Endocrine System Flashcards
What regulates the secretions of hormones
Hypothalamic-pituitary axis (HPA)
HPA regulates secretion of hormones from which glands
Pituitary
Thyroid
Parathyroid
Adrenal
What is another word for pituitary
Hypophysis
When does a positive feedback loop occur
When the pituitary gland senses a decrease in the blood levels of a hormone produced by the target cell or tissue
Negative feedback loop
Prevents the unregulated release of a hormone from the pituitary gland into the blood when the target cell or tissue may be non-responsive
Chemical structure of hormones
Amines- derived from amino acids (tryptophan, tryosine)
Peptides- derived from peptides (cystine, glycine)
Steroids- derived from cholesterol
Where are hormones produced
Hypothalamus
Where are hormones stored/ delivered after production
Pituitary gland
Where are RHs secreted
Hormones stored on anterior lobe of pituitary gland
What is ADH/ antiduiretic hormone also called
Oxytocin and Vasopressin
What is secreted on the posterior pituitary lobe
ADH
What gland lies superioly to kidneys
Suprarenal gland
Layers of suprarenal glands
Cortex
Medulla
What hormones are secreted in the cortex of suprarenal gland
(Corticosteroids)
CORTISOL
ALDOSTERONE
androgens
Hormones secreted by medulla of suprarenal gland
Epinephrine (adrenaline)
Norepinephrine (noradrenaline)
What is aldosterone
An mineralocorticoid that plays a mohair role in blood pressure, ion and fluid balance
What triggers the positive feedback mechanism for secretion of aldosterone from adrenal cortex
RAAS
When is the positive feedback triggered
When there is low blood pressure and low blood volume
When is negative feedback triggered
Once blood pressure, ion and fluid levels are back to normal
What is cortisol
A glucocorticoid that plays a role in the body’s response to stress
Explain how stress is relieved
1.CRF (corticotropin- releasing factor) is secreted from the hypothalamus into capillary plexus
2.CRF stimulates anterior pituitary lobe to secrete ACTH (adrenocorticotropin hormone)
3. ACTH stimulates secretion of cortisol from adrenal cortex
Hormones contained by follicles of thyroid gland
Thyroid hormones
Secretions of thyroid gland
T3 (triiodothyronine)
T4 (thyroxine)
What secrets Calcitonin and its function
C cells
Decrease plasma calcium levels
Function of C cells
Regulate blood calcium levels along with parathyroid hormone
During the process of stress relief,what factor is secreted from hypothalamus
CRF
Where is CRF secreted to from hypothalamus
Primary capillary plexus
Which lobe of pituitary gland is stimulated by CRF
To secrete which hormone during stress relief?
Anterior
ACTH to secrete cortisol
Summary of how cortisol is secreted
CRF to primary capillary plexus
ACTH to anterior lobe of pituitary
Cortisol secretion (adrenal cortex)
Results of cortisol secretion
Gluconeogenesis
Protein mobilisation
Fat mobilisation
Stability of lysosomes
What structures of thyroid gland contain thyroid hormones
Follicles
Secretion of thyroid hormone
Stimulated by thyrotropin releasing hormone (TRH)
Where is TRH released to
Median eminence of hypothalamic stalk
What does release of TRH trigger
Secretion of TSH to stimulate T3 and T4
What do T3 and T4 do after secretion
Bind to plasma proteins and get transported to target cells
How does thyroid hormone act if target cells
Increase metabolic activity
Number and activity of mitochondria
Active transport of ions through membrane channels
Pancreatic cells
Alpha- glucagon
Beta- insulin
Delta- somatostatin
Inhibitory hormone of pancreas
Somatostatin
Effects of insulin
Uses GLUT transporters for metabolism of carbs(glucose), proteins and fats
Function of parathyroid hormone
Increase plasma calcium levels (opposite of calcitonin)
Where are parathyroid glands located
Posterioly to thyroid gland
Effects of parathyroid hormone
A drop in blood calcium triggers calcium sensing receptors to signal parathyroid glands to secrete PTH
What does PTH do after secretion
Acts on kidneys to secrete active form of VITAMIN D
Bone mobilize calcium for blood raising calcium levels
Function of vitamin D
Increase ABSORPTION of calcium by bone
What does PTH do to phosphate levels and calcium levels
Decrease - phosphate
Increase- calcium
Active form of vitamin D
Acts on intestines to increase calcium and phosphate absorption
Amine hormones
T3+T4
Peptide hormones
Produced on the anterior lobe of pituitary gland including insulin
Steroid hormones
Aldosterone
Aldosterone & cortisol
Mineralcorticoid & glucocorticoid
