ENDOCRINE SYSTEM Flashcards
- responsible for the synthesis and secretion of chemical messenger known as hormones which are disseminated throughout the body via the bloodstream where they act on specific target organs.
- the secretory cells release their hormones into the interstitial space from which they are rapidly absorbed into the circulation.
- Unlike exocrine glands, _______________ have no duct system and therefore sometimes called the ductless glands.
Endocrine Glands
Endocrine Glands is also called the
ductless glands
are highly vascular and you have blood vessels that are fenestrated (there are holes for the passage of large molecules)
Endocrine organs
Types of Endocrine Glands
- Pituitary Gland
➢ a specialized appendage of the brain which secretes several hormones.
➢ small slightly elongated gland approximately 1 cm in diameter situated in the Sella turcica of the sphenoid bone and it is connected to the base of the brain via the infundibulum or stalk.
➢ Pea shaped structure measuring 1-1.5 cm in diameter
➢ formerly regarded as the master gland because it influences the rest of the endocrine glands; however, the hypothalamus regulates the function of the anterior lobe of the pituitary gland hence this was regarded untrue
Pituitary Gland
Pituitary Gland also known as
Hypophysis or Hypophysis Cerebri
➢ makes up 75% of the total weight of the gland
➢ arises as an epithelial outgrowth from the roof of the primitive oral cavity known as the Rathke’s pouch
➢ secreting the hormones
Anterior Pituitary
Anterior Pituitary also called the
adenohypophysis
Divisions of the Pituitary Gland
- Anterior Pituitary
- Posterior Pituitary
Hormones secreted by Anterior Pituitary:
o Growth hormones – long bones
o Thyroid stimulating hormone – thyroid gland
o GnRh (follicles stimulating hormone, luteinizing hormone) – testis and ovary
o Prolactin – mammary gland for milk production.
o ACTH (adrenocorticotrophic hormone) – adrenal glands/cortex
o MSH (melanocyte stimulating hormone) – skin
➢ derived from downgrowth of nervous tissue from the hypothalamus to which it remains joined by the pituitary stalk
➢ coming from the floor of diencephalon.
➢ It will just store the hormones that will come from hypothalamic nuclei.
➢ does not synthesize hormones. Instead stores and releases two hormones
➢ Secretions from this lobe are produced by the cell bodies of the supraoptic nucleus (produces vasopressin or ADH) and the
paraventricular nucleus (produces oxytocin) of the hypothalamus
Posterior Pituitary
Posterior Pituitary also called
neurohypophysis
(produces vasopressin or ADH)
supraoptic nucleus
(produces oxytocin)
paraventricular nucleus
Hormones stored by Posterior Pituitary:
o ADH (antidiuretic hormone, Vasopressin)
o Oxytocin (pitocin)
modified neuroglial cells found in the pars nervosa believed to store and release 2 hormones
Pituicytes
2 HORMONES IN POSTERIOR PITUITARY
o Pitocin (oxytocin)
o Pitressin or ADH
➢ increases water reabsorption at the distal convoluted tubules of the kidneys.
➢ has a vasopressor effect hence also called vasopressin
➢ raises blood pressure by constricting arterioles
Pitressin or ADH
➢ Stimulates uterine contraction
➢ stimulates milk ejection (milk “letdown) from the mammary glands in response
➢ to the mechanical stimulation provided by the suckling infant
Pitocin (oxytocin)
- a small organ, 6-8 mm long located at the caudal end of the
diencephalon of the brain. - consists of cells called pinealocytes
- Hormones secreted: Melatonin derived from serotonin, which may
promote sleepiness
Pineal Gland
Pineal Gland also called
epiphysis cerebri or conarium
- a lobulated gland lying in front of the neck at the upper part of the trachea
- there are 2 lobes connected at the midline by the isthmus
- homeostasis
- Contains follicles, which secrete 2 thyroid hormones: thyroxine (T4) and triiodothyronine
(T3)
o Actions of the thyroid hormones:
➢ increase basal metabolic rate
➢ helps maintain normal body
temperature - it is formed by various follicles of different sizes and shape lined by simple cuboidal cells containing colloid material containing thyroglobulin
- It lowers blood calcium by inhibiting osteoclast activity, preventing excessive calcium release from bones.
Thyroid Gland
follicles secretes 2 thyroid hormones:
thyroxine (T4)
triiodothyronine (T3)
between capillaries are dense capillary network supported by
reticular fibers
is secreted in response to hypercalcemia (high calcium levels).
