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the nervous and endocrine systems
coordinate body functions
nervous system releases
neurotransmitters
endocrine system releases
hormones
hormones
bind to target cell receptors
exocrine glands
secrete products into ducts, NOT hormones. sudoriferous glands, sebaceous glands, mucous glands, digestive glands
endocrine glands
secrete hormones; do not have ducts and secrete into interstitial fluid/ diffuse into blood. pituitary, thyroid, parathyroid, adrenal, pineal,
secreting cells
can be found in hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, placenta *NOTE THAT NOT ALL OF THESE ARE PART OF THE ENDOCRINE SYSTEM, BUT THEY PERFORM SIMILAR FUNCTION
endocrine gland locations
hypothalamus, pineal, pituitary, parathyroid and thyroid, thymus, pancreas, adrenals, ovary and testes
hormone activity
enters blood capillary to circulate from a endocrine cell, is released to hormone receptors on distant target cells that contain specific receptors in order to produce action on target cells
lipid soluble hormones
bound to transport proteins; steroid, thyroid, nitric oxide
water soluble hormones
freely into plasma; amine hormones, peptide and protein hormones, eicosanoid hormones. we have more of these
chemical hormone classes
amino acid-based (amino acid derivatives, peptides, proteins), steroids/lipid based (from cholesterol - gonadal and adrenocortical hormones)
hormone response vary
depending on hormone and target cell
hormone responses
- synthesis of new molecules
- changing cell membrane permeability
- transport of substance
- altered rate of metabolic actions
- contraction of smooth or cardiac muscle
lipid soluble hormones bind to
receptors within target cells
steps to lipid soluble hormone action
lipid soluble hormone diffuses into the cell, activated receptor complex alters gene expression, newly formed mRNA directs synthesis of specific proteins on ribosomes, new proteins alter cell's activity
water soluble hormones bind to
receptors on the exterior surface of the target cell
steps to water soluble hormone action
binding of hormone to its receptor, activating G protein activating adenylyl cyclase, which converts ATP to cAMP, cAMP serves as second messenger to activate protein kinase, kinase phosphorylates cellular proteins, which cause reactions that produce physiological responses, phosphodiesterase inactivates cAMP (may occur after step 2 as well)
target cell response to hormone
based on hormone's concentration (hyper and hypo secretion), hormone receptors
synergistic effect
some hormones work well when another is in assistance
antagonistic effect
some hormones oppose the actions of others
up-regulation
target cells form more receptors in response to low hormone levels. can try to correct hypofunction and low regulation of hormone.
down-regulation
target cells lose receptors in response to high hormone levels
short burst hormone secretion regulation
signals from nervous system (adrenal medulla, sympathetic preganglionic neuron), chemical blood changes (blood glucose concentration and release of insulin or glucagon), others hormones (Thyroid stimulating hormone)
most hormone regulation achieved by
negative feedback
negative feedback loop controlling glucocorticoids
hormone of adrenal cortex, when level in the blood decreases, it stimulates the secretion of CRH from hypothalamus that reaches cells in anterior pituitary that secretes ACTH and targets zona fasciculata in adrenal cortex to secrete glucocorticoids.
hypothalamus and pituitary gland work together to
control endocrine glands
anterior lobe
75% of weight of pituitary, secretes 7 hormones; made of glandular epithelial tissue
posterior lobe
made of neural tissue, releases two hormones made by hypothalamus; made of neural tissue
hypophyseal portal system
system within the blood where releasing and inhibiting glands from the hypothalamus are secreted to pituitary gland; two capillaries connected by portal system
negative feedback loops
control secretions of thyrotrophs, gonadotrophs, corticotrophs
growth hormone
most plentiful anterior pituitary hormone, released in bursts by somatotrophs; controlled by growth hormone-releasing hormone + growth hormone-inhibiting hormone
anterior pituitary secretions
human growth hormone (hGH) *doesn't target other endocrine gland*, thyroid stimulating hormone (TSH), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), adrenocorticotropic hormone (ACTH), melanocyte-stimulating hormone (MSH) *action not well known other than others have higher numbers in this hormone*
growth hormone (GH)
somatotropin; stimulates tissues to synthesize and secrete insulin-like growth factors that promote body tissue growth - acts on target cells
thyroid stimulating hormone (TSH)
thyrotropin; synthesis and secretion of thyroid hormones
follicle stimulating hormone (FSH)
gonadotrophs; females initiate development of oocytes and ovarian secretion of estrogens, men stimulate testes to produce sperm
luteinizing hormone (LH)
gonadotrophs; females stimulate secretion of estrogens and progesterone, ovulation and formation of corpus luteum; men stimulate testes to produce testosterone
prolactin (PRL)
lactotrophs; promotes milk production by mammary glands
adrenocorticotropic hormone
corticotropin; secretion of glucocortoids like cortisol
melanocyte-stimulating hormone
corticotrophs; causes darkening of skin when present in excess.
