Chp 10 Endocrine system Flashcards
Distinguish between endocrine and exocrine glands.
Endocrine glands are ductless and release hormones directly into the bloodstream, affecting target organs. Examples: thyroid, pituitary, adrenal glands.
Exocrine glands have ducts and release their secretions onto body surfaces or into cavities. Examples: sweat glands, salivary glands, and the digestive enzymes secreted by the pancreas.
Identify the major endocrine glands on a diagram or model.
glands include
Hypothalamus
Pituitary gland (anterior and posterior lobes)
Thyroid gland
Parathyroid glands
Pineal gland
Thymus
Adrenal glands (adrenal cortex and adrenal medulla)
Pancreas (endocrine and exocrine function)
Gonads (ovaries in females, testes in males)
Distinguish between neurotransmitters, paracrine signals, and hormones.
Neurotransmitters: Released by neurons into synapses to transmit signals to adjacent cells (e.g., dopamine, serotonin).
Paracrine signals: Local chemical messengers that act on nearby cells without entering the bloodstream (e.g., prostaglandins).
Hormones: Chemical messengers released by endocrine glands into the bloodstream to affect distant target organs (e.g., insulin, cortisol).
Explain the three negative-feedback mechanisms that control hormone secretion.
Hormonal control: A hormone triggers the release of another hormone (e.g., hypothalamus releasing hormones that stimulate the pituitary).
Neural control: The nervous system directly stimulates hormone secretion (e.g., adrenal medulla releasing epinephrine in response to stress).
Humoral control: Changes in blood levels of certain substances regulate hormone release (e.g., insulin released in response to increased blood glucose).
List the actions of hormones of the pituitary gland.
Anterior pituitary hormones:
Growth hormone (GH): Stimulates growth and cell division.
Thyroid-stimulating hormone (TSH): Stimulates thyroid hormone production.
Adrenocorticotropic hormone (ACTH): Stimulates adrenal cortex hormone release.
Follicle-stimulating hormone (FSH): Stimulates egg and sperm production.
Luteinizing hormone (LH): Triggers ovulation and testosterone production.
Prolactin (PRL): Stimulates milk production.
Posterior pituitary hormones:
Antidiuretic hormone (ADH): Promotes water retention in kidneys.
Oxytocin: Stimulates uterine contractions and milk ejection.
Describe the major pituitary gland disorders.
Hyposecretion of GH: Pituitary dwarfism (in childhood).
Hypersecretion of GH: Gigantism (in childhood), Acromegaly (in adulthood).
Hyposecretion or hypersecretion of TSH: Leads to secondary thyroid disorders.
Hyposecretion of ADH: Causes diabetes insipidus (excessive urination and thirst).
List the actions of thyroid hormones.
Thyroxine (T4) and Triiodothyronine (T3): Increase metabolism, protein synthesis, and neural activity.
Calcitonin: Lowers blood calcium levels by promoting calcium storage in bones and excretion by the kidneys.
Describe the major thyroid disorders.
Hyperthyroidism (Graves’ disease): Excess thyroid hormones leading to weight loss, rapid heartbeat, and bulging eyes.
Hypothyroidism:
In infants and children: Cretinism (stunted growth, intellectual disability).
In adults: Myxedema (fatigue, weight gain, cold intolerance).
Iodine deficiency: Causes simple goiter (enlarged thyroid).
List the actions of parathyroid hormone.
Parathyroid hormone (PTH):
Increases blood calcium levels by stimulating calcium release from bones.
Enhances calcium absorption in the intestines.
Reduces calcium excretion by the kidneys.
Activates vitamin D to help absorb calcium.
Describe the major parathyroid disorders.
Hyposecretion of PTH: Causes tetany, leading to muscle spasms and potential death.
Hypersecretion of PTH: Weakens bones, making them soft and prone to fractures.
List the actions of adrenal hormones.
Adrenal medulla hormones (fast response to stress):
Epinephrine and norepinephrine: Increase heart rate, blood pressure, and blood glucose for fight-or-flight response.
Adrenal cortex hormones (long-term stress response):
Mineralocorticoids (e.g., Aldosterone): Regulates sodium and potassium balance to control blood pressure.
Glucocorticoids (e.g., Cortisol): Helps in glucose production, reduces inflammation, and responds to chronic stress.
Androgens: Minor effects in males, but contribute to sex drive in females.
Describe the major adrenal disorders.
Hyposecretion of cortisol: Addison’s disease (fatigue, weight loss, low blood pressure).
Hypersecretion of cortisol: Cushing’s syndrome (weight gain, high blood sugar, weakened immunity).
List the actions of pancreatic hormones.
Glucagon (from alpha cells): Increases blood glucose by stimulating glycogen breakdown in the liver.
Insulin (from beta cells): Lowers blood glucose by promoting glucose uptake into cells.
Describe the major pancreatic disorders.
Hyposecretion of insulin or insulin resistance: Leads to diabetes mellitus (high blood sugar, excessive thirst, frequent urination).
Hypersecretion of insulin: May cause hypoglycemia (low blood sugar, dizziness, fainting).
