SC+LEC+and+LAB_Chap10_PPT_Endocrine

Chapter Overview

  • Topic: Endocrine System

  • Source: Seeley’s ESSENTIALS OF ANATOMY & PHYSIOLOGY, Eleventh Edition

  • Authors: Cinnamon VanPutte, Jennifer Regan, Andrew Russo

  • Copyright: 2022 © McGraw Hill LLC

Characteristics of the Endocrine System

  • Composed of endocrine glands and specialized endocrine cells throughout the body.

  • Secretes hormones into the bloodstream (not via ducts).

  • Hormones travel to target tissues which have specific receptors for those hormones.

  • Hormones elicit specific physiological responses in target tissues.

Functions of the Endocrine System

  • Regulation of metabolism

  • Control of food intake and digestion

  • Modulation of tissue development

  • Regulation of ion levels (e.g., sodium, potassium)

  • Control of water balance

  • Influence on cardiovascular function

  • Regulation of blood glucose and nutrient levels

  • Control reproductive functions and processes

  • Stimulation of uterine contractions and milk release

  • Modulation of immune system function

Types of Hormones

  • Water-soluble Hormones:

    • Include proteins, peptides, and amino acids.

    • Most common examples: growth hormone, antidiuretic hormone, prolactin.

  • Lipid-soluble Hormones:

    • Include steroids and eicosanoids.

    • Examples: luteinizing hormone and androgens.

Hormone Receptors and Mechanisms of Action

  • Hormones bind to specific receptors based on their solubility:

  • Lipid-soluble hormones bind to nuclear receptors (can easily cross cell membranes).

  • Water-soluble hormones bind to membrane-bound receptors (cannot cross cell membranes).

The Pituitary Gland

  • Small gland in the brain controlled by the hypothalamus.

  • Divided into anterior and posterior regions.

  • Secretes at least six different hormones.

Anterior Pituitary Control

  • Synthesizes hormones under hypothalamic control.

  • Releasing hormones stimulate production and secretion of specific hormones.

  • Inhibiting hormones decrease secretion of specific anterior pituitary hormones.

Posterior Pituitary Function

  • Stores and releases hormones produced by hypothalamic neuroendocrine cells.

  • Main hormones: antidiuretic hormone (ADH) and oxytocin.

Anterior Pituitary Hormones

  • Growth Hormone (GH):

    • Target: most tissues.

    • Functions: stimulates growth of bones, muscles, organs.

    • Abnormalities: excess leads to giantism, deficiency leads to pituitary dwarfism.

  • Thyroid-Stimulating Hormone (TSH):

    • Target: thyroid gland.

    • Functions: regulates thyroid hormone secretion.

    • Abnormalities: excess causes goiter; deficiency causes thyroid shrinkage.

  • Luteinizing Hormone (LH):

    • Targets: ovaries (females) and testes (males).

    • Functions: promotes ovulation and progesterone production (females); stimulates sperm and testosterone production (males).

  • Follicle-Stimulating Hormone (FSH):

    • Targets: follicles in ovaries (females) and seminiferous tubules (males).

    • Functions: follicle maturation and estrogen secretion (females); sperm production (males).

  • Prolactin:

    • Targets: mammary glands, ovaries.

    • Functions: milk production.

  • Melanocyte-Stimulating Hormone (MSH):

    • Targets: skin melanocytes.

    • Functions: stimulates melanin production.

Posterior Pituitary Hormones

  • Antidiuretic Hormone (ADH):

    • Target: kidneys.

    • Functions: conserves water; deficiency can lead to diabetes insipidus.

  • Oxytocin:

    • Target: uterus.

    • Functions: increases uterine contractions during labor.

Thyroid Gland

  • One of the largest glands; requires iodine for function.

  • Thyroid Hormones: regulate metabolic rates and growth.

  • Calcitonin: reduces blood calcium levels when high.

Thyroid Hormone Disorders

  • Hypothyroidism: low metabolism, weight gain, fatigue, low temperature.

  • Hyperthyroidism: increased metabolism, weight loss, nervousness, high temperature, potential Graves' disease.

Parathyroid Gland

  • Produces parathyroid hormone (PTH).

  • Targets: bones and kidneys.

  • Functions: regulates blood calcium levels. Increased Ca2+ leads to osteoclast activity and reduced urine calcium loss.

Adrenal Glands

  • Located above each kidney, composed of medulla (inner) and cortex (outer).

Adrenal Medulla Hormones

  • Epinephrine (Adrenaline):

    • Target: heart, blood vessels, liver, fat cells.

    • Functions: involved in the fight-or-flight response.

Adrenal Cortex Hormones

  • Aldosterone:

    • Target: kidneys.

    • Functions: regulates ion balance, retains Na+ and water, secretes K+.

  • Cortisol:

    • Target: most tissues.

    • Functions: increases fat and protein breakdown for energy, reduces inflammation and immune response.

  • Androgens:

    • Target: most tissues.

    • Functions: secondary sexual characteristics in males, sex drive in females.

Pancreas

  • Mixed gland with exocrine (digestive enzymes) and endocrine (insulin, glucagon) functions.

  • Alpha cells secrete glucagon; beta cells secrete insulin; delta cells secrete somatostatin.

Insulin Functions

  • Regulates blood glucose levels post-meal by promoting glucose storage as glycogen.

  • Diabetes Mellitus:

  • Symptoms: hyperglycemia, intense thirst, fatigue, frequent urination.

  • Type I: insulin dependent; Type II: generally insulin independent, linked with obesity.

Glucagon Functions

  • Target: liver, stimulates glucose release when levels drop between meals.

Reproductive Hormones

  • Testosterone (from testes): supports sperm production and reproductive organ development.

  • Estrogen/Progesterone (from ovaries): involved in menstrual cycle and reproductive health.

Thymus Gland Hormone

  • Thymosin: promotes immune system development.

Pineal Gland Hormone

  • Melatonin: regulates circadian rhythms; influenced by light and impacts puberty onset.