W12 Reproductive

Question 1

Define sexual reproduction and discuss the importance of reproductive systems.

Answer 1

Sexual reproduction requires two parent organisms,mixtures of genetic characteristics. Wider diversity of genetics in our gene pool, so if a pathogenic organism comes in others may be resistant. (genetic diversity).

Question 2

List the essential and accessory organs of the male reproductive system and give the generalized function of each.

Answer 2

These are essential organs for the production of gametes that support the reproductive process.

Essential: Gonads of the male, testes.

Accessory : genital ducts convey the sperm to outside of the body: epididymides, vasa deferentia, ejaculatory ducts and the urethra.

Glands that produce seminal plasma: seminal vesticles, prostate gland and bulbourethral glands.

Perineum: includes penis, testes, anus (gouche).

Question 3

Describe the gross and microscopic anatomy of the testes.

Answer 3

Tests: Spermatogensis: is production of mature male gametes by seminiferous tubules.

Testosterone: hormone, development of muscle mass, hair. → located in scrotum, keeping the testes outside the body keeps it lower (3 degrees ↓) than core body temp which is needed for sperm production.

Surrounded by tunica vaginalis, derive from peritoneum (OUTTER) Tunica albuginea, the fibrous capsule of the testis (INNER) Surround the seminiferous tubules are Leydig cells which produce testosterone.

Sertoli (sustentacular) cells: promote spermatogensis. Secrete inhinin, which inhibits (FSH).

Leydig (interstitial) cells: testosterone cells

Question 4

Discuss the primary functions of testosterone

Answer 4

Produced by Leydig cells.

Maintaince of spermatogensis.

Proper functioning of accessory reproductive glands.

Maintains sex drive.

Causes epiphyseal plates to close

Question 5

Describe the process of meiosis and how it differs from mitosis.

Answer 5

Miosis is where their is two copies of each parents genes (identical) (2 daughter cells) .

Where as Meiosis is divided into one copy of parent cells (genetically unique) (4 sex cells)

Question 6

Define spermatogenesis and spermiogenesis. State the name of the cells at each stage and what happens at each division.

Answer 6

Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature spermatozoa.

Question 7

List the hormones of the hypothalamo-pituitary-testicular axis and state their actions on the axis

Answer 7

Gonadoprophin-releasing hormone (GnRH) from the hypothalamus stimulates the release of lutenizing hormone (LH) and fllicle stimulation hormone (FSH).

FSH: acts on the setoli cells, stimulates spermatogensis & stimulates inhibin secretion.

LH: acts of Leydig cells: stimulates testosterone secretion.

Question 8

Describe the structure of a mature spermatozoon.

Answer 8

Spermatozoa: composed of a head, middle piece and tail.

Head: covered by acrosome, which has splitting enzyme that are released during capacitation.

Middle piece: mitochondria arranged end-to-end around a core.

Tail: divided into principal and short pieces

Question 9

Trace the passage of an individual sperm cell, in sequence, from its point of formation, through the genital ducts, to the exterior of the body.

Answer 9

Epididymis: where sperm matures. → Vas Deferens is a tube extension of epididymis → enlarged terminal portion joins the duct from a seminal vesicle to form the ejaculatory duct.

→ Ejaculatory duct: passes throug the prostate gland, terminates in the urethra.. → Urethra consists of 3 regions, prostatic (surrounding prostate) →, membranous (from prostate to the perineum,→ penile (runs through penis and opens to the outside at the external urethral orifice.

Question 10

Describe the structure, location, and function(s) of the following: seminal vesicles, prostate gland, bulbourethral glands.

Answer 10

Seminal Vesticles; Produce alkaline fluid, fructose serves as energy source from sperm motility.

Prostate gland: add 30% of secretes, cirate (nutrients for sperm).

Bulbourethral gland: secretes small amounts of alkaline fluid that counteracts acid of the male urethra and vagina.

