A&P

1 . No because the Sertoli cells which form the basement membrane up to the lumen of these tubules serves as an avascular barrier inhibiting blood from reaching the sperm and set off immune responses aimed at the antigens present in the sperm cell 's surface (Tortora and Derrickson 2006 ,

.1059

2 . FSH and LH levels will be unaffected by castration because these hormones are secreted by cells in the pituitary and not by the testes Only testorone , synthesized in the testes , will fall during castration (p .627

3 . Semen is

propelled to the corpus spongiosom prior to ejaculation . It has to be less rigid and engorged as the corpus cavernosa in for it to contain the semen and release it only until the emotionally triggered reflex that leads to ejaculation (pp .1068-69

4 . The vaginal epithelium changes type during puberty to prepare it for the reproductive functions that the maturing female will now be capable of . The mucosa of the vagina is made up of non-keratinized stratified squamous epithelium whose function is to line surfaces that have to be perenially moist and represent the first line of defense against infection-causing microbes that can be acquired during sexual intercourse (p .118

5 . Up-regulation is relevant during the first 14 days of the ovarian cycle , also known as the follicular stage , because in the event that FSH and LH hormone levels in the body are low , it ensures that receptors increase to make the ovary more sensitive to the actions of available FSH and LH . FSH and LH start the process of follicular growth and development of the ovarian follicles towards the maturation of one until it is ready for ovulation (p .619 , 1084

6 . Nursing a baby at one breast would lead to the ejection of milk in both breasts . This is because suckling stimulates the touch receptors in the nipples that generate nerve impulses to the hypothalamus . This leads to increased secretion of oxytocin which makes the cells around the mammary ducts and glands of BOTH breasts contract and the compression causes milk to be ejected out of the breast where the baby is suckling as well as in the other (p .632 , 1133

7 . Both processes occur through exocytosis or the movement of materials out of a cell by the fusion of vesicles into the cell membrane (p . 72

8 . How does inflation of the lungs at birth affect the route of blood flow through the heart ? When the lungs expand during the baby 's first inhalation , the lungs expand and blood flow to this organ increases Blood returning from the lungs to the heart increases pressure in the left atrium which closes the foramen ovale by pushing the valve that guards it against the interatrial septum . The ductus venosus also collapses and venous blood from the viscera of the fetus flows into the hepatic portal vein to the liver and then via the hepatic vein to the inferior vena cava (p .795 , 1133

9 . A fertilized egg prevents the entry of excess sperm or polyspermy through fast block also called depolarization where a sperm can not fuse with a depolarized egg cell . Polyspermy is also prevented through slow block . Here , the intracellular release of calcium ions as the egg cell depolarizes promotes exocytosis which inactivates ZP3 or the sperm receptors and toughen the zona pellucida or the layer beneath the cell membrane (p .1105

10 . Estrogen advances the development and maintenance of the structures in the female reproductive system and the breasts and aids in the building of strong bones . Progesterone works with estrogen to make the endometrium in good condition and ready for implantation of a fertilized egg cell and to prepare the mammary glands for milk secretion (p .1084 HCG prevents the onset of menstruation which would lead to the wasting of the corpus luteum . HCG results in the stimulation of the corpus luteum for it to continually produce progesterone and estrogen in for the embryo and fetus to attach to the uterus lining during and after fertilization . HCS makes the mammary glands ready for milk secreation aid in the regulation of some aspects of metabolism in the baby and mother and boosts growth in the mother by heightening protein synthesis (p . 1127

List of References

Tortora , G . J . and Derrickson , B (2006 . Principles of Anatomy and Physiology (11th ed . New Jersey : John Wiley and Sons Inc ...