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The Endocrine System. Hormones. Chemical substances secreted by endocrine (ductless) glands. These chemicals are carried by blood to their respective target cells. Tend to control slow long-term activities in the body. What would be a slow long-term process?. Primary Functions of Hormones.

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The Endocrine System

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The endocrine system

The Endocrine System



Chemical substances secreted by endocrine (ductless) glands. These chemicals are carried by blood to their respective target cells.

Tend to control slow long-term activities in the body.

What would be a slow long-term process?

Primary functions of hormones

Primary Functions of Hormones

  • Homeostasis

  • Growth and Development

  • Reproduction

  • Energy Metabolism

  • Behavior

Chemical composition of hormones

Chemical Composition of Hormones






Some protein polypeptide hormones

Some Protein/Polypeptide Hormones











Negative feedback loop


glucose release from liver

glucagon from pancreas



blood glucose high

Negative Feedback Loop

blood glucose low

Biological cycles

Biological Cycles

Mechanism of action on target cells


endocrine cell

receptor protein

target cell

Mechanism of Action on Target Cells

Water soluble hormone


Mechanism of action on target cells1


endocrine cell

intracellular receptor

target cell

Mechanism of Action on Target Cells

lipid soluble hormone


Tropic versus nontropic hormones

Tropic Versus Nontropic Hormones

Tropic hormones- stimulate the production and secretion of hormones by other endocrine glands; ex. TSH

Nontropic hormones- stimulates cellular growth, metabolism, or other functions; ex. thyroxine

Major endocrine organs


pineal gland

pituitary gland

thyroid gland

thymus gland

parathyroid glands

adrenal glands




Major Endocrine Organs

Endocrine organs of the brain

pineal gland


pituitary gland

Endocrine Organs of the Brain

The endocrine system

Pineal Gland

Produces melatonin (synthesized from seratonin, a derivative of tryptophan)

  • Secreted directly in CSF to blood

  • High levels at night make us sleepy; low level during day

  • Pineal gland is stimulated by darkness and inhibited by light

  • Function in regulating circadian rhythms (sleep, body temp, appetite)  biological clock

The endocrine system

The Pituitary Gland

The endocrine system

Posterior Pituitary

Hormones of the posterior pituitary

Hormones of the Posterior Pituitary

Antidiuretic Hormone (ADH)


The endocrine system


(+ feedback)



The endocrine system

Anterior Pituitary

Hormones of the anterior pituitary

Hormones of the Anterior Pituitary

  • Growth Hormone (GH)

  • Thyroid Stimulating Hormone (TSH)

  • Adrenocorticotropic Hormone (ACTH)

  • Gonadotropins (FSH, LH)

  • Prolactin (PRL)

  • Melanocyte-stimulating Hormone (MSH)

Growth hormone gh

Growth Hormone (GH)

  • Stimulates protein building

  • Stimulates cell growth (cell size and number), especially in muscle and bone.

  • Also stimulates fat breakdown.

Gh levels

strenuous exercise

GH Levels



The endocrine system


hyposecretion of GH

Little People Big World

Kenadie - worlds smallest girl due to primordial dwarfism



hypersecretion of GH

Bao Xishun, a 7ft 8.95in herdsman from Inner Mongolia



hypersecretion of GH

7 ft 1 ¼ inches

Thyroid stimulating hormone tsh

Thyroid-Stimulating Hormone (TSH)

  • Acts on the thyroid gland, stimulating it to release T3 & T4

  • These thyroid hormones increase glucose catabolism and body heat production.

  • Regulated via negative feedback

Adrenocorticotropic hormone acth

Adrenocorticotropic Hormone (ACTH)

  • Acts on the adrenal cortex, stimulating it to secrete glucocorticoids (e.g., cortisol).

  • Helps make glucose from amino acids and fatty acids

  • Regulated via negative feedback

The thyroid gland

The Thyroid Gland




Thyroid hormones

Thyroid Hormones

Thyroid gland selectively uptakes iodine to produce T3 & T4

  • Thyroxine (T4)

  • Triiodothyronine (T3)

  • Both control metabolic rate and cellular oxidation

  • Calcitonin - lowers blood Ca++ levels and causes Ca++ reabsorption in bone



Lack of iodine in diet

hyposecretion of T3 & T4

Hyposecretion of t3 t4

hyposecretion of T3 & T4


Myxedema hyposecretion of t3 t4

Myxedemahyposecretion of T3 & T4

After thyroid treatment


Exophthalmos hyperthyroidism


Parathyroid glands

Parathyroid Glands

Parathyroid hormone pth

Parathyroid Hormone (PTH)