Question 11

Identify the components and functions of the male external genitalia.

Answer 11

Scrotum: skin-covered pouch suspended from the perineal region.

Dartos fascia and muscle.

Cremaster muscle: forms an elongated puch. Testis temperature is kept constant by dartos muscle, cremaster muscle, pampinform plexus. Spermatic cords

Penis: structure composed of corpora cavernosa, and corpus spongiosum (spongy mass that becomes erect).

Question 12

Discuss the composition of seminal fluid.

Answer 12

60% semincal fluid

30% prostatic fluid

10% sperm

Question 13

Discuss male fertility

Answer 13

When sperm count falls below 25 mil/ml of semen functional sterility occurs. Size shape and motility of sperm.

ANDROPAUSE.

Question 14

List the functions of the female reproductive system. Ovaries produce secondary oocytes and hormones.

Answer 14

To produce offspring and thereby continuity of the genetic code. Provide gametes that may unit with a male gamete to form the first cell of an offspring.

Question 15

List the essential and accessory sex organs of the female reproductive system and give the generalised functions of each.

Answer 15

Essential: Gonads (ovaries)

Accessory organs: Fallopian tube, uterus, vagina. Mammary glands

Question 16

Describe the structure of the ovaries

Answer 16

Are a pair of gonads.

Structure: Ovarian cortex: contains ovarian follicles.

Ovarian medulla: contains blood vessels, lymphatics and nerves, CT.

Ovarian follicles: consists of oocytes and associated cells in stage development

• Zona pellucida
• corona radiata
• antrum

Corpus luteum: develops from remnants of an ovulated follicle; produced progesterone, oestrogens/ inhibin.

Fallopian tubes: narrow tube that extends laterally from the uterous, fimbrae, fertilisation occurs here. transport ova to uterus.

Question 17

Identify the two functions of the ovaries.

Answer 17

Produce ova; female gametes. (oogenesis/ folliculogenesis) Produce hormones: female sex hormones

Question 18

Explain the steps in the development of mature ova from ovarian follicles.

Answer 18

Oogenesis, a primary oocyte undergoes meiotic division to produce a sing ovum and 3 small polar vodies. Meiosis I and meiosis II

Question 19

State the names of the different types of follicles formed during folliculogenesis and describe any major differences.

Answer 19

Primordial follicle

Oocyte initially surrounded by single layer of granulosa cells

• Primary follicle
• Granulosa cells begin to divide and the outer layer of granulosa cells eventually condenses into layer of theca cells

Secondary follicle The cells begin secreting increasing amounts of an estrogen-rich fluid that pools around the oocyte in a space called an antrum

• Vesicular or mature or Graafian follicle
• Follicle ready to ovulate (release the ovum)
• Clump of cumulus cells attaches oocyte to follicle wall
• Cumulus cells secrete progesterone, which helps attract sperm cells toward the ovum and promotes sperm motility

Ovulation: Release of an ovum at the end of oogenesis

• Ovulation involves the rupture of an ovarian follicle and the subsequent release of fluid and an ovum
• Blood fills the antrum and part of the peritoneal cavity
• The blood clot filling the antrum, sometimes called the corpus hemorrhagicum, is soon replaced by proliferating granulosa and theca interna cells to form a yellow body called the corpus luteum.

Question 20

Identify the structure and functions of the uterus.

Answer 20

Uterine wall is made up of 3 layers;

1. Endometrium
2. Myometrium
3. Perimetrium

Functions: Transportation of sperm - menstration - Implantation of fertalised ovum - Foetus development - Labour

Question 21

Discuss the location, structure, divisions, and functions of the uterine tubes

Answer 21

Composed of three layers:

1. endometrium (inner layer),
2. myometrium (middle layer),
3. perimetrium (external layer).

Function:Part of the reproductive tract; permits sperm to ascend toward uterine tubes

Question 22

Discuss the location, structure, and primary functions of the vagina

Answer 22

Location: Two 10 cm long canals leading from the ovaries to the uterus, also called oviducts or Fallopian tubes.

