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NOTES: CH 46 – Animal Reproduction (part 1)
MALE REPRODUCTIVE SYSTEM
Functions:
1) Produce sperm;
2) Deliver sperm to female repro. tract;
3) Produce androgens (male sex hormones).
MALE REPRODUCTIVE SYSTEM - Anatomy
● TESTES
-develop in abdomen; descend into scrotum before birth;
-made up of tightly coiled tubes (SEMINIFEROUS TUBULES) where sperm are formed;
-scattered between tubules are the LEYDIG CELLS (produce testosterone and other androgens).
(Leydig cells)
TESTIS
● SCROTUM:
-a pouch of skin that encloses the testes for protection and temperature regulation
MALE REPRODUCTIVE SYSTEM - Anatomy
● EPIDIDYMIS
-6 meters of tubes; sperm cells are here for approx. 20 days;
-location where sperm become motile, gain ability to fertilize.
MALE REPRODUCTIVE SYSTEM - Anatomy
● VAS DEFERENS (muscular tube)
● EJACULATORY DUCT
● URETHRA-tube that drains both repro. & excretory products
MALE REPRODUCTIVE SYSTEM - Anatomy
● PENIS-3 cylinders of erectile tissue (when filled with blood, penis becomes erect);-head of penis = glans penis; has thinner covering; is covered by foreskin.
MALE REPRODUCTIVE SYSTEM
There are 3 sets of accessory glands (add secretions to semen):
1) SEMINAL VESICLES (2):
● produce 60% of semen volume/fluid;
● fluid contains mucus, fructose sugar (energy!), coagulating enzyme, prostaglandins.
MALE REPRODUCTIVE SYSTEMAccessory glands
(continued):
2) PROSTATE GLAND:● secretes thin, milky, slightly alkaline fluid;● fluid helps to balance the pH environment of the vagina.
MALE REPRODUCTIVE SYSTEMAccessory glands
(continued):
3) BULBOUREHTRAL GLANDS (2):● secrete viscous mucus PRIOR to ejaculation● fluid neutralizes any acidic urine in the urethra;● carries some sperm;● a.k.a. Cowper’s glands.
SEMEN● consists of: sperm cells and
secretions from the seminal vesicles, prostate gland, bulbourethral glands
*typical semen production = 2-5 mL;
*semen first coagulates; then thins & sperm begin to swim through the female reproductive tract…
FEMALE REPRODUCTIVE SYSTEM
Functions:
1) Produce egg cells;
2) Produce female hormones;
3) Nurture & protect developing fetus.
FEMALE REPRODUCTIVE SYSTEM - Anatomy
● OVARIES:
-about size & shape of almonds
-contains many FOLLICLES…
The follicles…*surround, nourish, protect egg
cells;
*produce estrogens;
*mature and release egg during monthly cycle (1 follicle per month, starting at puberty and ending at menopause)…this is OVULATION;
*each becomes a CORPUS LUTEUM following ovulation;
*disintegrate if egg is not fertilized.
FEMALE REPRODUCTIVE SYSTEM - Anatomy
● OVIDUCTS (“FALLOPIAN TUBES”):-cilia “pull” the egg cell in and convey the egg down the duct;-fertilization occurs HERE!!!
● UTERUS (“womb”):-thick, muscular organ; expands du ring pregnancy;-inner lining = ENDOMETRIUM, which contains many blood vessels
FEMALE REPRODUCTIVE SYSTEM - Anatomy
● CERVIX (neck of uterus)
● VAGINA (birth canal)-thin-walled chamber where sperm are deposited;-hymen = vascularized membrane which covers vaginal opening from birth until it is ruptured
FEMALE REPRODUCTIVE SYSTEM - Anatomy
● BARTHOLIN’S GLANDS-small glands near vaginal opening;-secrete mucus during sexual arousal response.
● LABIA MINORA / LABIA MAJORA-enclose and protect vaginal opening / urethral opening
Sexual Response:Two types of physiological
reactions predominate in both sexes during sexual arousal/response:
● Vasocongestion: filling of a tissue with blood
● Myotonia: increased muscle tension
GAMETE PRODUCTION:
● Spermatogenesis: production of sperm cells
● Oogenesis: development of ova
-see figures 46.12 (pg. 1006-1007)
Differences between spermatogenesis & oogenesis:
SPERMATOGENESIS:● All 4 meiotic products
develop into mature sperm● Sperm cells continue to
develop throughout a male’s life
● Stages of meiosis occur continuously, in an uninterrupted sequence
Differences between spermatogenesis & oogenesis:
OOGENESIS:
● Uneven cytokinesis; most cytoplasm goes to 2° oocyte (becomes ovum); the other products (polar bodies) disintegrate
● Female is born with all of her egg cells
● Has long “resting” periods of meiosis