Term | Definition |
exocrine glands | glands that have ducts through which they release hormones |
endocrine glands | ductless glands that secrete hormones directly into the bloodstream |
Hormones | are chemical messengers that change the activity of target cells. Often they
increase or decrease a secretion made by the cell. |
Peptin | (protein hormones) – most hormones
Receptors are in the cell membrane |
Steroids | sex hormones and adrenal hormones, Based on cholesterol, Receptors either enter the nucleus bound to hormone or are already
within the nucleus, Change expression of genes by the target cell |
Hormones Function | originate at a specific site
target specific cells via receptors
can affect cells far from the gland
effects of hormones are relatively slow compared to the nervous system |
Receptors | Allow hormones to enter specific target cells
Change shape when the hormone binds
When the hormone binds to a receptor, the receptor activates G proteins |
g protiens | activate another protein in the cell membrane called an effector molecule |
Effector molecule | a reaction that changes ATP to cyclic
AMP (cAMP) |
cyclic AMP | acts as a catalyst for a reaction that begins a series of enzymatic reactions that communicates a message to the cell. This series
of reactions is called signal transduction. |
signal transduction | One signal transduction series
that is well understood removes a glucose from glycogen in the liver in the
last reaction of the series |
enzymes | provide a favorable site for an enzymatic reaction but the enzyme itself is not
changed |
enzymes nature | the original signal from a
hormone molecule is amplified many times |
hypothalamus | new “master” gland because it secretes releasing and inhibiting hormones that regulate release of hormones from the pituitary
GHRH |
pituitary | forms from a fusion of endocrine (anterior pituitary) and neural (posterior
pituitary) tissue during embryonic development |
Anterior pituitary | MSH seems to be involved in control of appetite in people |
Growth hormone | targets muscle cells and the epiphyseal plate of growing
bones and causes them to increase in size and divide |
Growth hormone Work directly | by releasing fat reserves and
Stimulating release of glycogen from liver. Growth hormone has a
diabetogenic effect |
Growth hormone Work indirectly | through IGF’s, insulin-like growth factors, by
stimulating uptake of amino acids for making proteins and sulfur for making cartilage. Building processes like these are anabolic processes |
Hypersecretion of GH | gigantism |
gigantism | – cardiovascular problems are
common in gigantism or acromegaly - growth of hands, feet, face, organs after attaining adult height |
Hyposecretion of gh | Achondroplasia and Laron syndrome |
Achondroplasia | usually the parents are normal height. The gene
for achondroplasia is a dominant gene from new mutation during embryonic development. |
Achondroplasia con't | Since it is dominant, the mutation in either the maternal or paternal copy produces the trait. Two copies are usually lethal. |
Laron syndrome | recessive autosomal defect in GH receptor |
Human GH | can be produced by recombinant gene technology
There is little evidence that giving normal children extra GH affects their
adult height |
Human GH con't | Lower levels of GH as people age mean higher percent of body is fat.
Effects of giving GH to normal people may include Cancer, diabetes, joint pain and edema |
Thyroid stimulating hormone | Negative feedback with levels of thyroid hormones |
Adrenocorticotropic hormone | ACTH – stimulate adrenals to release
corticosteroids, especially glucocorticoids released during stress |
Gonadotropins | FSH stimulates maturation of gametes in females and males. LH stimulates ovulation in females. |
Prolactin | stimulates production of milk
Nursing stimulates further production. Prolactin is found in males. |
Posterior pituitary | Is a storage site for two hormones that are made by nuclei in the hypothalamus |
Oxytocin | uterine contractions and milk let-down reaction In men and women is associated with sexual pleasure and pleasurable
feelings from touching. It is sometimes called the cuddle hormone. |
ADH | Increases the return of water to the bloodstream at the kidney tubules
Alcohol consumption inhibits ADH |
Diabetes insipidus | can be caused by injury to the hypothalamus
This condition is not serious as long as the person is conscious and can drink fluids. There is no change in blood glucose levels associated with diabetes
insipidus |
Thyroid hormone – | also called T4. Affects essentially all cells except brain, gonads, thyroid itself.
