Anatomy and physiology Chapter 28

What is Sexual Reproduction

The process in which organisms produce offspring germ cells called gametes

What are the main components of the reproductive

The main components are gonads (produce gametes and secrete hormones), ducts (transport, receive, and store gametes), and accessory sex glands (produce materials that support gametes).

What fields study the female and male reproductive systems?

Gynecology (female) and urology (male and urinary systems).

What is the process of fertilization in sexual reproduction

Fertilization involves one set of chromosomes from each parent, forming a new cell

What is the role of gonads in sexual reproduction?

Gonads produce gametes and secrete hormones

What structures are involved in the male reproductive system?

Testes, ducts (epididymis, vas deferens, ejaculatory duct, urethra), accessory sex glands (seminal vesicles, prostate, bulbourethral glands), and supporting structures like the penis.

What does semen contain

Semen consists of sperm and glandular secretions.

What is the function of the scrotum

The scrotum supports the testes and regulates their temperature for proper sperm production.

How does the scrotum regulate temperature

The cremaster muscle elevates the testes when it’s cold and relaxes during warmth to maintain the ideal temperature for sperm survival (3°C below core body temperature).

What is the dartos muscle’s role in the scrotum

The dartos muscle causes wrinkling of the scrotal skin, helping with temperature regulation

What are the testes

The testes are paired oval-shaped gonads located in the scrotum, responsible for producing sperm

What are seminiferous tubules

Seminiferous tubules in the testes are where sperm cells are made.

What is the blood-testis barrier

Formed by tight junctions between Sertoli cells, it prevents an immune response against the surface antigens of spermatogenic cells.

What are the Sertoli cells and what is their function

Sertoli cells nourish spermatogenic cells, mediate hormone effects, and phagocytose excess cytoplasm during sperm development.

When do the testes descend

The testes descend into the scrotum during the 7th month of fetal development, passing through the inguinal canal.

What is cryptochidism

Surgical treatment is often necessary before 18 months if the testes do not descend spontaneously

What is spermatogenesis

Spermatogenesis is the process by which the seminiferous tubules produce haploid sperm from spermatogonia (stem cells).

What is the starting cell in spermatogenesis

 Spermatogenesis begins with diploid spermatogonia, which divide by mitosis to form primary spermatocytes.

What happens during meiosis in spermatogenesis

 Primary spermatocytes undergo meiosis I to form haploid secondary spermatocytes, which further undergo meiosis II to form spermatids.

What is spermiogenesis

Spermiogenesis is the final stage of spermatogenesis where spermatids mature into fully functional sperm.

What is spermiation

Spermiation is the release of mature sperm from the sertoli cells into the lumen of the seminiferous tubules

What is the treatment for cryptochidism

Surgical treatment is often necessary before 18 months if the testes do not descend spontaneously

What are the leydig cells

Leydig cells (also called interstitial endocrinocytes) are located between seminiferous tubules and secrete testosterone

What is the function of sustentaculer cells

Sustentaculer cells nourish spermatocytes, mediate hormonal effeects, and control sperm release from the seminiferous tubules

What are somatic cells and how many chromosomes do they contain

Somatic cells are diploid cells that contain 23 pairs of chromosomes, totaling 46 chromosomes

What is the composition of sex chromosomes in males and females

Females have two x chromosomes, and males have one X and one smaller Y chromosome

What are gametes and how many chromosomes do they contain

Gametes are haploid cells with a single set of chromosomes, totaling 23 chromosomes

How are gametes produced

Gametes are produced by meiosis, a special type of cell division

What happens during prophase 1 of meiosis 1

Chromosomes become visible, the mitotic spindle appears, and the nuclear membrae and nucleoli disappear

What is synapsis in prophase 1

Synapsis is the pairing of homologous chromosomes to form a tetrad

What is crossing over

Crossing over is the exchange of portions of chromatids between homogolous chromosomes, leading to genetic recombination

How does genetic recombination contribute to diversity

Genetic recombination produces gametes that are genetically different from both parents

What happens during metaphase 1 of meiosis 1

Homologous pairs of chromosomes line up along the metaphase plate, with microtobules attached

What happens during anaphase 1

Homologous chromosomes are pulled to opposite ends of the dividing cell, with each chromosome still consisting of two chormatids

What occurs during telophase 1

Telophase 1 and cytokinesis are similiar to mitotic divison, resulting in two haploid cells

What is the purpose of meiosis 2

Meiosis 2 divides the haploid produced in meiosis 1, resulting in four genetically unique haploid gametes

How does meiosis 2 differ from mitosis

In meiosis 2, centromeres split and sister chromatids move towards opposite poles, similiar to mitosis

Where does sperm formation occur

Sperm formation occurs in the seminiferous tubules of the testes

What cells are involved in sperm formation

The seminiferous tubules contain spermatogonia (stem cells), primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa. Sertoli cells support the process.

