Protein hormones cannot cross cell membranes and bind to surface receptor were they bind to surface receptor, a signal transduction to produce a chainreaction relays signal from outside. Were as steroid hormones are fat-soluble hormones that can cross cell membranes and bind to receptors inside target cell to turn specific genes on or off

What is the mane of the body part at number 6?  

Which chamber of the heart receives the deoxygenated blood from the systemic system first?

  In this diagram what is at number 1.

The adrenal glands are located deep inside the brain and secrete Growth hormone, follicle- stimulating hormone (FSH), and luteinizing hormone (LH)

  The structure at number 3 is?

How does negative feedback work?

When a neuron is at rest the voltage, that will need to be overcome to send the signal down the neuron is called?

Muscles usually have antagonistic muscle pairs were each muscle is paired with a muscle of the opposite effect, so one relaxes, one contracts.

The long thin tube extending from the neuron is called?