Function: The uterine tubes receive the ovulated oocyte and provide a site for fertilisation.

The vagina is a tubular organ located between the rectum, urethra and bladder.

Functions: Vagina is the lower portion of the birth canal. Lubricates during intercourse, semen, menstruation

Question 23

Identify the structures that together constitute the female external genitalia

Answer 23

Contains the mons pubis, labia majora, labia minora, glans clitoris, urinary meatus, vaginal orifice, and greater vestibular glands

• Each labium majus is composed mainly of fat and connective tissue with numerous sweat and sebaceous glands on the inner surface.
• The two labia minora come together anteriorly in the midline. The area between the labia minora is the vestibule.
• The glans clitoris is covered with highly sensitive skin involved in sexual stimulation that produces the female sexual response

Question 24

Identify the phases of the reproductive cycle.

Answer 24

Ovarian cycle: montly series of events associated with the maturation of an egg.

Follicular phase, ovulation occurs mid cycle, luteal phase.

Uterine/endometrial/menstrual cycle: cyclic changes that the uterine endometrium goes through each month in response to ovarian hormones in the blood

Question 25

Explain the hormonal control of cyclical changes that occur in the ovaries and uterus.

Answer 25

Proliferative phase: under the influence of estrogen

• Proliferation of endometrial cells
• Growth of endometrial glands and spiral arteries of the endometrium

Secretory phase: under the influence of progesterone:

Endometrial gland secretion prepares endometrium for implantation

Menstrual phase: • Low levels of progesterone and estrogen induces shedding of all but the deepest part of the endometrium:

Question 26

List the actions of the ovarian hormones

Answer 26

Estrogen: • brain: feedback regulation of GnRH & gonadotropins, behaviour & neuroprotection,bone: growth &; closure

Metabolism: anabolic • renal: Na+ reabsorption & hence water retention) • cardiovascular: HDL levels

Progesterone: •thickens the endometrium •quietens myometrium •thicker cervical mucus •breast development •increases body temperature •Diuresis • Inhibin: •Inhibition of FSH secretion

Question 27

Discuss the importance of the female reproductive cycles, infertility

Answer 27

Ovarian cycle • Produce ova at regular intervals • Regulate endometrial cycle through estrogen and progesterone

Question 28

Compare and contrast menarche and menopause.

Answer 28

Puberty: Triggered by rising levels of GnRH • stimulates anterior pituitary to produce LH & FSH • Follicles develop and begin to secrete oestrogen (and progesterone) • Changes that occur at puberty are primarily due to the actions of estrogen • Menarche - first menstrual period • Varies according to race, nutrition, health, and heredity Menopause • Cessation of menstruation/menstrual cycles • diagnosed retrospectively as no menstrual periods for 12 months • average age of 52 • Triggered by a decrease in follicle number and the follicles insensitivity to the gonadotropin hormones • Results of loss of ovarian hormones • atrophy of uterus, vagina and breasts • skin becomes thinner, bone mass declines, and risks of cardiovascular disease increase • hot flashes/flushes (sudden dilation of cutaneous arteries) occur several times a day

Question 29

Describe the structure of the breasts and the mechanism controlling lactation.

Answer 29

Breasts lie over the pectoral muscles and are connected by fascia • Estrogens and progesterone control breast development Function of the breasts • Function of mammary glands is lactation • Mechanism of lactation • Ovarian hormones make the breasts structurally ready to secrete milk • Shedding of the placenta cuts off a major source of estrogens • Estrogens had been suppressing prolactin during pregnancy • Prolactin stimulates milk synthesis • Oxytocin stimulates myoepithelial cells to eject milk 58 Importance of lactation • Some advantages of breast milk • Nutrients • Passive immunity from antibodies present in the colostrum and milk • Emotional bonding between mother and child