BIO 3422 Lecture Notes - Lecture 9: Ph, Parafollicular Cell, Osteoclast
16 Dec 2017
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Parathyroid hormone (pth)- come from thyroid gland (gland beside the thyroid: secreted in response to low ca, effects increases ca by: Increase activity of osteoclasts = break down bone to free up ca and po3- (osteoblasts ossify cartilage) Increase reabsorption of ca, decrease reabsorption of po3- Calcitonin effects reduce ca level: secreted/stimulated/released in response to high ca levels by parafollicular cells/c-cells in thyroids, inhibits osteoclast activity (bone not broken down, so no free ca to be reabsorbed). Ph must be maintained to prevent proteins from denaturing. Henderson/hasselbach equation ph = 6. 1 + log [hco3]/[co2] Homeostasis input equals output (acid in = acid out) Acid in (enters body) by our diet (lemon), metabolic pathway/intermediates (lactate), metabolism produce co2 (largest source of acid production) Acid out (leaves from body) by breathing/respiration, kidneys can remove excess acid. Mechanisms to maintain plasma ph (buffers, lungs (ventilation), kidneys (renal metabolic regulation and is the ultimate adjuster to maintain balance)
