Skip to main content
뒤로

The Endocrine System - Anatomy & Physiology

컨트롤 버튼이 '내비게이션' 모드로 변경되었습니다.
1/25

이 집합의 용어 (25)

  • Difference between endocrine and exocrine glands
    Endocrine glands produce hormones released into the blood and are ductless. Exocrine glands produce non-hormonal substances like sweat and have ducts to carry secretions to membrane surfaces.
  • Three types of chemical messengers
    1. Hormones: long-distance signals traveling in blood or lymph. 2. Autocrines: act on the same cell that secretes them. 3. Paracrines: act locally on nearby cells.
  • Two main classes of hormones by chemical composition
    1. Amino acid-based hormones (water soluble): amino acid derivatives, peptides, proteins. 2. Steroids (lipid soluble): synthesized from cholesterol, including gonadal and adrenocortical hormones.
  • How do hormones affect target cells?
    Hormones alter cell activity by changing membrane permeability, stimulating enzyme/protein synthesis, activating/deactivating enzymes, inducing secretion, or stimulating mitosis.
  • Mechanism of action for water-soluble hormones
    Bind to plasma membrane receptors, activate G protein, which activates adenylate cyclase to convert ATP to cAMP, the second messenger that activates protein kinases.
  • Mechanism of action for lipid-soluble hormones
    Diffuse into target cells, bind intracellular receptors, receptor-hormone complex enters nucleus, binds DNA, initiates transcription and protein synthesis.
  • Three stimuli that control hormone release
    1. Humoral stimulus: changes in blood levels of ions/nutrients. 2. Neural stimulus: nerve fibers stimulate hormone release. 3. Hormonal stimulus: hormones stimulate other endocrine glands.
  • Factors affecting activation of target cells by hormones
    Blood hormone levels, number of receptors (up-regulation/down-regulation), and binding affinity between hormone and receptor.
  • Types of hormone interactions at target cells
    Permissiveness: one hormone needs another to act fully. Synergism: combined effect greater than alone. Antagonism: one hormone opposes another.
  • Role of hypothalamus in pituitary relationships
    Hypothalamus produces ADH and oxytocin transported to posterior pituitary for storage and release; secretes releasing/inhibiting hormones to anterior pituitary via portal system.
  • Negative vs positive feedback in hormone regulation
    Negative feedback reduces original stimulus to maintain balance. Positive feedback amplifies the stimulus, e.g., oxytocin during labor.
  • Function of oxytocin
    Stimulates uterine contractions during labor and milk ejection; promotes affection and well-being feelings.
  • Function of antidiuretic hormone (ADH)
    Reduces urine production and increases urine concentration by promoting water reabsorption in kidneys.
  • Hormones secreted by anterior pituitary
    Growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL).
  • Steps in thyroid hormone synthesis
    Follicular cells produce thyroglobulin; iodide oxidized to iodine; iodine attaches to thyroglobulin forming MIT and DIT; MIT and DIT combine to form T3 and T4; hormones released into blood.
  • Parathyroid hormone (PTH) functions
    Increases blood calcium by activating osteoclasts, enhancing kidney calcium reabsorption, and promoting vitamin D activation for intestinal calcium absorption.
  • Zones and hormones of adrenal cortex
    Zona glomerulosa: mineralocorticoids (aldosterone). Zona fasciculata: glucocorticoids (cortisol). Zona reticularis: gonadocorticoids (androgens).
  • Regulation and function of aldosterone
    Released in response to low blood pressure or high potassium; increases sodium retention and potassium excretion in kidneys, raising blood volume and pressure.
  • Metabolic effects of cortisol
    Promotes gluconeogenesis, glycogenolysis, fat mobilization, and protein catabolism to increase blood glucose and fuel availability.
  • Short-term stress response hormones and effects
    Sympathetic stimulation causes adrenal medulla to release epinephrine and norepinephrine, increasing heart rate, vasoconstriction, bronchodilation, and blood glucose.
  • Long-term stress response (HPA axis)
    Hypothalamus releases CRH → anterior pituitary releases ACTH → adrenal cortex releases cortisol and aldosterone, promoting energy mobilization and fluid retention.
  • Pancreas exocrine vs endocrine functions
    Exocrine: acinar cells secrete digestive enzymes into ducts. Endocrine: pancreatic islets produce glucagon (alpha cells) and insulin (beta cells).
  • Insulin effects on blood glucose
    Promotes glucose uptake by cells, glycogenesis, lipogenesis, protein synthesis, and inhibits glycogenolysis and gluconeogenesis; lowers blood glucose.
  • Glucagon effects on blood glucose
    Stimulates glycogenolysis, gluconeogenesis, and glucose release by the liver; raises blood glucose levels.
  • Role of thymus in endocrine system
    Releases thymic hormones that act as paracrines to facilitate T lymphocyte development for immune function.