Exam Two - endocrine two Flashcards
_______ secretes steroid hormones
adrenal cortex
name the layers of the adrenal cortex from outer to inner
zona glomerulosa
zona fasciculata
zona reticularis
adrenal medulla
Zona glomerulosa produces?
aldosterone
- sodium potassium balance
zona fasciculata produces?
glucocorticoids
(cortisol is the main one)
zona reticularis produces?
androgens
The adrenal medulla produces?
catecholamines
- epinephrine (80%)
- corepinephrine (20%)
Which axis controls cortisol secretion?
HPA axis
What are the three main components of the HPA axis?
hypothalamus
anterior pituitary gland
adrenal cortex
in the HPA axis, the hypothalamus secretes what hormone?
CRH corticotropin releasing hormone
in the HPA axis the anterior pituitary gland releases what hormone?
ACTH adrenocorticotropic hormone
in the HPA axis, the adrenal cortex releases what hormone?
cortisol
_______ is transported by corticosteroid-binding protein in the blood
cortisol
________ also stimulates the anterior pituitary gland to release ACTH in the HPA axis
POMC or pro-opimelanocortin
T or F: cortisol has a negative feedback loop to control the release of CRH and ACTH?
True!
T or F? cortisol secretion control is continuous and diurnal
true
POMC
- produced in anterior pituitary gland
- stimulated by CRH
- post-transitional modification produces ACTH and other peptides
- tissues other than adrenal gland affected by POMC fragments and peptides
Adrenal steroid synthesis is produced in the _________
adrenal cortex
_______ is the base of all steroid hormones
cholesterol
cortisol systemic effects
- long-term stress mediation
- protective against hypoglycemia (permissive)
- mostly catabolic
- promotes gluconeogenesis
- immune system suppression
- causes negative calcium balance
- influences brain/nerve function (memory/attention enhanced, mood changes, decreased pain sensitivity)
Adrenal glucocorticoids therapeutic uses
- immunosuppressant effects (inflammatory responses, treat bee stings, poison ivy, pollen allergies, prevent rejection of transplant organs)
- exogenous administration may shut down ACTH production and adrenal cells (producing adrenal cells atrophy, must carefully taper)
Hypercortisolism
- adrenal tumor secretes cortisol
- pituitary tumore secretes ACTH
- iatrogrenic hypercortisolism
primary hypercortisolism
adrenal gland
secondary hypercortisolism
pituitary tumor
tiertiary hypercortisolism
hypothalamus
cushings disease
secondary hypercortisolism
cushings syndrome
iatrogenic hypercortisolism
hypocortisolism
addisons disease - hyposecretion of all steroid hormones
TH function
- promotes oxidative metabolism, protein synthesis, increases body heat
- long-term effects on metabolism
- not essential for life BUT
- essential for growth and development in children and infants
thyroid follicles are…
epithelial cells
_____________ made in follicle cells
glycoprotein thyroglobulin
center filled with ____ which holds supply of hormones
colloid
thyroid hormones bind to plasma proteins such as ___________-
thyroid-binding globulin (TBG)
target cells use __________ to remove iodine from T4 to make active T3
deiodinases
C-cells produce _________-
calcitonin
TH functions
- promotes oxidative metabolism, promotes protein synthese, increases body heat
- long term effects on metabolism
- not essential for life
- essential for growth and development in children and infants (necessary for full expression of GH in children)
TH synthesis
1 - a Na I symporter brings I into the cell. The transporter moves I into colloid
2 - follicular cell synthesized enzymes and thyroglobulin for colloid
3 - thyroid peroxidase adds iodine to tyrosine to make T3 and T4
4 - thyroglobulin is taken back into the cell in vesicles
5 - intracellular enzymes separate T3 and T4 from the protein
6 - free T3 and T4 enter the circulation
MIT
I + tyrosine
monoiodotyrosine
DIT
I + MIT
dilodotyrosine
T3
MIT + DIT
T4
DIT + DIT
T3 is more ____ but T4 is more_______
active, stable
control of thyroid secretion
hypothalamus releases TRH
Ant. Pituitary releases TSH
Thyroid gland releases T3&T4
negative feedback from T3 and T4 at Ant. Pituitary and hypothalamus
causes of hyperthyroidism
- pituitary tumors secreting TSH
- autoimmune disease: thyroid-stimulating immunoglobulins mimic TSH (graves disease)
effects of hyperthyroidism
- goiters
- increases oxygen consumption and metabolic heat production
- increases muscle protein catabolism and may cause muscle weakness
- hyperexcitable reflexes and psychological disturbances
- influence heart b-adrenergic recepts
- exophthalmos (bug eye)
treatments for hyperthyroidism
- surgical removal of gland
- destroy with radioactive iodine
- block biosynthesis of hormone
cause of hypothyroidism
- autoimmune disease (hashimotos)
- insufficient dietary disease
- others
effects of hypothyroidism
- goiters
- reduced metabolic rate and oxygen consumptions (weight gain and cold senesitivities)
- decreased protein synthesis
- muscle weakness and aches
- fatigue
- myxedema (puffy)
- nervous system changes in adults including: slowed reflexes speech and thought, memory problems, depression
- bradycardia (slow)
- cretinism (developmental disorder)
treatment of hypothyroidism
- thyroid medication (exogenous T4/3)
_______ hypothyroidism is due to lack of iodine in diet
primary
treatment for hypothyroidism
oral thyroid meds
treatment for hyperthyroidism
removal or destruction of gland or block hormone synthesis
GH effects are mostly…
anabolic
GH and IGF stimulate…
protein synthesis
GH jobs…
- increase lipolysis and gluconeogenesis
- decrease glucose uptake by muscle
- increase blood glucose
IGF only…
increase bone growth
GH and IGF
increase muscle growth
increase soft tissue growth
increase cell proliferation and differentiation
GH and IGFs inhibit ______ and promote __________
GHRH (negative feedback loop)
CHIH (somatostastin)
IGFs inhibit ___ secretion directly
GH
severe childhood deficiency of GH leads to
dwardism
childhood of over-secretion of GH leads to
gigantism
adults with excessive secretion of GH develop
acromegaly
issues with genetically engineered human growth hormone (hGH)?
- raises ethical questions
- limited effectiveness
- numerous side effects like insult resistance
