Endocrine System

What is the name of the signal molecule released by a neuron from the endocrine signaling?

Neurohormone

Hypothalamic Regulatory Hormones

(no need to memorize hormones, but they’re either releasing/inhibiting hormones)

• Organ: Hypothalamus

• Water or Lipid: Water soluble

• Target: APG

Oxytocin

• Organ: Hypothalamus (make), PPG (releases)

• Water soluble

• Stimulus: Neural

• Target:

1. Myometrium (smooth muscle of uterus) to contract during childbirth

2. Myoepithelial (smooth muscle in mammary gland) to contract + release milk

3. Limbic system to promote bonding, love

• Hyposecretion: Less bonding

• Hypersecretion: No negative impact

Antidiuretic Hormone (ADH) Vasopressin

• Organ: Hypothalamus (make), PPG (release)

• Water soluble

• Stimulus:

1. Neural (low BP)

2. Hormonal (angiotensin II)

3. Humoral (low H2O, Na+)

• Target:

1. Collecting tubules of nephron to increase water reabsorption

2. Smooth muscle of tunica media of arteries to vasoconstrict

• Hyposecretion: Diabetes insipidus

• Hypersecretion: SIADH (Syndrome of Inappropriate Antidiuretic Hormone secretion)

Hyposecretion of ADH

1. Central diabetes insipidus: NO ADH secretion

2. Nephrogenic diabetes insipidus: ADH receptors defective

• Symptoms: polyuria, intense thirst

• Hypernatremia: cells shrivel, high Na+ —> hyperpolarized

Hypersecretion of ADH

1. SIADH

• Symptoms: retain H2O, edema, cerebral edema

• Hyponatremia: cells swell/burst, depolarize

Growth Hormone

• Organ: APG

• Water soluble

• Stimulus: Hormonal —> regulatory neurohormone from hypothalamus

• Target: Liver —> secrete insulin growth like factor 1 (IGF 1)

Which stimulates bones, muscle, cartilage to grow

—> Lipolysis

—> Gluconeogenesis (increased blood glucose)

• Hyposecretion: Child = Pituitary dwarfism

• Hypersecretion: Child = Gigantism (even proportions), Adult = Acromegaly (hands, feet, face only)

Prolactin

• Organ: APG

• Water soluble

• Stimulus: Hormonal —> from hypothalamus

• Target: Mammary glands to produce milk

• Hyposecretion: Less milk production

• Hypersecretion: Galactorrhea —> excess milk production (bf females), Impotence (males)

Thyroid Stimulating Hormone

• Organ: APG

• Water soluble

• Stimulus: Hormonal —> from hypothalamus

• Target: Thyroid gland to stimulate production of thyroid hormones

• (Hypo/hyper covered later)

Adrenocorticotropic Hormone

• Organ: APG

• Water soluble

• Stimulus: Hormonal —> from hypothalamus

• Target: Cortex of adrenal gland to release corticosteroid hormones

• (Hypo/hyper covered later)

Follicle Stimulating Hormone

• Organ: APG

• Water soluble

• Stimulus: Hormonal —> from hypothalamus

• Target:

1. Male: Sertoli cells in testes to release androgen binding protein for sperm production

2. Female: Granulosa cells to produce estrogen to mature primary follicle + ovary to release mature egg during ovulation

• Hyposecretion: Failure to sexually mature

• Hypersecretion: None

Luteinizing Hormone

• Organ: APG

• Water soluble

• Stimulus: Hormonal —> from hypothalamus

• Target:

1. Male: Leydig cells in testes to produce testosterone

2. Female: Theca cells in ovary to produce estrogen + ovary to release mature egg during ovulation

• Hyposecretion: Failure to sexually mature

• Hypersecretion: None

Melatonin

• Organ: Pineal gland

• Water soluble

• Stimulus: Neural —> low light stimulate production

• Target: Brain to produce sleep

• Hyposecretion: Insomnia

• Hypersecretion: Seasonal affective disorder, tired, depressed

Thyroid

• Has follicles

• Circle of cells surrounding a fluid center, fluid is called colloid

• Follicle cells make thyroglobulin

• Thyroglobulin goes into colloid where iodine is adding/making T3 & T4

• T3 & T4 leave follicle into blood

Thyroid Hormones - T3 & T4

• Organ: Thyroid

• ***Lipid soluble (uses facilitated diffusion to attach receptor inside cell) (uses a protein carrier to travel in blood - made by liver)

