Endocrine System Flashcards
endocrine glands synthesize and secrete ____ directly into the ___ ____
endocrine glands synthesize and secrete HORMONES directly into the CIRCULATORY SYSTEM
list the endocrine glands or organs that secrete hormones
- pituitary
- hypothalamus
- thyroid
- parathyroids
- adrenals
- pancreas
- testes
- ovaries
- pineal gland
- kidneys
- gastrointestinal glands
- heart
- thymus
Where are the adrenal glands located? What do they consist of?
on top of the kidneys. They consist of the ADRENAL CORTEX and the ADRENAL MEDULLA
where is adrenocorticotropic hormone (ACTH) produced and what does it stimulate?
ACTH is produced by the anterior pituitary gland in response to STRESS.
It stimulates the ADRENAL CORTEX to produce CORTICOSTEROIDS
3 major classes of corticosteroids:
- GLUCOCORTICOIDS (e.g., cortisol and cortisone)
- MINERALOCORTICOIDS (e.g., ,aldosterone)
- CORTICAL SEX HORMONES (e.g., androgens)
what are glucocorticoids involved in?
glucocorticoids, such as CORTISOL and CORTISONE, are involved in GLUCOSE REGULATION and PROTEIN METABOLISM.
Glucocorticoids RAISE BLOOD GLC LEVELS by promoting PROTEIN BRAKDOWN and GLUCONEOGENESIS and decreasing protein synthesis.
Antagonistic to effects of insulin
role of mineralocorticoids?
mineralocorticoids, like ALDOSTERONE, regulate plasma levels of SODIUM and POTASSIUM and the TOTAL ECF VOLUME.
Aldosterone causes active reabsorption of sodium and passive reabsorption of water in the NEPHRON of the KIDNEY. This results in an increase in BLOOD VOLUME and BP.
What happens when there is an excess production of aldosterone?
this results in an excess retention of water and resulting high blood pressure
Overproduction of androgens in females may lead to
masculinizing effects, such as excessive facial hair
What does the adrenal medulla produce?
epinephrine and norepinephrine (i.e. catecholamines)
name the slender cord which connects the pituitary gland to the hypothalamus
infundibulum
direct vs tropic hormones
direct hormones = act directly on their target organ
tropic hormones = stimulate other endocrine glands to release hormones
Tropic hormones of the ANTERIOR PITUITARY:
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Adrenocorticotropic hormone (ACTH)
- Thyroid-stimulating hormone (TSH)
Direct hormones of the ANTERIOR PITUITARY
- Prolactin
- Endorphins
- Growth hormone (GH)
- Melanocyte-stimulating hormone (MSH)
role of FSH
in women, FSH causes MATURATION OF OVARIAN FOLLICLES, which in turn secrete ESTROGEN.
in men, FSH stimulates MATURATION OF THE SEMINIFEROUS TUBULES and SPERM PRODUCTION
role of LH
In women, LH stimulates OVULATION and maintenance of the CORPUS LUTEUM. Also responsible for regulating progesterone secretion in women.
In men, LH stimulates the interstitial cells of the testes to synthesize testosterone
ACTH role
ACTH stimulates the ADRENAL CORTEX to synthesize and secrete GLUCOCORTICOIDS and is regulated by CRF
TSH role
TSH stimulates the THYROID GLAND to synthesize and release thyroid hormones
prolactin role
stimulates milk production in female mammary glands
GH role
growth hormone promotes bone andmuscle growth, protein synthesis, and lipid metabolism/catabolism.
does the posterior pituitary sunthesize hormones? What does it do?
no, it stores and releases OXYTOCIN and ANTIDIURETIC HORMONE. Hormone secretion is stimulated by APs descending the hypothalamus
where are oxytocin and antidiuretic hormone produced?
in the neurosecretory cells of the HYPOTHALAMUS
role of oxytocin
oxytocin is secreted at childbirth. Its role is to increase the strength and frequency of uterine muscle contractions.
