THE REPRODUCTIVE SYSTEM Chapter 19

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Chapter 19
THE REPRODUCTIVE SYSTEM
Introduction
• Reproduction: process by which genetic
material is passed from one generation to
the next
Introduction (cont’d.)
• Meiosis produces sex cells
– Sperm from male and egg from female join to
form zygote
– Zygote develops into embryo
– Embryo develops into fetus
THE MALE REPRODUCTIVE SYSTEM
Introduction
• Testes: produce sperm and male sex
hormones
• Accessory glands: produce secretions
• Accessory organs: scrotum
• Penis: transporting and supporting structure
Introduction (cont’d.)
The Scrotum
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Outpouching of abdominal wall
Supports the testes
Divided internally by a septum
Scrotal sac elevates and descends
The Testes
• Tunica albuginea: capsule covering with
lobules
• Convoluted seminiferous tubules
– Spermatogenesis
The Testes (cont’d.)
• Spermatogenesis
– Spermatogonia > primary spermatocytes >
secondary spermatocytes > spermatids >
spermatozoa
• Sertoli cells: supply sperm cells with
nutrients
The Testes (cont’d.)
• Interstitial cells of Leydig: produce
testosterone
The Testes (cont’d.)
The Anatomy of the Spermatozoa
• Three hundred million produced daily
• Anatomy
– Head: contains genetic material and acrosome
• Acrosome has enzymes that aid sperm in
penetrating covering of ovum
– Middle piece: contains mitochondria
– Tail: propels sperm
The Anatomy of the Spermatozoa
(cont’d.)
• Anatomy of a sperm cell
The Functions of Testosterone
• Controls development, growth, and
maintenance of male sex organs
• Stimulates muscle buildup and bone
development
• Causes sperm maturation
• Causes thyroid cartilage enlargement
• Produces body hair patterns
The Ducts of the System
• Seminiferous tubules: transport sperm cells
• Rete testis: network of ducts
• Ductus epididymis: site of sperm cell
maturation
• Epididymis located on posterior border of
testis
The Ducts of the System
(cont’d.)
• Vas deferens: straightened portion of
epididymis
– Enclosed in spermatic duct
• Ejaculatory duct: ejects spermatozoa into
urethra
The Ducts of the System
(cont’d.)
• Urethra: terminal duct
– Prostatic urethra, cavernous urethra, urethral
orifice
The Accessory Glands
• Seminal vesicles: produce viscous part of
semen
• Prostate gland: produces fluid part of
semen
• Bulbourethral glands: produce mucus
Semen
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Mixture of sperm cells and secretions
Provides energy to the sperm via fructose
Neutralizes acidity of vagina
Acts as a transport medium
Contains enzymes that activate sperm
Average volume is 2.5 to 6 mL
Seminalplasmin: destroys certain bacteria
The Penis
• Delivers spermatozoa to female
reproductive tract
• Glans penis: end of the shaft
• Prepuce: loose skin covering glans penis
– Circumcision: removal of prepuce
The Penis (cont’d.)
• Contains masses of spongy tissue with
sinuses
• Sinuses fill with blood resulting in erection
– Compress veins so blood is retained
– Help penis penetrate vagina
• During ejaculation, sphincter at base of
urinary bladder is closed
THE FEMALE REPRODUCTIVE SYSTEM
Introduction
• Primary sex organs
– Ovaries
• Accessory organs
– Uterine tubes, uterus, vagina, external genitalia
• Accessory glands: produce mucus
Introduction (cont’d.)
The Ovaries
• Held in position by ligaments
• Covered by germinal epithelium
• Tunica albuginea: cortex contains ovarian
follicles
• Ovarian follicles: eggs in various
developmental stages
• Primary follicle: contains oocyte
The Ovaries (cont’d.)
The Ovaries (cont’d.)
• Oogenesis
– Begins in developing female fetus (700,000
produced)
– Puberty: ovarian cycle begins
• Primary oocyte: first meiotic division
• Mature egg: second meiotic division
The Uterine or Fallopian Tubes
• Transport ova to the uterus
• Infundibulum: funnel-shaped end with
fimbriae
• Cilia sweep an ovum into uterine tube
• Egg moved by peristalsis toward uterus
• Fertilization occurs in upper third of tube
The Uterus
• Site of menstruation, egg implantation and
labor
• Pear shaped
• Uterine cavity: interior of the body
• Cervical canal: interior of the cervix
• Uterine wall: endometrium, myometrium,
perimetrium
The Menstrual Cycle
• Menstrual phase
– Endometrial lining shed along with blood and
mucus
– Ovarian follicles begin development
• Preovulatory or proliferative phase
– Secondary follicle matures into graafian follicle
– Ovulation is rupturing of graafian follicle
The Menstrual Cycle (cont’d.)
• Postovulatory or secretory phase
– Corpus luteum develops
• Secretes estrogen and progesterone
– If fertilization and implantation do not occur
• Corpus luteum degenerates and new cycle starts
– If fertilization and implantation occur
• Corpus luteum maintained for four months
Animation – Ovulation
Click Here to Play Ovulation Animation
The Functions of Estrogen
• Development of female secondary sex
characteristics
– Breast development, pubic hair, fat deposits,
widening of the pelvic bone
• Enlargement of:
– Uterine tubes, uterus, vagina, external genitalia
The Vagina
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Passageway for menstrual flow
Receptacle for the penis
Lower portion of birth canal
Fornix: surrounds vaginal attachment to
cervix
The External Genitalia of the
Female
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Vulva: external genitalia
Labia: majora and minora
Clitoris: erectile tissue
Vestibule: vaginal and urethral orifices
Glands: Skene’s and Bartholin’s
The External Genitalia of the
Female (cont’d.)
THE PERINEUM
The Perineum (cont’d.)
• Diamond-shaped region at inferior end of
trunk between buttocks and thighs
• Divided into:
– Anterior urogenital triangle containing external
genitalia
– Posterior anal triangle containing anus
THE ANATOMY AND FUNCTION OF THE MAMMARY
GLANDS
The Anatomy and Function of
the Mammary Glands (cont’d.)
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Produce milk in females
Contain 15 to 20 lobes with lobules
Lobules contain milk-secreting cells
Milk is conveyed through series of tubules
Areola: circular pigmented area around
nipple
The Anatomy and Function of
the Mammary Glands (cont’d.)
PREGNANCY AND EMBRYONIC DEVELOPMENT
Pregnancy and Embryonic
Development (cont’d.)
• Egg fertilization 12-24 hours after ovulation
• Zygote: fertilized egg
• Moves down uterine tube into uterus
– Blastula
• Zygote embeds in endometrium, placenta
develops
Pregnancy and Embryonic
Development (cont’d.)
• Primary germ layers
– Ectoderm: skin and nervous system
– Mesoderm: muscles and bones
– Endoderm: linings of organs and glands
• Amnion: fluid-filled sac
– Attached to embryo by umbilical cord
• Parturition: childbirth
Summary
• Discussed the organs of the male
reproductive system
• Discussed the role of testosterone
• Described the process of spermatogenesis
• Discussed the organs of the female
reproductive system
Summary (cont’d.)
• Discussed the role of estrogen
• Described the process of oogenesis
• Described the phases of the menstrual
cycle
• Discussed pregnancy and embryonic
development

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