Endocrine System Flashcards
Endocrine system
secrete chemicals (hormones) into blood
Endocrine system is composed of ..
ductless glands and endocrine tissues
3 types of hormones
- steroids
- hormones derived from amino acids
- peptide and protein hormones
Steroids
derived from cholesterol which is a lipid (testosterone, vitamin D and estrogen)
2 hormones derived from amino acids
- tyrosine
- tryptophan
Tyrosine
amino acid used to make thyroid hormone (thyroxine)
Tryptophan
amino acid used to make serotonin and melatonin
Peptide and protein hormones
formed from chains of amino acids held together by peptide bonds. hydrophilic and water soluble (oxytocin and growth hormone)
Endocrine glands are glands with..
no other function than to secrete hormones
4 endocrine glans
- pituitary gland
- thyroid gland
- parathyroid gland
- adrenal gland
Pituitary gland
suspended from hypothalamus, is in sella turcica of sphenoid bone, highly vascular (allows release of hormones directly into blood)
2 lobes of the pituitary gland
- anterior pituitary
- posterior pituitary
Anterior pituitary secretes hormones that ..
affect growth, metabolism and reproduction
Anterior pituitary hormone secretion regulated by..
hormones released by the hypothalamus
6 Hormones secreted from the anterior pituitary gland
- growth hormone (GH)
- thyroid stimulating hormone (TSH)
- adrenocorticotropic hormone (ACTH)
- Leutinizing hormone (LH)
- prolactin (PRL)
- follicle stimulating hormone (FSH)
Growth hormone
promotes growth or metabolism
Thyroid stimulating hormone
stimulates secretion of thyroid
Adrenocorticotropic hormone
stimulates secretion adrenal steroids
3 reproductive hormones
- luteinizing hormone (LH)
- follicle stimulating hormone
- prolactin (PRL)
Prolactin
stimulates milk formation
Posterior pituitary
An extension of the hypothalamus that is formed from nervous tissue
Hormones produced in the hypothalamus, stored and secreted from the posterior pituitary are..
- oxytocin
- antidiuretic hormone (ADH)
Oxytocin
stimulates uterine contractions during childbirth
Antidiuretic hormone
(vasopressin) stimulates water reabsorption in the kidney
Thyroid gland
on the superior surface of the trachea (below the trachea) butterfly shaped
Thryoid gland is composed of two different cell types each with their own hormones ..
- follicles: epithelial cells
- parafollicles: surrounds the follicle
Follicles of thyroid gland
produce thyroxine (t4) hormone. controls metabolism, growth and development. produced in lumen of the gland and is secreted from the cell.
Parafollicular cells secrete calcitonin which…
stimulates calcium uptake by bone, decreasing plasma calcium (builds bone matrix)
Parathyroid glands are located ..
4 glands located in posterior surface of the thyroid gland
Parathyroid glands secrete
parathyroid hormone (PTH)
Parathyroid hormone increases ..
calcium levels by breaking down bone matrix (osteoclasts)
Adrenal glands located on
superior surface of each kidney
The two adrenal glands
- adrenal cortex
- adrenal medulla
Adrenal cortex secretes..
steroids only
3 layers of adrenal cortex
- zona glomerulosa
- zona fasciculata
- zona reticularis
Zona glomerulosa
secretes mineralocorticoids (mainly aldosterone) for salt balance
Zona fasciculata
secretes glucocorticoids (predominately cortisol which regulates the stress response)
Zona reticularis
secretes androgens (small amounts of testosterone which functions in female sex drive)
2 main hormones of the adrenal medulla
-epinephrine (80%)
-norepinephrine (20%)
(combat short term stress)
Endocrine tissues
found in organs that have additional functions
3 main endocrine tissues
- pancreas (islets of the langerhans)
- hypothalamus
- gonads
Pancreas- islets of the langerhans 2 cell types
- alpha cells
- beta cells
Alpha cells
secrete glucagon: used to increase blood glucose during a hypoglycaemic state
Beta cells
secrete insulin (decrease blood glucose)
Testes
leydig cells secrete testosterone
Ovaries
primary and secondary follicles secrete estrogen and the corpus luteum secretes estrogen and progesterone
Corpus luteum =
estrogen and progesterone
Hormones circulate thought the blood acting on ..
target cells (any cell that has a receptor for specific hormone
Regulating hormones are released from the ..
hypothalamus and regulate the secretion of hormones from the pituitary gland
Parathyroid hormone can increase blood calcium levels by ..
- decreasing calcium excretion from kidney
- increasing vitamin D activation in kidney (which increases calcium reabsorption in intestine)
Hypothalamus has 3 endocrine functions
- produce regulatory hormones that either stimulate or inhibit release of hormones from the anterior pituitary
- synthesizes hormones that are release from posterior pituitary
- nervous functions (control body temp, thirst, urine output, hunger, etc)
Other endocrine tissues
- digestive tract (secretin)
- heart (atrial natriuretic peptide)
- kidney (renin)
- placenta (reproductive hormone)
