Endocrine System (Chapters 16 Part A & B)

Describe the endocrine system.

It’s a network of glands that secrete hormones into the blood to regulate the metabolic function of other cells.

Define hormones.

They are chemical substances released by cells into extracellular fluids that travel through the blood to regulate the metabolic activity of target cells.

Explain how the endocrine system coordinates body functions.

It works with the nervous system to coordinate and integrate the activity of body cells by influencing metabolic activities via hormones transported in blood.

Compare the speed and duration of endocrine responses to nervous system responses.

Endocrine responses are slower but longer lasting than nervous system responses.

List the main functions controlled by the endocrine system.

Reproduction, growth, and development, maintenance of electrolyte/water/nutrient balance, and regulation of cellular metabolism and energy balance.

What are the two main chemical classifications of hormones based on solubility?

Water-soluble hormones and lipid-soluble hormones

Describe how water-soluble hormones act on cells.

They bind to plasma membrane receptors and cannot enter the cell.

Explain how lipid-soluble hormones act on cells.

They enter the cell and bind to intracellular receptors that directly activate genes.

Identify the three types of stimuli that trigger endocrine gland hormone release.

Humoral, neural, and hormonal stimulis

How do negative feedback systems control blood hormone levels?

Increased hormone effects on target organs can inhibit further hormone release, maintaining homeostasis.

Which hormones are secreted by the posterior pituitary?

Oxytocin and antidiuretic hormone (ADH).

What are the main effects of oxytocin?

It stimulates strong uterine contractions during childbirth and triggers milk ejection.

Describe the role of antidiuretic hormone (ADH) in the kidneys.

ADH targets kidney tubules to reabsorb water and prevent urine formation.

Explain why the posterior pituitary is not classified as a true endocrine gland.

Because it only stores and releases hormones produced by the hypothalamus.

List the six hormones produced by the anterior pituitary.

Growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL).

Define the primary function of growth hormone (GH).

It promotes growth by stimulating cells to enlarge and divide

How is the secretion of growth hormone (GH) regulated?

Growth hormone-releasing hormone (GHRH) and growth hormone-inhibiting hormone control how much GH is released.

Describe the effects of thyroid-stimulating hormone (TSH).

It stimulates thyroid gland development and the secretion of thyroid hormones.

What triggers the release of adrenocorticotropic hormone (ACTH)?

It’s triggered by corticotropin-releasing hormone (CRH)

Explain the functions of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

FSH stimulates gamete production, while LH promotes gonadal hormone production

"What is the primary function of prolactin?"

"Prolactin's primary function is to stimulate milk production in females."

"What condition arises from GH hypersecretion in children?"

"Gigantism results from GH hypersecretion in children."

"Define acromegaly."

"Acromegaly is GH hypersecretion in adults causing enlargement of hands, feet, and facial bones."

"What condition results from GH hyposecretion in children?"

"Pituitary dwarfism results from GH hyposecretion in children."

"Explain diabetes insipidus."

"Diabetes insipidus is caused by ADH deficiency from hypothalamic or posterior pituitary damage, leading to excessive urine output and dehydration risk."

"What are common symptoms of hyperprolactinemia?"

"Common symptoms of hyperprolactinemia include inappropriate lactation, absence of menses, infertility in females, and impotence in males."

"Identify the two main types of cells in the thyroid gland and their secretions."

"The two main types of cells in the thyroid gland are follicular cells, which secrete thyroid hormones (T3 and T4), and parafollicular cells, which secrete calcitonin."

"Describe the role of follicular cells in the thyroid gland."

"Follicular cells secrete thyroxine (T4) and triiodothyronine (T3)."

"Explain the primary functions of thyroid hormones T3 and T4."

"They increase basal metabolic rate, regulate tissue growth and development, and increase blood pressure, temperature, metabolism, and heart rate."

"How does calcitonin affect blood calcium levels?"

"Calcitonin lowers blood calcium by inhibiting osteoclast activity and promoting calcium uptake into bone."

"Define parathyroid hormone and its role in calcium regulation."