  • PTH release:

  • stimulates osteoclasts to reabsorb bone

Hyperparathyroidism- too much Ca++ drawn out of bone; could be due to tumor

Hypoparathyroidism- most often follow parathyroid gland trauma or after removal of thyroid--- tetany, muscle twitches, convulsions; if untreatedrespiratory paralysis and death

The pancreas

The Pancreas

The endocrine system

  • Pancreas:

  • Regulates glucose uptake by cells

  • Controlled via negative feedback: insulin & glucagon

  • Blood sugar level: 90 mg/mL

Islets of langerhans


alpha cells

beta cells

Islets of Langerhans



  • Produced by the  cells of the Islets of Langerhan

  • Catalyze oxidation of glucose for ATP production

  • Lowers blood glucose levels by promoting transport of glucose into cells.

  • Stimulates glucose uptake by the liver and muscle cells.

  • Stimulates glycogen synthesis in the liver and muscle cells.

  • Also stimulates amino acid uptake and protein synthesis of muscle tissue



  • Produced by the  cells of the Islets of Langerhans

  • Stimulates change of glycogen to glucose in the liver.

  • Synthesis of glucose from lactic acid and non carbohydrate molecules such as fatty acids and amino acids

  • Causes  in blood glucose concentration

hypoglycemic- low blood sugar; deficient in glucagon

Diabetes mellitus

Diabetes Mellitus

The endocrine system

Type I Diabeteshyposecretion of insulininsulin dependantjuvenile onsetType II Diabeteslate onset (adult)insensitivity of cells to insulinmanage by exercise & diet

The endocrine system

Symptoms (Type I):

  • sugar in blood and urine

  • urinate too often and produce too much urine

  • Too thirsty

  • Too hungry

The endocrine system

Type I (IDDM):

  • Arteriosclerosis

  • Cardiovascular problems

  • Gangrene

  • Eye problems

  • Kidney damage

The endocrine system


  • Insulin replacement

  • Pancreas transplant

  • Pancreatic cell transplant

  • Fetal pancreatic islet cell transplant

Adrenal glands

Adrenal Glands

Hormones of the adrenal medulla

Hormones of the Adrenal Medulla

  • Adrenalin (epinephrine): converts glycogen to glucose in liver

  • Noradrenalin(norepinephrine): increases blood pressure

  • (sympathetic nervous system)

    • Corticosteroids: glucose levels)

  • Hormones of the adrenal cortex

    Hormones of the Adrenal Cortex

    • Glucocorticoids- cortisol

    • Decrease protein synthesis

    • Increase release and use of fatty acids

    • Stimulates the liver to produce glucose from non carb’s

    • Mineralcorticoids- aldosterone

    • Stimulates cells in kidney to reabsorb Na+ from filtrate

    • Increases water reabsorption in kidneys

    • Increases blood pressure

    • Sex Steroids- small amts (androgens)

    • Onset of puberty

    • Sex drive

    Cushing s syndrome

    Cushing’s Syndrome

    Hypersecretion of cortisone; may be caused by an ACTH releasing tumor in pituitary

    Symptoms: trunkal obesity and moon face, emotional instability

    Treatment: removal of adrenal gland and hormone replacement

    Addison s disease

    Addison’s Disease

    Hyposecretion of glucocorticoids and mineral corticoids;

    Symptoms- wt loss, fatigue, dizziness, changes in mood and personality, low levels of plasma glucose and Na+ levels, high levels of K+

    Treatment- corticosteroid replacement therapy

    The endocrine system


    Located anterior to the heart

    Produces- thymopoetin and thymosin helps direct maturation and specialization of T-lymphocytes (immunity)

    The endocrine system


    Ovaries- produce estrogen and progesteroneresponsible for maturation of the reproductive organs and 2ndary sex characteristics in girls at puberty

    The endocrine system

    Female Reproductive System

    The endocrine system


    Testes- produce sperm and testosterone (initiates maturation of male repro organs and 2ndary sex characteristics in boys at puberty)

    The endocrine system


    • A disease in which too much T3 and T4 are produced.

    • The posterior pituitary produces which two hormones and what is their function?

    • What is acromegaly?

    • What organ does glucagon target?

    • The target tissue for lutenizing hormone is ____.

    • Where are epinephrine and norepinephrine produced?

    • If your adrenal cortex produced low levels of aldosterone, your urine would be _____?

    • What effect does parathyroid hormone have on your bones?

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