Endocrine Flashcards
The endocrine system consists of three components
- the cell, which sends a chemical message by means of a hormone
- the target cells, or end organs, which receive the chemical message
- the environment through which the chemical is transported (blood, lymph, extracellular fluids) from the site of synthesis to the sites of cellular action.
The endocrine system controls or regulates…
metabolic processes governing energy, production, growth, fluid and electrolyte balance, response to stress and sexual reproduction.
Endocrine Glands
Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Ovaries Testes Islets of Langerhans
Structures sometimes considered endocrine glands; although they are not usually included
Pineal body
Thymus
GI glands
Placenta
Hormone
a complex chemical substance produced and secreted into body fluids by a cell or group of cells that exerts a physiologic controlling effect on other cells.
Local hormones
create their effect near the point of secretion
General hormones
produced in one organ or part of the body and are carried through the bloodstream to a distant part, or parts, of the body where they initiate or regulate physiologic activity of an organ or group of cells.
Regulation of hormonal secretion is based on:
Negative feedback.
Anterior pituitary
- Master gland
- the endocrine gland primarily responsible for stimulation and inhibition of target glandular secretions
Anterior pituitary hormones
GH –> muscles, bones, organs –> hyper = giantism –> hypo = small stature
Gonadotropin –> sex organs –> hyper = precocious puberty
ACTH –> adrenal cortex
Prolactin –> mammary; milk production –> hyper = too much milk –> hypo = no milk
TSH –> Thyroid –> hyper = overactive thyroid –> hypo = thyroid dysfunction
MSH –> skin
Posterior pituitary hormones
Oxytocin –> uterus; contractions & milk ejection –> hyper = premature ctx –> hypo = delayed/weak ctx
ADH –> kidney (distal tubules) –> hyper = SIADH –> hypo = DI
Thyroid
Thyroxine, T3, T4 –> widespread
Calcitonin –> skeleton –> stim osteoblasts –> hyper = decreased serum Ca –> hypo = weak bones
Parathyroid
PTH –> bone, kidney, GI tract –> stimulates osteoclasts –> hyper = increased serum CA, weak bones
Adrenal cortex
Glucocorticoid (wide spread), Mineral corticoids (kidney), sex hormones
Adrenal medulla
Catecholamines: 1. epinephrine, 2. norepinephrine
Pancrease
Glucagon and insulin
Gonads
Estrogen, progesterone, testosterone
Pituitary gland is controlled by:
either hormonal or neuronal signals from the hypothalamus. Hypothalamus secretes releasing hormones and inhibitory hormones.
Glandular hormones that are not under the control of the pituitary gland are:
glucagon, parathyroid hormone, antidiuretic hormone, aldosterone, and insulin
Two regulatory systems that maintain hemostasis are:
- the endocrine system
- autonomic nervous system
Collectively called neuroendocrine system
Endocrine dysfunction may result from an
intrinsic defect in the target gland (primary) or from a diminished or elevated level of tropic hormones (secondary).
An overproduction of the anterior pituitary hormones can result in:
gigantism (excess GH), hyperthyroidism hypercortisolism (Cushing syndrome), and precocious puberty (excess gonadotropins)
Panhypopituitarism
the loss of all anterior pituitary hormones, leaving only posterior pituitary function intact
**children with this condition should wear a medical bracelet.
Hypopituitarism
is defined as diminished or deficient secretion of pituitary hormones. The consequences of the condition depend on the degree of dysfunction:
Gonad. deficiency: abs./regr. of 2ndary sex charact.)
GH def: delayed somatic growth
TSH def: hypothyroidism
Corticotropin def: manifestations of adrenal hypofunction