chapter 16

Endocrine System

Produces hormones that regulate body functions and travel through the bloodstream to target tissues.

Hormones' Longevity

Hormones travel through the blood and remain active longer than nervous system signals.

Endocrine Glands

Ductless glands that produce hormones.

Factors Affecting Target Cell Activation

Amount of hormone, number of receptors, and strength of hormone-receptor bond.

Types of Hormone Release Stimuli

Humoral, neural, and hormonal stimuli.

Example of Humoral Stimulus

Low blood calcium causing release of parathyroid hormone.

Example of Neural Stimulus

Sympathetic nerves stimulate adrenal medulla release of catecholamines.

Example of Hormonal Stimulus

TSH stimulates the thyroid gland to release thyroxine.

Pituitary Gland Alternate Name

Hypophysis, also known as the master gland.

Hormonal Secretion by Pituitary

The pituitary gland secretes eight hormones.

Connection between Pituitary and Hypothalamus

The infundibulum connects the pituitary gland to the hypothalamus.

Posterior Pituitary Hormones

Oxytocin and ADH are stored and released by the posterior pituitary.

Functions of Oxytocin

Uterine contractions, orgasm, milk let-down, and bonding behaviors.

Function of ADH

ADH causes kidneys to reabsorb more water and produce concentrated urine.

Growth-Stimulating Hormone

Growth hormone (GH) stimulates growth and protein production.

Milk Production Hormone

Prolactin stimulates milk production.

TSH Function

TSH stimulates the thyroid gland to release thyroid hormones.

ACTH Function

ACTH stimulates the release of glucocorticoids and androgens from the adrenal cortex.

Gonadotropins

FSH and LH are the two gonadotropins.

FSH Function

FSH stimulates gamete production in males and females.

LH Function in Females

In females, LH matures follicles.

LH Function in Males

In males, LH stimulates testosterone release.

Thyroid Gland Location

The thyroid gland is located on the trachea, inferior to the larynx.

Largest Pure Endocrine Gland

The thyroid gland is the largest pure endocrine gland.

Thyroid Hormones

T3 (triiodothyronine) and T4 (thyroxine) are the two thyroid hormones.

Regulation by Thyroid Hormones

Thyroid hormones regulate basal metabolic rate, growth, and blood pressure.

Symptoms of Hypothyroidism

Low metabolism, cold intolerance, puffy eyes, lethargy, weight gain.

Symptoms of Hyperthyroidism

High metabolism, sweating, bulging eyes, nervousness, weight loss.

Hormone Lowering Blood Calcium Levels

Calcitonin lowers blood calcium levels.

Hormone Raising Blood Calcium Levels

Parathyroid hormone (PTH) raises blood calcium levels.

Actions of PTH

PTH breaks down bone, increases kidney calcium reabsorption, and increases intestinal calcium absorption.

Adrenal Medulla Hormones

The adrenal medulla releases epinephrine and norepinephrine.

Function of Aldosterone

Aldosterone maintains sodium balance and regulates salt.

Glucocorticoids Definition

Glucocorticoids are hormones that regulate metabolism, stress response, blood glucose, and blood pressure.

Adrenal Layer Producing Glucocorticoids

The zona fasciculata produces glucocorticoids.

Adrenal Layer Producing Weak Androgens

The zona reticularis produces weak androgens.

Hormone Raising Blood Glucose Levels

Glucagon raises blood glucose levels.

Pancreatic Cells Producing Glucagon

Alpha cells produce glucagon.

Hormone Lowering Blood Glucose Levels

Insulin lowers blood glucose levels.

Pancreatic Cells Producing Insulin

Beta cells produce insulin.

Type 1 Diabetes

Type 1 diabetes occurs when not enough insulin is produced.

Type 2 Diabetes

Type 2 diabetes occurs when insulin is made but doesn’t function properly.

Common Symptoms of Diabetes Mellitus

Sugar in urine, ketones in urine, weight loss, excessive urination, thirst, and hunger.

Hormone Produced by Pineal Gland

Melatonin is produced by the pineal gland.

Suppressor of Melatonin Production

Sunlight and blue light suppress melatonin production.

Function of Thymus

The thymus produces hormones needed for T-lymphocyte development.