• Stimulus: Hormonal (low TH —> hypothalamus release regulatory hormone —> APG to release TSH —> Thyroid to release TH)

• Target: Most cells to stimulate cell metabolism

Hyposecretion: low energy, weight gain, goiter

1. Hashimoto’s disease - Type 4 HS, attack follicle cells

2. Myxedema —> low TH release

3. Goiter - low iodine, follicle makes thyroglobulin, sends to colloid but no iodine so T3 + T4 cannot be made and colloid swells resulting in goiter

Hypersecretion: high metabolism, weight loss, bulging eyes

1. Grave’s disease - Type 4 HS, mimics TSH

Hypocalcemia

RMP -70mV

• Neuron RMP: less Ca2+, more positive (e.g. -60mV), easier to reach threshold potential (-55mV) so, spontaneous AP, seizures

• Heart: Weak, low HR

• Muscle contraction: Weak

• Skeletal: Weak bones

Hypercalcemia

• Neuron RMP: more negative, greater stimulus to reach threshold potential

• Heart: Tachycardia, HF

• Muscle contraction: Increased

Bone Cells & Matrix

Matrix —> calcium phosphate

• Osteogenic cell - stem cell

• Osteoblast - make matrix

• Osteoclast - breakdown matrix

• Osteocyte - surrounded by matrix, maintain matrix

Calcitonin

• Organ: Thyroid

• Water soluble

• Stimulus: Humoral —> high blood calcium

• Target: (both to lower calcium levels)

1. Inhibit osteoclasts

2. PCT to inhibit Ca2+ reabsorption

• Hyposecretion: Hypercalcemia

• Hypersecretion: Hypocalcemia

*Trick to remember: Calcitonin —> “tone” it down

Parathyroid Hormone

• Organ: Parathyroid

• Water soluble

• Stimulus: Humoral —> low blood calcium

• Target: (to increase blood calcium)

1. Stimulates osteoclasts

2. DCT + Collecting tubules to reabsorb Ca2+, and PCT to secrete phosphate

3. Kidneys to convert cholecalciferol to calcitrol (active vitamin D) to target small intestines to increase Ca2+ absorption

• Hyposecretion: Hypocalcemia

• Hypersecretion: Hypercalcemia

Hyponatremia

• Cells: Swells or burst/lyse (hypotonic) (too much water inside cell)

• Glucose absorption: Decreased absorption

• Nervous RMP: Little impact, but decreased depolarization

• Heart: Arrythmias

• BP: Hypotension

• Skeletal muscle contraction: Weak

Hypernatremia

• Cells: Cremate or shrivel (hypertonic) (less water inside cell)

• Glucose absorption: Increased absorption

• Nervous RMP: Hyperpolarized

• Heart: Arrythmias

• BP: Hypertension

Hypokalemia

• pH: alkaline

• Nervous RMP: Hyperpolarized, slower repolarization

• Heart: Hyperpolarized, arrhythmias

• Skeletal muscle contraction: Weaker

Hyperkalemia

• pH: acidosis

• Nervous RMP: Depolarized, less negative, closer to threshold

• Heart: Increase T wave (ventricle repolarization), arrhythmias, HF

• Skeletal muscle contraction: Weaker

Mineralocorticoids - Aldosterone (most abundant)

• Organ: Adrenal cortex - zona glomerulosa

• Lipid soluble (uses a protein carrier to travel in blood)

• Stimulus: Hormonal —> angiotensin II

• Targets: DCT + CT of nephrons to reabsorb Na+ and H2O and secrete K+

• Hyposecretion: Addison’s disease (see cortisol)

• Hypersecretion: Aldosteronism (edema, hypertension, hypokalemia)

Glucocorticoids - Cortisol (most abundant)

