Endocrine System Flashcards
What is the role of the endocrine gland?
Endocrine gland - secrete hormones into the blood
What is the role of the exocrine gland?
Exocrine glands - secrete substances into ducts that transport them to external environment (eg. sweat, saliva, digestive enzymes)
What are the functions of hormones?
Regulate the growth and development of tissues and organs
Regulate metabolic process
Regulate chemical composition of the blood and internal environment
Cause contraction of cardiac muscle and smooth muscle
What are the components of the endocrine system?
Parathyroid glands (4) - posterior portion of the neck
Thyroid gland
Adrenal glands
Pancreas
Pineal gland
Pituitary gland
Hypothalamus
Ovaries
Testes
Describe how the anterior pituitary gland works.
Hypothalamic neurons secrete releasing/inhibiting hormones
Hormones enter the capillary network + travel down to the anterior pituitary
Hormones stimulate/inhibit the release of pituitary hormones
Pituitary hormones enter the bloodstream
Describe how the posterior pituitary gland works.
Hypothalamic neurons secret the “pituitary” hormones
Hormones travel down the axons to the posterior pituitary (stored in the axon terminals)
Action potentials reaching the axon terminals stimulate the release of the hormones into the bloodstream
What are two examples of anterior pituitary gland hormones?
Human Growth Hormone (hGH)
-release of growth factors which stimulate growth and metabolism
Thyroid-Stimulating Hormone (TSH)
-release of thyroid gland hormones (T4/T3)
Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
-ovulation and the release of estrogen/progesterone from the ovaries
-sperm production and the release of testosterone from the testes
Prolactin
-production and release of milk in the mammary glands
Adrenocorticotropic Hormone (ACTH)
-release of glucocorticoids from the adrenal cortex
Melanocyte-Stimulating Hormone
-unknown (may stimulate the production of melanin by melanocytes in the skin)
What are the two types of posterior pituitary gland hormones?
Oxytocin
-contraction of smooth muscle in uterine wall during labor
-release of milk in the mammary glands after delivery
-there is some evidence that it may be associated with orgasm
Antidiuretic Hormone (ADH)
-inhibits production of urine in the kidneys
-causes general vasoconstriction (increased blood pressure)
What is the pineal glands? What does it do?
-Small gland in the posterior portion of the roof of the third ventricle
Stimulation by the hypothalamus causes it to secrete melatonin, which induces drowsiness
Visual input from the eyes either stimulates (dark) or inhibits (light) the secretion of melatonin
What are the hormones of the thyroid glands?
T4 and T3
-Increases metabolism of nutrients (by increasing cellular oxygen consumption)
-Increases body temperature (by increasing cellular heat production)
-Increases heart rate + force of contraction (by enhancing the effects of catecholamines)
-Regulates growth and development (especially of the nervous system)
Calcitonin
-Decreases Ca++ in the blood (by inhibiting osteoclasts and increasing Ca++ uptake in bone)
Describe the parathyroid glands.
Stimulated by Ca++ in blood
Secrete parathyroid hormone (PTH)
Main function is to increase Ca++ in the blood
What are the two types of cells in the pancreas?
Acrini cells - secrete digestive enzymes into the GI tract
Islet cells - secrete hormones into the bloodstream
What is the role of the adrenal glands?
Increase in sympathetic (fight or flight) responses in various tissues around the body
Heart - increases heart rate and force of contraction
Lungs - airway dilation
Liver - glycogen breakdown and release of glucose
What are the hormones of the ovaries?
Estrogen and Progesterone
-regulates menstrual cycle
-maintains pregnancy and prepares the mammary glands for lactation
- development of female reproductive tissue and female secondary sex characteristics (eg. breast enlargement, hip widening)
Relaxin
-”relaxes” ligaments around the pelvis and elsewhere by affecting collagen production and breakdown
-stimulates dilation of the cervix and inhibits uterine contractions during labor
What is the hormone of the testes?
Testosterone
-regulates production of sperm
-development of male reproductive tissue and male secondary sex characteristics (eg. increased muscles/bone mass, growth of body hairs)
