Endocrine System

The endocrine system

• cells, glands, and organs that secrete hormones. hormones are chemical messengers which play an integral role in regulating body functions and maintaining homeostasis

• control body processes via chemical substances secreted in glands & organs

Nervous System + Endocrine System = homeostasis

• BOTH: react to stimuli; maintain homeostasis; systems of the body that send signals; hypothalamus is the link between the two systems

• nervous system: fast reaction time & short duration; uses impulses to send signals; organs are brain, spinal cord, & nerves; impulses travel via neurons; CNS/PNS

• endocrine system: slower response time/reaction time & longer duration; uses hormones to send signals; organs are glands & secreting organs; the hormones travel through bloodstream; hormones: adrenaline, insulin; TSH, etc.

endocrine glands

• ductless glands that secrete into interstitial fluid or directly into the bloodstream

• ex: Insulin, ADH

exocrine glands

• secrete into a duct that opens onto mucous membrane or the skin

• sweat glands; salivary glands; digestive secretions from the pancreas

glands

located throughout the body; each contains group of specialized cells that secrete hormones

hormones

chemical messengers that regulate body processes, in response to body signals- unlocks, initiates, and regulates body activities

receptors

protein molecules that stimulate changes in target cells in response to hormone stimulation

humoral stimulus

• hormone release cause by altered levels of critical ions or nutrients in the blood

• example: thyroid and parathyroid glands secrete hormones depending on calcium levels in blood

neural stimulus

• hormone release caused by neural input (nerves)

• example: central nervous system signals adrenal gland to produce epinephrine/norepinephrine

hormonal stimulus

• hormone release caused by another hormone (tropic hormone)

• example: hypothalamus secretes releasing hormones that stimulate the anterior pituitary to release hGH (human growth hormone)

structures of the endocrine system

• glands:

  • pituitary; thyroid; parathyroid; adrenal; pineal

• organs that secrete hormones:

  • hypothalamus; gonads; pancreas; thymus

pineal gland

secretes melatonin (sleep hormone)

• secretion is inhibited by light

• secretion is stimulated by darkness

hypothalamus (“The boss”)

a region in the brain that works to maintain HOMEOSTASIS through:

• coordination of the Autonomic Nervous System: Controls major body states like temperature, appetite, and thirst

• production of hormones & signals release of hormones from the pituitary gland

• is neuroendocrine: has both neural and endocrine function

pituitary gland (“middle management”)

gland with two lobes, anterior and posterior. sits right below the hypothalamus

• receives hormones and signals from hypothalamus

• also makes and releases many hormones

hypothalamus~ hormones

region of the brain; coordinates autonomic NS and pituitary gland. Endocrine function is through hormones

Hormones:

• makes some neurosecretory hormones (called this because it sends neuropeptide hormones along nerve axons to posterior pituitary)

• sends out releasing hormones and inhibitory hormones to keep the body in homeostasis

pituitary gland~ hormones

• posterior (neurohypophysis)

• anterior (adenohypophysis)

  • secrete/release hormones that affect multiple other glands and organs

posterior pituitary

neuropeptide hormones are made in the hypothalamus and sent to posterior pituitary along nerve axons. these hormones are stored in the posterior pituitary until needed~ Oxytocin; ADH (Antidiuretic hormone/vasopressin)

Oxytocin~ hormone stored in posterior pituitary

plays a role in uterine contractions in labor and stimulates milk release in mammary glands

ADH (AntiDiuretic Hormone/Vasopressin)~ hormone stored in posterior pituitary

increases water absorption in kidneys; causes vasoconstriction

Hypothalamus & Anterior Pituitary

hypothalamus sends releasing hormones (RH) to anterior pituitary

the releasing hormones from hypothalamus signal the anterior pituitary to release hormones:

FSH, LH, ACTH, TSH, Prolactin, Endorphins, Growth hormone

Thyroid gland

thyroid receives signal from anterior pituitary in the form of TSH (thyroid stimulating hormone)

• T3, T4, Calcitonin

parathyroid glands

Parathyroid Hormone (PTH): causes removal of calcium from bone to blood and increased calcium reabsorption in kidneys when calcium blood levels are too low

calcium levels must be maintained within a very small range or death can result! a client with severe calcium deficiency will exhibit muscle spasms (tetany) and sometimes seizures!

