Endocrine System Flashcards
What are endocrine glands?
Glands that release hormones into the bloodstream.
What distinguishes endocrine glands from exocrine glands?
Endocrine glands release hormones into the bloodstream, while exocrine glands secrete substances into ducts.
Define hormones.
Compounds released into the bloodstream by endocrine glands that stimulate specific receptors on target organs.
What is a tropic hormone?
A hormone that regulates hormone secretion by another endocrine gland.
Provide an example of a tropic hormone.
Luteinizing Hormone (LH).
What is a non-tropic hormone?
A hormone that exerts its influence on non-endocrine target tissues.
Provide an example of a non-tropic hormone.
Testosterone.
What are steroid hormones primarily composed of?
Cholesterol (lipid compound).
How do steroid hormones affect a cell?
They diffuse through the cell membrane and combine with a specific receptor in the cytoplasm.
What are protein and protein-related hormones primarily composed of?
Protein.
How do protein hormones affect a cell?
They combine with a receptor on the cell membrane, signaling the production of an enzyme.
What mechanism maintains homeostasis of hormone levels?
Negative feedback.
What is the function of the pineal gland?
Secretes melatonin to regulate circadian rhythms.
Where is the pituitary gland located?
In a bony cavity at the base of the brain, just below the hypothalamus.
What are the two parts of the pituitary gland?
Posterior pituitary and anterior pituitary.
What regulates the hormones of the anterior pituitary?
Hypothalamic hormones and feedback from target glands.
What is the releasing factor for Thyroid Stimulating Hormone (TSH)?
Thyrotropin releasing hormone (TRH).
What hormones are produced by the thyroid gland?
Tetraiodothyronine (T4) and triiodothyronine (T3).
What is hyperthyroidism?
Overproduction of thyroid hormones.
What is hypothyroidism?
Underproduction of thyroid hormones.
What causes Grave’s Disease?
The body erroneously produces thyroid-stimulating immunoglobulin (TSI).
List symptoms of Grave’s Disease.
- Increased metabolic rate
- Increased heart rate
- Bulging eyes
- Weight loss.
What is goiter?
An enlarged thyroid gland.
What is the primary effect of growth hormone (GH) before and during puberty?
Longitudinal growth of bone and cartilage.
What condition results from low secretion of growth hormone in children?
Dwarfism.
What is the function of follicle stimulating hormone (FSH) in women?
Stimulates growth and development of ovarian follicles.
What does luteinizing hormone (LH) do in men?
Stimulates production of testosterone.
What hormones do the testes produce?
Androgens, primarily testosterone.
What are the main functions of estrogen?
- Female secondary sex characteristics
- Development of breasts
- Widening of hips.
What is the function of prolactin (PRL)?
Enhances female breast development and stimulates milk production.
What is the function of adrenocorticotropin hormone (ACTH)?
Targets the adrenal cortex to release cortisol.
What hormones are released by the adrenal medulla?
- Epinephrine (adrenaline)
- Norepinephrine (noradrenaline).
What is the primary hormone produced by the adrenal cortex?
Cortisol.
What is the function of oxytocin?
Stimulates contraction of the myometrium and promotes milk ejection.
What is the role of antidiuretic hormone (ADH)?
Regulates water balance in the body.
What is another name for Antidiuretic Hormone?
Vasopressin
What stimulates the contraction of the myometrium?
Oxytocin
What is the trigger for oxytocin release during childbirth?
Pressure on the cervix caused by the fetus’ head
What physiological process does oxytocin promote after childbirth?
Ejection of milk from the mammary glands
Describe the positive feedback loop involving oxytocin during birth.
Pressure on the cervix increases oxytocin release, causing stronger contractions, which further increases pressure
What are the two major effects of Antidiuretic Hormone (ADH)?
- Enhances water reabsorption by the kidneys
- Causes contraction of arteriolar smooth muscle
What regulates the major control for ADH?
Input from hypothalamic osmoreceptors
What are Islets of Langerhans?
Endocrine tissues of the pancreas that secrete insulin and glucagon
What type of cells in the Islets of Langerhans secrete insulin?
Beta cells
What type of cells in the Islets of Langerhans secrete glucagon?
Alpha cells
When is insulin released?
When blood sugar level is high
What is the primary function of insulin?
Decrease blood sugar levels
What happens to glucose in the liver and skeletal muscle when insulin is present?
Converted to glycogen
When is glucagon released?
When blood sugar levels are low
What is the primary function of glucagon?
Increase blood sugar levels
What condition is characterized by inadequate insulin production or action?
Diabetes Mellitus
What are the two types of Diabetes Mellitus?
- Juvenile onset (Type I - insulin dependent)
- Adult onset (Type II - non-insulin dependent)
What causes Type I Diabetes Mellitus?
Complete destruction of beta cells by the immune system
What is a common treatment for Type I Diabetes Mellitus?
Insulin
What is a common characteristic of Type II Diabetes Mellitus?
Reduced sensitivity of insulin’s target cells
What hormone is released by the parathyroid gland when calcium ion concentration is low?
Parathyroid hormone (PTH)
What is the function of parathyroid hormone (PTH)?
Increase calcium ion concentration in blood plasma
What hormone is produced by the thyroid gland in response to high calcium levels?
Calcitonin
What is the effect of calcitonin on blood calcium levels?
Decreases calcium ion concentration
What gland produces Thymosin?
Thymus
What does Thymosin enhance?
- Production of new T-cells
- Immune capabilities of existing T-cells
What are prostaglandins?
Hormones that have a pronounced effect in a localized area
