BIOD27H3 Lecture : BGYB30H3 Lecture 24 Notes Reproduction and Development 4-Dec 1
11 Aug 2010
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BGYB30H3 Lecture 24 Notes
-estrogen causes secondary sex characteristics such as the development of the breasts and fat
distribution in hips and upper thighs
-androgens from the adrenal cortex cause hair growth such as armpit, pubic hair
-four phases of sexual response
-excitement phase involves stimulation of erection reflex in women and men
-excitement phase causes
x Increased blood flow into the penis through corpus cavernosa and corpus spongiosum
x Increased blood flow to the vagina and uterus
x Lubrication of vagina and penis
-plateau is the sexual intercourse
-orgasm is the peak of the plateau phase in which there is ejacuation in men and orgasm in
women
-orgasm in women is not required for fertilization
-orgasm phase causes contractions in the lower pelvic muscles
-resolution is where body returns back to homeostasis through decreased blood pressure and
respiration rate
-in erection reflex, tactile stimuli activate mechanoreceptors, which send info to spinal cord
-spinal cord inhibits sympathetic nervous system and activates parasympathetic nervous
system
-stimulating parasympathetic nervous system causes penile arterioles to dilate to increase
blood flow
-erotic stimuli (erogenous zones) and thoughts can cause erection reflex through ascending and
descending pathways to and from the brain; not a reflex mechanism
-REM sleep can cause non-sexual erections and orgasm
-capactiation allows sperm to swim rapidly and fertilize the egg
-when fertilizing the egg, enzymes cause acrosomal reaction by dissolving the outer portions of
the egg casing
-fertilization takes place in the distal portion of the Fallopian tube
-second meiotic division is suspended in the egg until sperm fertilizes the egg
-sperm membrane fuses with oocyte membrane during penetration and the nucleus is released
into the cytoplasm of the egg
-cortical reaction after fertilization prevents penetration of other sperm; prevents polyspermy
-as zygote moves to the uterus, it divides until day 5 when it reaches the uterus as a blastocyst
-chorion of the blastocyst and endometrial cells help it to connect to the endometrium wall
-chorion becomes the placenta; its villi break down blood vessels to bathe the embryo in
maternal blood
-allantois becomes the umbilical cord while amnion secretes fluid
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-hCG is secreted from developing chorionic villi and placenta; similar to LH and binds to LH
receptors in the corpus luteum;
-hCG keeps the endometrium intact through secreting progesterone
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Document Summary
Estrogen causes secondary sex characteristics such as the development of the breasts and fat distribution in hips and upper thighs. Androgens from the adrenal cortex cause hair growth such as armpit, pubic hair. Excitement phase involves stimulation of erection reflex in women and men. Increased blood flow into the penis through corpus cavernosa and corpus spongiosum. Increased blood flow to the vagina and uterus. Orgasm is the peak of the plateau phase in which there is ejacuation in men and orgasm in women. Orgasm in women is not required for fertilization. Orgasm phase causes contractions in the lower pelvic muscles. Resolution is where body returns back to homeostasis through decreased blood pressure and respiration rate. In erection reflex, tactile stimuli activate mechanoreceptors, which send info to spinal cord. Spinal cord inhibits sympathetic nervous system and activates parasympathetic nervous system. Stimulating parasympathetic nervous system causes penile arterioles to dilate to increase blood flow.
