BIOB33 ASSIGNED READINGS
Radiologists: physicians who specialize in the performance and analysis of diagnostic images of internal
X-Rays: form of high energy radiation than can penetrate living tissues. Beam of X-rays travels through
the body and strikes a photographic plate. Not all the xrays arrive on film, some are absorbed or
deflected. The resistance to x-ray penetration is called radiodensity.
Air->fat->liver->blood->muscle->bone , increasing radiodensity
-radiodense tissues appear in white(ie bone), and less dense tissues are seen in shades of gray to black
Barium-contrast x-ray: barium is very radiodense, used to xray upper digestive tract, the contours of the
gastric and the intestinal lining can be seen outlined against the white of the barium solution.
CT Scans: aka CAT scans, use a single x-ray source rotating around the body. Construction of a three-
dimensional structure of the body.
Lecture 2: Repairing Injuries to the Skin
-the skin can regenerate, because STEM CELLS persist in both epithelial and connective tissue
-deeper the cut, the longer it will take because it involves a much greater surface area to be repaired
4 stages of repairing skin
-the formation of a blood clot temporarily restores the integrity of the epidermis. Cells of the
staratum basale begin rapid division and beings to migrate along the edges of the wound in an attempt
to place the missing epidermal cells. If the wound occupies an extensive area, dermal repairs must be
under way before epithelial cells can cover the surface. Granulation Tissue: combination of blood clot,
fibroblast, and an extensive capillary network.
-appearance of collagen fibers and typical ground substance
-scar tissue can be considered a practical limit to the healing process. The process is highly
variable, we do not know what regulates the extent of scar tissue formation. Scar tissue does not occur
after surgeries on fetus, growth factors???
Keloid: thick, raised area of scar tissue, covered by a shiny, epidermal surface.
Lecture 3 Spermatogensis and Meiosis
-primary spermatocyte->secondary spermatocye->spermatids
-4 spermatids per primary spermatocyte
-spermatogensis is directly stimulated by testosterone and indierectly stimulated by FSH
-each spermatid matures into a spermatozoon via spermiogensis
-embedding of spermatid in cytoplasm of Nurse Cell
-detatches when fully matured
Five Important Functions of Nurse Cells:
-maintain of the blood-testis barrier
-support of spermatogenesis
-relies of nurse cells stimulated by testosterone, FSH
-support of spermiogenesis
-nurse cells promote development
-secretion of inhibin
-hormone that stops fsh production
-secretion of androgen-building protein (ABP)
-responsible for elevating concentration of androgens to stimulate spermiogenesis
-begins as activated primordial follicles develop into Primary follicles
-step two: formation of Secondary Ovarian Follicles
-only some primary follicles develop into secondary follicles
-accumulation of follicular fluid
-Step 3: Formation of a Tertiary Ovarian Follicle