The Endocrine System Flashcards
one of the body’s most important systems, especially with the control of the body’s function
The endocrine system
Endon - within; krimen – to separate; meaning?
separating internally
Primary function of the endocrine system
for hormone production
secretory products by parenchymal cells of endocrine organs released in minute amount into the circulation in response to an internal or external stimuli
Hormones
sites affected by hormones, which may be cells, tissues or entire organs
Target organs
are glands that secrete their products through the ducts, and discharge it into the external environment, to organs or the outside the body.
Exocrine glands
are ductless, therefore the secreted hormones are released into the interstitial spaces that surround the cells. The hormones are delivered to the nearest capillaries, and spread throughout the body.
Endocrine Glands
Primary endocrine organs (5)
Fxn for hormone production
Hypophysis (pituitary gland)
Thyroid gland
Parathyroid gland
Pineal gland (epiphysis)
Adrenal gland
Organs with endocrine and exocrine functions (4)
Testis
Ovary
Pancreas
Placenta
Organs with endocrine functions secondary to their primary functions (3)
Kidney
Liver
Thymus
A small, reddish organ attached to the ventral midline of the brain by a small hollow stalk called “infundibulum”
Larger in females
Hypophysis
Hypo – ?
physis – ?
meaning “growth on the undersurface of the brain”
under
growth
*Division of the Hypophysis
◦ “master gland” of the body
◦ Composed of glandular parenchyma and has extensive blood supply
◦ Contains the hypophyseal cleft or intraglandular cleft (large compressed vesicle)
Anterior pituitary or adenohypophysis
*Division of the Hypophysis
◦ Pale and fibrous in texture
Posterior pituitary or neurohypophysis
*Pars distalis of adenohypophysis
causes growth of almost all cells and tissues of the body.
Growth Hormone (STH)
*Pars distalis of adenohypophysis
causes the adrenal cortex to secrete adrenocortical hormones.
Adenocorticotropin (ACTH)
*Pars distalis of adenohypophysis
causes the thyroid gland to secrete thyrodine(T4) and triidothyronine (T3).
Thyroid-stimulating hormone (TSH)
*Pars distalis of adenohypophysis
causes growth of follicles in the ovaries before ovulation; promotes the formation of sperm in the testes.
Follicle-stimulating hormone (FSH)
*Pars distalis of adenohypophysis
plays an important role in causing ovulation; also causes secretion of female sex hormones by the ovaries and testosterone; ICSH counterpart in males
Luteinizing hormone (LH)
*Pars distalis of adenohypophysis
promotes development of the breasts and secretion of milk.
Prolactin (lactogenic hormone)
*Pars nervosa of the neurohypophysis
(aka vasopressin), causes the kidneys to retain water, thus increasing the water content of the body; also, in high concentrations causes constriction of the blood vessels throughout the body and elevates the blood pressure.
Antidiuretic Hormone-
*Pars nervosa of the neurohypophysis
contracts the uterus during the birthing process, thus helping expel the puppies; also contracts myoepithelial cells in the breasts, thereby expressing milk from the breasts when the puppy suckles
Oxytocin
Developmental anatomy of endocrine system
From the oral ectoderm and ventral surface of neural tube
Blood Supply of Pars distalis (2)
internal carotid artery and posterior communicating arteries
*Blood Supply of Pars intermedia
relatively avascular
*Blood Supply of Pars nervosa
posterior hypophyseal artery (principal branch of the intercarotid artery)
Paired, elongated, dark red structures lying lateral to the first 5-8 tracheal rings
Largest among the ductless glands which perform only an endocrine function
Can be palpated during physical examination especially when enlarged
Larger in females than in males
Thyroid Gland
Hormone produced by the thyroid gland
thyroxine
*Thyroid Gland
Developmental anatomy:
develops from pharyngeal entoderm
*Thyroid Gland
Blood supply: (2)
primary cranial and caudal thyroid arteries
*Thyroid Gland
Nerve supply:
thyroid nerve
Small oval bodies associated with the thyroid
4 independent glands (PT I, II, II, IV); number associated with their respective pharyngeal pouches
Parathyroid Gland
Hormone produced by the parathyroid gland
parathormone
maintains Ca:P blood levels
parathormone
Blood supply of parathyroid gland
cranial thyroid artery
Pineal gland is also known as the? (3)
pineal body, conarium or epiphysis cerebri
It produces melatonin, a serotonin derived hormone, which affects the modulation of sleep patterns
Its shape resembles a tiny pine cone (hence its name), and it is located in the dorsal midline surface of the brain
Pineal Gland
Adrenal gland is Also called
“suprarenal gland”
Paired, bilobed organs, the left is larger located at the lumbar level of the 2nd vertebra
Right is situated at the level of the last thoracic vertebra
Adrenal Gland
white or faint yellow in fresh preparation due to large amount of lipid storage
Adrenal cortex
– dark brown or black in color
◦ Catcholamines: epinephrine/adrenaline,
norepinephrine/noradrenaline
Adrenal medulla
3 zones of the adrenal cortex
zona glomerulosa (mineralocorticoids)
the zona fasciculata (glucocorticoids – cortisol)
zona reticularis (androgens).
*Adrenal cortex
◦Steroid hormones (?)
corticosteroids
◦ Arterial branches from phrenicoabdominalis and rami adrenales cranialis, branches from abdominal aorta - middle adrenal artery; branches from renal artery – rami adrenales caudalis
Blood supply
important hormones of the pancreas (4) which circulate in the blood
insulin
glucagon
somatostatin
pancreatic polypeptide
also a digestive organ, secreting pancreatic juice containing digestive enzymes that assist digestion and absorption of nutrients in the small intestine
Pancreas
Dual function: to produce germ cells and sex hormones: estrogen and progesterone
Ovary
Most dog breeds come to estrus ___x a year (monestrous)
1-2
produce sperm (spermatogenesis) and to produce testosterone
testis
Produces renin which regulates blood volume, blood pressure, and ionic concentration
Kidney