smallest known endocrine glands. embedded underneath thyroid gland

calcium level homeostasis

2 glands regulate calcium levels in blood=

thyroid and parathyroid secretions in a feedback loop maintain normal levels of calcium in the blood

• high blood calcium level: calcitonin secretion (from thyroid) increases> breakdown of bone matrix decreases> Ca+ from blood to bone> Ca+ level in blood decreases> normal

• low blood calcium level: parathyroid hormone secretion increases> breakdown of bone matrix increases> Ca+ sent from bone to blood> Ca+ level in blood rises> normal

thymus gland

involved in immune system development

• (T-cells), primarily in childhood

• gland shrinks in adulthood

adrenal glands

the adrenal glands are covered in an outer capsule and have outer and inner segments:

• inner: Medulla

• outer: Cortex

Adrenal Cortex: Outer section~ Adrenal glands

Hypothalamus sends releasing hormone> ACTH released from pituitary> ACTH stimulates Adrenal Cortex

Corticosteroid Hormones: Glucocorticoids:

• Cortisol (chronic stress increases production)

  • maintenance of BP; metabolism regulation; decreased immune function

Mineralocorticoids: Example Aldosterone

• Aldosterone: reabsorption of sodium in kidneys; starts with secretion of renin in the kidneys due to low BP; RAAS system results in secretion of aldosterone

  • increased sodium and water reabsorption + vasoconstriction = increased BP

Sex hormones: supplementary sex hormones like testosterone and estrogen

Adrenal Medulla: Middle section~ Adrenal glands

Catecholamines: (Acute stress response- “Fight or Flight”)

Epinephrine (aka adrenaline) & Norepinephrine (aka noradrenaline)

• increased BP & HR; increase muscle contractility; increase energy available by increase blood glucose; vasodilation; bronchodilation

Dopamine

• reward/motivation/mood; increase HR & BP; motor control pathways

pancreas

Glucagon

• when blood sugar is low, stimulates the breakdown of glycogen in the liver into glucose , which is then released into the bloodstream

• stimulates breakdown of fats and proteins for conversion into glucose

Insulin

• amount released increases with increase of blood glucose

• increases cell membrane permeability to glucose; “unlocks” the cells so glucose can exit bloodstream and enter the cell

• regulates carbohydrate, protein & fat metabolism and storage

insulin/glucagon feedback loop to maintain glucose homeostasis

pancreas releases insulin if the blood sugar gets too high, releases glucagon if the blood sugar gets too low

with diabetes, your pancreas doesn’t stop making glucagon when you eat and doesn’t make enough or any insulin, so blood glucose rises (→ hyperglycemia)

Testicles~ Gonads

LH and FSH from anterior pituitary stimulate release of:

testosterone:

• male sex characteristics

• sperm production

• libido

Ovaries~ Gonads

LH and FSH from anterior pituitary stimulate release of:

Estrogen & Progesterone:

• female sex characteristics

• ova (egg) production

• menstrual cycle

• pregnancy & lactation

suffix “-tropin”

indicates that the substance (hormone) has a stimulating effect on the target organ (usually another gland)- tells it to make/release something

ex: anterior pituitary> Gonadotropins: FSH + LH> egg release increased estrogen & progesterone production or sperm production/androgen production

Prostaglandins

Prostaglandins “hormone like” produced in every body cell

• hormone like because they act as chemical messengers

• not actually hormones- don’t travel through the blood stream; often affect cells close by

• often involved in a response to injury or stress

Ibuprofen works primarily as an anti-inflammatory agent by inhibiting prostaglandin production

role: blood clotting; vasodilation/vasoconstriction; bronchodilation/bronchoconstriction; fever; pain perception; eye pressure adjustment; stomach acid inhibition; GI tract motility

melatonin

pineal gland
induces sleep

growth hormone (hGH)

anterior pituitary
promotes growth of bones, muscles, tissue

TSH (thyroid stimulating hormone)

anterior pituitary
stimulates thyroid to make T4 and T3

T4

thyroid
inactive precursor to T3

T3

thyroid
cell metabolism, protein synthesis

Calcitonin

thyroid
stimulates storage of calcium in bone when blood calcium is too high “calci bone in”

parathyroid hormone

parathyroid gland
stimulates release of calcium out of bone to blood when serum Ca levels are too low

