anterior pituitary Flashcards
what is Thyroid-stimulating Hormone (TSH) – thyrotropin
made by pituitary thyrotropes
acts on the thyroid gland to stimulate the release of thyroid hormones (T3 & T4)
what is Luteinising Hormone (LH) & Follicle-stimulating Hormone (FSH) - gonadotropins
made by pituitary gonadotropes
act on the ovaries and testes to stimulate the production of sex hormones and also stimulate the production of eggs and sperm
what is prolactin
made by pituitary mammotropes
acts on the breast to initiate and maintain milk production
what is the synthesis of peptide hormones
Synthesized as large preprohormones (inactive)
Cleaved in the endoplasmic reticulum to prohormone (inactive)
Cleaved to the active hormone and packaged in Golgi
Release from vesicles via exocytosis (contains some prohormone)
immunohistochemical staining for hormones
Anterior pituitary immunologically stained for:
1 .luteinizing hormone (black stain)
2. prolactin (purple stain)
3. unstained cells secrete the other pituitary hormones
cell types in the anterior pituitary
somatropes, thyrotropes, corticotropes, gonadotropes and mammotropes
what is a somatotrope
GH –> general tissue growth
thyrotropes
TSH –> increase metabolic rate
corticotropes
ACTH –> cortisol release
gonadotropes
FSH/LH –> sec hormone release
mammotropes
prolactin –> milk production
Adenohypophysis
Releasing and inhibitory hormones released into blood in primary plexus.
Hormones remain concentrated (not diluted into general circulation).
Hormones delivered to anterior pituitary cells by secondary plexus.
direct effects of growth hormone
reduced-fat stores, increased muscle bulk, increased organ size and function, and increased linear growth
what is insulin-like growth factors
Produced by the liver (time lag of 12 hr)
Circulate bound to proteins (prolongs half-life)
Exerts the growth-promoting effects of growth hormone
GH and IGFs may work together
(eg. IGF stimulates proliferation of osteoclasts, GH stimulates differentiation of osteoclasts)
what influences the hypothalamus
CNS, Metabolic, Endocrine
how does the CNS impact the hypothalamus
REM sleep decreases GH release
Phase IV sleep increases GH release
how does metabolism impact hypothalamus
Glucose inhibits GH release
Amino acids increase GH release
how does the endocrine affect hypothalamus
Cortisol decreases GH release
Estrogen increases GH release
dwarfism
lack of GH in child
laron’s dwarf
lack of GH sensitivity
gigantism
excess GH in children
acromegaly
excess GH in adult
what is acromegaly
Symptoms may be due to raised GH, or compression on tissues by a tumour, changes in the levels of other hormones.
what are the symptoms of acromegaly
Arthralgia (75%) Paraesthesia or carpal tunnel syndrome (40%) Hypertension (28%) Excessive sweating (hyperhidrosis, 64%) Sleep apnoea (60%) Visual field defects (19%) Amenorrhea in women (72%) Headaches (55%)
