Week 7 - the human reproductive systems Flashcards Preview

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Flashcards in Week 7 - the human reproductive systems Deck (77)
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1
Q

Describe the anatomy of the male reproductive system

A
  • Composed of:
    • Testes
    • Reproductive ducts (epididymis, ductus deferens and urethra)
    • Accessory glands (seminal vesicles, prostate glands and bulbourethral glands)
    • Supporting structures (scrotum & penis)
2
Q

Described the testes

A
  • Small ovoid organs which are the gonads of males
  • Located in pouch-like scrotum which is divided by connective tissue septum into two internal compartments
  • Both exocrine and endocrine glands
3
Q

What are the endocrine and exocrine functions of the testes?

A
  • major exocrine secretion from the testes is sperm cells
  • Major endocrine function is the secretion of testosterone
4
Q

What are sperm sensitive to and how are these conditions maintained?

A
  • Sperm cells are highly temperature sensitive (require cool)
  • Aided by the scrotum which is suspended outside the body below the penis where the temperature is lower than body temperature
5
Q

Describe the structure of the testis

A
  • A capsule consisting of fibrous connective tissue, tunica albuginea, surrounds each testis
    • This membrane enters the testis and form many septa that divide into lobules
  • There are two types of connective tissue between septa:
    • Seminiferous tubules and Leydig cells (interstitial cells)
6
Q

Where specifically in the testis are sperm and testosterone produced?

A
  • Sperm cells develop in the seminiferous tubules
  • Leydig cells secrete testosterone
7
Q

Describe the difference in the testes before and after the onset of puberty

A
  • Before puberty the Leydigs cells and seminiferous tubules are not functional
  • At the onset of puberty the Leydigs cells increase in size and number and the lumen of the seminiferous tubules develops and spermatogenesis begins (sperm production)
8
Q

How do the testis prepare for spermatogenesis?

A
  • They prepare for spermatogenesis before puberty by increasing the number of sperm precursos (stem) cells called spermatogonia
  • Spermatogonia are mitotically active and produce daughter cells, some of which remain as spermatogonia and continue to proliferate daughter cells and other daughter cells differentiate to form primary spermatocytes
9
Q

Describe spermatogenesis

A
  1. The onset of meiosis is where cell division begins whn primary spermatocytes divide
  2. Each primary spermatocyte undergoes the first meiotic division to become secondary spermatocytes
    • ​Primary spermatocytes are tetraploid and secondary spermatocytes are diploid
  3. Each secondary spermatocyte passes through a secondary meiotic division to produce spermatids which are haploid
  4. Last phase of spermatogenesis is called spermiogenesis in which each spermatid form the mature sperm cell (spermatozoan)
  5. Spermatozoa are released into the lumen of seminiferous tubules
10
Q

What are spermatozoans?

A
  • Spermatozoans are mature sperm cell
    • The result of the last stage of spermatogenesis, spermiogensis
11
Q

What are spermatids?

A
  • The product of the meiotic division of secondary spermatocytes
12
Q

Outline the structure of spermatozoa

A
  • Each spermatozoa develops a head, midpiece and a tail (flagellum)
  • Head contains chromosomes and the nucleus of the head is covered by acrosome which contains the enzymes necessary for the sperm to penetrate the female sex cell
  • Midpiece contains mitochondria to produce ATP for microtubule movement witihin the flagellum - leading to movement
    *
13
Q

Decribe the passage of spermatozoa once they have been released into the lumen of seminiferous tubules

A
  • Spermatozoa pass in sequence through the efferent ductules, epididymis, ductens deferens, ejaculatory duct and urethra on their passage out of the body
14
Q

Outline the shape and location of the epididymis

A
  • The epididymis is a comma-shaped structure on the posterior side of the tesis which stems from the covoluted efferent ductules
    *
15
Q

What is the function of the epididymis?

A
  • The final stage of the maturation of spermatozoa (sperm cells) occurs here
  • Tempory storage of sperm cells in the epididymis enables them to develop the ability to fertilise the female sex cell
16
Q

Describe the structure of the epididymis

A
  • The duct of the epididymis is lined with stereocilia, which consists of pseudostratified columnar epithelium with elongated microvillae
  • Stereocilia increases the surface area of the epithelial cells, which absorb fluid from the lumen of the duct of the epididymis
17
Q

Describe the location of the ductus deferens

A
  • The ductus deferens is the tube that emerges from the tail of the epididymis and passes from the scrotal sack upwards into the pelvic cavity and approached the prostate gland
18
Q

Describe the structure of the ductus deferens

A
  • It becomes associated with blood vessels and nerves that supplies the testis which constitute the spermatic cord
  • The end of the ductus deferens enlarges to form an ampulla
  • It is lined by pseudostratified columnar epithelium which is enclosed by smooth muscle
19
Q

What is the function of the smooth muscle in the ductus deferens?

