Endo Flashcards
What is the hypothalamus made up of
- Nuclei (concentrations of neuronal cell bodies)
- Nerve tracts (axons)
What does the hypothalamus do
Regulates and coordinates responses to changes in the external and internal environment
What behavior does the hypothalamus regulate
- Reproductive
- feeding
- rage
What does the hypothalamus maintain
- body temperature
- metabolism (hunger, safety, body mass, metabolic rate)
- water balance (blood volume, thirst/intake, urine output)
- growth
- stress
- reproduction
What are the 2 main neurohormones secreted by the posterior pituitary gland
- Vasopressin (Anti-diuretic Hormone - ADH)
- Oxytocin
What are the actions caused by vasopressin
- Decrease water excretion in kidneys (anti-diuretic)
- Vasoconstriction
What are the actions caused by oxytocin
- Parturition: stimulates contraction of uterine smooth muscle
- Lactation: milk ejection during breastfeeding due to contraction of smooth muscle
What stimulates oxytocin to secrete
- Pressure of baby in birth canal
- Sucking baby
- fear and anxiety
What are 5 different types endocrine cells, each producing their own hormones
- TSH (Thyroid Stimulating Hormone) → Thyrotrophs (Thyroid gland)
- ACTH (Adrenocorticotropic) → Corticotrophs (Adrenal cortex)
- Prolactin → Lactotrophs (breast)
- GH (Growth Hormone) → Somatotrophs (Liver and other tissues)
- LH (Luteinising Hormone) and FSH (Follicle Stimulating Hormone) → Gonadotrophins (Gonads)
What are the actions of Prolactin
- Stimulates alveolar epithelium of mammary gland to synthesise and secrete of milk
- many non reproductive roles such as immune system and behaviour
What other hormones are required for milk synthesis (lactopoiesis)
- cortisol
- thyroid hormone
- insulin
What are the Growth Hormone concentrations in blood during the day/night
Low levels during day time (when awake)
high levels from 10pm-4am (when sleeping)
How does the growth hormone pulsatile between females and males
- Females = small amplitude, frequent (more continuous)
- Males = large amplitude, infrequent (more pulsatile)
What are the actions of Growth Hormone
- Increases number and size of cells un soft tissues such as skeletal muscle
- increases thickness and length of long bones
- also has metabolic effects
What is involved in the regulation of Growth Hormone
From the hypothalamus there is an increase in GHRH and a decreases in Somatostain this leads to the anterior pituitary gland to produce GH which then targets the Liver and other tissues
What is activated in Growth Hormone signaling
Growth hormone activates theJanus kinase (JAK)–signal transducer and activator of transcription (STAT) signaling pathway
Why are plasma IGF1 levels so stable from hour to hour when its secretion is stimulated by a pulsatile pattern of HG
Synthesis takes time following GH = lag but also OGF binding proteins maintain pool circulating IGF1
In the growth of long bones, what causes the difference in between proliferation and hypertrophy
- Proliferation is due to GH
- Hypertrophy is due to IGF1
What happens to GH/IGF1 after growth plate closure in long bones
They can no longer cause further growth however can increase the thickness of bones)
GH by its self does not create optimal growth, what is needed to achieve optimal growth?
- Thyroid hormones
- Glucocorticoids
- Sex steroids (Testosterone & Oestrogen)
- Insulin
What is excess GH called in children and what can it cause?
Gigantism, usally abnormally tall however they will have normal body proportions
How do other growth drugs work such as Sermorelin, Mecasermin, Octreotide, and Lanreotride
- Sermorelin = GHRH agonist
- Mecasermin = rhIGF1
- Octreotide = Somatostain analogue (inhibit GH excess)
- Lanreotride = similar to Octreotide used for thyroid tumours
