large dense core vesicles - generally house peptide hormones

small synaptic vesicles - generally contain non-peptide transmitters

slow transmission - tend to have longer range effects

act via G-protein --> indirectly modulate ion channels

generally have longer response

ANS: direct nerve connections from the CNS to peripheral organs, classic neurotransmitters, immediate moment-to-moment control

Pit: relies on hormonal release into circulation to affect peripheral target organs, peptide transmitters, slower developing control and feedback

Anterior pituitary (aka adenohypophysis): non-neural tissue, makes up 80% of pituitary

Posterior pituitary (aka neurohypophysis): neural tissue, makes up 20% of pituitary

Corticotrophs

Somatotrophs

Thyrotrophs

Gonadotrophs

Lactotrophs

CRH (corticotropin releasing hormone)

ACTH (adrenocorticotropin hormone aka corticotropin)

Glycoprotein released from hypothalamic neurons (paraventricular neurons)

41 amino acid peptide

POMC (proopiomelanocortin)

Produced in basal ganglia, cortex, and pituitary

39 amino acid peptide

ACTH: acts on adrenal cortex

alpha, beta-melanocortin: increases skin pigmentation

beta-lipotropin (LPH): stimulates release of fatty acids from adipose tissue

CRH and vasopressin (AVP)

stress

hypoglycemia

AVP released by posterior pituitary

Reaches anterior pituitary via inferior hypophyseal artery

Highest levels in the morning but dependent on sleep-wake cycle (ie. jet-lag can alter pattern)

Opposes circadian patter of growth hormone secretion

Acts on adrenal cortex

Stimulates steroid hormone synthesis and growth of cortex (trophic action)

Result in high ACTH levels and adrenal hormones --> inc. in size of cortex

Androgenital syndrome: masculization of femal fetus

ACTH negatively feedsback to the hypothalamus.

Cortisol negatively feedsback to both the hypothalamus and the anterior pituitary.

Located on top of each kidney.

Medulla: inner region, neural tissue

Cortex: outer region, non-neural tissue

zona glomerulosa

zona fasiculata

zona reticularis

Adrenal coretx

Ovaries

Testes

Glucocorticoids

Mineralocorticoids

Adrenal androgens (androgenic steroids)

zona glomerulosa - mineralocorticoids

zona fasiculata - glucocorticoids, adrenal androgens

zona reticularis - glucocorticoids, adrenal androgens

 Cortisol

Corticosterone

Stimulates breakdown of muscle and other organs - inceases release of amino acids

Stimulates lipolysis - breakdown of fat

Stimulates gluconeogenesis - production of glucose from amino acids and lipids

Conserves glucose for use by CNS - inhibits uptake into muscle and fat cells

Exerts stron anti-inflammatory effects - large doses decrease production of antibodies

Increased serum potassium levels and lowered sodium levels

Decreased blood flow to kidneys

Weakly responsive to ACTH

Increases potassium secretion

Promotes sodium reabsorption by kidneys

Increases water reabsorption through osmosis

Sodium reabsorption in the distal tubules of the kidney in increased water reabsorption

May results in hypertension (high blood pressure)

Expression is low before puberty.

Increased expression at puberty contributing to developmental changes in both genders

Patients lack cortisol from the zona fasiculata: patients lack negative feedback of ACTH, aldosterone levels can be low

Results in overproduction of ACTH and cause skin to darken due to increase release of MSH (a bioactive peptide from POMC)

Prolonged exposure of the body's tissue to high levels of cortisol: aldosterone levels can also be high

Symptoms: obesity, weak muscles, fatigue

Most cases caused by pituitary tumors: benign tumors may secerte increased amounts of ACTH

Overproduction of ACTH may accompany increased beta-endorphin production

High stress --> high ACTH --> beta-endorphin --> blunt pain

Severely traumatized individual appear to be free from pain.

