Researchers have identified about substances that are made in our body and brain that act as neurotransmitters.\

Answer;

- 100

Researchers have identified about 100 substances that are made in our body and brain that act as neurotransmitters.

Explanation;

-Neurotransmitters are the chemicals which allow the transmission of signals from one neuron to the next across synapses. They are also found at the axon endings of motor neurons, where they stimulate the muscle fibers.

-Neurotransmitters enable neurotransmission, which is the process by which signaling molecules (neurotransmitters) are released by the axon terminal of a neuron (the presynaptic neuron), and bind to and activate the receptors on the dendrites of another neuron.

answer; /// i believe the correct answer is (thrombocytopenia); (a)

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.