Oxytocin is also induced by suckling; it stimulates milk secretion in the mammary glands
Antidiuretic hormone is aka
ADH or vasopressin
role of ADH
increases the permeabilitt of the nephron’s collecting duct to water,, thereby promoting WATER REABSORPTION and increasing blood volume, which subsequently increases blood pressure.
when is ADH secreted?
when osmoreceptors in the hypothalamus sense an increase of plasma osmomolarity, or when baroreceptors sense a decrease in blood volume
The hypothalamus is part of the ____ and is located directly above the ___ ___
The hypothalamus is part of the FOREBRAIN and is located directly above the PITUITARY GLAND
thyroid hormones:
- thyroxine (T4)
2. triiodothyronine (T3)
T4 and T3 are formed by ____
thyroglobulin (a glycoprotein)
calcitonin
decreases plasma Ca++ concentration by inhibiting the release of Ca++ from bone.
This is regulated by plasma Ca++ levels.
Calcitonin is antagonistic to parathyroid hormone
The pancreas is both an ___ organ and an ___ organ
The pancreas is both an EXOCRINE organ and an ENDOCRINE organ
the endocrine function of the pancreas is performed by:
small glandular structures called the ISLETS OF LANGERHANS, which are composed of alpha and beta cells
Alpha cells in the islets of Langerhans of the pancreas produce and secrete ____, ,while beta cells produce and secrete ____
Alpha cells in the islets of Langerhans of the pancreas produce and secrete GLUCAGON,while beta cells produce and secrete INSULIN
role of glucagon
stimulates protein and fat degradation, conversion of glycogen to glucose, and gluconeogenesis, all which serve to increase blood glc levels
role of insulin
protein hormone secreted in response to high blood glc.
It stimulates the uptake of glc by muscle and adipose cells and the storage of glc as glycogen in muscle and liver cells, thus lowering blood glc levels.
Also stimulates synthesis of fats from glucose and the uptake of aa’s.
insulin’s actions are antagonistic to those of ___ and ____
glucagon and glucocorticids
Where are the parathyroid glands located?
in the posterior surface of the thyroid
what do the 4 parathyroid glands synthesize and secrete?
parathyroid hormone (PTH)
role of PTH?
to regulate plasma Ca++ concentration.
Raises Ca++ conc by stimulating Ca++ release from the bone and decreasing Ca++ excretion in the kidneys
When blood volume falls the kidneys produce ____
renin.
Renin is an enxyme that converts angiotensinogen to angiotensin I. Angiotensin I is converted to angiotensin II, whch stimulates the adrnal cortex to secrete ALDOSTERONE
erythropoietin (EPO)
released by the KIDNEYS.
stimulates RBC production
Role of gastrin
Gastrin is released by the stomach and carried to the gastric glands where it stimulates the secretion of HCl in response to food in the stomach.
Secretin
hormone which is secreted by the small intestine when acidic chyme enters from the stomach.
It stimulates the secretion of bicarbonate solution from the pancreas to neutralize acidity
cholecystokinin
hormone released by small intestine in response to presence of fats. Causes contraction of the gallbladder and release of bile into the small intestine
What is the pinea gland? what does it secrete?
the pineal gland is a tiny structure at the base of the brain that secretes the hormone MELATONIN
which hormone is thought to play a role in the regulation of circadian rhythm?
melatonin
hormones are classified into two main groups:
peptide hormones
steroid hormones
2 ways in which hormones affect the activities of their taget cells: via _____ receptors or _____ receptors
extracellular and intracellular
peptide hormones act as ___ ____, which bind to specific receptors on the ___ of the target cell and trigger…
peptide hormones act as FIRST MESSENGERS, whih bind to specific receptors on the SURFACE of the target cell and trigger a AERIES OF ENZYMATIC REACTIONS (e.g., ATP –> cyclic AMP first step in chain of reactions)