• Organ: Adrenal cortex - zona fasiculata

• Lipid soluble (uses a protein carrier to travel in blood)

• Stimulus: Hormonal

Regulatory hormone of hypothalamus —> ACTH by APG —> Cortisol by adrenal cortex

• Targets:

1. Liver + Kidneys for glycogenolysis, gluconeogenesis (to increase blood glucose: vasoconstriction, anti-inflammatory, decrease immune system/ low WBCs)

2. Brain to wake from sleep - circadian rhythm

• Hyposecretion: Addison’s disease

1. Low aldosterone + low cortisol

2. Bronzed skin (increased melanin)

3. Low BP

4. Weight loss

5. Salt craving

• Hypersecretion: Cushing’s disease

1. Steroid diabetes - temporary hyperglycemia caused by use of corticosteroid meds

2. Buffalo hump

3. Moon face

4. High BP

5. Weight gain

6. Facial and body hair

Gonadotropins - Androgen

• Organ: Adrenal cortex - zona reticularis

• Lipid soluble - protein carrier

• Stimulus: Hormonal —> ACTH

• Targets: Unclear, libido

• Hyposecretion: Unknown

• Hypersecretion: Masculinization in females

Epinephrine & Norepinephrine

• Organ: Adrenal medulla

• Water soluble

• Stimulus: Neural

• Targets: Sympathetic NS - fight or flight —> short term stress vs cortisol is long term stress

• Hyposecretion: Unknown

• Hypersecretion: HTN, prolonged fight or flight response

Glucagon

• Organ: Pancreas

• Water soluble

• Stimulus: Humoral - low blood glucose levels

• Targets: Liver to perform glycogenolysis to increase blood glucose levels

• Hyposecretion: Unknown

• Hypersecretion: Unknown

Insulin

• Organ: Pancreas

• Water soluble

• Stimulus: Humoral - high blood glucose levels

• Targets:

1. Cells to take in glucose (and K+)

2. Liver to stimulate glycogenesis

• Hyposecretion: DM

• Hypersecretion: Hyperinsulinism (anxiety, nervousness)

Testosterone

• Organ: Testes

• Lipid soluble - carrier protein

• Stimulus: Hormonal - LH

• Targets:

1. Spermatogonium to perform meiosis

2. All cells for various cell metabolism and secondary traits (e.g. muscle mass, deep voice)

• Hyposecretion: Less masculine traits, low sperm production, potential infertility

• Hypersecretion: Aggression, low sperm, infertility

Spermatogenesis Pathway

1. Stimulus: Low testosterone, low sperm

2. Hypothalamus to release regulatory hormone

3. APG to release FSH + LH

4. (2 things)

• FSH targets Sertoli cells in testes to release androgen binding protein (ABP)

• LH targets Leydig cells in testes to make testosterone

5. Testosterone + ABP signal spermatogonium to develop into sperm

6. (2 things)

• High levels of testosterone inhibit hypothalamus to turn off pathway

• High sperm stimulates cells in testes to make inhibin, which also inhibits the hypothalamus to turn off pathway

Estrogen

• Organ: Ovaries

• Lipid soluble - carrier protein

• Stimulus: Hormonal - FSH + LH

• Targets:

1. Primary follicle to mature

2. Endometrium to thicken

3. All cells for cell metabolism and secondary traits (e.g. fat deposits, breast development)

• Hyposecretion: Infertility, no menstrual flow

• Hypersecretion: Infertility

Progesterone

• Organ: Ovaries (corpus luteum)

• Lipid soluble - carrier protein

• Stimulus: Hormonal - LH

• Targets: Endometrium to thicken

• Hyposecretion: Infertility, irregular menstruation

• Hypersecretion: Unknown

Ovarian Cycle —> changes in ovary

• 1-3 —> follicular —> mature follicle

• 14 —> ovulation —> egg released into oviduct

• 15-18 —> corpus luteum secreting estrogen+ proges. + then dives up

Uterine Cycle —> changes in endometrium

• 1-7 —> menses —> shedding of endometrium

• 8-14 —> proliferative —> thicken endometrium

• 15-28 —> secretory —> thicken + maintain endometrium

Menstrual Cycle