Endocrine System Flashcards
What are the three main functions of the endocrine system
Helps to maintain homeostasis; allows the body to react appropriately to stress; regulates growth, development and reproduction
What is the endocrine system organised into
Endocrine glands; can be tissues and organs
What is the function of endocrine glands
Produce hormones, and release them into the bloodstream
What are hormones
Chemical messengers released into the bloodstream
Where do hormones travel to, and where are they effective
Travel to all parts of the body, but only effective in specific target cells; they work together
Name 4 endocrine glands
Hypothalamus; pituitary; thyroid; pancreas
How many hormones does the hypothalamus produce
9
How many hormones (from the H-T) regulate the anterior pituitary; name them
7; gonadotropin R; thyrotropin R; corticotropin R; prolactin (releasing and inhibiting); growth hormone R; somatostatin I
What are the other hormones produced by the hypothalamus, and where are they released
Oxytocin and antidiuretic; released in the posterior pituitary
Where is the pituitary (master gland) located
Directly below the hypothalamus in Sella turcica of sphenoid
What connects the pituitary gland to the hypothalamus
The pituitary stalk
What are the 2 lobes of the pituitary gland
Anterior adenohypophysis and posterior neurohypophysis
What is located very close to the pituitary gland, that is involved in sight
Optic chiasm
When is the peak secretion of the pineal gland
In 1-5yr olds; 75% lower by puberty
What does the pineal gland produce during the day (at night)
Serotonin (melatonin)
Where is the thymus gland located
In the mediastinum superior to the heart
What hormones does the thymus gland secrete, and what do they regulate
e.g. thymopoietin and thymosins; regulate development and later activation of T-lymphocytes
Where is the thyroid gland (largest gland) located
In the neck, just below the larynx and surrounding the trachea
What are the 2 types of cells in the thyroid gland
Follicular cells and parafollicular cells
What hormones do follicular cells secrete, and what do they regulate
Secrete thyroxine (T4) and triiodothyronine (T3); increase the rate of metabolism
What hormones do parafollicular cells secrete, and what do they regulate
Secrete calcitonin; decreases calcium and phosphate in the blood
How many parathyroid glands are there and where are they located
4; located on the posterior aspect of the thyroid gland, 2 on either side
What hormone do the parathyroid glands secrete, and what does it regulate
Parathyroid hormone; increases the amount of calcium
What does an increase in the absorption of calcium in the blood lead
Increases the resorption of bone to release calcium, and decreases the amount of calcium excreted in the urine
Where are the suprarenal glands located
At the upper pole of each kidney
What 2 distinct regions is the glandular tissue of the suprarenal glands organised into, and what type of tissue makes up each region
Outer cortex (epithelial tissue) and an inner medulla (neural tissue)
What hormones does the suprarenal cortex produce
More than 25 steroid hormones that are synthesised from cholesterol
What are the suprarenal hormones collectively called
Corticoids
Divide the suprarenal hormones into their 3 groups
Mineralocorticoids; glucocorticoids; sex steroids
Where are chromaffin cells located and what do they store and produce
Within the adrenal medulla; adrenaline and noradrenaline
What is the endocrine portion of the pancreas called
Pancreatic Islets (of Langerhands); make up 1% of its weight
What are the main hormones produced by the pancreas, and what do they regulate
Glucagon (alpha cells, increases) and insulin (beta cells, decreases); together they regulate blood glucose levels
What is the function of the other 99% of the pancreas
Exocrine function; produces and secretes digestive enzymes
What is the function of the hormones produced by the ovaries and testis
Regulate the reproductive system
What hormones do the ovaries secrete
Oestrogen and progesterone
What hormone do the testis secrete, and what cells secrete this within the testis
Leydig cells produce, and secrete testosterone