ACTH (AdrenoCorticoTropicHormone)

anterior pituitary
stimulates adrenal glands to make cortisol & aldosterone

endorphins

anterior pituitary (primarily)
inhibits pain reception

Cortical Steroids: Cortisol

adrenal gland (cortex)
(stress) stabilizes BP, reduced immune function, regulates metabolism

Cortical Steroids: Aldosterone

adrenal gland (cortex)
increases water and sodium reabsorption, vasoconstriction (increase BP)

Catecholamines: Epinephrine (adrenaline) + Norepinephrine (noradrenaline)

adrenal gland (Medulla)
fight or flight; increases BP, HR, BG, muscle contractility, vasodilation, bronchodilation

Catecholamines: Dopamine

adrenal gland (Medulla)
mood/reward/motivation, affects motor control pathways, increases BP, HR

ADH (vasopressin)

made in hypothalamus, stored and released by posterior pituitary

increases water and sodium reabsorption (keep more water in body) ⬆︎BP & vasoconstriction

oxytocin

made in hypothalamus, stored and released by posterior pituitary

stimulates uterine contractions and breast milk release

FSH (follicle stimulating hormone)

anterior pituitary
stimulates testicles to make sperm, testosterone
stimulates ovaries to make estrogen, progesterone, ova (eggs)

LH (luteinizing hormone)

anterior pituitary

stimulates testicles to make sperm, testosterone
stimulates ovaries to make estrogen, progesterone, ova (eggs)

estrogen

Gonads (testicles, ovaries)
female sex characteristics, ova (eggs), regulates menstrual cycle

progesterone

Gonads (testicles, ovaries)
female sex characteristics, ova (eggs), regulates menstrual cycle & pregnancy

testosterone

Gonads (testicles, ovaries)
male sex characteristics, sperm production, libido

prolactin

anterior pituitary
lactation in mammary glands

insulin

pancreas (beta cells)

“unlocks” cells (increases membrane permeability) to allow glucose into cells

glucagon

pancreas (alpha cells)
breaks down glucose stored in the liver (glycogen) & stimulates breakdown of fats and protein in glucose (the body’s usable form of energy)

why endocrine disorders occur?

• inappropriate response to hormonal signals

• damage to endocrine gland

• absence of gland

• hypofunction or hyperfunction of gland

• neoplasm (tumor)

• autoimmune response

diagnostic tests~ endocrine system

x ray

• your role> explain to pt, transport to radiology

ct or mri exam (with or without contrast)

• your role> explain to pt, screen for contrast allergies, transport to ct

blood tests

• your role> explain to pt, transport to lab, notify team of abnormal results

urine tests

• your role> explain to pt, collect, label correctly, transport to lab, notify team of abnormal results

pituitary disorders~ common diagnostic tests

imaging: mri scan is the gold standard for detecting pituitary tumors. ct scan, x ray

blood tests (to check hormone levels)

urine tests

gigantism/acromegaly~ anterior pituitary disorders

gigantism & acromegaly: hypersomatotropism = overproduction of human growth hormone

cause: abnormality of pituitary (usually benign tumor)

gigantism: excessive hGH onset in childhood

s/sx: overgrowth bones, extreme height, delayed puberty

acromegaly: excessive hGH adult onset:

s/sx: overgrowth of tissues, soft tissue swelling, facial coarseness & hirsutism, enlarged hand/feet, thickened skin, excess perspiration, joint/body aches, deep hoarse voice

risk for: hearr disease, diabetes common; partial vision loss possible; hepatosplenomegaly and cardiomegaly over time; HF

hypersomatotropism (gigantism, acromegaly)~ tx/nursing care

tx:

• irradiation of pituitary gland

• surgery: removal of pituitary adenoma

• medications

• treatment can stop disease progression but can’t alter abnormal growth that has already occurred

nursing care

• early identification of growth abnormality> early diagnosis & treatment

• support for disturbed body image/anxiety

• screen & educate about common complications

  • risk for heart disease, HTN, and risk for DM

hypersomatotropism (gigantism, acromegaly)~ nutrition

• at risk for DM, heart disease (atherosclerosis, hypertension)

