BIOD27H3 Chapter Notes - Chapter 5: Gonadotropin, Luteinizing Hormone, Thyroid-Stimulating Hormone

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Chapter 5 pituitary Hormones
-Female Pit gland is much smaller than Males
-Females becomes larger during pregnancy
Anatomy of the Pituitary Gland
- Also known as hypophysis
- Composed of tissues derived from two diverse origins. Embryological origins of adenohypophysis and
neurohypophysis are different
- Composed of : adenohypophysis (anterior lobe) and neurohypophysis( posterior lobe)
1)Adenohypophysis
- mostly glandular tissue
-composed of pars distalis and tuberalis
2)Neurohypophysis
- consists of neuronal processes that originate from neurons in the hypothalamus
-composed of pars Nervosa
Vascularisation and Innervation
Size of each lobe of the pit gland varies between diff species and may reflect the hormonal output of the
glands required for successful adaptation to a particular habitat
The pituitary gland receives its blood supply from the superior and inferior hypophysial arteries
Superior and Inferior branches of Superior hypophyseal artery penetrates the stalk and the hypothalamus
Pars distalis
- is vacularized by hypophyseal portalvessels that arise from capillary bed from the hypothalamus
- No evidence that neurons innervate or otherwise influence cell activity of pars distalis
Pars Nervosa
- receives a separate blood supply from the inferior hypophysial artery
- composed of axonal endings of neurons whose cell bodies are located in hypothalamic nuclei
- hypothalamic nuclei: paraventricular nuclei and supraoptic nuclei
- all hormones produced by the post. Lobe are released directly in to the efefretn portal veins to be
carried through the systematic circulation to act at target tissues
- some evidence indicates that some adenohypophyseal blood maybe shunted to the
neurohypophysis pit hormones may be able to modify CNS function
Cytotogical Methods Distinguish Different Pituitary Cell Types
Pars distalis
- cells are differentiated into somatotrophs, lactotrophs (mamotrophs), corticotrophs, thytotrophs, and
gonadotrophs
- ^ terms relate to hormonal product synthesized by each of these cells
- The cell types can slo be referred to as acidophils, basophils and chromophobes depending on their
affinity for certain dyes
- Acidophils: somatotrophs and lactotrophs
- Basophils: thyrotrophs and corticotrophs
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