Endocrine System(Complete) Flashcards
What are hormones?
Chemical messengers produced by endocrine glands.
They travel in the bloodstream to target an organ, where they cause a response.
What are the chemical nature of many hormones?
Proteins
What hormones are made using cholesterol?
Oestrogen
Progesterone
Testosterone
What features do endocrine glands have?
They are ductless glands
They secrete hormones directly into the bloodstream
GIve examples of endocrine glands.
Pituitary gland
Thyroid gland
Adrenals
What features do exocrine glands have?
They have ducts
They deliver their secretions through ducts that carry them to their destination
Give examples of exocrine glands.
Salivary glands
Sweat Glands
Tear Glands
Compare the endocrine and the nervous system.
Endocrine system: Chemical transmission Slower action Widespread- many target organs Long-lasting effect
Nervous system: Electrical transmission Fast action Localised-specific target organs Short term effects
Explain why hormonal responses are slower than nervous responses.
Hormonal responses are chemical
Nervous responses are electrical
Where is the pituitary gland located?
The base of the brain
What hormone does the pituitary gland produce?
Human growth hormone
What is the function of the human growth hormone?
Causes elongation of the skeleton
It stimulates body cells to absorb amino acids and build protein
Where is the pineal gland located?
Within the brain
What hormone does the pineal gland produce?
Melatonin
What is the function of melatonin?
It causes mental relaxation and sleep
Enhances immunity
Where is the hypothalamus located?
Under the thalamus
Within the brain
What hormone does the hypothalamus produce?
TRH-Thyroid Releasing Hormone
What is the function of TRH?
It stimulates the pituitary gland to secrete TSH-Thyroid Stimulating Hormone
Where is the thyroid gland located?
In the neck, on the trachea
What hormone does the thyroid gland produce?
Thyroxine
What is the function of thyroxine?
Regulates the rate of metabolism, eg how fast mitochondria undergo aerobic respiration.
Where are parathyroids located?
Within the thyroid gland in the neck
What hormone do parathyroids produce?
Parathormone
What is the function of parathormone?
Regulates calcium metabolism, causes removal of calcium from the bone and adds it to blood plasma.
Where is the thymus gland located?
Behind the sternum
In the upper thoracic cavity
What hormone does the thymus gland produce?
Thymosin
What is the function of thymosin?
Causes B and T lymphocytes to mature and fight infection
Where are adrenal glands located?
On top of each kidney
What hormone do the adrenal glands produce?
Adrenaline
What are the functions of adrenalin?
improved mental alertness
Increases heart and breathing rates
Where are islets of Langerhans located?
Within the pancreas
What hormone do the islets of Langerhans produce?
Insulin
What is the function of insulin?
Regulates blood glucose levels by stimulating muscle, fat and liver cells to absorb excess glucose from blood and store it as glycogen
Explain why the pancreas may be described as a dual function gland.
The islets of Langerhan within the pancreas carry out the endocrine function by secreting the hormone insulin
Most of the remainder of the gland acts as an exocrine gland by secreting pancreatic juice with digestive enzymes into the pancreatic duct and into the duodenum
Give 2 hormone supplements.
Insulin
Oral contraceptive pills
What is the role of insulin?
It is injected in the treatment of diabetes as insulin deficient
What is diabetes?
A disease that is caused by the failure to make insulin or the inability of cells to absorb insulin
What are the typical symptoms of diabetes?
High blood glucose levels Glucose present in urine Severe thirst Weight loss Fatigue
How is diabetes treated?
Injections of insulin
Controlling carbohydrates in the diet
Regular exercise
What hormones are found in oral contraceptive pills?
Oestrogen
Progesterone
What is the function of the oral contraception pill?
High levels of oestrogen and progesterone inhibit LH and FSH
Ovulation can no longer occur
What are the symptoms of a deficiency of thyroxine?
In children- reduced mental and physical development resulting in cretinism In adults- causes myxoedema: Physical and mental fatigue Weight gain Hair loss
What are the corrective measures taken for someone with a deficiency in thyroxine?
Adults- ingest thyroid-hormone tablets called Eltroxin
Newborn babies- given thyroxine to prevent cretinism if thyroxine levels are low
What are the symptoms of an excess of thyroxine?
Goitre- an enlarged thyroid gland Grave's disease: Raised heart and breathing rates Weight loss Bulging eyes
What are the corrective measures taken for someone with an excess of thyroxine?
Surgical removal of a measured portion of thyroid gland
Ingesting radioactive iodine
What is negative feedback?
When the level of a hormone in the blood controls the production of another hormone or itself
Describe the control mechanism for thyroxine production.
Thyroxine levels in the blood are low:
The pituitary gland secretes TSH
TSH travels in the bloodstream to the thyroid gland and stimulates the production of more thyroxine
This causes the levels of thyroxine to increase
An increased level of thyroxine inhibits the production of TSH which in turn reduces the levels of thyroxine
