Chapter 11 Endocrine System

Hormones

Regulatory molecules secreted into the blood by endocrine glands.

Target Cells

Cells that must possess specific receptors for a hormone to elicit a response.

Synergistic Interaction

When hormone interactions work together to amplify the effect.

Antagonistic Interaction

When hormone interactions work against each other to balance effects.

Polar Hormones

Hormones that do not enter target cells but bind to plasma membrane receptors.

Nonpolar Hormones

Hormones that can pass through the plasma membrane and bind to intracellular receptors.

Steroid Hormone Action

Steroid hormones pass through the plasma membrane, bind to DNA, and stimulate genetic transcription.

Thyroxine (T4)

The major hormone secreted by the thyroid gland that regulates metabolism.

Cyclic AMP (cAMP)

A second messenger that is produced from ATP by adenylate cyclase; involved in hormone action.

Oxytocin

Hormone that stimulates contractions during birth and milk ejection during breastfeeding.

Antidiuretic Hormone (ADH)

Hormone that stimulates water retention by the kidneys, reducing urine output.

Cretinism

A condition of severely stunted physical and mental growth due to lack of thyroid hormones.

Grave’s Disease

An autoimmune disorder that causes overstimulation of the thyroid gland, leading to hyperthyroidism.

Parathyroid Hormone (PTH)

Hormone that increases blood calcium levels by acting on bones, kidneys, and intestines.

Insulin

Hormone secreted by beta cells of the pancreas that stimulates uptake of glucose from the blood.

Melatonin

Hormone secreted by the pineal gland that regulates circadian rhythms.

Feedback Inhibition

Mechanism where increased levels of hormones inhibit their own production.

Adrenocorticotropic Hormone (ACTH)

Hormone that stimulates the adrenal cortex to secrete glucocorticoids like cortisol.

Growth Hormone (GH)

Hormone that promotes growth and protein synthesis across various body tissues.

Thyroid Stimulating Hormone (TSH)

Hormone that stimulates the thyroid gland to secrete T3 and T4.

Follicle Stimulating Hormone (FSH)

Hormone that promotes gamete production in gonadal tissues.

Epinephrine (Adrenaline)

Hormone that functions as both a neurotransmitter and a hormone, involved in stress response.