Endocrine System Overview

Anatomy & Physiology

Endocrine System Overview

Endocrine system works with nervous system to coordinate activities of body cells

Endocrine glands- ductless; make hormonesHormones influence metabolic activities

Exocrine glands- external secretions onto surface or other organ; sweat, mammary, lacrimal, salivary glands

Endocrine System Overview (continued)

Hormones: chemicals released into blood to regulate metabolic functions of body cells

Hormones can be circulating or local

Main Types of Hormones

Circulating Hormones:1. Amino acid based: most common 2. Steroids: made from cholesterol

Local Hormones1. Autocrines: affect cells that secrete them2. Paracrines: affect local and other cells

Control of Hormone Release Typically regulated by negative feedback system;

receptors (upregulated or down)

3 Stimuli that Release Hormones

1. Neural: nerve fibers stimulate hormone release 1. Fight-or-flight

2. Hormonal: release in response to hormones made by other endocrine organs

1. Chain of command (pg. 271)

3. Humoral: secrete in response to changing levels of nutrients in blood

1. glucagon

Major Endocrine Organs

Pituitary gland- “Vice president”; secretes 6 hormones from anterior; 2 posterior Includes: Growth Hormone (GH), PRO,

ACTH, TSH, FSH, LH; posterior: ADH and oxytocin

Thyroid gland- butterfly shaped; in neckThyroid hormone (TH)- body’s major metabolic

hormoneCalcitonin- regulates blood levels of calcium

Major Endocrine Organs (continued)

Parathyroid gland- found behind thyroid; Secretes parathyroid hormone (PTH)

Important in controlling blood Ca+ levels

Adrenal gland- pyramid shaped; top of kidneys A. cortex-makes corticosteroids including

gonadocorticoids (sex hormones) Androgens: testosterone and estrogens

A. Medulla: epinephrine & norepinephrine Pancreas- endocrine/exocrine gland

insulin and glucagon Regulate blood sugar

Major Endocrine Organs (continued)

Gonads(Ovaries or Testes- sex hormonesFemale: estrogens and progesteronesMale: testosterone

Pineal gland- pine cone-shaped; secretes melatonin (regulates sleep cycles)

Thymus- beneath sternum; shrinks from child to adulthood.Makes peptide hormones; T lymphocytes

Other Hormone-Producing Structures

GI tract, placenta, kidneys, skin, and adipose tissue can produce hormones Adipose & fatty tissue- leptin &

prostaglandinsKidneys- erythropoietin (EPO)