A
  • Sperm cells are propelled through the ductus deferens which is aided by the peristaltic contractions of the smooth muscle
20
Q

Describe the location and structure of the ejaculatory duct

A
  • The seminal vesicle is adjacent to the ampulla of each ductus deferens
  • It joins the seminal vesicle with the ductus deferens
  • It projects into the prostate gland and permits the entry of sperm cells into the urethra which passes through the penis
21
Q

What are the main accessory glands?

A
  • Male accessory glands include two seminal vesicles, one prostate gland and two bulbourethral glands:
    • Seminal vesicles
    • Prostate gland
    • bulbourethral gland
22
Q

Outline the seminal vesicles

A
  • Seminal vesicles are sack-shaped glands that contribute to approximately 60% of the seminal fluid volume
23
Q

Outline the prostate gland

A
  • Situate below bladder
  • Consists of musclular and glandular tissue
  • Urethra passes through the centre of the penis which ends in the external urinary orifice
  • Secretions of the prostate gland constitute approximately 30% of ejaculate which helps to activate the sperm and maintain their motility
24
Q

Outline the bulbourethral glands

A
  • Small pair of glands situated close to the urethra
    • Decreases with size and age
  • They empty their secretions into the penile portion of the urethra which contributes to 5% of the seminal fluid volume
  • Secretions of these glands serve two main purposes:
  1. Lubricate the urethra to protect the sperm cells from friction damage during ejaculation
  2. Neutralise the acidic urine in the terminal urethra
25
Q

Outline a condition of the prostate gland

A
  • Benign prostatic hypertrophy (BPH) is a non-cancerous condition common in older men
  • BPH is characterised by enlargement of the prostate gland causing the urethra to be squeezed making the process of urination difficult
26
Q

Outline the treatment options for benign prostatic hypertrophy

A
  • Prostatectomy (surgical removal of prostate gland)
  • Drugs such as Avodart and Flomax can be used to reduce the symptoms of BPH and improve urine flow in some cases
    *
27
Q

Outline prostate cancer

A
  • Prostate cancer also causes the enlargement (hypertrophy) of the prostate gland and malignant tumour growth can develop due to restrictions in the flow of urine
28
Q

What is prostatitis ?

A
  • Prostatitis is a condition that occurs due to the inflammation of the prostate gland
29
Q

How does benign prostatic hyperplasia occur?

A
  1. Proliferation of glandular tissue in the transitional zone of the prostate
    1. This is the area immediately surrounding the urethra
    2. The impairment of apoptosis is a factor in causing BPH
  2. The prostate enlarges which compresses and disturbs the urethra in this region which causes disruption of the flow of urine
30
Q

What are the two classes of drug that are used to treat BPH?

A
  1. Anti-androgen drugs
  2. Alpha-adrenergic blockers
31
Q

Outline the action of the anti-androgen drugs for the treatment of BPH

A
  • BPH is thought to be caused by excessive androgen stimulation
  • Testosterone is converted into its active form 5-alpha-DHT by 5-alpha reductase
  • Drugs that block 5-alpha reductase reduce the androgenic stimulation of the protate causing regression in prostate size
32
Q

Outline the action of alpha-adreneergic blockers in the treatment of BPH

A
  • Alpha-adrenergic blokcers compete with noradrenalin for attachment to receptors in muscle fibres at the base of the bladder and in the wall of the urethra
  • This has the effect of lessening spasm and encouraging muscle relaxation
  • These drugs may also encourage apoptosis in glandular cells of the prostate to help restore the balance
33
Q

How do alpha-adrenergic blockers and anti-androgen drugs affect the blood concentrations of prostate-specific antigen (PSA)?

A
  • Anti-androgen drugs may reduce the blood levels of PSA whilst alpha-adrenergic blockers do not have an effect
  • Since both have different mechanisms of action, they can be used in combination to treat BPH
34
Q

Describe prostate carcinoma

A
  • Caused by the impairment of apoptosis and usually begins in the peripheral zone of the prostate
  • Cells multiply out of control and invade the stroma and extend into seminal vesicles
  • Once the capsule of the prostate has been breached the tumour spread widely to the lymphatic system, liver, lungs and bones
35
Q

What are lower urinary tract symptoms (LUTS) caused by and what are they?

A
  • Characterised by problems voiding, e.g. hesitation in urination, reduction in stream, a feeling the bladder is not fully empty and dribbling after urination
  • Nocturia which is frequent urination at night and can interefere with sleep
  • Sometimes the bladder doesnt empty fully which increases the risk of infection, bladder stone formation and cancer development
  • Storage problems due to the irritation of muscles of the bladder wall and muscles around the proximal urether causing frequent urination
36
Q

Besides surgery, what are the other treatment options for prostate cancer?