"Parathyroid hormone (parathormone) is secreted in response to low blood calcium; it raises blood calcium by stimulating osteoclasts, enhancing kidney calcium reabsorption, and promoting vitamin D activation."

"What causes the formation of a goiter?"

"A goiter is caused by iodine deficiency leading to low thyroid hormone levels, which increases TSH secretion and results in thyroid gland enlargement."

"List the symptoms of hypothyroidism in adults."

"Symptoms include myxedema, low metabolic rate, dry skin, puffy eyes, constipation, lethargy, and feeling chilled."

"Describe Graves’ disease and its symptoms."

"Graves’ disease is an autoimmune hyperthyroidism that causes elevated metabolic rate, sweating, rapid heartbeats, nervousness, weight loss, and possible exophthalmos."

"What is hyperparathyroidism and what are its effects on the body?"

"Hyperparathyroidism is caused by a parathyroid tumor leading to excess PTH, resulting in bone loss, kidney stones, nervous system depression, and fragile bones (osteitis fibrosa cystica)."

"Identify the two main parts of the adrenal gland."

"The adrenal gland consists of the adrenal cortex and the adrenal medulla."

"What are the three layers of the adrenal cortex and their associated hormone types?"

"The three layers are zona glomerulosa (mineralocorticoids), zona fasciculata (glucocorticoids), and zona reticularis (gonadocorticoids)."

"What is the main mineralocorticoid and its physiological effects?"

"Aldosterone is the main mineralocorticoid; it stimulates the kidney to reabsorb Na+, increasing blood volume and pressure, and excretes K+."

"Explain aldosteronism and its consequences."

"Aldosteronism is characterized by excess aldosterone secretion, causing hypertension, edema, and potassium depletion, which can lead to muscle and neuron dysfunction."

"What is the most abundant glucocorticoid and its effects on the body?"

"Cortisol is the most abundant glucocorticoid; it increases blood glucose, fatty acids, amino acids, and blood pressure."

"Describe the role of cortisol in Cushing’s syndrome."

"Cortisol hypersecretion in Cushing’s syndrome causes bone loss, immune suppression, inflammation inhibition, moon face, and buffalo hump obesity."

"Explain the hormones secreted by the adrenal medulla."

"The adrenal medulla secretes catecholamines, primarily epinephrine (80%) and norepinephrine (20%)."

"How do catecholamines from the adrenal medulla affect the body?"

"Catecholamines cause vasoconstriction, increased heart rate, increased blood glucose, and redirect blood flow to the brain, heart, and skeletal muscles."

"Define adrenal gonadocorticoids and their significance."

"Adrenal gonadocorticoids are weak androgens like androstenedione and DHEA, which contribute to puberty, sex drive in women, and serve as an estrogen source post-menopause."

"Identify the endocrine cells of the pancreas and their respective hormones."

"Alpha cells produce glucagon, while beta cells produce insulin."

"What is the function of glucagon in the body?"

"Glucagon raises blood glucose levels by stimulating glycogen breakdown and glucose release by the liver."

"How does insulin function in glucose regulation?"

"Insulin lowers blood glucose by facilitating cellular uptake and storage."

"Explain the causes of diabetes mellitus."

"Diabetes mellitus is caused by hyposecretion of insulin (Type 1) or hypoactivity of insulin (Type 2)."

"List the three cardinal signs of diabetes mellitus."

"The three cardinal signs are polyuria (excessive urination), polydipsia (excessive thirst), and polyphagia (excessive hunger)."

"What hormones are produced by the ovaries?"

"The ovaries produce estrogens and progesterone."

"Describe the roles of estrogens in females."

"Estrogens are responsible for the maturation of reproductive organs, the appearance of secondary sexual characteristics, breast development, and the regulation of the uterine cycle."

"Identify the hormone secreted by the testes."

"The testes secrete testosterone."

"What effects does testosterone have on the male body?"

"Testosterone initiates male reproductive organ maturation, development of male secondary sexual characteristics, sex drive, and sperm production."

"What hormones are secreted by the placenta?"

"The placenta secretes estrogens, progesterone, and human chorionic gonadotropin (hCG)."