BIOLOGY QUARTER 4

• Gonads

  Primary sex organs
• Gonads


  • Testes in males
  • Ovaries in females

  
• Gonads


  Produce gametes (sex cells) and secrete hormones
• Gametes


  • Sperm – male gametes
  • Ova (eggs) – female gametes
• Testes


  • Coverings of the testes
  • Tunica albuginea – capsule that surrounds each testis
  • Septa – extensions of the capsule that extend into the testis and divide it into lobules

  
• Seminiferous tubules


  • Each lobule contains one to four
  • Tightly coiled structures
  • Function as sperm-forming factories
  • Empty sperm into the rete testis
• Interstitial cells


  Produce androgens such as testosterone
• Epididymis


  • Comma-shaped, tightly coiled tube
  • Found on the superior part of the testis and along the posterior lateral side
  • Functions to mature and store sperm cells (at least 20 days)
  • Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens
• Ductus Deferens (Vas Deferens)


  • Carries sperm from the epididymis to the ejaculatory duct
  • Passes through the inguinal canal and over the bladder
  • Moves sperm by peristalsis
  • Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue sheath
  • Ends in the ejaculatory duct which unites with the urethra
• Vasectomy


  Cutting of the ductus deferens at the level of the testes to prevent transportation of sperm
• Urethra


  • Extends from the base of the urinary bladder to the tip of the penis
  • Carries both urine and sperm
  • Sperm enters from the ejaculatory duct
  • Regions: Prostatic urethra, Membranous urethra, Spongy (penile) urethra
• Seminal Vesicle


  • Located at the base of the bladder
  • Produces a thick, yellowish secretion (60% of semen)
  • Contains fructose (sugar), Vitamin C, Prostaglandins, and other substances that nourish and activate sperm
• Prostate Gland


  • Encircles the upper part of the urethra
  • Secretes a milky fluid
  • Helps to activate sperm
  • Enters the urethra through several small ducts

  
• Bulbourethral Gland


  • Pea-sized gland inferior to the prostate
  • Produces a thick, clear mucus
  • Cleanses the urethra of acidic urine
  • Serves as a lubricant during sexual intercourse
  • Secreted into the penile urethra
• Semen


  • Mixture of sperm and accessory gland secretions
  • Advantages: Fructose provides energy for sperm cells, Alkalinity helps neutralize the acidic environment of vagina, Inhibits bacterial multiplication, Enhances sperm motility
• Scrotum


  • Divided sac of skin outside the abdomen
  • Maintains testes at 3°C lower than normal body temperature to protect sperm viability
• Penis


  • Delivers sperm into the female reproductive tract
  • Regions: Shaft, Glans penis (enlarged tip), Prepuce (foreskin)

  
• Spermatogenesis


  • Production of sperm cells
  • Begins at puberty and continues throughout life
  • Occurs in the seminiferous tubules
• Ovaries


  • Composed of ovarian follicles (sac-like structures)
  • Structure of an ovarian follicle: Oocyte, Follicular cells

  
• Ovarian Follicle Stages


  • Primary follicle – contains an immature oocyte
  • Graafian (vesicular) follicle – growing follicle with a maturing oocyte
  • Ovulation – when the egg is mature the follicle ruptures
  • Occurs about every 28 days
  • The ruptured follicle is transformed into a corpus luteum

  
• Support for Ovaries


  • Suspensory ligaments – secure ovary to lateral walls of the pelvis
  • Ovarian ligaments – attach to uterus
  • Broad ligament – a fold of the peritoneum, encloses suspensory ligament

  
• Uterine (Fallopian) Tube


  • Receive the ovulated oocyte
  • Provide a site for fertilization
  • Attaches to the uterus
  • Does not physically attach to the ovary
  • Supported by the broad ligament

  
• Uterine Tube Function


  • Fimbriae – finger-like projections at the distal end that receive the oocyte
  • Cilia inside the uterine tube slowly move the oocyte towards the uterus (takes 3–4 days)
  • Fertilization occurs inside the uterine tube

  
• Uterus


  • Located between the urinary bladder and rectum
  • Hollow organ
  • Functions: Receives a fertilized egg, Retains the fertilized egg, Nourishes the fertilized egg
• Support for the Uterus

  • Broad ligament – attached to the pelvis
  • Round ligament – anchored interiorly
  • Uterosacral ligaments – anchored posteriorly
• Regions of the Uterus


  • Body – main portion
  • Fundus – area where uterine tube enters
  • Cervix – narrow outlet that protrudes into the vagina
• Walls of the Uterus


  • Endometrium – Inner layer, Allows for implantation of a fertilized egg, Sloughs off if no pregnancy occurs (menses)
  • Myometrium - middle layer of smooth muscle
  • Serous layer – outer visceral peritoneum
• External Genitalia (Vulva)


  • Mons pubis, Labia, Vestibule, Clitoris
• Oogenesis

  • The total supply of eggs is present at birth
  • Ability to release eggs begins at puberty
  • Reproductive ability ends at menopause
  • Oocytes are matured in developing ovarian follicles
• Menstrual (Uterine) Cycle


  • Cyclic changes of the endometrium
  • Regulated by cyclic production of estrogens and progesterone
  • Stages: Menses, Proliferative stage, Secretory stage
• Mammary Glands


  • Present in both sexes, but only function in females
  • Modified sweat glands
  • Function is to produce milk
  • Stimulated by sex hormones (mostly estrogens) to increase in size
• Childbirth (Partition)


  • Labor – the series of events that expel the infant from the uterus
  • Initiation of labor: Estrogen levels rise, Uterine contractions begin, The placenta releases prostaglandins, Oxytocin is released by the pituitary
• Developmental Aspects of the Reproductive System


  • Reproductive system organs do not function until puberty
  • Puberty usually begins between ages 10 and 15
  • The first menses usually occurs about two years after the start of puberty
  • Most women reach peak reproductive ability in their late 20s
  • Menopause occurs when ovulation and menses cease entirely
  • Ovaries stop functioning as endocrine organs
  • There is a no equivalent of menopause in males, but there is a steady decline in testosterone
• Digestion


  Phases: Ingestion, Movement, Mechanical and Chemical Digestion, Absorption, Elimination
• Types of Digestion


  • Mechanical (physical): Chew, Tear, Grind, Mash, Mix
  • Chemical - Enzymatic reactions to improve digestion of: Carbohydrates, Proteins, Lipids
• Mouth


  • Teeth mechanically break down food into small pieces
  • Tongue mixes food with saliva (contains amylase, which helps break down starch)
  • Epiglottis is a flap-like structure at the back of the throat that closes over the trachea preventing food from entering it
• Esophagus


  • Approximately 20 cm long
  • Functions: Secrete mucus, Moves food from the throat to the stomach using muscle movement called peristalsis
  • If acid from the stomach gets into the esophagus, it can cause heartburn
• there is a steady decline in testosterone
• Phases of Digestion


  • Ingestion
  • Movement
  • Mechanical and Chemical Digestion
  • Absorption
  • Elimination
• Types of Digestion

  • Mechanical (physical)
  • Chemical - Enzymatic reactions