unit 9 Flashcards
target organ
target sites where hormone acts; has specific protein receptors
amino acid based hormones
made of proteins, peptides, and amines
steroid hormones
crosses membrane easily; made from cholesterol
endocrine system
-Second controlling system of the body
-Uses chemical messengers (hormones) that are released into the blood
hormones control what several major processes
Reproduction
Growth and development
Mobilization of body defenses
Maintenance of much of homeostasis
Regulation of metabolism
prostaglandins
made from highly active lipids that act as local hormones
direct gene activation
used by steroid hormones and thyroid hormones
second messenger systems
used by protein and peptide hormones
direct gene activation steps
- Steroid hormones (and thyroid hormones) diffuse through the plasma membrane of target cells
- Once inside the cell, hormone enters the nucleus
- Then, the hormone binds to a specific protein within the nucleus
- Hormone-receptor complex binds to specific sites on the cell’s DNA
- Certain genes are activated to transcribe messenger RNA
- New proteins are synthesized
second messenger systems steps
hormone (first messenger) -> activates enzyme -> catalyzes reaction to produce second messenger molecule
negative feedback
- maintains hormone levels in blood
- a stimulus or low hormone levels
- stops once an appropriate level in blood is reached
- restores homeostasis and then hormone levels decrease
positive feedback
hormone levels don’t decrease; blood clots, child birth, lactation
tropic hormone
causing release of second hormone from endocrine gland; FSH, LH, TSH and TH, ACTH
hormonal stimuli
endocrine organs are activated by other hormones; most common; hypothalamus secretes hormones that stimulate the anterior pituitary gland to secrete hormones that stimulate other endocrine
glands to secrete hormones
humoral stimuli
changing blood levels of certain ions and nutrients stimulate hormone release; parathyroid hormone and insulin
neural stimuli
nerve fibers stimulate release; under control of sympathetic nervous system; epinephrine and norepinephrine
endocrine glands
ductless glands; hormones directly into blood or lymph (organ that produces hormones)
exocrine glands
organs that produce hormones and other products (mixed)
anterior lobe
produces releasing hormones; proteins or peptides (function through secondary messengers) releasing hormones and inhibiting hormones
posterior lobe
makes products and stores them; ADH and oxytocin making and storing - hypothalamus to posterior
ADH
kidney; urine volume decreases and increases blood pressure
oxytocin
mammary glands and uterine muscles; positive feedback hormone
kidney/intestine
stimulates production of RBC; stimulates active transport of dietary calcium ions
heart
sodium ion reabsorption in kidneys and decreases blood volume and pressure (adrenal cortex)
placenta
hormones to maintain pregnancy; hCG, estrogen, progesterone, hPL, relaxing hormones
effects of aging on endocrine system and body homeostasis
- efficiency of all endocrine glands gradually decreases
- increase of diabetes mellitus and immune system depression, lowers metabolic rate and cancer rates in some areas
- menopause: osteoporosis, inc heart disease, mood changes
How hormones promote body homeostasis
In the pancreas insulin and glucagon maintain blood sugar homeostasis
endocrinology
scientific study of hormones
and endocrine organs
endocrine system process
- Hormones are produced by specialized cells.
- Cells secrete hormones into extracellular fluids and then hormones move to blood stream.
- Blood transfers hormones to target sites known as TARGET ORGANS.
- These hormones then regulate the activity of other cells.
when hormones arouse cells or alter cellular activity:
- Change plasma membrane permeability or membrane potential by opening or closing ion channels
- Activate or inactivate enzymes
- Stimulate or inhibit cell division
- Promote or inhibit secretion of a product
- Turn on or turn off transcription of certain genes
hormones needed to grow
thyroid hormone and GH (abnormally small stature if inadequate amounts) (they need iodine)
process to produce T3 and T4 and hormones involved
hypothalamus -(TRH)-> pituitary -(TSH)-> thyroid (thyroxine T3 and T4 = # of iodine) (myxedema if inadequate amounts)
insulin process
- glucose into cells
- glucose to liver to make more glucagon
- glucose -> fat storage
hypothalamus
produces releasing hormones
and inhibiting hormones to anterior pituitary; makes oxytocin and antidiuretic hormones to posterior pituitary
pituitary gland
stores hormones made by hypothalamus; oxytocin and ADH; tropic hormones; GH and prolactin
pineal gland
Hangs from the roof of the third ventricle; secretes melatonin=sleep/wake cycle and coordinates the hormones of fertility
thyroid gland
base of throat; produces thyroid hormone and calcitonin
parathyroid gland
posterior of the thyroid; Secrete parathyroid hormone (PTH)=regulator of calcium ion homeostasis of the blood (tetany)
thymus
posterior to the sternum; produces thymosin
adrenal gland
on top of kidneys; Adrenal cortex (Mineralocorticoids, Glucocorticoids, and Sex hormones) and adrenal medulla
pancreas
Mixed gland, with both endocrine and exocrine functions; insulin and glucagon = maintain blood sugar
gonads
sex cells and hormones; ovaries (estrogen and progesterone) and testes (testosterone)
thyroid hormone
Needed for tissue growth and development; major metabolic hormone; iodine containing T3 and T4
calcitonin
decreases blood calcium levels
thymosin
Matures some types of white blood cells
Important in developing the immune system
Mineralocorticoids
Regulate mineral (salt) content in blood, particularly sodium and potassium ions
Release of aldosterone is stimulated by
response to a drop in blood pressure
Aldosterone production is inhibited by
blood pressure is too high
Glucocorticoids
Promote normal cell metabolism; resist long-term stressors; Anti-inflammatory properties
Sex hormones
Most of the hormones produced are androgens (male sex hormones), but some estrogens (female sex hormones) are also formed
Adrenal medulla
- Epinephrine (adrenaline)
- Norepinephrine (noradrenaline)
progesterone
Helps in the implantation of an embryo in the uterus
estrogen
Stimulate the development of secondary female characteristics
