bio 30 unit a2

Endocrine System

Body system that works with the nervous system to maintain homeostasis.

Hormone

Chemical messenger secreted into the bloodstream by endocrine glands.

Endocrine Glands

Ductless glands that release hormones directly into the blood.

Target Cell

A cell with receptors for a specific hormone.

Non-target Cell

A cell without the proper receptor for a hormone.

Tropic Hormone

A hormone that stimulates another gland to release hormones.

Non-tropic Hormone

A hormone that acts directly on target tissues.

Steroid Hormone

Lipid-based hormone that can pass through the cell membrane.

Non-steroid Hormone

Protein-based hormone that binds to receptors on the cell membrane.

Antagonistic Hormones

Hormones that have opposite effects.

Example of Antagonistic Hormones

Insulin and glucagon.

Positive Feedback

A process where the response increases the original stimulus.

Example of Positive Feedback

Oxytocin during childbirth.

Negative Feedback

A process where the response reduces the original stimulus.

Example of Negative Feedback

TSH and thyroxine regulation.

Hypothalamus

Brain region that links the nervous and endocrine systems.

Functions of the Hypothalamus

Produces ADH and oxytocin and releases hormones that control the pituitary gland.

GnRH

Gonadotropin-releasing hormone; stimulates release of FSH and LH.

Pituitary Gland

“Master gland” that controls many other endocrine glands.

ADH (Antidiuretic Hormone)

Helps the body conserve water by increasing water reabsorption in the kidneys.

When is ADH Released?

During dehydration when osmoreceptors shrink.

ADH Hyposecretion Disorder

Diabetes insipidus.

What is Diabetes Insipidus?

Inability to conserve water, causing large amounts of dilute urine.

TSH (Thyroid Stimulating Hormone)

Stimulates the thyroid gland to release thyroid hormones.

ACTH (Adrenocorticotropic Hormone)

Stimulates the adrenal cortex to release its hormones.

hGH (Human Growth Hormone)

Stimulates growth of bones, muscles, and organs.

hGH Hyposecretion

Dwarfism.

hGH Hypersecretion

Gigantism or acromegaly.

Prolactin

Stimulates milk production.

Oxytocin

Causes uterine contractions and milk letdown.

FSH (Follicle Stimulating Hormone)

Stimulates gamete production.

FSH in Females

Stimulates estrogen production.

LH (Luteinizing Hormone)

Stimulates ovulation and sex hormone production.

LH in Females

Triggers ovulation and progesterone production.

LH in Males

Stimulates testosterone production.

Thyroid Gland

Located in the neck below the larynx.

Thyroid Hormones

Thyroxine and calcitonin.

Thyroxine (T4)

Regulates metabolic rate by increasing cell respiration and glucose use.

Hyperthyroidism Disorder

Grave’s disease.

Hypothyroidism Disorders

Cretinism and goitre.

Calcitonin

Lowers blood calcium levels by promoting calcium deposition in bones.

Importance of Calcium

Needed for bones, muscles, nerves, and blood clotting.

Parathyroid Glands

Four small glands embedded in the thyroid gland.

PTH (Parathyroid Hormone)

Raises blood calcium levels.

PTH and Calcitonin

Antagonistic hormones.

How PTH Raises Blood Calcium

Stimulates calcium release from bones and reabsorption in the kidneys and GI tract.

Adrenal Glands

Glands located on top of each kidney.

Adrenal Cortex

Outer layer that produces aldosterone, cortisol, and sex hormones.

Adrenal Medulla

Inner layer that produces epinephrine.

Aldosterone

Increases sodium reabsorption and water retention.

Effect of Aldosterone

Increases blood pressure.

Aldosterone Hyposecretion Disorder

Addison’s disease.

Cortisol

Long-term stress hormone that reduces inflammation and increases blood glucose.

Epinephrine (Adrenaline)

Short-term stress hormone that triggers fight-or-flight.

Effect of Epinephrine

Increases blood glucose and blood flow to muscles.

Pancreas

Endocrine and exocrine gland below the stomach.

Islets of Langerhans

Pancreatic cell clusters that secrete insulin and glucagon.

Insulin

Lowers blood glucose levels.

How Insulin Lowers Blood Glucose

Helps cells take in glucose and stores glucose as glycogen in the liver.

Insulin Hyposecretion Disorder

Diabetes mellitus.

Glucagon

Raises blood glucose levels.

How Glucagon Raises Blood Glucose

Stimulates breakdown of glycogen into glucose in the liver.

Glucagon and Insulin

Antagonistic hormones.

Type I Diabetes Mellitus

Insulin-dependent diabetes caused by inability to produce insulin.

Type II Diabetes Mellitus

Occurs when body cells do not respond properly to insulin.

Type I Diabetes Treatments

Insulin injections, insulin pump, pancreas transplant, or islet transplantation.

Type II Diabetes Risk Factors

Obesity and lack of regular exercise.

Type II Diabetes Treatment

Diet, exercise, and medication.

Testosterone

Male sex hormone that promotes spermatogenesis and secondary sex characteristics.

Estrogen

Female sex hormone that promotes endometrium growth and secondary sex characteristics.

Progesterone

Maintains the endometrium and inhibits uterine contractions.

Master Gland

Pituitary gland.

Fight-or-Flight Hormone

Epinephrine.

Long-Term Stress Hormone

Cortisol.

Blood Calcium Lowering Hormone

Calcitonin.

Blood Calcium Raising Hormone

Parathyroid hormone (PTH).

Blood Glucose Lowering Hormone

Insulin.

Blood Glucose Raising Hormone

Glucagon.

Water Balance Hormone

ADH.

Hormone Responsible for Childbirth Contractions

Oxytocin.

Hormone Responsible for Milk Production

Prolactin.

Hormone Responsible for Ovulation

LH.

Hormone Responsible for Growth

hGH.

Hormone That Controls the Thyroid

TSH.

Hormone That Controls the Adrenal Cortex

ACTH.

What gland stores and releases ADH and oxytocin?

Posterior pituitary.

What gland produces ADH and oxytocin?

Hypothalamus.

What hormone causes sodium reabsorption in the kidneys?

Aldosterone.

What hormone increases metabolic rate?

Thyroxine (T4).

What hormone lowers blood calcium?

Calcitonin.

What hormone raises blood calcium?

Parathyroid hormone (PTH).

What hormone is released during dehydration?

ADH.

What hormone is responsible for milk ejection (letdown)?

Oxytocin.

What hormone is responsible for milk production?

Prolactin.

What hormone stimulates the thyroid gland?

TSH.

What hormone stimulates the adrenal cortex?

ACTH.

What hormone stimulates gamete production?

FSH.

What hormone triggers ovulation?

LH.

What hormone causes glycogen to be broken down into glucose?

Glucagon.

What hormone promotes glycogen formation?

Insulin.