Session 8- The HPA axis and growth hormone Flashcards
What is the other name for the anterior pituitary gland
Adenohypophysis
What is the other name of the posterior pituitary gland
Neurohypophysis
Where does the anterior pituitary arise
Evagination of oral ectoderm (Rathke’s pouch)
Primitive gut tissue
Where does the posterior pituitary arise
Neuroectoderm
Primitive brain tissue
What relationship does the posterior pituitary have with the hypothalamus
The posterior pituitary gland is physically connected to the hypothalamus, since the hypothalamus drops down through the infundibulum to form the posterior pituitary
Where are the hormones produced in the posterior pituitary
Supraoptic and paraventricular nuclei of the hypothalamus
Where are hormones stored before they’re released into the hypophyseal system
Median eminence
Hypothalamus to Anterior pituitary
Hypothalamus synthesizes and releases hormones and are transported down ans stored in median emminence
Hypothalamus hormone stimulates ptuitary to release hormones
Anterior pituitary hormone released
What 2 hormones are produced in the hypothalamus for release from the posterior pituitary
Oxytocin
ADH
What does oxytocin do
Milk let down and uterus contractions during birth
What does ADH do
Regulation of body water volume
What are the tropic hormones produced in the hypothalamus
TRH- thyrotropin releasing hormone
PIH- prolactin release-inhibiting hormone- dopamine
CRH- Corticotropin releasing hormone
GnRH- gonadotropin releasing hormone
GHRH- growth hormone releasing hormone
GHIH- growth hormone-inhibiting hormone- somatostatin
What are tropic hormones
Affect the release of other hormones in target tissue
What hormones are produced in the anterior pituitary
Thyroid stimulating hormone
Adenocorticotropic hormone
Luteinising hormone
Follicle stimulating hormone
Prolactin
Growth hormone
Thyroid stimulating hormone
Secretion of thyroid hormone from thyroid gland
ACTH
Adenocorticotropic hormone
-secretion of hormones from the adrenal cortex
Cortisol released which induces rage stress response and metabolic actions
LH
Luteinising hormone - ovulation and secretion of sex hormones
FSH
Follicle stimulating hormone- development of eggs and sperm
Growth hormones
Growth and energy metabolism. Stimulates IGFs
Where is growth hormone produced
Anterior pituitary
What inhibits and stimulates the production of Growth hormone
Stimulates- GHRH
Inhibits- somatostatin
What ensure proper folding of growth hormone
Signal peptide must be cleaved
What effect does GH have
Cells of the liver and skeletal muscle produce and secrete IGFs
What does IGF do
Stimulate bone growth and cartilage growth
In adults help maintain muscle mass an bone mass. Promotes healing and tissue repair as well as modulating metabolism and body composition
When does GH increase
Deep sleep
Stress
Exercise
Decrease in glucose or fatty acids
Fasting
When does GH decrease
Rapid eye movement sleep
Increase in glucose or free fatty acids
Obesity
Long loop negative feedback of GH secretion
Mediated by IGFs
- inhibit release of GHRH
- stimulates the release of somatostatin from hypothalamus
- inhibit release of GH from anterior pituitary
Short loop of GH secretion negative feedback
Mediated by GH itself via stimulation of somatostatin release
What is pituitary dwarfism
Proportionate typ of dwarfism
Complete or partial deficiency
Delayed or no sexual development
Response to GH THERAPY
How does GH exert its effects on cells
GH receptors activate Janus kinases
GH binds to JAK
Dimerisation of chains
Auto phosphorylation
Activation of signalling pathways
Transcription factor activation of igf production
What do IGFs modulate
Hypertrophy
Hyperplasia
Increase rate of protein synthesis
Increase rate of lipolysis
How does insulin influence growt
Enhances somatic growth; interacts with IGF
receptors
How does thyroid hormone influence growth
Promote CNS development and enhance GH
secretion
How do androgens influence growth
Accelerate pubertal growth spurt; increase muscle mass; promote closure of epiphyseal plates
How do estrogens promot growth
Decrease somatic growth; promote closure of epiphyseal plates
effect of glucocorticoids on growth
Inhibits somati growth
