Endocrine Glands Flashcards
Endocrine System
Organs whose secretory products are hormones> Pituitary (hypophysis), thyroid, parathyoid, adrenal, pancreas, gonads
-second great communication system beyond the nervous system
-blood borne messengers which control and integrate many body functions
>Reproduction
>organic metabolism
>energy balance
>mineral metabolism
>growth
Endocrine VS Nervous System
Endocrin system-
- slow and general
- blood borne
- receptors (on cell membrane protein/ peptide hormones, within cell steroid hormones)
Nervous system
- fast precise local
- action potentials
- receptors only at synapse
Hormone
Chemical substance secreted into the blood and carried to other sites of the body where its actions are exerted
Target cells
cells capable of responding to hormone must have receptors for hormone. Presence of specific receptors determines specificity of actions of hormones
Hypophysis
Pituatary
- lies in sella turcica of sphenoid bone
- size of a pea
- attached to hypothalmus via the infundibulum and pituatary stalk
what are the two major divisions of the hypophisis?
adenohypophysis=anterior lobe
neurohypophysis=posterior lobe
Neurohypophysis
posterior lobe
- axon and axon terminals from neurons in nuclei of hypothalamus; glial cells
- hormones formed in the hypothalamus travel down axons, stored in axon terminals in posterior lobe
What does the Neurohypophysis secrete and f(x)
1.) ADH- antidiuretic hormone, regulated by osmoreceptors of hypothalamus
f(x) increase reabsorption of water at kidney to regulate plasma osmolarity and vasoconstrict to increase blood pressure in high concentrations
2.) Oxytocin-regulated by sensory input contraction of
f(x) myoepithelial cells of mammary gland for milk let down, smooth muscle of uterus for parturition (delivery), “trust” “love” hormone
what controls the activity of the anterior pituitary?
Hypothalmic secretions serve as releasing factors and/ or inhibiting factors for secretions of the anterior lobe
adenohypophysis
anterior lobe, hypothalmic control via the venous portal system
capillaries of hypothalamus>portal veins>capillaries of anterior pituatary> veins to heart= hypothlmo-hypophyseal portal system
3 cells of anterior lobe of pituatary
acidophils, basophils, chromophobs
Acidophils
GH-growth hormone, regulate growth and metabolism
PRL-Prolactin, milk synthesis and secretion
Chromophobes-empty cells
Basophils
Secrete series of hormones which regulate other endocrine glands
Glycoproteins w/ to sub units: alpha and beta
ACTH-adrenocorticotropic hormone, regulates adrenal cortex
TSH- Thyroid stimulating hormone, regulates production and release of thyroxin from thyroid gland
FSH- Follicle stimulating hormone, regulates activity of follicular cells of ovary and seminiferous tubules of the testis
LH-Luteinizing hormone, regulates: ovulation and development of corpus luteum in ovary; interstitial cells in testis
What hormones are released from the anterior pituatary where do they effect the body?
- ) growth hormone GH- bones and muscles
- ) Prolactin PRL-mammary glands
- )Follicle stimulating hormone FSH- testis ovaries
- ) Thyrotropic hormone TSH- thyroid
- ) adrenocorticotropic hormone ACTH- adrenal cortex
Thyroid Gland
- largest endocrine gland 20-30 grams
- 2 lobes overlap junction of larynx and trachea
- connected anteriorly by an isthmus; pyramidal lobe sometimes
Thyroid gland cells:
follicular cells and C cells
Follicular cells- synthesize thyroxine, secrete it into follicular cavity where it binds to thyroglobulin; resorb thyroglobulin to release thyroxine into blood
C Cells- parafollicular cells, cluster of light cells found between follicles, secrete calcitonin
Thyroid Gland Secretions
Thyroid hormone- increases metabolic rate , influences mental acuity and growth development of CNS and of tissues in general
Calcitonin- decreases plasma calcium, mianly by decreasing bone reabsorption and increasing bone deposition
Hyperthyrodism
cold intolerance, low metabolism, mentally sluggish
Parathyroid Glands
4 small glands located on the dorsal aspect of lobes of thyroid gland
Parathyroid hormone
releases in response to decreases in plasma calcium. It increases plasma calcium by increasing bone reabsorption and decreasing bone deposition, increasing GI absorption of calcium and increasing reabsorption of calcium at the kidney
decreased plasma calcium causes tetany, muscle spasms
Adrenal Glands
paired glands. located superior of kidneys
Structure of adrenal glands
80% cortex, outer
20% medulla, inner
Adrenal Medulla
basically a sympathetic ganglion converted to endocrine function
- secretes epinephrine and norepinephrine (the neurotransmitter of the sympathetic system)
- same actions as sympathitic NS activity, increase heart rate; vasoconstriction, increase blood pressure; increase blood sugar, decreased intestinal activity
3 layers of the Adrenal Cortex
- ) Zona Glomerulosa
- ) Zona fasciculata
- ) Zona reticularis
