1. Male Reproductive System p414-417
UNIT B
Chapter 14: Reproductive System
Section 14.1
Male Reproductive System p
Organisms that carry out sexual reproduction produce gametes, haploid sex cells that are united during fertilization.
Gonads (testes) produce gametes (sperm cells)
Seminal fluid: a nutrient-rich fluid in which sperm leave the penis during ejaculation
Semen: combination of sperm and seminal fluid
gametes: haploid sex cells that become united during fertilization
reproductive system: a type of organ system differing in males and females; in males it consists of the testes, other glands, and various ducts that conduct semen to and through the penis; in females it consists of the ovaries, oviducts, uterus, vagina, and external genitals
testes: (sing., testis) part of the male reproductive system; produce sperm and sex hormones
seminal fluid: nutrient-rich fluid in which sperm leave the penis
semen: combination of sperm and seminal fluid
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2. What do you know?

3. The Male Reproductive System
Note urethra carries either urine or semen (at different times)
Why do testes hang?

4. UNIT B
Chapter 14: Reproductive System
Section 14.1
Genital Tract
Testes: paired structures that produce sperm and sex hormones
Epididymides: (s. epididymis) ducts outside the testes where sperm mature
Vasa deferentia: : (s. vas deferens) store sperm; empty into an ejaculatory duct
Urethra: connected to the ejaculatory duct
testes: (sing., testis) part of the male reproductive system; produce sperm and sex hormones
epididymis: the site where sperm produced by the testes mature
vas deferens: storage location for mature sperm before they pass into the ejaculatory duct
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5. UNIT B Three glands contribute to seminal fluid:
Chapter 14: Reproductive System
Section 14.1
Three glands contribute to seminal fluid:
Seminal vesicles: paired, base of bladder,
joins v.d., contribute nutrients and fluids
Prostate gland: single, donut- shaped
gland surrounding urethra, contributes
basic solution to semen (sperm are more
viable in a basic solution)
Cowper’s glands: (bulbourethral glands)
pea-sized, posterior to prostate, either side
of urethra, secrete a mucus-rich fluid that helps lubricate the penis
Seminal fluid: pH 7.5, fructose, prostaglandins
urethra: a small tube that extends from the urinary bladder to an external opening that removes urine from the body; in the male reproductive system, it connects to the ejaculatory ducts
seminal vesicles: paired glands that lie at the base of the bladder, each with a duct that joins with a vas deferens
prostate gland: a gland that produces a slightly basic secretion to help buffer the acidic environment of the vagina
Cowper’s glands: male sex glands that secrete a mucus-rich fluid to help lubricate the penis and facilitate penetration during sexual intercourse

6. Penis Anatomy Penis: male organ of sexual intercourse Circumcision: surgical removal of the foreskin
Long shaft, enlarged tip (glans), normally covered by foreskin.
Spongy, erectile tissue containing distensible blood spaces exgends through the shaft. Beneath the skin and the connective tissue lies the urethra, surrounded by erectile tissue. This tissue expands to form the glans penis, which in uncircumcised males is partially covered by the foreskin (prepuce).
b. Two other columns of erectile tissue in the penis are located dorsally.

7. Erection and Orgasm in Males
UNIT B
Chapter 14: Reproductive System
Section 14.1
Erection and Orgasm in Males
Erection
Erectile tissue extends throughout the shaft of the penis
Sexual excitement causes the arteries in the penis to relax and widen
Increased blood flow causes the penis to enlarge and become erect, compressing veins
During sexual arousal, autonomic nerve impulses lead to the production of cGMP (cyclic guanosin monophosphate) in smooth mscle cells, nd the erectile tissue fills with blood. Veins become compressed.
Erectile dysfunction (impotency) when erectile tissue doesn’t expand enough to compress the veins.
Viagra inhibits an enzyme that breaks down cGP, ensuring a full erection (also affects retina  vision problems)
Figure 14.2 Penis anatomy. b. Two other columns of erectile tissue in the penis are located dorsally.
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8. Erection
Erectile tissue expands and fills with blood due to nerve impulses and the release of a hormone (cGMP) Veins are restricted and do not take blood away from the penis Males who are impotent have an enzyme that breaks down the cGMP and therefore erectile tissue does not expand/veins are not restricted Viagra inhibits (stops) the breakdown of cGMP and therefore rerectile tissue can expand.

9. UNIT B Ejaculation and Orgasm
Chapter 14: Reproductive System
Section 14.1
Ejaculation and Orgasm
When sexual stimulation intensifies, sperm enter the urethra from the vasa deferentia and the accessory glands contribute secretions to the semen
Rhythmic muscle contractions cause semen to be ejaculated from the penis
These contractions are part of male orgasm (climax of sexual stimulation)
Sphincter closes off bladder
A refractory period occurs after ejaculation, where sexual stimulation does not cause an erection
More than 400 million sperm are expelled in 2 to 6 mL of semen during ejaculation
Refractory period increases with age
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10. Male Gonads (Testes) UNIT B Produce sperm and male sex hormones
Chapter 14: Reproductive System
Section 14.1
Male Gonads (Testes)
Produce sperm and male sex hormones
Lie within the scrotum
The scrotum helps regulate testicular temperature by holding the testes closer or farther away from the body
Increases in temperature may decrease sperm production
scrotum: a saclike structure outside the abdominal cavity of a male that houses the testes
Testes begin development inside abdominal cavity but descend into scrotal saces during last two monts of fetal development.
Hernia- organ pushes through an opening in the muscle or tissue that holds it in place
Figure 14.3 Testis and sperm. a. The lobules of a testis contain seminiferous tubules.
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11. Hernia - organ pushes through an opening in the muscle or tissue that holds it in place
In an inguinal hernia, the intestine or the bladder protrudes through the abdominal wall or into the inguinal canal in the groin. About 96% of all groin hernias are inguinal, and most occur in men because of a natural weakness in this area

