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Chapter 45. Chemical Signals in Animals. Hormones. Hormones are chemical signals. The endocrine system consists of: Endocrine cells which are hormone-secreting cells and Endocrine glands which are hormone-secreting organs. Specific target cells respond to specific hormones.

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slide1

Chapter 45

Chemical Signals in Animals

slide2

Hormones

  • Hormones are chemical signals.
    • The endocrine system consists of:
      • Endocrine cells which are hormone-secreting cells and
      • Endocrine glands which are hormone-secreting organs.
  • Specific target cells respond to specific hormones.
slide3

Primary Function of Hormones

  • Homeostasis
  • Growth and Development
  • Reproduction
  • Energy Metabolism
  • Behavior
slide4

stimulates

glucose release from liver

glucagon from pancreas

stimulates

inhibits

blood glucose high

Negative Feedback Loop

blood glucose low

slide6

hormones

endocrine cell

receptor protein

target cell

Mechanism of Action on Target Cells

response

slide7

hormones

endocrine cell

intracellular receptor

target cell

Mechanism of Action on Target Cells

response

slide8

Tropic vs 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

invertebrate nervous systems clearly illustrate endocrine and nervous system interactions
Invertebrate nervous systems clearly illustrate endocrine and nervous system interactions
  • Invertebrates have a wide variety of hormones that are involved in the regulation of homeostasis.
slide10
An example from hydra:
      • One hormone stimulate asexual reproduction.
      • Another hormone prevents sexual reproduction.
  • An example from a mollusk:
      • The hormone that regulates egg laying also inhibits feeding and locomotion.
slide11
Arthropods have extensive endocrine systems regulating molting in insects and crustaceans.
      • The regulation of molting in insects.
        • Ecdysone also promotes the development of adult features.
        • Neurosecretory cells in the brain produce Prothoracicotropic hormone (PTTH), which regulates the secretion of ecdysone.
      • Juvenile hormone (JH) promotes the retention of larval characteristics.
slide13

Different signal-transduction pathways in different cells can lead to different responses to the same signal.

fig 45 10

Major Endocrine Organs

Major endocrine glands:

Hypothalamus

Pineal gland

Fig. 45-10

Pituitary gland

Organs containing

endocrine cells:

Thyroid gland

Thymus

Parathyroid glands

Heart

Liver

Adrenal

glands

Stomach

Pancreas

Kidney

Testes

Small

intestine

Kidney

Ovaries

slide16

pineal gland

hypothalamus

pituitary gland

Endocrine Organs of the Brain

slide17

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
slide18

hypothalamus

anterior pituitary

posterior pituitary

Pituitary Gland

slide19

Posterior Pituitary

Hypothalamus

Posterior Pituitary

Anterior Pituitary

slide20

Hormones of the

Posterior Pituitary

Antidiuretic Hormone (ADH)

Oxytocin (+ feedback)

slide21

Anterior Pituitary

Hypothalamus

Posterior Pituitary

Anterior Pituitary

slide22

Hormones of the

Anterior Pituitary

  • Growth Hormone (GH)
    • Dwarfism
    • Gigantism & Acromegaly
  • Thyroid Stimulating Hormone (TSH)
  • Adrenocorticotropic Hormone (ACTH)
  • Gonadotropins (FSH, ICSH, LH)
  • Prolactin (PRL)
  • Melanocyte-stimulating Hormone (MSH)
slide23

Growth Hormone (GH)

  • Acts on the liver, stimulating it to release several polypeptide hormones.
  • Stimulates amino acid uptake and protein synthesis in target cells.
  • Ultimately stimulates cell growth (cell size and number), especially in muscle and bone.
  • Also stimulates fat breakdown.
slide25

Dwarfism

hyposecretion of GH

Little People Big World

Kenadie - worlds smallest girl due to primordial dwarfism

gigantism
Gigantism

hypersecretion of GH

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

acromegaly
Acromegaly

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.
  • Negative feedback mechanism involved in regulating levels.
adrenocorticotropic hormone acth
Adrenocorticotropic Hormone (ACTH)
  • Acts on the adrenal cortex, stimulating it to secrete glucocorticoids (e.g., cortisol).
  • Glucocorticoids promote the synthesis of glucose from noncarbohydrate sources such as amino acids, and fatty acids
  • Negative feedback mechanism involved in regulating levels.
slide30

Thyroid Gland

larynx

thyroid

trachea

slide32

Thyroid Hormones

Thyroid gland selectively uptakes iodine to produce T3 & T4

  • Thyroxine (T4)
  • Triiodothyronine (T3)
  • Both control metabolic rate and cellular oxidation
  • Calcitonin (from parafolicular cells)- lowers blood CA ++ levels and causes CA++ reabsorption in bone
slide34

Thyroid Disorders

  • Hyperthyroidism (Grave’s, Goiter)
  • Hypothyroidism (Cretinism, Myxedima)
goiter
Goiter

Lack of iodine in diet

hyposecretion of T3 & T4

myxedema hyposecretion of t3 t4
Myxedemahyposecretion of T3 & T4

After thyroid treatment

myxedema

slide40

Parathyroid Hormone (PTH)

  • PTH release:
  • stimulates osteoclasts
  • enhances reabsorption of Ca++ by kidneys
  • increases absorption of Ca++ by intestinal mucosal cells
  • 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
slide43

Pancreas

  • Regulates glucose uptake by cells
  • Controlled via negative feedback: insulin & glucagon
  • Blood sugar level: 90 mg/mL
slide45

Insulin

  • 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
slide46

Glucagon

  • 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

slide49

Type I Diabeteshyposecretion of insulin insulin dependant juvenile onsetType II Diabetes late onset (adult) insensitivity of cells to insulin manage by exercise & diet

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

slide56

Thymus

Located anterior to the heart

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

slide57

Gonads

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

slide59

Gonads

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

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