endocrine system Flashcards
what is an exocrine gland
least one duct and secrete their product on surface or in the lumen of a hollow organ
what is an endocrine gland
ductless glands which secrete hormones directly into the bloodstream
what does the endocrine system regulate
- growth
- development
- metabolism
- adaptive of body in stressful situations producing hormones
what carry hormones to target organs
blood and lymph
what are the central regulatory formations of the endocrine system
- hypothalamus
- hypophysis- pituitary gland
- pineal gland
what are the peripheral endocrine organs
- thyroid
- parathyroid
- adrenal glands
what organs have endocrine and nonendocrine functions
- gonads
- pancreas
- placenta
what are isolated endocrine cells
- secrete steroids and other hormones
what does the hypothalamus secrete
- oxytocin and antidiuretic hormone
- simulate or inhibit secretion of pituitary hormones
what do the axons of neurosecretory cells do
form hypothalamo-hypophyseal tract terminate in posterior pituitary as accumulations of herring bodies
what does the supraoptic nucleus secrete
vasopressin - ADH
what does ADH do
- increases permeability of water in distal convoluted tubules and collecting tubules making urine hypertonic
- contract smooth muscle tissue of small arteries and increase blood pressure
what does the paraventricular nuclei create
oxytocin
what does oxytocin do
- stimulates contraction of smooth muscle tissue in uterine during child birth
- myoepithelial cells of mammary glands during nursing
what do parvocelluar neucliei secrete
- Liberians and statins
what are statins
inhibit the production of relevant pituitary hormones
what are Liberins
stimulate the production of specific pituitary hormones
where are hypothalamic releasing hormones released
median eminence from neurosecretory terminals of neurones into the primary capillary plexus of the hypothalamo - hypophyseal portal system
what does the portal system do
carries hormones to secondary capillary plexus in the adenohypophysis
where is the pituitary gland/ hypophysis found
sella turcica of sphenoid bone
what are the two parts of the hypophysis
- adenohypophysis - pars distalis, para tubercles and para intermedia
- neurohypophysis
where does the adenohypophysis arise from
invagination from ectodermal roof or primitive mouth cavity forming rathke pouch
where does the neurohypophysis arise from
neuro-ectoderm from evagination from the floor of the diencephalon
what is the pituitary gland composed of
- glandular tissue - secretes hormones
- neural tissue - stories oxytocin and ADH
what forms the branching cords of epithelial cells
para distal and para tuberials with capillaries in-between
what are the cells forming adenohypophysis
- chromophil cells
- chromophore cells
what are chromophobes
- degranulated inactive resting cells capable of differentiation into chromophils
- follicular cells that support network around other cells
what are the types of acidophils
- mammotropic cells - produce prolactin to promote milk secretion
- somatotropin cells - produce somatotropin with acts on growth of long bones
what is the growth hormone called
insulin like growth factors - IGFs
where is IGF-1 produced
liver and other tissues in response to growth hormone
how does IGF-1 work
- binds to receptors on target tissue producing tyrosine kinase activation
what are the effects of IGF-1
- stimulates linear growth
- increase muscle mass
- decrease adiposity
- increase organ size
what is acromegaly
- skin growth resulting in coarsening features
- exaggeration of eyebrow ridges and skin folds on face
- jaw is enlarged and skin becomes greasy
what are the subtypes of basophils
- thryotropic cells - thyrotropin - stimulates thyroid hormone synthesis
- corticotropic cells - ACTH - secretion of adrenal cortex hormone
- gonadotropic cells - FSH and LH
what does FSH do
promotes ovarian follicle development and estrogen secretion and spermatogenesis
what does LH do
promotes ovarian follicle movement, ovulation and progreterone in females and androgen secretion in males
what is pars intermedia
surrounds a serious of small cyst cavities that represent the residual human of rathkes pouch
what cells are in the pars intermedia
melanocyte- stimulating hormone (MSH) - produces melanin
lipotropin (LPH) - simulates metabolism of fat
what cells make up the posterior lobe of the pituitary gland
pituicytes - don’t produce hormones
what cells make up the pineal gland
- pinealocytes - secretary cells producing melatonin and serotonin
- interstitial - separate pinealocytes from one another
what are the functions of the pineal gland
- day and night cycles
- increases melatonin at night
what happens when melatonin increases
1) decreased production of gonadotrophin in hypothalamus
2) decreases pituitary gonadotrophin secretion
3) decreased gonadal growth and hormonal secretion
what do thyroid hormones stimulate
- rate of metabolism
- normal growth and development
what is the difference between T3 and T4
T3 - 3 iodine atoms
T4 - 4 iodine atoms
what does calcitonin do
decreases blood calcium levels by inhibiting bone resorption
what does thyroid epithelium consist of
follicular cells - produce T3 and T4
C-cells - produce calcitonin
what are the characteristics of follicular cells
- cuboidal if active, squamous if invasive
- highly active cells become columnar
- under control of adenohypophysis
what are the characteristics of parafollicular/ c-cells
- well developed rER, large golgi and numerous mitochondria
- not under control of adenohypophysis
what does the parathyroid glands consist of
- chief (principle) cells
- oxyphil cells
what is the stricture of chief cells
- basophilic
- produce PTH
what does parathyroid hormone do
acts on osteoclasts of bone tissue —> resorption of bone matrix and releases calcium into blood
what is the structure of oxyphil cells
- acidophilic
- polygonal shape
- larger than chief cells
what are the sub divisions of the adrenal gland
outer zona glomerulosa
middle zona fasciculate
inner zona reticularis
what does the zonaa glomerulosa consist of
columnar basophilic cells
what does the zona glomerulosa secrete
mineralocorticoid hormone which regulates sodium and potassium and water balance
how does aldosterone work
- acts on the distal tubules of nephrons in kidney
- stimulates resorption of sodium and extraction of potassium
- regulation of blood pressure
what is the zona glomerulosa under feedback of
renin-angiotensin-aldosterone system
what does the zona fasciculate secrete
glucocorticoids - regulate carbohydrate metabolism, breakdown of proteins and fats, anti-inflammatory properties and suppresses immune response
what controls the secretion of glucocorticoids
ACTH of adenohypophysis
what does the zona reticularis secrete
androgens and glucocorticoids
what is zona reticularis under control of
ACTH of adenohypophysis
what are the effects of adrenaline
- increase heart rate,
- increase blood pressure,
- reduce blood flow to viscera and skin,
- stimulate the conversion of glycogen to glucose,
- increase sweating,
- induce dilation of bronchioles,
- increase rate of respiration,
- decrease digestion,
- decrease urine production.
what cells are in the adrenal medulla
- epinephrin secreting cells - adrenaline
- norepinephrine secreting cells - noradrenaline
