-Growth

-Metabolism

-Homeostasis

-Reproduction

Cell-cell comunication

-Made in glands

-Transported by blood

-Distant tissue receptors

-Activates physological response

Location: Mediastinum, superior to heart

Involuntary after puberty

Secretes hormones that regulate development and later later activation of T-lymphocytes

-Thymopoietin & thymosins

Rates of enzymatic rxns

Transport of ions or molecules across cell membranes

Gene expression and protein synthesis

Exert effects in low concentrations

Bind to target cell receptors

-Made in advance; stored in secretory vesicles

-Exocytosis

-Dissolved in plasma

-Short half life

-Cell membrane receptors

-Activation of 2nd messenger systems; may activate genes

-Modification of existing proteins & induction of new protein syntheis

Thyroxine

(thyroid hormones are tyrosine derivatives)

Synthesized on demand frm precursers

-Simple diffusion

-Bound to carrier proteins

-Long half life

-Cytoplasm or nucleus or membrane receptors

-Activation genes for transcription/translation

-Induction of new protein synthesis

-Made in advance; stored in secretory vesicles

-Exocytosis

-Dissolved in the plasma

-Short half life

-Cell membrane receptors

-Activation of 2nd messenger systems

-Modification of existing proteins

-Epinephrine, norepinephrine

-Made in advance; Precurser stored in secretory vesicles

-Simple diffusion

-Long half life

-Nucleus

-Activation of genes for transcription & translation

-Induction of new protein synthesis

1. Msgr RNA in ribosomes bind a.a to peptide chain (preprehormone). Chain is directed into ER lumen by a signal sequence of a.a
2. Enzymes in ER chop off the signal sequence, creating an inactive prohormone
3. Prohormone movement: ER-Golgi complex
4. Secretary vesicles bud off Golgi. The enzymes chop off the prohormone into 1 or more active peptides plus additional frags.
5. Secretory vesicle releases its components by exocytosis into extracellular space
6. Hormone moves into circulation for transport to target

Dissolve in EFC

Lipophobic (why they must bind to surf recept)

Hormone binding triggers signal transduction wth 2nd messengers

leads to enzyme activation

or opening of channels

Cellular response ensues (often gene expression)

-Cholesterol-derived

Lipophilic & can enter target cell

Cannot be stored in vesicles

Synthesized as needed

Need binding protein for transport in bloodstream

-Cytoplasmic or nuclear receptors(mostly)

-Activate DNA

Slower acting, longer half life

1. Most bound to plasma protein carriers. Only unbound hormones can diffue into target cell.
2. In cytoplasm or nucleus, some bind to membrane receptors that use 2nd messenger systems to create rapid cellular responses
3. The receptor hormone complex binds to DNA & activates or represses genes
4. Activated genes create new mRNA that move back into the cytoplasm
5. Translation produces new proteins for cell processes

Derived from 1-2 a.a's

-Tryptophan(eg melatonin)

-Tyrosine (eoinephrine, T3 &T4)

-Ring structure

-Thyroid hormones bind to intracellular receptors

-Catecholamines bind to cell membrane receptors

-Epinephrine

-Norepinephrine

-Dopamine

Thyroid Follicles

-Simple cuboidal epithelial cells secrete T3 & T4

Increases bodys metabolic rate & O2 consumption

Calorigenic Effect- Increase heat production

Increase Heart Rate and contraction strength

Increase respiratory rate

Stimulates appetite and breakdown CHO, lipids and proteins

-Stimulus

-Afferent signal(receptor & Input signal)

-Integration

-Efferent signal (the hormone)

-Physiological action

-Negative feeback

-Adrenal medulla

E.g catecholamines

-Hypothalamus

e.g Anterior pituitary

-Hypothalamus

E.g posterior putuitary

1. Hormone made & pckaged in neuron body
2. Vesicles transported fown the cell
3. Vesicles containing hormone stored in posterior pituitary
4. Hormones released into blood

• Targets kidneys

Increased H20 Rentention, reduce urine

Also funcs as neurotansmitter

• Labor contractions, lactation
• Possible role in:

