent and the calcium get removed from the intracellular fluid via the sarcoplasmic Ca++ ATPase through the sarcolemmal Na+/Ca++ exchange.

2.Chronic stress in adolescents may result in decreased stature -True

Chronic stress interfers with the hypothalamic-pituitary gland-adrenocorticotropical system and responses from this system becomes reduced whcih cause the hormonal imbalance which delays the growth and causes decreased stature.

3.The presence of food in the stomach is a stimulus for acid secretion -True

The gastric acid secretion is stimulus dependent.The process of eating and food arrival to the stomach stimulates the gastric secretion and further enterogastric reflexes get stimulated by the presence of acid in small intestine and in stomach .

4.The name for a chemical, released by an immune cell which attracts other leukocytes to the area.- a. interferons

When infection occurs ,the chemical signal mediated by the interferons stimulate the macrophages near to the infection site at tissues.The chemical signal can be either complement peptides,cytokines and clotting system peptides.

5.A feed forward mechanism is an anticipatory response to stimulus. -True

The feedforward or anticipatory response gets generated in the areas of brain when the stimuli reflects that the food is about to be ingested.The feedforward reponses affects the digestion, thermoregulation and physical activities.