12. UNIT B Seminiferous Tubules
Chapter 14: Reproductive System
Section 14.1
Seminiferous Tubules
A testis is composed of lobules, each containing tightly coiled seminiferous tubules (~250m)
Seminiferous tubules contain cells undergoing spermatogenesis (production of sperm)
Intersitial cells that lie between the tubules secrete male sex hormones (androgens)
seminiferous tubules: long, coiled structures contained within chambers of the testis where sperm are produced
Figure 14.3 Testis and sperm. b. Light micrographs of a cross section of the seminiferous tubules, where spermatogenesis occurs. Note the location of interstitial cells in clumps among the seminiferous tubules.
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13. UNIT B Chapter 14: Reproductive System Section 14.1
Figure 14.3 Testis and sperm. a. The lobules of a testis contain seminiferous tubules.
b. Light micrographs of a cross section of the seminiferous tubules, where spermatogenesis occurs. Note the location of interstitial cells in clumps among the seminiferous tubules.
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14. Spermatogenesis (production of sperm)
UNIT B
Chapter 14: Reproductive System
Section 14.1
Spermatogenesis (production of sperm)
Occurs in the walls of the seminiferous tubules
Spermatogonia become primary spermatocytes that undergo meiosis I to produce secondary spermatocytes
Secondary spermatocytes undergo meiosis II to produce four haploid spermatids
Spermatids differentiate into sperm
Sertoli cells support, nourish, and regulate the spermatogenic cells
spermatogenesis: the production of sperm in males
Sertoli cells: cells that support, nourish, and regulate the spermatogenic cells
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16. UNIT B Chapter 14: Reproductive System Section 14.1
Figure 14.3 Testis and sperm. c. Diagrammatic representation of spermatogenesis, which occurs in the walls of the tubules.
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17. UNIT B Sperm Mature sperm (spermatozoa) have three distinct parts
Chapter 14: Reproductive System
Section 14.1
Sperm
Mature sperm (spermatozoa) have three distinct parts
Head - acrosome is a cap that stores enzymes needed to penetrate the egg.
nucleus contains 23 chromosomes
Middle piece - Mitochondria produces ATP for the movement of the tail
Tail – flagellum like structure
Sperm usually do not live more than 48 hours in the female genital tract
sperm: male gamete having a haploid number of chromosomes and the ability to fertilize an egg, the female gamete
Figure 14.3 Testis and sperm. d. A sperm has a head, a middle piece, tail, and an end piece. The nucleus is in the head, which is capped by the enzyme-containing acrosome.
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18. Mature sperm

19. Hormonal Regulation in Males
UNIT B
Chapter 14: Reproductive System
Section 14.1
Hormonal Regulation in Males
Hypothalamus secretes gonadotropin-releasing hormone (GnRH).
GnRH: stimulates the pituitary gland to release gonadotropic hormones:
follicle-stimulating hormone (FSH)
promotes sperm production in the seminiferous tubules (which secrete inhibin, a hormone which inhibits FSH synthesis)
luteinizing hormone (LH)
AKA interstitial-cell-stimulating hormone (ICSH) because it promotes the production of testosterone by interstitial cells
hypothalamus: an integrating centre that helps maintain homeostasis; regulates hunger, sleep, thirst, body temperature, and water balance; also controls the pituitary gland and thereby serves as a link between the nervous and endocrine systems
pituitary gland: small gland that lies just inferior to the hypothalamus; consists of the anterior and posterior pituitary, both of which produce hormones
gonadotropin-releasing hormone (GnRH): a hormone that stimulates the anterior pituitary to secrete the gonadotropic hormones
follicle-stimulating hormone (FSH): a hormone released by the anterior pituitary; in males it promotes the production of sperm; in females it promotes the development of the follicle in the ovary
luteinizing hormone (LH): a hormone secreted by the anterior pituitary; in males it controls the production of testosterone by the interstitial cells; in females it promotes the development of the corpus luteum in the ovary; also called interstitial cell-stimulating hormone (ICSH) in males
interstitial cell-stimulating hormone (ICSH): a hormone secreted by the anterior pituitary in males; promotes the production of sperm; also called luteinizing hormone (LH)
testosterone: main sex hormone in males that helps maintain sexual organs and secondary sex characteristics
interstitial cells: cells of the male reproductive system that secrete the androgens (such as testosterone)

20. The main sex hormone in males
UNIT B
Chapter 14: Reproductive System
Section 14.1
Testosterone
The main sex hormone in males
Essential for normal development and functioning of male reproductive structures
Maintains male secondary sex characteristics that develop at puberty (body hair, deeper voices, greater muscular development)
Can also lead to receding hairline and pattern baldness in males
Both males and females may take testosterone or other related asteroid hormones in form of anabolic steroids  health problems kidneys, circ system hormonal imbalances . Testes shrink, feminization of other traits
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21. Crash Course Male Repro System: https://www. youtube. com/watch

22. UNIT B Chapter 14: Reproductive System Section 14.1
Figure 14.4 Hormonal control of testes. GnRH stimulates the anterior pituitary to produce FSH and LH. FSH stimulates the testes to produce sperm, and LH stimulates the testes to produce testosterone. Testosterone from interstitial cells and inhibin from the seminiferous tubules exert negative feedback control over the hypothalamus and the anterior pituitary, and this ultimately regulates the level of testosterone in the blood.
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