endocrine system function and assessment

Endocrine (Ductless) Glands secrete
secreted in response to specific stimulus
circulated by the blood
exerts effects on target tissues with receptors
negative feedback system

posterior - neurohypophysis (ADH, oxytocin)
anterior - adenohypophysis(GH, TSH, ACTH, Prolactin, FSH, LH)

antidiuretic hormone
Stimulated by: - water content in body/dehydration (hypothalamus detects)
action: + water reabsorbed by kidney, - urine output; water into blood = +blood volume/BP; arteriole vasoconstriction (hemorrhage)

action: contraction of the smooth muscle in the uterus and mammary gland
“positive feed back mechanism”

growth hormone
action: +cell division
GHRH (+; hypoglycemia), GHIH (-; hyperglycemia)

thyroid stimulating hormone
target: thyroid
action: stimulates growth of thyroid; secretion of T3, T4
stimulated by: hypothalamus, need for thyroxine (-feedback loop)

aderenocorticotropic hormone
action: stimulates secretion of corticol
stimulated by: physiological stress (injury, disease, hypoglycemia)

action: initiates and maintains milk production by mammary glands

follicle stimulating hormone
action: (gonadotropin) stimulate maturation of ova and sperm
target: ovaries/testes

luteinizing hormone
action: (gonadotropin) ovulation, stimulation of estrogen/progesterone; testosterone
stimulated by: GnRH (hypothalamus)

T3
T4
calcitonin

action: increase energy production, protein synthesis, + cellular respirating of glucose, fatty acid = +metabolic rate = +energy/heat production
essential to physical growth, mental development, reproductive maturation
stimulated by: thyroid stimulating hormone (TSH)

target: bone tissue (esp. important during childhood)
action: maintain normal blood levels of calcium/phosphate; strong/stable bone matrix
stimulated by: hypercalcemia (too much in blood)
calciTONin TONes down serum calcium

4 parathyroid glands
action: antagonist to calcitonin; +Ca/-P in blood
stimulated by: hypocalcemia (inhibited by hypercalcemia)
most important Ca regulator in adults

suprarenal
one of top of each kidney
inner adrenal medulla + outer adrenal cortex

chromaffin cells secrete catacholamines (epi/norepi)
sympathomimetic (mimic sympathetic nervous system)

+ heart rate/force of contraction, vasoconstriction in skin/viscera vasodilation in skeletal muscles dilates bronchioles
decreases peristalsis
stimulates liver to convert glucagon to glucose
+use of fats for energy
+the rate of cell respiration

vasoconstriction in the skin and viscera = +blood pressure

3 steroid hormones
salt sugar sex
aldosterone cortisol sex hormones

reaborb sodium ions to blood and excretion of potassium ions in urine by the kidney

gluconeogenesis (conversion of triglycerides, lactic acid, and some amino acids to glucose) in the liver, increase use of glucose, anti-inflammatory effect

growth spurt in puberty and libido in women

Islets of Langerhans”
alpha cells = glucagon
beta cells = insulin
delta cells = somatostatin

energy production
stimulates liver to catabolize glycogen to glucose (glycogenolysis); + use fats and excess amino acids (gluconeogenesis); + blood sugar levels
stimulated by: hypoglycemia

+transport of glucose from the blood into cells (+permeability of cell membranes to glucose); glucose to glycogen (storage)
-blood glucose = + use of glucose for energy, store excess glucose, - energy production from other food sources
(Works opposite of Glucagon), stimulated by: hyperglycemia

inhibits secretion of both insulin and glucagon, decreased nutrient absorption

- Growth Hormone: - muscle mass, + in fat storage
- TSH/Thyroid Hormone: -basal metabolic rate, energy
-Insulin Secretion: - glucose tolerance, not diabetes

0.5-5 U/ml
+ = primary hypothyroidism
- = primary hypethyroidism

80-200 ng/100ml
- = hypothyroidism
+ = hypoerthyroidism

4-12mcg/100ml
- = hypothyroidism
+ = hyperthyroidism

<25 pg/ml
+ = hyperparathyroidism
- = hypoparathyroidism

8.5-10.5 mg/100ml
+ = some cancers, hyperparathyroidism
- = hypothyroidism

2.4-4.7 mg/dL

+ = hypoparathyroidism
- = hyperparathyroidism

<5ng/mL
+ = acromegaly
- = small stature

2.3-3.1 pg/mL
+ = SIADH
- = diabetes insipidus

<120 pg/ml at 6-8am
+ = addison's disease
- = cushing's syndrome, long term corticosteroid therapy

1.010-1.025
- = diabetes insipidus

5-25 mcg/100ml
+ = cushing's syndrome
- = addison's disease

0.7-6.8mg/24hr
+ = pheochromocytoma

70-100 mg/dL
+ = stress, cushing's syndrome
101-125 = prediabetes
- = hypoglycemia, addison's disease

Blood sugar should be less than 140 mg/dL at 2 hours
140-199 = pre-diabetes

4% - 7%
+ = poor diabetes control

Stimulation Tests
Suppression Tests
Urine Tests: hormone by-product, both VMA and Cortisol collected by 24 hour sample, ice or preservative
Nuclear Scanning: thyroid
CT or MRI
Ultrasound
Biopsy