Chapter 17 things I need to memorize pt 5

3 chemical classes

Steroids, Peptides, and Monoamines

• Derived from cholesterol

• Sex steroids and corticosteroids

Steroids

• Chains of amino acids

• Ex.: hormones from pituitary, hypothalamus, insulin

Peptides and glycoproteins

• Made from amino acids

• Catecholamines, melatonin, thyroid hormone

Monoamines

– Sympathetic N.S. stimulates adrenal medulla during stress

– In childbirth, stretch receptors stimulate release of oxytocin

Neural stimuli

– Releasing & inhibiting hormones from the hypothalamus

– TSH, ACTH, FSH, LH

Hormonal stimuli

– High blood glucose stimulates release of insulin

– Low blood calcium stimulates secretion of parathyroid hormone

Humoral stimuli

Refers to blood-borne stimul

Humoral stimuli

Most monoamines and peptides are

hydrophilic

Steroids and thyroid hormone are

Hydrophobic

Steroids and thyroid hormone bind to

Transport proteins

What does half-life mean?

The time it takes for a hormone’s concentration in the blood to decrease by half

Have longer half-life

Bound hydrophobic hormones

– Protected from liver enzymes and kidney filtration

Bound hydrophobic hormones

short half-life; 85% unbound, 15% binds weakly to albumin and others

Aldosterone

– Cannot penetrate target cell

– Bind to surface receptors and activate intracellular processes through second messengers

Peptide hormones

– Penetrate plasma membrane and bind to internal receptors (usually in nucleus)

– Influence expression of genes of target cell

– Take several hours to days to show effect due to lag for protein synthesis

Steroid hormones

Thyroid Hormone enters target cell by means of an

ATP dependent transport protein

means number of receptors is increased

– Sensitivity is increased

Up-regulation

reduces number of receptors

– Cell less sensitive to hormone

– Happens with long-term exposure to high hormone concentrations

Down-regulation

– Multiple hormones act together for greater effect

• Synergism between FSH and testosterone on sperm production

Synergistic effects

– One hormone enhances the target organ’s response to a

second later hormone

• Estrogen prepares uterus for action of progesterone

Permissive effects

– One hormone opposes the action of another

• Insulin lowers blood glucose and glycogen raises it

Antagonistic effects

Most hormones are taken up and degraded by _________ and ______________

Liver and Kidneys