Affects basal metabolic rate via glucose metabolism. Is necessary for normal development of skeletal and nervous systems |
Hypothyroidism – | overweight, sluggish, mental lethargy, feeling cold,
constipation, dull skin, coarse hair |
Hyperthyroidism – | underweight, nervous, hyperactive, feeling hot, diarrhea, thin skin, fine hair |
Hypothyroidism - | untreated in babies causes stunting of growth and mental retardation
– called Cretinism |
Goiter – | thyroid is unable to make thyroid hormone due to a lack of iodine in the diet Low levels of TH result in high levels of TSH and enlarged thyroid. Goiter belt was once
in the Midwest where iodine-rich seafood not available |
Grave’s disease – | autoimmune disease where an antibody mimics TSH and results in high levels of TH
Bulging eyes are a characteristic symptom also sweating and nervousness |
Calcitonin | is released by the thyroid. Calcitonin increases uptake of calcium from the
bloodstream. This hormone is mainly important during childhood when bones are
growing. |
Parathyroids – | release PTH which is the antagonist of calcitonin. Cancer of
the parathyroids can result in spontaneous fractures and loss of height |
Mineralocorticoids – | aldosterone, regulation of blood pressure by
affecting retention of salts and water. Water follows salt. |
Glucocorticoids – | mostly cortisol –release energy in the form of glucose from liver and breakdown of fats and proteins. Depress immune system
and inflammation.
Help maintain normal blood sugar levels |
Gonadocorticoids – | androgens -precursors of testosterone- and estrogens in both sexes Source of testosterone in women Hypersecretion results in virilization – beard in women |
Medulla | Extension of sympathetic nervous system. Secretes mostly epinephrine – |
epinephrine – | increased volume of blood to the heart and muscles and relaxed bronchioles |
Norepinephrine – | has a greater effect on peripheral vasoconstriction and blood pressure |
Cushing’s – | oversecretion of glucocorticoids syndrome may be caused by pituitary tumor or long-term use of steroids for inflammatory diseases. |
Cushing’s – Symptoms | include edema giving the person a “moon” face buffalo hump of fat behind the neck, severe infections fatigue, and muscle weakness |
Addison’s disease – | undersecretion of aldosterone.
Dehydration is likely |
pancreas | targets mainly liver and muscle cells
Brain, spleen, pancreas itself can receive glucose without insulin |
Glucagon by alpha cells | Stimulates release of glucose into bloodstream
Promotes breakdown of glycogen to glucose |
Insulin by beta cells | Stimulates uptake of glucose from bloodstream |
Diabetes mellitus
Type I – | juvenile onset |
Polydipsia | excess thirst |
Polyuria | excess release of urine |
Polyphagia | excess hunger |
Viscous blood - | excess glycoproteins on red blood cells can cause strokes, gangrene, and ketoacidosis |
causes of Diabetes mellitus
Type I – | Genetic predisposition
Production of antibodies to a protein similar to beta cells and destruction of beta cells |
Type II diabetes | Incidence increases with age
In overweight and inactive people
Loss of sensitivity of receptors for insulin
Pool of receptors is present in the cytoplasm |
Diabetes insipidus – | caused by damage to hypothalamus or posterior
pituitary so too little ADH is secreted
Same three p’s, but glucose levels are not involved |
Thymus gland – | secretes hormones necessary for development of T lymphocytes |
Pineal gland | Secretes melatonin Indirect connection to the amount of light entering the eyes
Involved in diurnal cycles of alertness
Reproductive cycles of animals with seasonal reproduction |
Atrial natriuretic peptide | lowers blood pressure by inhibiting release of
renin and aldosterone |
Kidney | raises blood pressure and works with aldosterone in the RAAS
system |