human reproduction Flashcards
: What is sexual reproduction?
Creation of offspring by fusion of male gamete (sperm) & female gamete (egg) to form a zygote.
What is asexual reproduction?
Creation of offspring without fusion of egg & sperm.
Differences between Asexual and Sexual Reproduction?
- Asexual: One parent, no gametes, genetically identical offspring.
- Sexual: Two parents, gametes required, genetically varied offspring
Why is sexual reproduction considered an evolutionary enigma?
- Sexual females have half as many daughters (“twofold cost”).
- Despite the cost, almost all eukaryotes reproduce sexually.
Mechanisms of Asexual Reproduction?
- Budding: New individuals from outgrowths (e.g., Hydra).
- Binary Fission: Parent splits into two (invertebrates).
- Fragmentation: Body parts develop into individuals.
What is hermaphroditism?
Each individual has both male & female reproductive systems (e.g., snails, worms).
What is sex reversal?
Some species can switch sexes:
* Male → Female (e.g., oysters)
* Female → Male (e.g., coral reef fish)
What is external fertilization?
Eggs are fertilized outside the female’s body in a moist environment
What is spawning?
Individuals release eggs and sperm into water at the same time, often triggered by chemical/environmental cues.
What is internal fertilization?
Sperm deposited inside/near female tract; fewer gametes produced, higher zygote survival, often with parental care.
Basic pattern of human reproductive anatomy?
- Gonads (produce gametes)
- Ducts (store/deliver gametes)
- Mating structures
Why are testes located outside the body in mammals?
Lower temperature needed for normal sperm production
Penis structure and function?
- Three cylinders of spongy erectile tissue.
- Erection caused by blood flow.
- Glans (head) has sensitive thin skin, covered by foreskin (prepuce).
Path of sperm from testes to exit?
Seminiferous tubules → Epididymis → Vas deferens → Ampulla → Seminal vesicle → Ejaculatory duct → Urethra
Testes structure?
- Seminiferous tubules: site of sperm formation.
- Leydig cells: produce testosterone.
- Sertoli cells: nourish sperm (“nurse cells”).
Composition of semen?
Sperm + secretions from:
* Ampullae (fructose, nutrients)
* Seminal vesicles (60% semen, fructose, prostaglandins)
* Prostate (pH buffer)
* Bulbourethral glands (mucus to neutralize acid)
Female external reproductive structures?
Clitoris and 2 sets of labia
Female internal reproductive organs?
Gonads (ovaries), ducts (oviducts, uterus, vagina).
What is the endometrium?
Lining of the uterus rich in blood vessels.
Function of ovaries?
- Contain follicles with oocytes.
- Support cells surround developing eggs
How does the egg reach the uterus?
- Through the oviduct (fallopian tube), moved by cilia.
What is the clitoris?
A highly sensitive structure with a glans covered by a prepuce.
What is the vulva composed of?
: Labia majora, labia minora, hymen, clitoris.
Function of mammary glands?
- Secrete milk via small sacs of epithelial tissue.
- Not reproductive organs but vital for reproduction.
