Tag: the human brain

The tissue of the brain and spinal cord, consisting mainly of nerve fibres with their myelin sheaths is the white matter, that transmit signals from one region of the cerebrum to another and between the cerebrum and lower brain centres. In contrast, the darker tissue of the brain and spinal cord, consisting mainly of nerve cell bodies and branching dendrites is the grey matter. The function of grey matter is to route sensory or motor stimuli to interneurons of the CNS in order to create a response to the stimulus through chemical synapse activity.
So, the correct answer is option C.

Based on the presence and absence of notochord animals are distinguished into chordates and non chordates. Nerve cord is ganglionated, double ventral and solid.

The sympathetic nervous system deals with the response to stress and danger, releasing epinephrines (adrenaline), and in general, increasing activity and metabolic rate. So, due to sympathetic stimulation, heart rate increases, to provide body more and more oxygen and nutrients.

Peristalsis of the intestines is the example of the action of the autonomous nervous system. The organs of our body (viscera), such as the heart, intestines and stomach, are regulated by a branch of the nervous system known as the autonomic nervous system. It consists of autonomic neurons that conduct impulses from the central nervous system (brain and/or spinal cord) to glands, smooth muscle and cardiac muscle. ANS neurons are responsible for regulating the secretions of certain glands (i.e., salivary glands) and the regulation of heart rate and peristalsis (contraction of smooth muscle in the digestive tract), among other functions. So, the correct answer is option D.