Thyrocalcitonin
- are small oval endocrine glands closely associated posteriorly with the thyroid gland
- supplied by inferior thyroid artery
- secretes parathormone, which directly elevate blood calcium levels
- usually there are:
o 2 superior parathyroid glands
o 2 inferior parathyroid glands
Parathyroid Gland
if your ____________ will decrease your calcium level, your ____________ will increase your calcium level.
- calcitonin
- parathormone
small flattened endocrine glands closely applied to the upper pole of the kidneys
Adrenal (Suprarenal) Gland
2 Components Of The Adrenal Gland:
- Adrenal Cortex
- Adrenal medulla
➢ outer and thicker portion
➢ 3 layers of cell: zona glomerulosa, zona fasciculata and zona reticularis
▪ Secretions:
o Mineralocorticoids
o Glucocorticoids
o Androgens
Adrenal Cortex
➢ promote libido in females and are converted to estrogen,
➢ also stimulate growth of axillary and pubic hairs in boys and girls and contribute to the prepubertal growth spurt
Androgens
(aldosterone and deoxycortisones)
➢ regulate fluids and electrolytes
➢ help adjust blood pressure and blood volume
Mineralocorticoids
(e.g. cortisone)
➢ regulate metabolism and resistance to stress
Glucocorticoids
➢ Secretes the catecholamines – epinephrine and norepinephrine
➢ Produces effects that enhance those of the sympathetic division of the autonomic nervous system during stress
Adrenal medulla
- pistol shaped flattened organ, the head part of which is enclosed by the duodenum, the body at the back of stomach and tail related with spleen
- not only exocrine gland but also has important endocrine functions
- the endocrine portion is the Islets of Langerhans
- the exocrine portion is secretion of enzymes.
- pancreatic islets vary in size and most numerous at the tail of the pancreas
Pancreas
Cells in the Islets of Langerhans
- Alpha Cells
- Beta cells
- Delta Cells
- F Cells
➢ less numerous containing acidophilic granules.
➢ found at the periphery of the islet and secrete glucagon – which increases blood sugar
Alpha Cells
➢ found at the center of the islets
➢ it secretes insulin which decreases blood sugar
Beta cells
➢ secrete somatostatin, which inhibits secretion of insulin and
Delta Cells
➢ secrete pancreatic polypeptide
F Cells
- are paired organs lodging in the scrotum are responsible for the production of the male gametes, spermatozoa, and male sex hormones
- the endocrine portion is the interstitial cells of Leydig which secrete these androgens:
o Testosterone
o Dihydrotestosterone
o Androstenedione
Testis
Its main hormone _____________ regulates production of sperm and stimulates the development and maintenance of masculine secondary sex characteristics such as beard growth and deepening of the voice
testosterone
- the follicular cells of the ovarian follicle secrete estrogen and the corpus luteum secretes progesterone
- These hormones regulate the female reproductive cycle:
o Regulate oogenesis
o maintain pregnancy
o prepare the mammary gland for lactation
o promote development and maintenance of female secondary sex characteristics
o placenta also producing a hormone – syncytiotrophoblast, human chorionic gonadotropin (HCG)
Ovaries
➢ autoimmune disorder associated with increased circulating levels of thyroid hormones
Grave’s Disease
➢ disorder of metabolism and chronic hyperglycemia
Diabetes Mellitus
➢ refers to the manifestations of excessive corticosteroids
➢ e.g. Central obesity, moon face, buffalo hump, osteoporosis, hypertension, hyperglycemia
Cushing’s Syndrome
➢ disorder caused by the destruction of the adrenal cortices characterized by chronic deficiency of cortisol, aldosterone and androgens causing skin pigmentation
Addison’s Disease
Endocrine Gland Diseases
- Grave’s Disease
- Diabetes Mellitus
- Cushing’s Syndrome
- Addison’s Disease
secrete estrogen
ovarian follicle
secretes progesterone
corpus luteum
secrete androgens
Leydig (Testis part)
secrete pancreatic polypeptide
F Cells
secrete somatostatin
Delta Cells
secretion of enzymes.
exocrine portion
Secretes the catecholamines
Adrenal medulla
secretes parathormone
Parathyroid Gland
secretes thyrocalcitonin
Thyroid Gland
thyrocalcitonin secreted by
parafollicular cells
follicles secrete 2 thyroid hormones:
Thyroxine (T4)
Triiodothyronine (T3)
secretes melatonin
Pineal Gland
secretes several hormones.
Pituitary Gland
NEVER BACK DOWN NEVER WHAT!!!!!!!!!!!!!!!?????????????????
NEVER GIVE UP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
