Answer:
<u>b. first thoracic</u>
Explanation:
Sympathetic nervous system is<u> one of the divisions of the autonomic nervous system</u>. The other divisions are <u>parasympathetic nervous system</u> and <u>enteric nervous system</u>.
Autonomic nervous system is composed of <u>preganglionic neurons</u> and <u>postganglionic neurons.</u>
Similarly, the sympathetic nervous system is composed of postganglionic and preganglionic neurons.
The cell bodies of<u> preganglionic neurons of sympathetic nervous system is found in intermediolateral cell columns of spinal cord segments T-T12 and L1-2 or 3</u>. Therefore, sympathetic nervous system is also called <u>thoracolumbar division.</u>
The cell bodies of parasympathetic nervous system are found in the <u>brainstem nuclei which exit via cranial nerves 3, 7, 9, 10 and also in the sacral spinal cord segements S2-4</u>, therefore parasympathetic nervous system is also known as <u>craniosacral division.</u>
<u>QUESTION:</u>
<u>b. first thoracic</u>
<u>This is the correct answer choice as sympathetic nervous system cell bodies are found in intermediolateral cell column of T1-12 and L1-2 or 3 spinal cord segments. Hence, a sympathetic nerve is most likely to leave via first thoracic vertebra.</u>
<u>Third lumbar is less likely as sympathetic nervous system does not extend to this level in every individual.</u>
Barnacles belong to phylum Crustacea.
Answer:
A is the correct answer
Explanation:
the existed about 3.8to 4.0 billion years ago
Answer: A compound is a substance in which two or more elements are combined together chemically.
Explanation: Elements present in a compound are always in a fixed proportion and can be separated only by a chemical method. For example, water is a compound composed of hydrogen and oxygen atoms in the ratio of 2:1. The chemical formula of water is H2O.
