Endocrinology S2 Flashcards
Posterior pituitary function
Secretes hypothalamic hormones such as oxytocin and vasopressin (ADH). It is not an endocrine gland
Anterior pituitary function
An endocrine gland that secretes and synthesizes its own hormones
What are epiphyseal growth plates?
Cartilage on long bonds that create new bone and eventually become actual bone in adults
Cartilage cells name
Chondrocytes
Chondrocyte mechanism
Divide to add length to bone and disintegrate as we age, becoming replaced by osteoblasts
Growth hormone
A peptide hormone made and released by the anterior pituitary. Release stimulated by GHRH from the hypothalamus
Growth hormone function
Stimulates IGF-1 in the liver for cartilage growth and bone formation
IGF-1 mechanism
Acts on chondrocytes to increase recruitment, proliferation and cartilage matrix
GH catabolic actions
1) breaks down materials to make bone
2) stimulates glycolysis for energy
3) increases AA uptake to decrease apoptosis
Hormones for growth (5)
1) GH and IGF-1
2) thyroid hormones
3) insulin
4) sex steroid
5) cortisol (for energy)
Gigantism
Bones get longer from too much GH in childhood
Acromegaly
Bone and skin thickening due to too much GH in adulthood
Thyroid follicles
Contain colloid and C cells and contain vesicles of thyroglobulin which use iodine to make a precursor of thyroid hormone
C cells
Secrete calcium and aren’t involved in hormone function
Thyroid peroxidase
Adds iodine to tyrosine on thyroglobulin to make thyroid hormone precursors
Thyroid hormones and iodine composition
1) T3 made from MIT and DIT (3 iodines)
2) T4 made from DIT and DIT (4 iodines)
TRH
Trytoptopin releasing hormone and is secreted by the hypothalamus to ant pit to release TSH
TSH
Thyroid-stimulating hormone, a peptide hormone that activates GCPRs
TSH mechanism
Released from ant pit and releases T4 and T3 and is stimulated by TRH
Thyroid hormone mechanism
T3 and T4 circulate blood bound to proteins and bind to nuclear thyroid receptors to alter gene transcription
Thyroid hormone functions
increase metabolic functions, enhance speeching and thinking, works with GH, increases heart rate, etc
Hyperthyroidism
Thyroid hormone excess causing weight loss, goitre (large gland) and treated by blocking T3/4 or gland removal
Graves’ Disease
Autoimmune disease against TSH receptor causing the receptor to always be on. Causes goitre
Hypothyroidism
Thyroid deficiency due to lack of iodine/under-active gland. Causes goitre, low HR, slowed speech, stunted growth, weight gain, etc
Iodine deficiency
Unable to produce T4/T3 and causes goitre due to excess TSH and TRH secretion (no negative feedback)