Due to simulatenous release of beta-endorphins along with corticotrophin in response to stressful stimulus of injury

GH releasing hormone

Inhibited by somatostatin

Peptide hormone

Somatotroph

Adipose tissue: causes breakdown of triglycerides and suppresses ability of fat cells to take up lipids form circulation

Metabolism: stimulates the formation of proteins form amino acids (anabolism), maintain blood glucose levels by inhibiting insulin activity

Stimulates release of IGF-1 (insulin-like growth factor) from the liver.

IGF-1: 70 amino acid peptide comprised of two chains connected by a disulfide bond

Stimulates bone growth by increasing proliferation of chondrocytes

Stimulates muscle growth: proliferation and differentiation of myoblasts, uptake of amino acids and protein synthesis in muscle

Exercise

Stress

Low blood glucose

Fasting

Sleeping

Rise progessively with age in children

Greater increase at onset of puberty then decreases to adult levels

Deficiency: dwarfism - severity of growth retardation is linked to age of onset of disease

Human growth hormone (hGH) can be used to promote growth

Before puberty: gigantism - normal body proportions

After puberty: Acromegaly - enlargement of distal body parts (hands, feet, skull, jaw, nose)

Pituitary tumors may increase GH levels

May cause diabetes: GH effects on metabolism atntagonize those of insulin

High blood pressure, heart disease, arthritis

GH negatively feedsback to the hypothalamus.

IGF-1 negatively feedsback to the hypothalamus.

Tripeptide (3 AA)

Stimulates release of thrytoid stimulating hormone (TSH) and prolactin

Binds receptors on thyroid gland to induce T3 and T4 secretion

Stimulates thryoid cell growth

Increasess synthesis of thyroid hormones

Increases blood flwo to thyroid gland

Cellular differentiation

Growth

Metabolism

Increase lipolysis

Increase carbohydrate metabolism: inc. insulin-mediated stimulation of glucose uptake by cells, inc. gluconeogenesis and glycogenlysis (inc. blood glucose levels)

Thyroid hormones are critical for development of the mammalian CNS.

Thyroid hormones are required for normal growth in immature animals.

Cardiovascular: inc. HR, cardiac contractility, and cardiac output, promote vasodilation

CNS: dec. thyroid hormones cause mental clouding, inc. causes anxiety

Repro: dec. thyroid hormones is associated with infertility

Iodine deficiency: I required for T3 and T4 synthesis

Damage to thyroid gland

Hypothyroidism: lethargy, fatigue, intolerance of cold; can be treated with synthetic thyroid hormone

Pituitary tumors

Grave's disease: autoimmune disorder in which antibodies are expressed which bind to and activate TSH receptors

Hyperthyroidism: anxiety, insomnia, increased HR; treat with drugs blocking thyroid hormone synthesis

Paraventricular nucleus (PVN)

Supraoptic nucleus (SON)

Oxytocin

Arginine vasopression (Anti-diuretic hormone)

9 amino acid peptide hormone

Synthesized by magnocellular cells of the PVN and SON

Stimulates uterine contractions during and after childbirth

Leads to milk letdown (lactation)

Milk is stored in alveoli of the mammary glands.

Alveoli are line by smooth muscle cells (myopeithelial cells)

Myoepithelial cells express oxytocin receptors -> binding causes contraction of myopeithelial cells -> milk ejection

Smooth muscel cells of uterus increase expression of oxytocin receptors during gestation

Oxytocin is released during labor causing contraction of smooth muscle cells

Oxytocin analogs (ie. Pitocin) can be administered to induce labor

9 amino acid peptide

Synthesized by magnocellular cells of the PVN and SON

Stimulated water conservation

Causes vasoconstriction in response to severe hemorrhage

Dec. BP: baroreceptors of the carotid sinus simtulate neurons in SON and PVN -> hypothalamic neurons release vasopressin from posterior pituitary

Binds to receptors in kidney and promote reabsorption of water back into circulation

Inc. plasma osmolarity: inc [salt] in bloodstream

Cicrumventricular organs and vasopressin neurons are osmosensitive: neurons transmit signal to PVN and SON causing water retention