Sperm transport

emotional bonding

sexual arousal & orgasm

Secreted by gonadotrope cells

-stimulates production of egg or sperm cells

Secreted by gonadrotrope cells

-Mainly stimulates hormone production

Females-Stimulates ovulation & corpus luteum to secrete progesterone & estrogen

Males-Stimulates interstitial cells of testes to secrete testosterone

Secreted by thyrotropes

-stimulates growth of thyroid gland & secretion of TH

Secreted by corticotropes

-Regulates response to stress, stimulates adrenal cortex

-corticosteroids regulate glucose, fat & protein metabolism

Secreted by lactropes

-female-milk synthesis after delivery

-Male-Increased LH sensitivity, thus Increased testosterone secretion

Secreted by somatotropes of anterior pituitary

Promote tissue growth

-mitosis & cellular differentiation

-Stimulates liver to produce IGF-I and II

protein synthesis: Increased DNA transcription

Stimulates lipid release from adipocytes

Glucose sparing effect=less glucose used for energy

Electrolyte balance:promotes Na, K, Cl retention, Ca absorption

-Bone, cartilage & muscle growth

-Stimulates growth at epiphyseal plates

-Increase osteoblastic activity and appositional growth affecting bone thickening and remodeling

-Blood conc. decreased by age 75 to 1/4 of that of adolescent

-Higher during deep sleep, after high protein meals, after vigorous exercise

-lower after high CHO meals

1. Hypothalamic stimulation-from CNS
2. Pituitary stimulation-from hypothalamic trophic hormones
3. Endocrine gland stimulation-from pituitary trophic hormones

Stimulation causes release of catecholamines

Hormonal effect is longer lasting

-Increases alertness,anxiety, or fear

-Raises metabolic rate

inhibits insulin secretion

stimulates gluconeogenesis and glycogenolysis

-Corticosteroids:

Mineralocorticoids

Glucocorticoids

Sex steroids

Mineralocorticoids

Especially cortisol, stimulates fat and protein catabolism, gluconeogensis & release of fatty acids and glucose into blood

Anti-inflammatory effect becomes immune supression wth long-term use

1. Hormones synthesizing trophic hormones release them into capillaries of the portal system
2. portal vessels carry trophic hormones to anterior pituitary
3. Endrocrine cells release their hormones into 2nd set of capillaries for distribution to body

15% of erythropoietin(stimulates bone marrow to produce RBCs)

Angiotensinogen(prohormone)

precuser of angiotensin II

produces 85% of erythropoietin

convert angiotensinogen to angiotensin I: increase in BP

Converts calcidiol to calcitriol

-Increase absorption by intestine & inhibits loss in urine

-more Ca available for bone depositation

10 enteric hormones

-coordinate digestive motility and secretion

Secretes estrogen, progesterone and others

-regulate estrogen, progesterone and others

regulate pregnancy, stimulate developement of fetus and mammary glands

Synergism-multiple stimuli(more then additive)

Permissiveness-Need second hormone to get full expression

Antagonism-Glucagons oppose insulin

Excess hormone

-tumors or cancer

-Graves disease-thyroxin

Deficient hormone

-Endermic Goiter: Iodine deficiency

-Toxic goiter(graves disease) antibodies mimic TSH, Increase TH

-Diabetes-Insulin

Pituitary Disorders

Hypersecretion of growth hormones

-Acromegaly

-Thickening of the bones & soft tissue

-Problems in childhood or adolescence

Gigantism if oversecretion

dwarfism if hyposecretion

Downregulation of receptors-hyperinsulinemia

Transduction abnormalites-e.g testicular feminization syndrome

Abnormalities of control mechanisms

Evolutionary conservation of hormone function

Comparative endocrinology

Pineal gland and melatonin example

Way body reacts to stress

3 stages:

1. Alarm reaction
2. Stage of resistance
3. Stage of exhaustion

1. Alarm reaction

Initial response

Increase in epinephrine and norepinephrine lvls

Increase in HR and BP

Increase in blood glucose lvls

Sodium and h2o retention (aldosterone)

After a few hours, glycogen reserves gone

Increase ACTH and cortisol lvls

Fat and protein breakdown

Gluconeogenisis

Depressed immune func.

Susceptibility to infection and ulcers

Stress that continues until fat reserves are gone

protein breakdown and muscle wasting

Loss of glucose homeostasis

Hypertension & electrolyte imbalances(loss K and H)

Hyokalemia and alkalosis(blood pH lvl) leads to death