Reproduction

Reproduction

1. functions

   • formation, storage and transport of gametes
   • production of a new human being
   • secretion of hormones

2. endocrine system

   • pituitary gland releases luteinising hormone (LH) and follicle stimulating hormone (FSH)
   • LH and FSH release are controlled by gonadotrophin releasing hormone (GnRH), this is released by the hypothalamus
   • LH and FSH have various functions and are controlled by negative feedback

3. testes and ovaries

   • sex hormones are made by both
   • ovaries secrete oestrogen and progesterone
     • these control the female secondary sexual characters
       • for instance the menstrual cycle and pregnancy
   • Testosterone controls the development of male secondary sexual characters
     • aids sperm production

4. Gametogenesis

   • process of gamete formation
   • occurs in ovary or testis
   • three main steps
     • proliferation of germ cells
     • meiosis
     • maturation

5. sex organs

   • primary sex organs
     • make haploid gametes and produce sex hormones
     • Accessory sex organs have structures which carry the gametes, bring about fertilization and protect the zygote
       • Seminal vesicles – fructose, prostaglandin, provides 60% of semen volume and also secretes fibrinogen
       • Prostate – secretes alkaline fluid, citric acid, provides clotting enzymes and PSA
       • Bulbourethral gland – produce mucus like substance
     • Secondary sexual characters are controlled by sex hormones
     • testes
       • lie outside the body in a skin sac called the scrotal sac / scrotum
       • Develop in the abdomen
       • mostly made of seminiferous tubules
         • the tubules have primitive germ cells which mature and move to the lumen
           • Tubules drain in the head of the epididymis then into the vas deferens
       • spermatogenesis
         • 2 main cells
           • Leydig are found in between the tubules and their main function is to produce testosterone by LH
           • Sertoli cells, are support cells in the tubules and make regulators for spermatogenesis and are glycogen rich

6. spermatoza

   • Spermatozoa leaving the testes are not fully mobile. They continue their maturation and acquire motility during their passage through the epididymis
   • Forward motility is acquired in the epididymis and involves protein activation

7. female reproductive system

   • primary reproductive organs of the female are the ovaries which produce the ova (egg cells) and sex hormones
   • The accessory organs
     • Fallopian or uterine tubes
       • Extends from the uterus to the ovaries
       • Possess cilia and the beating of cilia helps the ovum to move in the tube
         • ends of have many small fimbrae which catch the egg as it leaves the ovary during ovulation
     • uterus
       • thick muscular sac at the front of the pelvic cavity
       • Contraction of the smooth muscle in the wall of the uterus at the end of pregnancy, help push the baby out
       • In a non-pregnant woman, the uterus is small: 5-8 cm. long
         • during pregnancy, the uterus is stretched to hold the baby and its membranes
     • vagina
       • muscular tube leading from the vaginal orifice to the uterus
       • receives the male penis during sexual activity
     • vulva
       • external organs of the female which are found surrounding the openings of the urethra and the vagina
       • Included are the labia majora and labia minora, clitoris and the vestibule
   • ovaries
     • female glands
     • release ova and sex hormones
     • No new ova are made after birth
     • At birth, ova are arrested in prophase
   • Ovarian hormone function
     • oestrogen controls the development of secondary sexual characters
     • Progesterone stimulates uterine changes and affects breast tissue development
   • oogenesis
     • new ova aren't made after birth
     • After puberty, several follicles enlarge and one becomes the dominant follicle
     • granulosa cells and theca interna make oestrogen
     • 14th day of the cycle, the follicle ruptures, releasing the ovum
   • fertilization
     • chemoattraction of the sperm to the ovum by substances produced by the ovum
     • adherence to the zona pellucida, a gel-like membranous structure surrounding the ovum
     • penetration of the zona pellucida and the acrosome reaction
     • adherence of the sperm head to the cell membrane of the ovum, with breakdown of the area of fusion and release of the sperm nucleus into the cytoplasm of the ovum

Imagens e arquivos do mapa