Lec 24- Endocrine System Overview and Specific Glands Flashcards
Endocrine gland
Ductless glands that secrete hormones into the blood.
Hormone
A long distance chemical mediator is secreted by an endocrine gland into the blood, which transports it to its target cells.
Neurohormone
Hormones released into the blood by neurosecretory neurons
preprohormones
precursor of prohormones
e.g. preproinsulin
prohormones
are precursors of hormones
e.g. proinsulin
Half-life
is time required for blood level to be reduced by half.
Upregulation
Priming effect.
Occurs when a hormone induces more of its own receptors in target cells.\
Results in greater response on target cells.
Downregulation
Desensitization.
Occurs after long exposure to high levels of polypeptide hormone.
Critical in type II diabetes.
Subsequent exposure to this hormone produces a lesser response.
Due to decrease in # of receptors on targets.
Pulsatile secretion
Most peptide hormones have this.
Prevents downregulation.
Posterior pituitary
store and releases hormones made in hypothalamus.
Anterior pituitary
produces own hormones. Controlled by hypothalamus.
Infundibulum
Hangs off hypothalamus and carries the pituitary gland.
Hypothalamic-hypophyseal portal system
The hypophyseal portal system is a system of blood vessels in the microcirculation at the base of the brain, connecting the hypothalamus with the anterior pituitary. Its main function is to quickly transport and exchange hormones between the hypothalamus arcuate nucleus and anterior pituitary gland.
GH - growth hormone
promotes growth protein synthesis and movements of amino acids into cells.
TSH - Thyroid stimulating hormone
Stimulates thyroid to produce and secrete T4 and T3.
ACTH - Adrenocorticotrophic hormone
stimulates adrenal cortex to secrete cortisol.
FSH - folicle stimulating hormone
stimulates growth of ovarian follicles and sperm production.
LH - lutinizing hormone
causes ovulation and secretion of testosterone in testes.
PRL - Prolactin
stimulates milk production by mammary glands.
Cortisol
CRH hypothalamic hormone. Then ACTH anterior pituitary hormone. Which causes stimulation of adrenal cortex. Cortisol goes to many tissues.
This is the one that suppresses immune system when we wake up and during times of stress.
Sex steroids
Sex steroids, also known as gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate androgen or estrogen receptors.
Mineralcorticosteroids
FIND
Glucocorticoids
FIND
Thyroid gland
Secretes T4 and T3 which set BMR and are needed for growth development.
Follicle cells
outer layer of thyroid follicles that synthesize T4
Thyroxine - T4
Increase BMR. sympathetic mimicking. increases heart rate. Crucial role in normal CNS activity in adults.
Trooodothyronine - T3
Major biologically active form.
Increase BMR. sympathetic mimicking. increases heart rate. Crucial role in normal CNS activity in adults.
Hypersecretion
exaggerates a hormone’s effects and can produce side effects - can be due to benign tumors (adenomas) or cancerous tumors of endocrine glands.
Hyposecretion
diminishes or eliminates a hormone’s effect.
Can be due to destruction of the glands i.e. autoimmune attack.
Hashimoto’s disease - hypothyroidism
hyposecretion of thyroid, due to autoantibodies that bind to and activate the TSH receptor.
Grave’s Disease - hyperthyroidism
hypersecretion of thyroid, due to autoantibodies that bind to and activate the TSH receptor.
Cushing’s syndrome
hypersecretion of cortisol
Addison’s disease
Hyposecretion of cortisol
Diabetes Mellitus Type I - Juvenile diabetes - IDDM
hyposecretion of insulin
Reactive hypoglycemia
hypersecretion of insulin
Myxedema
(inadequate T4 and T3 = hypothyroid)
puffy face, hands, feet
Cretenism
(inadequate T4 and T3 = hypothyroid during development)
severe mental retardation
Exopthalmos
is a bulging of the eye anteriorly out of the orbit.
Characterization of Grave’s disease.