tropic hormones
hormones that stimulate other glands to release their hormones
hypothalamic releasing hormones
stimulating; secretion of hormone from anterior lobe
anterior lobe as master gland
because it can control the function of other endocrine glands
hypersecretion of GH
gigantism, results in adulthood of acromegaly
hyposecretion of GH
pituitary dwarfism
posterior pituitary gland
does not synthesize its own hormones but stores and releases them from axon terminals (oxytocin and anti-diuretic hormone (ADH)) produced by hypothalamus
axons and neurosecretory cells form the
hypothalamohypophyseal tract
ADH on targets
negative feedback; osmoreceptors; ADH targets kidneys and arterioles (small blood vessels) and causes vasal constriction, can work on special parts on the kidney to stimulate reabsorption of water and decreasing urine output. increase in blood volume (too much water in the blood) causes decrease in ADH, vice versa
oxytocin on targets
oxytocin targets uterus and mammary glands for positive feedback control during childbirth and stimulates ejection of milk *NOT LACTATION*, enhances contractions within the uterus
thyroid gland
butterfly shaped gland located anterior to trachea and inferior to larynx; have right and left lateral lobes connected by isthmus
follicular cells
stimulated by TSH to produce thyroxine (T4) (from anterior pituitary), triiodothyronine (T3) that contain iodide ions (amt according to number)
parafollicular cells
produce calcitonin to regulate calcium homeostasis
thyroid hormone actions (T4 thyroxine and T3 triiodothyronine) ***effects all body cells***
increases basal metabolic rate, maintains body temperature, stimulate protein synthesis, use of glucose and fatty acids for ATP, beta receptors attached to epinephrine upregulation, work with hGH and insulin to accelerate body growth
Hyperthyroidism
excessive activity of the thyroid gland; increased metabolic rate (high appetite, low weight)
hypothyroidism
decreased basal metabolic rate (slowed things), low body temperature, cold intolerance, low blood pressure
Thyrotropin-releasing hormone from hypothalamus and thyroid-stimulating hormone from anterior pituitary
stimulate synthesis and release of thyroid hormones: low levels in blood of T3 and T4 stimulates release of TRH, which carried to anterior pituitary releases TSH, released into blood and stimulates thyroid follicular cells, T3 and T4 released into blood by follicular cells, elevated levels inhibits release of TRH and TSH for negative feedback
myxedema
caused by extreme deficiency of thyroid secretion; also known as adult hypothyroidism; if lack of iodine then goiter can develop (enlargement on neck). happens as negative feedback when TSH is over secreted as a response to low TH levels. symptoms include low metabolic rate, thick and dry skin, puffy eyes and chills, constipation, edema, sluggishness, lethargy
Grave's disease
an autoimmune disorder that is caused by hyperthyroidism and is characterized by goiter and/or exophthalmos: bulging eyeballs; symptoms include elevated metabolic rate, sweating and irregular heartbeats, nervousness and weight loss. because antibodies mimic TSH, TH release is stimulated more than it needs to be
parathyroid glands
separate glands (4) on posterior surface of thyroid gland
chief cells
secretion of parathyroid hormone (PTH); activates osteoclasts and stimulates bone resorption for blood calcium concentration.
oxyphil cells
secrete excess PTH in cases of parathyroid cancer
adrenal glands
on top of each kidney; two regions: adrenal cortex and inner medulla (part of the sympathetic division of autonomic nervous system; receives stimulation from preganglionic sympathetic neurons and secretes epinephrine and norepinephrine)
adrenal gland cortex
zona glomerulosa (aldosterone/mineralocorticoids)glucose concentration , zona fasciculata (glucocorticoids and cortisol), zona reticularis (androgens); sympathetic nervous suystem
aldosterone
major mineralcorticoid that regulate sodium and potassium homeostasis "salt-retaining hormone" which promotes the retention of Na+ by the kidneys. na+ retention promotes water retention, which promotes a higher blood volume and pressure, detected when lower blood pressure
mineralcorticoids
secreted by zona glomerulosa that regulates mineral homeostasis
Renin-Angiotnensin-Aldosterone pathway (RAA)
controls secretion of aldosterone (reapsorption of sodium, removal potassium)
glucocorticoids
zona fasciculata, cortisol
secretion of glucocorticoids
regulated by negative feedback and ACTH to help control protein breakdown, glucose formation, lipolysis, resistance to stress, inflammation, immune responses
hypersecretion (cushing's syndrome)
depresses cartilage and bone formation and immune system, inhibits inflammation and disrupts neural, cardiovascular, gastrointestinal function caused by a tumor on pituitary, lungs, pancreas, kidney, or adrenal glands (can be characterized by lump on back of neck)
adrenal medulla
stimulated by sympathetic preganglionic neuron of autonomic nervous system
chromaffin cells
secrete adrenalin and noradrenalin involved in fight or flight
pancreas
both an endocrine and exocrine gland; also belongs to digestive system
pancreatic islits
form acini that are responsible for digestive enzyme secretion that are delivered to the gastrointestinal tract, pancreatic islits overall are responsible for secretion (contain alpha (glucagon), beta (insulin), delta (somatostatin), F (pancreatic polypeptide))
secretion of insulin and glucagon
controlled by negative feedback; insulin by beta cells and glucagon by alpha cells
diabetes mellitus (DM)
type 1 (hyposecretion of insulin) and type 2 (hypoactivity of insulin)
signs of DM
polyuria (large urine output), polydipsia (thirst), polyphagia (hunger and consumption)
type 1 treatment
insulin injections
gonads
ovaries and testes produce gametes
ovaries produce
estrogen and progesterone, relaxin, inhibin. estrogen promotes development of sex organs and reproductive system, progesterone maintains lining of uterus for pregnancy
testes produce
testosterone for secondary sex characteristics, and anabolic effects for protein synthesis and treatment of metabolic problems
pineal gland
secretion of melatonin
thymus
produces thymosin, thymic humoral factor, thymic factor, thymopoietin (maturation of the immune system's T cells)