Endocrine and the nervous system

Question 1

Explain what is meant by a classic endocrine response:

Answer 1

• Classic endocrine- secreted by one cell and diffused to a distant target cell
o Largest group of chemical signals
o Control long term homeostatic processes such as growth & reproduction

Question 2

Explain what is meant by paracrines:

Answer 2

• Paracrines- secreted by one cell and move to a nearby target cell
o Released in the damaged tissue by mast cells, causes the inflammatory response associated with injury
o Growth factors, e.g. nerve growth factors (NGF- promotes survival/growth of nerve cells); epidermal growth factor (EGF- stimulates cell division); vascular endothelial growth factor (VEGF- stimulates growth and branching of blood vessels)

Question 3

Explain what is meant by autocrines:

Answer 3

• Autocrines- similar to paracrines, except for they bind to receptors (and exert their effects) on the same cell that secreted them

Question 4

Explain what is meant by cytokines:

Answer 4

• Cytokines- secreted by a cell and then either act locally and/or diffuse to neighbouring target cell and/or transported to distant cells
o Interleukins and interferons, groups of small proteins released from white blood cells as part of the immune response

Question 5

What is meant by the term neurotransmitters:

Answer 5

• Neurotransmitters- released into the ISC secreted from the neurons at the axon terminal, then binds to target cell; this form of communication sometimes called synaptic signalling, due to synapse junction between the cells.
o E.g. acetylcholine (ACh), involved in triggering contraction of skeletal muscle

Question 6

What is meant by the term neurohormones:

Answer 6

• Neurohormones- hormones secreted by neurons (neurosecretory cells) but which diffuse into blood for transport to target cells, eg, vasopression (or ADH) from posterior pituitary gland