 What role do Leydig cells play in sperm formation?

Leydig cells, located between seminiferous tubules, secrete testosterone, which is necessary for spermatogenesis.

What are the functions of Sertoli cells?

Sertoli cells form the blood-testis barrier, support developing sperm, produce fluid, and regulate sperm release. They also secrete inhibin, which inhibits FSH production.

What is the first step in spermatogenesis?

Spermatogonium (stem cells) undergo mitosis, creating two daughter cells. One remains as a stem cell, and the other becomes a primary spermatocyte.

What happens during meiosis I in spermatogenesis?

Primary spermatocytes undergo meiosis I, with DNA replication, tetrad formation, and crossing-over occurring.

What happens after meiosis I in spermatogenesis?

Secondary spermatocytes, each with 23 chromosomes (each consisting of two chromatids), are formed.

What occurs during meiosis II in spermatogenesis?

Each secondary spermatocyte undergoes meiosis II, producing four haploid spermatids, all of which remain connected by a cytoplasmic bridge.

 How is the release of sperm synchronized?

The cytoplasmic bridge between spermatids accounts for synchronized release, with each sperm containing either an X or Y chromosome.

What is spermiogenesis?

Spermiogenesis is the maturation of spermatids into functional sperm cells.

 What is spermiation?

Spermiation is the release of a sperm cell from a Sertoli (sustentacular) cell into the lumen of the seminiferous tubules.

How is sperm adapted for its function?

Sperm have a head containing DNA and enzymes (acrosome), a midpiece with mitochondria for ATP, and a tail (flagellum) for locomotion.

What is the lifespan of sperm once ejaculated?

Sperm have a life expectancy of about 48 hours within the female reproductive tract.

What hormones regulate spermatogenesis?

 GnRH from the hypothalamus stimulates the anterior pituitary to secrete LH and FSH. LH aids spermatogenesis and stimulates testosterone production, while FSH initiates spermatogenesis.

What is the role of testosterone in spermatogenesis?

Testosterone controls the growth and development of sex organs, stimulates sperm maturation, and regulates male secondary sexual characteristics.

 What is the function of inhibin in hormonal control?

: Inhibin, produced by Sertoli cells, inhibits FSH secretion, helping regulate the rate of spermatogenesis.

How does the negative feedback system control testosterone production?

An increase in blood testosterone levels slows GnRH secretion, which reduces FSH and LH secretion, leading to a decrease in testosterone production.

What is the role of inhibin in feedback regulation?

 If sperm production is sufficient, Sertoli cells release inhibin to inhibit FSH secretion and decrease sperm production. If sperm production is low, less inhibin is released, and FSH secretion increases.

What does the duct system of the testes include?

The duct system consists of the seminiferous tubules, straight tubules, rete testis, efferent ducts, and ductus epididymis.

What is the pathway of sperm flow through the ducts of the testis?

The pathway is: Seminiferous tubules → Straight tubules → Rete testis → Efferent ducts → Ductus epididymis → Ductus (vas) deferens.

What is the function of the epididymis?

• It is the site of sperm maturation and storage. Sperm can remain stored for up to a month before being expelled or reabsorbed.

How long is the epididymis and what are its regions?

• It is 1.5 inches long along the posterior border of the testis, with head, body, and tail regions.
  
  

 What lines the ductus epididymis and what is its function?

 It is lined with pseudostratified ciliated columnar epithelium and contains smooth muscle to propel sperm during ejaculation. Sperm maturation occurs here.

What is the function of the ductus deferens?

 It stores sperm and propels them toward the urethra during ejaculation.

 What structures are part of the spermatic cord?

The spermatic cord contains the ductus deferens, testicular artery, autonomic nerves, veins, lymphatic vessels, and cremaster muscle.

 What do the ejaculatory ducts do?

• They are formed by the union of the ducts from the seminal vesicles and ducti deferens, and their function is to eject sperm into the prostatic urethra.
  
  

 What are the three parts of the male urethra?

Prostatic urethra, membranous urethra, and penile (spongy) urethra.

What is a vasectomy and its effect?

 A vasectomy is a male sterilization procedure where the vas deferens is cut and tied. It is 100% effective, but 40% are reversible.

What is the inguinal canal and what types of hernias occur there?

• The inguinal canal is a 2-inch tunnel in the abdominal wall. Inguinal hernias can be indirect (intestine through the deep ring) or direct (through the posterior wall of the inguinal canal).
  
