The Endocrine System I Flashcards
What is the function of the endocrine system?
Acts with the nervous system for communication & coordination to produce homeostasis
hormones are the product of this system
Where do hormones of once released?
Released into interstitial fluid and then diffuse directly into the blood or lymph
Where do hormones go after their in the blood/lymph
They are carried by the blood/lymph to the target cells
Compare hormone action & the NS
Hormone action is slower & longer lasting then actions produced by the nervous system
Why do only target cells respond to the hormone?
Due to specificity
What contributes to the sensitivity of hormones?
The # of receptors present on a target cell
What is down regulation
A decrese in the # of receptors cell that is produced when the (hormone) is consistently very high
What is the result of down regulation?
Decreased sensitivity
What is up regulation
An increase in the # of receptor cells produced when the (hormone) is low
What is the result of up regulation
Increased sensitivity of target cells
What are the 2 things hormones can do to rxn’s?
Inhibit
Stimulate
What are the major types of hormones?
2
Circulating
Lingering
What are circulating hormones?
They are released from their gland into the lymph/blood to be sent to all body areas
Have more lingering effects.
They are eventually metabolically inactivated by the liver & excreted by the kidneys
Describe local hormones
They have an effect on the cells that secreted them & nearby cells before entering the blood circulation
They tend to have a shorter action due to rapid inactivation
What are the types of hormones (by general function)?
3
Tropic hormones
sex hormones
anabolic hormones
Describe tropic hormones
Act by causing other endocrine glands to grow and/or secrete products
What are sex hormones?
Act on reproductive tissue specifically
What are anabolic hormones?
Cause tissue-building (anabolic) reactions to occur in their target cells
How do we classify hormones (by chemical nature)
2
steroid hormones
Non-steroid hormones
Describe steroid hormones
All contain cholesterol
They are hydrophobic
Travel in blood bound to transport & proteins which increase the stability of the hormone in the blood
What are examples of steroid hormones?
Cartisol, aldosterone, estrogen, testosterone, progesterone, thyroid hormone & nitric oxide
What is the purpose of transport proteins?
Prevent small hormone molecules from being filtered out of the blood into the urine (where they would be lost
Allow hormone levels in the blood to build up & provide a ready supply of additional hormones.
What happens once a steroid hormone reaches the target cell?
It readily crosses the plasma membrane & the nuclear membrane to reach it’s receptor, in the nucleus
Describe non-steroid hormones
Protein & amino acid derivatives
They are hydrophilic so they do not cross membranes easy
They travel in the blood freely (no proteins)
What are some examples of steroid hormones?
Protein hormones (insulin, parathyroid growth hormones Peptide hormones (oxytocin, antidioretic AA derivatives (norepinephrine, thyroxinel)
What are second messengers?
Used in non-steroid hormones
The hormone binds to the plasma membrane & the second messenger is activated so the hormone itself never has to enter the cell
What is hormone secretion regulated by?
A negative feedback mechanism
How does the NS influence the endocrine system?
The NS influences the autonomic nervous system & the hypothalamus
What is the hypophysis?
The pituitary gland attached to the hypothalamus (direct link to NS)
Controlled by the hypothalamus
Provides a distinct anatomical & brain connection
Regulates many body functions
- anterior lobe (adenohypophysis)
- posterior lobe (neurohypophysis)
What is the adenohypophysis?
Anterior pituitary
“master gland” of endocrine system
Composed of regular endocrine secretory cells
hormones are controlled by “releasing hormones in the hypothalamus”
most are stimulatory
Hormone secretion is under chemical control
What are the hormones of the adenohypophysis?
7
Growth hormone (GH) Thyroid - stimulating hormone (TSH) Adrenocorticotropic Hormone (ACTH) follicle - stimulating hormone (FSH) Lutenizing hormone (LH) Prolactin Melanocyte - Stimulating hormone
What is the growth hormone?
-somatotropin
-stimulates the division of cells and growth in the body via protein synthesis
-
What are the disorders of GH hormones?
1) gypersecretion - giantism and acromegaly
2) hyposecretion - hypopituitary dwarfism
Whare are the 2 releasing hormones in the hypothalamus?
1) GHIH
2) GHRI
What is the thyroid stimulation hormone?
controlled by the thyroid releasing hormone
What is the adrenocorticotropic hormone?
controls the release of cortical from the adrenal gland
What occurs onces the hormone reaches the nucleus?
directly influences the DNA
What can excessive stress cause?
it can override negative feedback resulting in too much cortisol
What is the follicle-stimulating hormone?
triggers the onset of puberty
What does the FSH affect in females?
secretion of estrogen
What does FSH affect in men?
development of tubules and sperm production
also helps develop gonads
What is gonadotropin?
hormone that contirbutes to gonad development
What is the lutenizing hormone?
females : stimulates ovulation and the secretion of estrogen and progesterone
males: stimulates testes and the release of testosterone
What is prolactin?
hormone that helps to initate brease development and milk production
What is the melanocyte stimulating hormone?
uncertain of true function
What are the neurohypopjhysis?
posterior pituitary .. composed of neural tissue
What hormones does the neurohypophysis secrete?
ocytocin and antidiuretic hormone
What is the antidiuretic hormone?
promotes water reabsorbtion in the kidneys .. controls blood volume and pressure
What does alcohol do to ADH?
inhibits it
results in dehydration
What does hypsecretionof ADH cause?
results in diabeties inspinatus
What is oxytocin?
released in large amounts during child birth
stimulates uterine contractions
What is the pineal gland?
regulates the bodies biological clock
What is melatonin
secreted by the pineal gland
can induce sleep levels
can influence the onset of puberty
What is the thyroid gland?
largest endocrine gland
highly vascularized
What hormones does the thyroid gland produce?
thyroid hormone and calcitonin
What is collid?
throglobylin attached to iodine
gives rise to the thyroid hormone
What are T3 cells?
triiodothyromine
What are T4 cells?
tetraiodthyronine
What is affected by the thyroid hormone
everything except the brain,testes, uterus, spleen and the gland itself
How hows TH affect tissue production?
aids in tissue growth and development
especially skeletal and nervous tissue
What carries T3 and T4 in the blood?
proteins:
1) thyroxine
2) abumin
What happens when our body lacks iodine
enlargement of the thyroid gland
called a goiter
What is graves disease?
hypersecretion of the thyroid hormone
What is cretinism?
hyposecretion of the thyroid hormone
What is myxedema?
hyposecretion of TH in adults
