Endocrinology • For each hormone, state the following: - name and location of secreting organ - chemical class and receptor type (where given) - target(s) and main effect on target(s) = function - control pathway Compare and contrast peptide, steroid and amine hormones.
Classes of hormones: 1. Peptide - chain of amino acids, protein 2. Steroid - derived from cholesterol 3. Amine - derived from an amino acid * Different mechanisms of action for peptide hormones working through membrane receptors and steroids, vitamin D and thyroid hormones working through nuclear receptors. * Different hormone actions exerted through changes in protein phosphorylation or through changes in gene expression.
Major functional areas under endocrine control • Digestion and glucose metabolism • Osmoregulation (principally regulation of water and NaCl balance) • Calcium balance • Growth • Reproduction • Immune function
Endocrine homeostatic control of [Ca++]plasma • Parathyroid Hormone (PTH) • Increases [Ca++]plasma • Most important in control of [Ca++]plasma • Calcitonin • Reduces [Ca++]plasma * warning - gross anatomy picture is next
Thyroid-Normal thyroid gland, anterior to trachea. Structure: a right lobe and a left lobe connected by a narrow isthmus. Normal weight: 10 to 30 grams. It cannot easily be palpated.
ParathyroidsFour (usually) found on dorsal surface of thyroid glands.(These are hyperplasic)Secrete PTH
Parathyroid Hormone Maintains homeostatic plasma [Ca2+] PTH stimulates…1) osteoclasts to resorb bone 2) kidneys to reabsorb Ca2+ 3) intestines to increase Ca2+ absorption
[Ca2+]plasma causes • PTH or ? • PTH causes [Ca2+]plasma or • Represent these on a graph.