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Endocrine System

Endocrine System

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Endocrine System

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  1. Endocrine System

  2. Glands • Organs which secrete substances • Made of epithelial cells • 2 types • Exocrine glands: secrete materials into ducts • Endocrine glands (ductless): secrete materials called hormones into bloodstream

  3. Hormones • Released in bloodstream • Usually in low concentrations • Each type of hormone recognizes only a certain type of tissue to regulate • Target Tissue: hormone increases or decreases activity

  4. Hormones • Regulate • Metabolism • Homeostasis • Growth • Reproduction • The process that controls the level of hormones in the blood is called negative feedback

  5. Organisms must maintain homeostasis to survive in diverse environments. • Homeostasis is the maintenance of constant internal conditions.

  6. Homeostasis is the maintenance of constant internal conditions. • Homeostasis is usually maintained through negative feedback. • Negative feedback systems return a condition to its normal (set) point.

  7. Human Endocrine System • Hypersecretion: excess • Hyposecretion: not enough • Can cause a disorder

  8. Glands • Pituitary (master gland) • Controlled by hypothalamus • Location= base of brain • Secretes • Follicle stimulating hormone (FSH) • ACTH • Thyroid simulating hormone (TSH) • Growth Hormone (GH)

  9. FSH • Stimulates development of eggs in ovaries

  10. ACTH • Adrenocorticotropic hormone • Stimulates adrenal gland

  11. TSH • Stimulates production of thyroxin in thyroid gland • Controls metabolic processes

  12. GH • Affects growth of bones and metabolism of glucose • Disorders • Hypersecretion: giantism (enlarged bones) • Hyposecretion: dwarfism (reduced bones) 7 feet 8 inches (2.36 meters) 29.2 inches (73 centimeters)

  13. Thyroid Lack of iodine enlarges thyroid (goiter) • Location= neck • Secretes thyroxin • Regulates rate of metabolism • Needed for mental and physical development Hypersecretion: nervousness, weight loss Hyposecretion: cretinism (mental retardation), small size

  14. Parathyroid • Location: Embedded in back of thyroid • Secretes parathormone • Controls metabolism of calcium • Nerve and muscle functions Hyposecretion: brittle bones, clotting probelms

  15. Adrenal Gland • location: top of kidneys • Has outer cortex and inner medulla • Secretes • Adrenaline (epinephrine) which raises blood sugar levels, increases heartbeat, increases breathing rate • “Fight or flight” hormone • Hyposecretion: inability to deal with stress

  16. Adrenal Gland • Secretes • Norepinephrine • Same effects as adrenaline

  17. Islets of Langerhans • Location: pancreas • Secretion • Insulin: lets glucose enter cells and liver to be stored as glycogen (lowers blood glucose level in blood) • Hypersecretion: low blood sugar • Hyposecretion: diabetes (sugar in blood and urine)

  18. Islets of Langerhans • Secrete • Glucagon: enables conversion from glycogen to glucose (increases blood sugar) • Hypersecretion: high blood sugar

  19. Gonads (sex glands) • Male= testes • Produce testosterone • Responsible for development of secondary sex characteristics (deep voice, facial hair) • Female= ovaries • Produce estrogen • Responsible for secondary sex characteristics (broad hips, breast development) • Hyposecretion: reduction of secondary sex characteristics

  20. Nervous vs. Endocrine • Both forms of cellular communication