Endocrine system Flashcards
Endocrine glands
are ductless
secrete hormones directly into the bloodstream
products are released into the interstitial space around the cells, from where they diffuse into the capillaries and reach the target organ
Examples of endocrine glands
pituitary gland ovaries testes thyroid gland adrenal glands pineal body
Both endocrine and exocrine glands are
stomach
pancreas
Exocrine glands
have a duct
secrete/excrete products (metabolites, enzymes and other substances)
products are secreted to the duct, through which they flow to exterior surface
Examples of exocrine glands
sweat glands salivary glands mammary glands liver prostate gland duodenum
Hypothalamus
the main neural control center of the endocrine system = “masterswitchboard”
GNRH (gonadotrophin-releasing hormone)
TRH (thyroid-releasing hormone)
Pituitary gland
pea-sized
“master gland”
controls the function of most other glands and secrete hormones
produces and releases 7 hormones in response to commands from the hypothalamus
TSH
stimulates the thyroid gland to produce thyroid hormones
Growth hormone
act upon certain body tissues, do not affect specific organ
stimulates protein synthesis and cell division in cartilage and bone tissue
regulates the bone and muscle growth and physical development
is important in children to excite growth
Prolactin
act upon certain body tissues, do not affect specific organ
travels to the breast tissue glands of nursing mothers
facilitates milk production
THYROID GLAND
located in the neck/ is found in the lower part of the neck below the larynx
produces 3 hormones – T3, T4, calcitonin
T3, T4 – collectively called the THYROID HORMONE
produced in the follicles of the thyroid gland
affects body growth, metabolic rate, development of bones and skeletal muscle
thyroid hormones affect many vital functions such as heart rate
thyroxine accelerates the release of energy in the tissues
Hypothyroidism
too little thyroid hormone = decreased production of the thyroid hormone
reduced metabolism
one of the common causes is Hashimoto’s disease
hypothyroidism can result from treatment of hyperactive thyroid
changes in the structure of the thyroid gland
can be treated with thyroid hormone pills
Symptoms of hyperthyroidism
Feeling tired Feeling nervous, stressed Feeling warm Shortness of breath during exercise Loss of strength Menstrual problems Weight loss Increased heart rate = rapid heartbeat Diarrhoea Psychological complaints – fear, irritability in some cases the thyroid gland might be enlarged the symptoms don’t occur at the same time
Goitre
enlarged thyroid gland
diffuse/localized
multiple nodules or generalized swelling of the thyroid gland = thyroid enlargement
is one of the most common thyroid problems
it has several causes such as infection
iodine deficiency
benign or malignant disease
malignant disease is extremely rare
Before treating goitre the underlying cause must be determined
can be treated with surgery or with radioactive iodine
Treatment of hyperthyroidism
treatment depending on the cause
can be treated with medication to reduce the production of thyroid hormone
another option is treatment with
radioactive iodine to stop the function of thyroid cells
surgery can also treat it
GRAVES’ DISEASE
it is an autoimmune disease where your body produces antibodies to stimulate the thyroid gland which produces excessive thyroid hormone more than the requirement for normal functioning of the body
It may also cause eye problems
Symptoms of hypothyroidism
Feeling tired Feeling cold Heart problems Increased in weight Depressed feelings Hair loss Hoarse and deeper voice Bowel problems in some cases the thyroid gland might be enlarged
HASHIMOTO’S DISEASE
there is an immune response of the body against the thyroid gland which causes decreased function of the thyroid
Symptoms of goiter
Visible swelling in the neck
Problems with swallowing or breathing
thrill – palpable vibration felt with the hand causes by increased blood flow in diffuse enlargement, for example in Graves’ disease
bruit – audible noise heard through stethoscope over the gland
PARATHYROID GLANDS
are embedded in the back of the thyroid gland secrete PTH (parathormone)