chapter 13 m&s

Endocrine system primary function

Produces hormones that work together to maintain homeostasis.

Homeostasis

Process through which the body maintains a constant internal environment.

Hormones

Chemical messengers that regulate activities of specific cells, organs, or both.

Pituitary gland (hypophysis)

Pea-sized gland divided into anterior and posterior lobes; hangs from a stalk below the hypothalamus.

ACTH

Adrenocorticotropic hormone; stimulates growth and secretions of the adrenal cortex.

FSH

Follicle-stimulating hormone; estrogen secretion in females and sperm production in males.

GH

Growth hormone (somatotropic); regulates growth.

LTH/Prolactin

Lactogenic hormone; stimulates and maintains breast milk secretion.

LH

Luteinizing hormone; ovulation in females, testosterone secretion in males.

MSH

Melanocyte-stimulating hormone; increases production of melanin.

TSH

Thyroid-stimulating hormone; stimulates thyroid hormone secretion.

ADH

Antidiuretic hormone; reduces water excretion via kidneys and helps control blood pressure.

Oxytocin

Stimulates uterine contractions during childbirth.

Pitocin

Synthetic oxytocin used to induce or speed labor.

Pineal gland

Very small gland in the central portion of the brain; also called pineal body.

Melatonin

Hormone that influences sleep–wake cycles (circadian rhythm).

Thyroid gland

Butterfly-shaped gland on either side of the larynx; regulates metabolism.

Thyroxine (T4)

Regulates metabolism.

Triiodothyronine (T3)

Regulates metabolism.

Calcitonin

Decreases calcium levels in blood; moves calcium into bones and teeth.

Parathyroid glands

Four small glands embedded in posterior surface of thyroid; regulate calcium levels.

Parathyroid hormone (PTH)

Regulates calcium in blood and tissues; works with calcitonin.

Thymus

Located near midline anterior thoracic cavity; secretes thymosin for immune system.

Thymosin

Stimulates maturation of lymphocytes into T cells.

Pancreas

Feather-shaped organ behind stomach; functions in digestive and endocrine systems.

Pancreatic islets

Endocrine parts of pancreas.

Glucagon

Hormone secreted by alpha cells; raises blood glucose.

Insulin

Hormone secreted by beta cells; lowers blood glucose.

Adrenal glands (suprarenals)

Located on top of kidneys; outer cortex and inner medulla.

Androgens

Sex hormones secreted by gonads, adrenal cortex, and fat cells.

Corticosteroids

Steroid hormones from adrenal cortex.

Aldosterone

Regulates electrolytes.

Cortisol

Corticosteroid with anti-inflammatory action.

Epinephrine

Adrenaline; stimulates sympathetic nervous system.

Norepinephrine

Hormone and neurohormone important for fight-or-flight response.

Gonads

Gamete-producing glands: ovaries in females, testicles in males.

Estrogen

Hormone secreted by ovaries; develops secondary sex characteristics.

Progesterone

Hormone released in second half of menstrual cycle.

Gonadotropin

Hormone that stimulates the gonads.

Androgens

Male sex hormones; include testosterone.

Testosterone

Steroid hormone secreted by testicles.

Leptin

Hormone from fat cells that regulates appetite; suppresses hunger.

Ghrelin

Hunger hormone; stimulates appetite.

Neurohormones

Produced by neurons, released into bloodstream; example: hypothalamus controlling pituitary.

Acromegaly

Abnormal enlargement of extremities due to excess GH after puberty.

Gigantism

Excessive growth from GH excess before puberty.

Hyperpituitarism

Overproduction of growth hormone.

Hypopituitarism

Insufficient production of growth hormone.

Pituitary adenoma

Slow-growing benign pituitary tumor.

Galactorrhea

Excess prolactin; spontaneous milk production.

Prolactinoma

Benign pituitary tumor causing infertility in women, erectile dysfunction in men.

Diabetes insipidus

Insufficient ADH production; unrelated to diabetes mellitus.

SIADH

Excess ADH production; often caused by cancer.

Pinealoma

Tumor of pineal gland; can cause insomnia.

Hypothyroidism

Underactive thyroid; low hormone production.

Hashimoto’s disease

Autoimmune thyroiditis causing hypothyroidism.

Cretinism

Congenital hypothyroidism.

Myxedema

Adult hypothyroidism; extreme deficiency.

Hyperthyroidism

Excess thyroid hormone; thyrotoxicosis.

Graves’ disease

Autoimmune hyperthyroidism.

Goiter

Enlargement of thyroid gland.

Exophthalmos

Abnormal protrusion of eyeballs.

Thyroid storm

Severe hyperthyroidism crisis.

Hyperparathyroidism

Excess parathyroid hormone; high calcium.

Hypoparathyroidism

Low or absent parathyroid hormone; low calcium.

Hypercalcemia

High blood calcium.

Hypocalcemia

Low blood calcium.

Myasthenia gravis

Abnormally large thymus; may include thymoma.

Insulinoma

Pancreatic tumor secreting excess insulin.

Pancreatitis

Inflammation of pancreas.

Hyperglycemia

High blood glucose; polydipsia, polyphagia, polyuria.

Hyperinsulinism

Excess insulin in blood.

Hypoglycemia

Low blood glucose.

Diabetes mellitus

Metabolic disorder causing hyperglycemia due to insulin issues.

Type 1 diabetes

Autoimmune destruction of pancreatic beta cells; insufficient insulin.

Type 2 diabetes

Insulin produced but body cannot use effectively.

Gestational diabetes

Diabetes onset during pregnancy; often resolves after delivery.

Diabetic coma

Stupor or coma caused by extreme blood glucose levels.

Diabetic ketoacidosis

Life-threatening acid buildup in blood due to diabetes.

Severe hypoglycemia

Insulin shock; very low blood glucose.

Diabetic retinopathy

Damage to blood vessels in eyes; may cause vision loss.

Addison’s disease

Adrenal glands produce insufficient cortisol or aldosterone.

Cushing’s syndrome

High cortisol levels from prolonged exposure.

Hypergonadism

Excess hormone secretion by gonads.

Hypogonadism

Deficient hormone secretion by gonads.

Gynecomastia

Excess male breast tissue from hormone imbalance.

RAIU

Radioactive iodine uptake test; measures thyroid function.

TSH assay

Measures thyroid-stimulating hormone in blood.

Thyroid scan

Nuclear medicine test to measure thyroid function.

FBS

Fasting blood sugar test; measures glucose after fasting.

OGTT

Oral glucose tolerance test; diagnoses type 2 or gestational diabetes.

CGM

Continuous glucose monitoring via sensor under the skin.

HbA1c

Blood test; average blood glucose over 3–4 months.

Fructosamine

Measures average blood glucose over previous 3 weeks.

HGH

Synthetic human growth hormone.

Hypophysectomy

Surgical removal of pituitary gland.

Antithyroid drugs

Slow thyroid hormone production.

RAI

Radioactive iodine treatment to destroy thyroid cells.

Lobectomy

Removal of one thyroid lobe.

Thyroid replacement therapy

Use of synthetic thyroid hormones (e.g., Synthroid).