  

What is the inguinal canal and what types of hernias occur there?

The inguinal canal is a 2-inch tunnel in the abdominal wall. Inguinal hernias can be indirect (intestine through the deep ring) or direct (through the posterior wall of the inguinal canal).

 What do the seminal vesicles secrete?

• They secrete alkaline fluid with fructose, prostaglandins, and clotting proteins, which neutralize vaginal acid and provide energy to sperm.
  
  

What are the main components secreted by the prostate gland?

• The prostate secretes citric acid (for sperm ATP), acid phosphatase, and proteolytic enzymes like PSA to liquefy semen.
  
  

What is the function of the bulbourethral glands?

They secrete mucus for lubrication and an alkaline substance that neutralizes acids in the urethra.

What is semen composed of and what is its purpose?

 Semen is a mixture of spermatozoa and secretions from accessory sex glands, providing nutrients and neutralizing acidity.

 What happens to semen after ejaculation?

• t coagulates within 5 minutes due to clotting proteins, then liquefies in 15-20 minutes due to enzymes like PSA.
  
  

What are the normal sperm count and semen characteristics?

Normal sperm count is 50-150 million/ml. Semen coagulates after ejaculation and reliquefies within 15 minutes.

What are the main parts of the penis?

 The penis consists of the root (bulb + crura), body, and glans penis.

What are the types of erectile tissue in the penis?

• The penis contains paired corpora cavernosa and a single corpus spongiosum, all surrounded by the tunica albuginea.
  
  

What is the glans penis?

 It is the enlarged distal end of the corpus spongiosum and contains the external urethral orifice.

 What is circumcision and when is it typically performed?

Circumcision is the removal of the prepuce (foreskin), often performed 3-4 days after birth.

What muscle encloses the bulb of the penis?

The bulbospongiosus muscle.

What muscle encloses the crura of the penis?

The ischiocavernosus muscle.

What causes erection in the penis?

A parasympathetic reflex causes erection, leading to the dilation of arteries supplying the penis. Nitric oxide mediates the local vasodilation.

 What happens during ejaculation?

Ejaculation is a sympathetic reflex. Muscle contractions close the sphincter at the base of the bladder and propel semen through peristaltic contractions in the ductus deferens, seminal vesicles, ejaculatory ducts, and prostate. The ischiocavernosus and bulbospongiosus muscles promote emission.

What are the main organs in the female reproductive system?

The ovaries, uterine (Fallopian) tubes, uterus, vagina, vulva, and mammary glands.

What do the ovaries produce?

The ovaries produce secondary oocytes and hormones.

 What is the function of the uterine tubes?

The uterine tubes transport fertilized ova.

Where does fetal development occur?

Fetal development occurs in the uterus.

Where are the ovaries located?

The ovaries are located in the upper pelvic cavity, on either side of the uterus.

 What ligaments maintain the position of the ovaries?

The broad ligament, mesovarium, ovarian ligament, suspensory ligament, and round ligament.

What are the main histological layers of the ovary?

The germinal epithelium, tunica albuginea, ovarian cortex, and ovarian medulla.

What is the function of a mature Graafian follicle?

A mature Graafian follicle expels a secondary oocyte during ovulation.

What does the corpus luteum do?

The corpus luteum produces progesterone, estrogens, relaxin, and inhibin until it degenerates into a corpus albicans.

What stages are involved in oogenesis?

Oogenesis includes reduction division (meiosis I), equatorial division (meiosis II), and maturation.

What are the stages of follicular development?

The stages are primordial, primary, secondary, Graafian, ovulation, corpus luteum, and corpus albicans.

What is an ovarian cyst?

An ovarian cyst is a fluid-filled sac in or on the ovary. Most require no treatment, but large ones may require surgery.

 What is the length of the uterine tube?

The uterine tube is about 4 inches long.

: What are the parts of the uterine tube?

The infundibulum, fimbriae, ampulla, and isthmus.

 What is the function of the cilia in the uterine tube?

 The cilia and peristalsis help move the secondary oocyte toward the uterus.

Where does fertilization typically occur in the uterine tube?

Fertilization occurs in the ampulla of the uterine tube, typically within 24 hours after ovulation.

What are the anatomical subdivisions of the uterus?

The fundus, body, isthmus, and cervix.

What is the normal position of the uterus?

The uterus normally projects anteriorly and superiorly over the urinary bladder (anteflexion).

What is uterine prolapse?

Uterine prolapse is a downward displacement of the uterus, which can be classified into first, second, or third degree based on severity.