Endocrine Flashcards
Endocrine Glands
Putuitary, Thyroid, Parathyroid, Adrenal, Pineal
Responses occur more slowly, but tend to last longer than the nervous system.
Ductless
Hormones
long-distance chemical signals that travel in blood and lymph
Autocrines and Paracrines
Are local chemical messengers and will not be considered part of the endocrine system
Amino acid based hormones
The majority: Amines, thyroxine, peptides, proteins
Steroids
Synthesizes from cholesterol. Gonadal and adrenocortical hormones. Affect the DNA of the cell.
Hormone action on cells
Alters plasma membrane permeability by opening or closing ion channels.
Stimulates synthesis of enzymes and other proteins
Activate or deactivate enzymes inducing secretory activity.
Stimulates mitosis
Water-soluble hormones
Amino acid based hormones. Cannot enter target cells, so act on plasma membrane receptors. Coupled by G proteins and start second messenger system.
Lipid-soluble hormones
Steroid and thyroid hormones.
Act on intracellular receptors that directly activate genes.
cAMP signaling mechanism
Hormone binds to receptor
Receptor activates G protein
G protein increases or decreases adenylate cyclase
AC converts ATP to cAMP (second messenger)
cAMP activates protein kinases
Large cascade occurs within cell
Up-regulation
target cells form more receptors in response to decreased levels of hormones
Down-regulation
target cells lose receptors in response to high levels of hormone
Many hormones travel on…
Albumin
Most hormones that are not bound have…
a short half-life in the body
Permissiveness
One hormone cannot exert its effects without another hormone being present
Synergism
More than one hormone produces the same effect on a target cell
Antagonism
One or more hormones oppose the actions of another hormone
Humoral Stimuli
Changing blood levels of ions and nutrients directly stimulates secretion of hormones.
Hormonal stimuli
Hormones stimulate other endocrine glands to release their hormones.
Posterior pituitary (lobe)
Pituicytes and nerve fibers
Secretes Oxytocin, ADH (actually made in hypothalamus)
Anterior Pituitary
TSH, FSH, LH, ACTH, GH, PRL (prolactin)
Growth Hormone
Stimulates most cells, but targets bone and skeletal muscle.
Promotes protein synthesis, encourages use of fats for fuel.
Enhances body protein, uses fat stores, conserves carbs.
GHRH, GHIH
Growth hormone releasing and inhibiting hormones made in the hypothalamus.
Too much GH
In children results in giantism
In adults results in acromegaly (large jaw, long-fingered hands, big feet, long brow.)
Too little GH
pituitary dwarfism
Thyroid stimulating hormone
Thyrotropin (TSH).
Produced by anterior pituitary.
Stimulates normal development and secretory activity of the thyroid.
TRH
Thyrotropin releasing hormone (released from hypothalamus) regulates TSH .
Adrenocorticotropic Hormone (Corticotropin)
Secreted by the anterior putuitary. Stimulates adrenal cortex to release corticosteroids.
regulated by CRH in the hypothalamus
LH and FSH
LH promotes FSH which promotes gamete production.
Prolactin (PRL)
Secreted by lactotrophs of the anterior pituitary.
stimulates milk production in breast tissue.
ADH and Oxytocin are released in response to…
Nerve impulses
Oxytocin
Stimulates uterine contractions during childbirth
Triggers milk ejection
Plays a role in sexual arousal
Pituitary tumors
Symptoms include bilateral decrease in visual field.
Can be seen on CT at sella tursica
ADH
Synthesized by hypothalamus and released by posterior pituitary.
ADH deficiency
DIabetes Insipidus (mimicks diabetes)
Not retaining water or sodium
polyuria
ADH hypersecretion
Hypertension
Congestive heart failure
Edema
Thyroid Gland
Produces calcitonin, TH (T3 is more active than T4)
Thyroid Hormone
Major metabolic hormone. Increase metabolic rate and heat production. Maintains blood pressure Tissue growth, developmental growth Reproductive capabilities
Action of TH
Diffuses into nucleus and acts on DNA synthesis which leads to protein synthesis
Hypothalamic TRH regulates TH release
Hypothyroidism
Weight Gain, Low metabolism, fatigue, depression, constipation.
Dx, TSH and T4
Hashimoto’s thyroiditis: may see goiter
Tx: Synthroid
Hyperthyroidism
High metabolism, irritability, palpitations, sweating, diarrhea, high appetite, tremmor
Grave’s disease: exopthalmus (surgical)
TSH and T4 are used to diagnose
Tx: destroy thyroid gland: radioactive iodine
Calcitonin
Produces by parafollicular cells.
Antagonist to PTH
Inhibits osteoclast activity
Reduces blood Calcium
Parathyroid Glands
Chief cells release PTH
Most important hormone in Ca homeostasis
Stimulates osteoclasts to digest bone matrix
Promotes activation of vitamin D
Hyperparathyroidism
Hyperplasia of parathyroid gland, adenoma
- Bones soften and deform
- Elevates Calcium, kidney stones
Tx: Removal of parathyroid gland(s)
Hypoparathyroidism
Following gland trauma or removal.
Hypocalcemia
Results in tetany, respiratory paralysis, and even death.
Adrenal Medulla
Made of nervous tissue, part of the sympathetic nervous system. Secretes Epi and Norepi
Adrenal Cortex
Three layers of glandular tissue that synthasize and secrete corticosteroids.
Zona glomerulosa
Makes aldosterone
Zona fasciculata
glucocorticoids and small amounts of androgens and estrogens
Zona reticularis
andosterone et. al
Mineralocorticoids
Aldosterone is the most potent in the body.
Regulates electrolytes in the body
Regulated by ACTH
Aldosteronism
Hypersecretion due to adrenal tumors.
Hypertension
Excretion of K leading to abnormal functions of neurons and muscle
Glucocorticoids
Keep blood sugars relatively constant.
Cortisol - most potent glucocorticoid
Cortocosterone - less potent
Under control of ACTH
Hypersecretion of Cortisol
Cushings Syndrome Depresses cartillage and bone formation inhibits inflammation depresses immune system Buffalo Hump
Hyposecretion of Cortisol
Addison’s disease
Weight loss
Hypotension
severe dehydration
Gonadocorticoids
Sex hormones
Most are androgens (male sex hormones)
Converted to testosterone in tissue cells
Estrogen in females
Pineal Gland
Secretes melatonin
- timing of sexual maturation and puberty
- day/night cycles
Pancreas
You know
Acinar Cells
Produce enzyme rich juice for digestion
Pancreatic Cells
Islets of Langerhans contain endocrine cells
Alpha Cells
Produce glucagon (hyperglycemic hormone)
Beta Cells
Produce insulin (hypoglycemic hormone)
Somatostatin
inhibits insulin and glucagon
Glucagon
Acts on liver
Breakdown of glycogen to glucose
Synthesis of glucose
Insulin
Lowers blood glucose levels
enhances membrane transport of glusose into fat and muscle cells
Diabetes Mellitus
Due to hyposecretion or hypoactivity of insulin.
cellular membranes are resistant to insulin
- polyuria
- polydipsia
- polyphagia
Hyperinsulinism
Excessive insulin secretion
- hypoglycemia
- decreased LOC
DKA
Generally occurs in Type I diabetes Marked hyperglycemia Dehydration and increase in ketones (acidosis) Need fluids and insulin initially high K, then hypokalemia
End organ effects of DM
Cardiovascular disease Retinopathy Peripheral Neuropathy Kidney Failure (microprotinuria) - should be on ACE inhibitor to protect kidneys
