Exam 3 Study Guide

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Exam 3 Study Guide

Study Guide
University of Southern California
Bisc 307l - General Physiology
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BISC 307L 2nd Edition Exam 3 Study Guide Calcium Balance in the Body Calcium in the Body 1% of the Ca in the body exists in free ionic form. The other 99% exists as hydroxyapatite, which forms the mineral portion of bones. Calcium in bones acts as a storage reservoir for maintenance of Ca in the body at appropriate levels. Ca 2+ Balance in the Body: The small intestine is the only place new Ca comes into the body, from our diet. This Ca will be pooped out, or go into the ECF. From here, it can be deposited into bones through cells called osteoblasts(building new bone), or be filtered into the kidney where it can be reabsorbed or excreted. Regulation of Body Calcium The 1% of plasma Ca in the body is regulated by 3 hormones from the thyroid and parathyroid glands: 1. Parathyroid hormone is essential for life, it raises plasma calcium. - stimulates bone resorption of calcium through osteoblasts - stimulates reabsorption from kidney tubule back to ECF - stimulates calcitriol 2. Calcitriol is a steroid hormone made from Vitamin D, it raises plasma calcium - stimulates Ca absorption from small intestine, it brings new Ca into the body (prolactin also has this effect) - also stimulates bone resorption 3. Calcitonin – opposes the effect of PTH, reduces blood calcium - stimulates bone deposition - is important in children for growth and in pregnant women to fight osteoporosis Reproductive System Overview of Sexual Differentiation Step 1: Differentiation of Gonads Humans have 22 pairs of autosomal chromosomes and one pair of sex chromosomes – gender depends on whether the fertilized egg bears an X or Y chromosome. Undifferentiated gonads have germ cells, the coelomic epithelium, and the mesenchyme. Under the influence of the male chromosome, the differentiation on the left occurs. In the absence of the sex determining Y chromosome – the gonads follow their default pattern for female differentiation as seen on the right(above). Step 2: Development of the reproductive tract So the gonads have differentiated. The next step is shown to the right. At an early stage, embryos of both sexes have two primitive duct systems: Wolffian and Mullerian. Under the influence of testosterone in males, Wolffian ducts become the male reproductive tract. Leydig cells secrete testosterone, while sertoli cells secrete antimullerian hormones that kill the mullerian duct cells. In females you have the default condition. Theca cells don’t secrete testosterone. The Wolffian ducts are testosterone dependent, so fourth power of the radius, since the viscosity of the blood stays relatively the same. And the length of the vascular system doesn’t change from moment to moment, leaving only the radius as the direct determinant of changes in resistance and therefore blood flow. Systemic circulation is much longer than the pulmonary circulation, but input of the second has to equal output of the first. In order for the left heart to force blood through both systems at the same rate, the left side has to pump harder ...

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