Week 5. Reproduction (Male)

Page 1: Title

• Human Reproduction Biology 30

Page 2: Introduction

• Human reproduction is essential for species survival.

• Unique to humans is the capability to reproduce year-round.

• Sexual reproduction introduces genetic variability.

  • Involves the creation of gametes through meiosis.

  • Results in the formation of a zygote through fertilization.

Page 3: Introduction

• Requires both male and female participants.

• Primary sex characteristics: specific physical features directly involved in reproduction.

  • Male examples: testes, penis, prostate gland.

  • Female examples: ovaries, uterus, vagina.

Page 4: Introduction

• Secondary sex characteristics: traits related to sexual dimorphism not directly involved in reproduction.

  • Male examples: facial hair, increased muscle mass, deeper voice.

  • Female examples: prominent breasts, wider hips.

Page 5: Introduction

• Males produce sperm; females produce ova (eggs).

• Fertilization occurs when sperm unites with ovum.

• Successful implantation leads to new human life development.

Page 6: The Male Reproductive System

• Components of the sperm:

  • Acrosome, head, midpiece, flagellum (tail).

  • Contains crucial cellular structures: centriole, mitochondria, nucleus.

Page 7: Differences in Gamete Production

• Males produce approximately 100 million sperm daily; females produce 1 egg per month.

• Pregnancy lasts ~9 months post-fertilization.

• Energy allocation influences mate selection:

  • Males seek attractive partners (gene selection).

  • Females prioritize partners with resources (cost of reproduction).

Page 8: Symmetrical Faces

• Symmetry may influence attractiveness in mate selection.

Page 9: Study Design and Face Symmetry

• Samples of facial symmetry manipulation to study preferences.

  • Reference: 'Preference for Facial Symmetry Depends on Study Design'

Page 10: Important Definitions

• Gonads: Reproductive glands producing gametes/hormones (ovaries/testes).

• Gamete: Male or female reproductive cell (sperm/ovum) with haploid chromosomes (n = 23).

• Duct: Tubes facilitating fluid passage.

Pages 11-12: Male Reproductive System Structures

• Key components:

  • Ureter, large intestine, urinary bladder, ductus deferens, urethra, seminal vesicle, prostate gland, Cowper's gland.

• Sperm originates in the testes and exits through the penis.

Page 13: Male Reproductive System Structures

• Recap of reproductive system components of male anatomy: urethra, seminal vesicles, ductus deferens, prostate gland, Cowper's gland.

Page 14: Path of Sperm

• Male reproductive system's purpose: deposit sperm into the female system for fertilization.

• Sperm are transported in semen, which provides swimming medium, neutralizes acidity, and nourishes sperm.

Page 15: Path of Sperm

• Semen Formation:

  • Sperm produced in testes, which are in the scrotum.

Page 16: Path of Sperm

• Sperm travel through the ductus deferens to the ejaculatory duct and urethra.

• Glands contributing to semen fluid: seminal vesicle, prostate gland, Cowper’s gland.

Page 17: Scrotum

• Houses the testes; maintains a cooler temperature for sperm development (thermoregulation).

• Testes descend into the scrotum during fetal development.

Page 18: Sperm Production

• Testes contain seminiferous tubules for sperm production (spermatogenesis).

• Sertoli cells within nourish developing sperm and produce testosterone.

• Epididymis stores and matures sperm; connected to ductus deferens.

Page 19: Male Anatomy Overview

• Image description and structures related to sperm production and anatomy: ductus deferens, interstitial cells, Sertoli cells, etc.

Page 20: Vas Deferens

• Transports sperm from the testes to the ejaculatory duct, merging with seminal vesicle duct at the urethra.

Pages 21-22: Seminal Fluid Composition

• Seminal Vesicle:

  • Secretes fructose for energy.

  • Produces prostaglandins to assist sperm movement.

• Prostate Gland:

  • Secretes alkaline fluid to protect sperm from acid.

• Cowper's Gland:

  • Produces lubricating mucus for sperm protection.

Page 23: Ejaculatory Duct

• Propels semen into the urethra.

• Sphincter controls urine flow, preventing simultaneous passage of semen and urine.

Page 24: Penis

• Transfers sperm to the female reproductive tract.

• Engorgement due to increased blood flow during arousal.

Page 25: Fun Fact

• Inquiry about human body bones, noting that 'the baculum' is not one of them.

Page 26: Erection Physiology

• Arteries engorge the penis with blood during arousal while veins constrict, causing penis elongation and stiffness.

Page 27: Penis Fractures

• Rare but possible; occurs with trauma to an erect penis.

• Injury involves rupture of a cylinder due to sudden bending.

Page 28: Comparison of Males and Females

• Males produce sperm continuously; females are born with a fixed number of eggs maturing monthly post-puberty.

• Female anatomy separates the repro and excretory systems.

Page 29: Questions

• Seminal vesicles:

  1. A) are where sperm mature

  2. B) secrete fluid that nourishes sperm.

  • Ovulation occurs with the release of a mature egg from one ovary.

Page 30: Hormones in Reproduction

• Hormones regulate reproductive processes through life stages:

  • Increase during puberty (ages 10-13 for males, 9-13 for females).

  • Decrease in middle age (andropause in men; menopause in women).

Page 31: Reproductive Hormones

• Certain hormones produced by both sexes: GnRH, FSH, LH.

• GnRH influences LH and FSH release; critical for gamete maturation and sex hormone production.

Page 32: Hormonal Regulation

• Hypothalamus produces hormones regulating anterior pituitary hormone release.

• Anterior pituitary stimulates reproductive hormone secretion based on feedback.

Page 33: Male Reproductive Hormones

• Testosterone production is higher in males; critical for development of male reproductive traits and secondary characteristics (body hair, voice changes).

Page 34: Regulation of Male Hormones

• GnRH from the hypothalamus activates FSH and LH secretion.

• FSH assists in spermatogenesis; Inhibin regulates FSH levels.

Page 35: Hormonal Feedback

• Overview of hormonal feedback loops involving testes, Sertoli cells, inhibin production, and spermatogenesis.

Page 36: Andropause

• Reduction in reproductive hormones, but viable sperm production continues into late life.

• Increased risk of certain cancers (e.g., prostate cancer).

Page 37: Additional Questions

• Effect of steroids:

  1. A) Decrease in FSH and LH release.

  • Peak in LH triggers ovulation in females.

Page 38-40: Reproductive Tissues Lab

• Cross-sectional diagrams illustrating testis and ovary structures, focusing on gamete production cells and surrounding tissue features.

Page 41-43: Reproductive Tissues Lab: Ovary

• Descriptions of ovarian structures, including primary/secondary follicles and developmental processes involved in oocyte maturation.