Coordination of Body Functions by Chemical Messengers

Adrenal medullae and the pituitary gland secrete their hormones primarily in response to chemical stimuli.

Neuroendocrine cells located in the hypothalamus secrete neurohormones that control the secretion of posterior pituitary hormones.

Endocrine hormones are carried by the lymphatic system to cells throughout the body.

Growth hormone causes growth in specific parts of the body, such as limbs only.

Insulin from the pancreas is essential for the body’s cells to use proteins for energy.

Neurotransmitters are released by dendrite terminals of neurons into the synaptic junctions.

Endocrine hormones are released into the extracellular fluid and influence the function of target cells at another location in the body.

Paracrines are secreted by cells into the bloodstream and affect neighboring target cells of a different type.

Autocrines are secreted by cells into the extracellular fluid and affect the function of different cells from the ones that produced them.

Cytokines can only function as endocrine hormones.