Steroid hormones are derived from? Examples?
(e.g. estradiol, testosterone, cortisol, aldosterone)
Peptide and protein hormones are synthesized from? Examples?
(e.g. prolactin, growth hormone, insulin, vasopressin)
Glycoproteins are peptides modified by addition of? Examples?
(e.g. luteinizing hormone, follicle stimulating hormone, thyroid stimulating hormone)
Amine hormones are modified derivatives of? Examples?
the amino acid tyrosine
(e.g. thyroid hormone, norepinephrine, epinephrine) or tryptophan (e.g. melatonin)
Pituitary Gland (Hypohysis)
What are the two parts?
- adenohypohysis (anterior lobe)
- neurohypohysis (posterior lobe)
The adenohypophysis is connected to the hypothalamus by
blood vessels – hypophysial portal circulation
The neurohypophysis is anatomically connected to hypothalamus by
- the infundibulum
- the infundibular stem
Pars distalis - cell types?
1. Chromophil Cells
A. Acidophils – most numerous cell type, red-staining cytoplasmic granules
B. Basophils – less numerous, blue-staining cytoplasmic granules
2) Chromophobe cells
These cells exhibit only faint/weak staining, and probably represent committed stem cells and immature forms of acidophils and basophils, as well as degranulated acidophils/basophils
Somatotrophic cells (Pituitary)–
synthesize/secrete growth hormone (hGH), the most important hormone for normal growth; also has important effects on protein, carbohydrate, and fat metabolism
Mammotrophic cells (Pituitary)–
synthesize/secrete prolactin (PRL), the major hormone responsible for milk production; also important in normal development of breast glandular tissue.
Thyrotrophic cells (Pituitary)–
synthesize/secrete thyroid stimulating hormone (TSH), which stimulates growth and activity of thyroid hormone- secreting cells of the thyroid gland
Corticotrophic cells (Pituitary) –
synthesize/secrete adrenocorticotrophic hormone (ACTH), which stimulates growth and activity of steroid hormone-secreting cells of the adrenal cortex
Gonadotrophic cells (Pituitary) –
synthesize/secrete luteinizing hormone (LH) and follicle stimulating hormone (FSH), which regulate growth and activity of ovaries and testes, including secretion of the sex steroids, estrogen and testosterone
What are the two postierior pituitary hormones? Describe synthesis.
- vasopressin (ADH)
- synthesized in the cell bodies,
- packaged in secretory vesicles,
- transported down the axons and accumulated in the axon terminals
- distended terminals are represented by Herring bodies in light microscopy
Pituitary adenomas –
typically very small, cytologically benign tumors of hormone secreting cells
Growth hormone-secreting adenomas cause
gigantism if present before closure of the growth plates or acromegaly when they develop after long bone growth has ceased.
ACTH-secreting adenomas result in
continuous stimulation of the adrenal cortex causing Cushing’s Disease
Prolactin-secreting adenomas (the most common pituitary adenoma) result in
galactorrhea (milk oozing from nipples) and hypogonadism/infertility in both males and females
Isolated hGH deficiency in children results in
decreased rate of linear growth, short stature, mild obesity, and (in many cases) delayed puberty.
Central (neurogenic) diabetes insipidus –
in the absence (or severe deficiency) of ADH, the collecting ducts cannot reabsorb water, so excess water is excreted in urine (as much as 10-12 liters per day).