• low fat, lot salt, whole grain, low sugar options

• maintain healthy weight

pituitary dwarfism~ anterior pituitary disorder

growth hormone deficiency (underproduction of somatotropin [hGH])

pituitary dwarfism: (Hypofunction of anterior pituitary)

• dx: labs hGH, imaging

• causes: genetic defects, severe brain injury (that damages the pituitary), being born without a pituitary gland

• s/sx: results in slow growth, usually small stature, delays in motor skills, bowing of legs

pituitary dwarfism~ tx/nursing considerations

tx: regular injections of synthetic hGH (human growth hormone) before a child’s growth plates have jointed together

nursing considerations:

• identification of children with growth problems/motor delay

• support self esteem, emphasize abilities & strengths, encourage normal peer socialization

• risk for orthopedic conditions

pituitary dwarfism~ nutrition

high risk for obesity (>50%)

• smaller bodies only require ½ as many calories as average sized peers

• may not be as physically active due to orthopedic conditions

• focus on diet and non weight bearing exercise

gigantism/acromegaly vs dwarfism

gigantism (children)

acromegaly (adults)

produced too much hGH

pituitary dwarfism= produced too little hGH

Diabetes Insipidus “dry inside”~ posterior pituitary disorders

underproduction of ADH (antidiuretic hormone/vasopressin)

cause: brain trauma, brain surgery, brain tumors, kidney impairment

s/sx:

• excessive fluid excretion (urination)

• hypotension (hypovolemia can lead to shock)

• hypernatremia (Na+ is concentrated)

• weakness

• 3 P’s: polyphagia, polydipsia, polyuria: voiding up to 20 liters/day; urine specific gravity <1.006 (very dilute)

Diabetes Insipidus~ tx/nursing considerations

dx: labs

treatment: medications, fluids

• desmopressin (similar action to ADH)

• vasopressin (synthetic ADH) to control urinary output

nursing care:

• I&O recorded very accurately

• monitor electrolytes

• daily weights

• assist with self care (pt will be weak)

Diabetes Insipidus~ nutrition

• no known casual role with nutrition

• low salt, low protein may help management

SIADH “soaked inside”~ posterior pituitary disorders

SIADH= syndrome of inappropriate antidiuretic hormone

• excessive secretion of ADH (antidiretic hormone)

• fluid retention (low/no urine output) resulting hyponatremia (it’s diluted), HTN

• causes: medications (SSRIs, SNRIs, opiates) CNS disorders, cancers/chemo, respiratory conditions

• s/sx: edema/fluid retention, severe hypertension, thick concentrated urine, diarrhea, headache, confusion, lethargy, seizures, coma

SIADH~ tx/nursing care

tx:

• medications to block antidiuretic action of ADH

• medication to raise sodium levels

• correction of underlying problems

nursing care

• monitor I&O, sodium levels & mental status

• safety measures to reduce risk of injury if hyponatremic (confusion, lethargy, seizures)

SIADH~ nutrition

restrict fluids (500-1000ml/day)

diabetes insipidus vs SIADH

diabetes insipidus: high urinary output, low levels of ADH, hypernatremia, dehydrated, lose too much fluid

SIADH: low urinary output, high levels of ADH, hyponatremia, over hydrated, retain too much fluid

*Both will present with excessive thirst

thyroid disorders~ common diagnostic tests

blood tests:

• T3, T4, TSH

radiographic evaluations (Thyroid scan)

• pt ingests or is injected with radioactive iodine: x ray performed

  • if thyroid absorbs high amt radioactive iodine= hyperactive= hyperthyroidism

  • if thyroid absorbs very little, it is hypoactive= hypothyroidism

thyroid ultrasound

• use sound waves to visualize size, shape, position of thyroid

• look for cysts, nodules, non invasive

Graves disease~ hyperthyroidism

overproduction of T4 thyroid hormones leading to ↑ metabolic rate

cause: not known, possible autoimmune attack on TSH receptors

s/sx: weight loss, increased appetite, heat intolerance, increased sensitivity to heat, tachycardia, palpitations, arrhythmias, diarrhea, anxiety, nervousness, irritability, insomnia, tremors, increased hair and nail growth, increased sweating

