Hormone Release

What controls the blood levels of hormones

negative feedback systems

Can blood hormone levels vary or are they constant

They can vary within narrow, desirable range

What is hormone release triggers by

Endocrine gland stimuli or nervous system modulation

What are the want endocrine glands can be stimulated

Humoral, neural, and hormonal

Describe humoral endocrine glands stimulation

Changing blood levels of ions and nutrients stimulate secretion of hormones. For example, when Ca is low, PTH is secreted to activate osteoclasts

What is neural endocrine clang stimuli

Nerve fibers initiate hormone release. SNS fibers stimulate the adrenal medulla to secrete catecholamines

What are catecholamines

dopamine, norepinephrine, epinephrine

What is hormonal endocrine stimulation

When hormones stimulate the release of more hormones. For example - hypothalamic hormone stimulates anterior pituitary hormones

Can the nervous system modulate hormones

Yes, it can make adjustments to hormone levels. It can override normal endocrine controls

What is target cells specificity

The target cell of the hormone must have specific receptors to which the hormone will bind

What does target cells activation depend on

Blood levels of hormones, relative Number or receptors in the target cells, and strength of the binding between the receptor and hormone

What is upregulation

increase in receptor number in response to low concentration of hormone

What is downregulation

Decrease in receptor number in response to high concentration of hormone

How do hormones circulate

In blood either free or bound.

Steroids and thyroid hormone are on plasma proteins; all other are free

What are hormones removed by

Degrading enzymes, kidneys, or liver

What does half life depend on for hormones

If they are water or lipid soluble hormones

What are the ways that hormones can interact at target cells

Permissive, synergism, or antagonist

What is the permissive interaction at target cells

One hormone cannot act without another. For example, reproductive hormones need thryroid hormones

What is it called when more than one hormone produces the same effects on a target cells, causing amplification

synergism

When one or more hormones have opposite effects, this is known as

Antagonist