Human Reproduction, Respiration, Circulation & Digestion – Lecture Review

Human Reproduction

• Fertilization & Zygote Formation

  • Fusion of a haploid sperm and haploid ovum ➔ forms a diploid zygote.

  • Zygote undergoes rapid mitosis (cleavage) and differentiates into the embryo plus extra-embryonic structures: placenta, umbilical cord, amniotic sac.

  • Significance: placenta enables nutrient / gas exchange; amniotic sac cushions; umbilical cord connects fetal and maternal circulations.

• Gamete Production

  • Sperm synthesized in the seminiferous tubules of the testes (male gonads).

  • Ova (eggs) mature inside follicles in the ovaries (female gonads).

  • Females are born with a finite pool of primary oocytes; no new oocytes form post-natally.

• Ovulation & Transport

  • Occurs mid-cycle (~day 14 of a 28-day cycle).

  • Released secondary oocyte enters the uterine/Fallopian tube where fertilization usually occurs.

  • Progesterone then prepares the endometrium (inner uterine lining) for implantation.

• Uterine & Cervical Anatomy

  • Cervix: narrow opening at the inferior end of the uterus; dilates during labor.

  • Endometriosis: ectopic growth of endometrial tissue; causes pelvic pain & infertility.

• Permanent Contraception

  • Tubal ligation: surgical tying/cutting of Fallopian tubes; blocks ova–sperm encounter.

  • Vasectomy: severing/occluding the vas deferens; blocks sperm from entering semen.

• Female Life Stages

  • Premenopause (reproductive years) vs. perimenopause & menopause (decline/cessation of ovarian cycles).

Male Reproductive Health

• Prostate Gland

  • Secretes alkaline fluid; can enlarge (benign prostatic hyperplasia) & is the #1 cancer site in males.

• Semen Composition

  • Spermatozoa + seminal plasma (fructose, prostaglandins, buffers, enzymes).

Digestive System

• Overview of the Alimentary Canal
  \text{Mouth} \rightarrow \text{Pharynx} \rightarrow \text{Esophagus} \rightarrow \text{Stomach} \rightarrow \text{Small Intestine} \rightarrow \text{Large Intestine}

• Oral Cavity

  • Salivary amylase begins hydrolysis of starch (carbohydrates).

  • Epiglottis prevents food entry into trachea during swallowing.

• Stomach

  • Secretes \text{HCl} (pH ≈ 2). Functions: kills microbes, denatures proteins, activates pepsinogen ➔ protein digestion.

  • Ulcers: mucosal sores; often due to Helicobacter pylori infection.

• Small Intestine

  • Primary site for enzymatic digestion & absorption of all biomolecules; large surface area via villi & microvilli.

• Large Intestine (Colon)

  • Reabsorbs water & electrolytes; forms feces.

  • Cecum (blind pouch) hosts fermentative microbes; enlarged in herbivores.

• **Accessory