• per table, plus exophthalmos (eye bulging)

• heat intolerance and insomnia

graves disease~ tx/nursing care

tx:

• medications: T4/T3 blockers

• radioactive iodine

• thyroidectomy if non responsive to other treatment

nursing care

• calm environment; low activity

• maintain normal body temperature (possible acetaminophen, cooling measures)

• if exophthalmos (eye bulging) present, protect eyes with patches, eyedrops, artificial tears

graves disease~ nutrition

increased calories & protein needed

hypothyroidism~ thyroid dysorders

deficiency of T3, T4 slows down metabolic processes

Hashimoto’s thyroiditis: chronic autoimmune disease (immune system attacks beta bells in thyroid). more common in women

• Cretinism: (Children) congenital hypothyroidism

  • lack thyroid hormones at birth and childhood

  • s/sx: poor growth, development & intellectual disability

• Myxedema: severe form of hypothyroidism causing swelling of soft tissues, dry/thick skin, decline in mental and physical functioning

  • s/sx: weight gain, decreased appetite, cold intolerance, increased sensitivity to cold, bradycardia, constipation, fatigue, depression, impaired memory, impaired concentration, mental fog, hair loss and thin nails, dry skin

• causes: decrease in thyroid gland activity, removal of thyroid gland, or Hashimoto’s

hypothyroidism~ tx/nursing care

tx: medication- synthetic versions of thyroid hormones with careful titrating

nursing care: assist with adherence to medical regimen (meds, labs)

• assess for and teach signs of Myocardial infarction: MI can result from long periods of slow circulation to hear muscle

hypothyroidism~ nutrition

there is no hypothyroidism diet

• claims abound but there is no actual evidence that eating or avoiding certain foods will improve thyroid function

adequate dietary iodine is essential for normal thyroid function (but most Americans get plenty)

hyperthyroidism vs hypothyroidism

hyperthyroidism: weight loss, increased appetite, heat intolerance, increased sensitivity to heat, tachycardia, palpitations, arrhythmias, diarrhea, anxiety, nervousness, irritability, insomnia, tremors, increased hair and nail growth, increased sweating

hypothyroidism: weight gain, decreased appetite, cold intolerance, increased sensitivity to cold, bradycardia, constipation, fatigue, depression, impaired memory, impaired concentration, mental fog, hair loss and thin nails, dry skin

goiter~ thyroid disorder

enlarged thyroid, visible as a lump in the neck. may be tender

cause: dietary iodine deficiency, Hashimoto’s thyroiditis, or Grave’s disease

• (the thyroid requires iodine to produce hormones)

patient can have hyper or hypothyroidism with goiter (or even neither)

only a problem medically if interferes with swallowing/breathing

goiter~ tx/nursing care

tx:

• thyroid replacement medications help with symptoms and may decrease the size of the goiter

• radioactive iodine treatment can destroy enough cells to shrink the gland

• occasionally surgery is needed if goiter interferes with breathing/swallowing

nursing care: identify pts at risk, address underlying cause, education

goiter~ nutrition

not common in US due to iodized salt

iodine rich foods include:

• seaweed, fish, shellfish, diary, fortified breads, cereals, milk

parathyroid disorders~ common diagnostic tests

• blood tests: PTH, calcium

• urine tests: calcium

• imaging

• biopsy

hyperparathyroidism~ parathyroid disorders

too much PTH (Parathyroid Hormone) results in hypercalcemia

• excess parathyroid hormone (PTH) produced releases too much calcium out of the bone and into the blood stream

• cause: most common is adenoma (non-cancerous growth)

• bones become soft and weak, easily broken

• s/sx: (stones, bones, groans, psychiatric moans)

  • disorientation (from high blood calcium)

  • bone & joint pain

  • fractures

  • fatigue

  • kidney stones

  • GI sx- NVD

hyperthyroidism~ tx/nursing care

tx:

• diuretics and large amounts of fluid to prevent renal stones (flush out calcium)

• thyroid lobectomy to remove part of the thyroid containing the parathyroid

nursing care:

• encourage weight bearing exercise to prevent bones from releasing calcium

• injury prevention until bones are recalcified

• monitor labs

hyperparathyroidism~ nutrition

dietary calcium is limited in some cases (to try to keep blood levels lower)

hypoparathyroidism~ parathyroid disorders

deficiency of parathyroid hormone (PTH) leading to not enough calcium in the blood

causes:

• most common is injury to the glands during thyroid or other neck surgery

• sometimes autoimmune

• rarely genetic

s/sx: low blood calcium leads to:

• tremors & tetany

• low cardiac output, arrhythmias, poor blood clotting

• muscle irritability can lead to laryngospasm or seizures

• hair loss, brittle nails

tetany

involuntary muscle cramp or spasm due to alterations in electrolytes, especially calcium

hypoparathyroidism~ tx/nursing care

tx:

• medications: calcium & vit D

• sedatives or anticonvulsants to prevent seizures

• PTH injections

nursing care

• monitor labs (especially calcium), medications, pt edu

hypoparathyroidism~ nutrition

encourage foods rich in calcium, magnesium, vit D

reduce phosphorus intake (meat, seeds, cheese, milk, soda, canned fish)

adrenal disorders~ common diagnostic tests

adrenal function tests:

• blood tests: ACTH, Cortisol, etc

• urine tests: look for metabolites of catecholamines

• imaging studies: (CT scan, MRI, ultrasonography, x ray)

hyperadrenalism “Cushing Syndrome”~ adrenal disorders

adrenal cortex (adrenal gland) producing too much cortisol, aldosterone, sex hormones
overactive adrenal glands

causes:

• tremors of adrenal glands or pituitary

• medications: steroid use can cause iatrogenic (caused by medical treatment) cushing syndrome

sx:

• abnormal fat distribution (abdomen heavy & hands down, arms & legs are thin, fat pad on back of neck buffalo hump)

• moon face (rounded)

• weakness, softened bones, backaches

• edema, decreased urinary output

• ↓K and ↑ Na and ↑glucose usually present

• HTN

• slow healing wounds, easily bruised

• mood swings common

cushing syndrome~ tx/nursing care

tx:

surgery: removal of tumors or adrenal glands

• lifelong adrenocortical hormone replacement if removal of adrenal glands

second line tx: medications to inhibit cortisol production (eg., ketoconazole [inhibits enzymes])

nursing care:

• protect from injury, infection control, vaccines, skin integrity

• monitor weight, vital signs, electrolytes, glucose levels

cushing syndrome~ nutrition

nutritious foods (fruits & vegetables, whole grains, lean proteins, healthy fats)

adequate calcium & vit D to help strengthen bones (bone loss common)

balanced meal plan and gentle exercise (low impact) to control weight

Addison’s disease~ adrenal disorder

underproduction of Adrenal hormones: cortisol, aldosterone

cause:

• primary: damage to adrenal cortex

  • autoimmune, cancer, infection

• secondary: pituitary malfunction (pituitary not producing enough ACTH so adrenal function ↓)

s/sx:

• dehydration, ↓ BP, extreme fatigue

• Gi disturbance (weight loss, NVD, abdominal pain)

• ↓glucose (hypoglycemia), ↓ sodium (salt cravings), ↓ thyroid

• skin and mucous membranes darken (bronze), thinning hair

addison’s disease~ tx/nursing care

tx:

• fludrocortisone (synthetic aldosterone)

• high sodium diet

nursing care:

• fall risk precautions

• I&Os, monitor BP, electrolytes & blood sugar

addison’s disease~ nutrition

high sodium, high protein

fluid to balance I&O without overloading system

5-6 small meals a day to prevent weight loss

diabetes mellitus~ pancreas

a metabolic condition involving elevated levels of glucose in the blood

type 1:

• autoimmune process; destruction of beta cells in pancreas

• lifelong insulin administration

• most common onset in young people and onset is typically rapid

type 2:

• insulin resistance: the body does not use insulin properly

  • this is the most common cause

• beta cells in the pancreas do not function properly; too little/excess insulin

• most commonly adults over 45 and onset is typically gradual

• can be managed with a combination of all or some of the following: insulin, oral medications, diets, exercise