A
  • Malignant prostate growths can be treated by cryotherapy (freezing) of prostate tissue, heat therapy, systemic chemotherapy , hormonal therapy and external-beam radiation
37
Q

Describe the structure of the penis

A
  • The penis contains three columns of erectile tissue:
    • Two columns are called corpora cavernosa and the third is called the corpus spongiosum
  • The urethra travels through the corpus spongiosum and opens into the external urethral orifice
  • At the base of the penis the corpus spongiosum expands to form the bulb of the penis and each corpus cavernosum expands to form the crus of the penis
  • The glans penis is formed by the expansion of the corpus spongiosum
  • A loose fold of skin called the foreskin covers the glans penis
38
Q

Describe two clinical focuses of the penis

A
  1. Circumcision - the surgical removal of the foreskin
    1. Uncircumcised males have higher incidence of penile cancer although the underlying causes are related to chronic infecting and pore hygeine
  2. Impotene - inability to acheive or maintain erection
    1. One cause is inability to concentrate on sexual sensations
    2. Can be caused by nerve damage arising from prostate surgery or restricted circulation
39
Q

How is the male reproductive system regulated?

A
  • Hormonal systems regulate the male reproductive system which involves the hypothalamus, pituitary gland and the testes
40
Q

Describe how the hypothalamus and pituitary are involved in the regulation of the male reproductive system

A
  • Neurons in hypothalamus secrete gonadotrophin-releasing hormone (GnRH) and luteinizing hormone-releasing hormone (LHRH)
    1. Secretion of GnRH stimulates the anterior pituitary glands to secrete two gonadotrophins called luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
41
Q

What are the effects if luteinizing hormone (LH) and follicle-stimulating hormone (FSH)?

A
  • LH binds to Leydig cells in the testes and stimulates them to increase the rate of testosterone synthesis and secretion
  • FSH binds to cells in the seminiferous tubules and stimulates sperm development
42
Q

What is the effect of a high level of gonadotrophin-releasing hormone in the blood?

A
  • High level of GnRH in the blood causes the anterior pituitary gland to become insensitive to stimulation by GnRH which causes less LH and FSH to be released
43
Q

What is the main hormone secreted by the testes?

A
  • Testosterone is the main male horome secreted by the testes and is classfied as an androgen because it promotes the development of male reproductive structures and male secondary sexual characteristics (masculinisation)
44
Q

What is infertility?

What is it most commonly caused by?

A
  • Infertility refers to reduced fertility
  • Most commonly caused by a low sperm count
  • Fertility can also be reduced if the sperm count is normal but the structure of the sperm is abnormal
45
Q

What can low sperm count be caused by?

A
  • Can occur due to damage to the testis due to trauma, cryptorchidism, radiation or infections (e.g. mumps)
  • Also occur as a result of inadequate secretions of LH and FSH which may arise due to hypothyroidism, infarctions of the hypothalamus or anterior pituitary gland and trauma to the hypothalamus
46
Q

How can abnormalities in the structure of sperm cells arise?

A
  • May occur due to chromosomal abnormalities, genetic factors or anti-sperm antibodies produced by the immune system
47
Q

How can fertility be increased?

A
  • Arificial insenimation can be used to increase fertility by collecting ejaculations and concentrating the sperm cells followed by subsequent introduction to the females reproductive tract
48
Q

What do the organs of the female reproductive system consist of?

A
  • Consists of:
    • ovaries
    • uterine
    • uterine tubes
    • uterus
    • vagina
    • external genital organs
    • mammary glands
49
Q

Describe the postition of the ovaries

A
  • The two ovaries are the gonads of females
  • Ovaries are attached to the posterior surface of the broad ligament by a peritoneal fold called the mesovarium
  • The suspensory ligament extends from the mesovarium to the body wall and the ovarian ligament attaches the ovaries to the uterus
50
Q

Describe the structure of the ovaries

A
  • Ovarian follicles are embedded in connective tissue matrix below the outer part of the ovary called the cortex
  • There are several ovarian follicles and they each contain an oocyte which is an immature stage of the female sex cell
51
Q

What hormones do the ovaries secrete and what is their function?

A
  • The ovries secrete estrogen and progesterone
  • Estrogen - stimulates the development and maintainance of female secondary sex characteristics and stimultes the proliferation of endometrial cells
    • Also responsible for the development of mammary glands
  • Progesterone - produced by the corpus luteum. Stimulates hypertrophy of the endometrial cells and with estrogen they produce a negative feedback effect on the hypothalamus and anterior pituitary after ovulation
52
Q

Outline what the uterine tubules are and what there structure is

A
  • There are two uterine tubes (fallopian tubes or oviducts) situated on each side of the uterus, attached to an ovary
  • Walls of each uterine tube consist of three layers: serosa, muscular layer and mucosa
  • Mucosa of uterine tubes supplies nutrients for the oocyte and the developing embryonic mass (if fertilisation has occured)
  • Ciliated epithelium assists in the movement of the oocyte or the developing embryonic mass through the uterine tubes
53
Q

Describe the location and structure of the uterus

A
  • Uterus (womb) is situated in the pelvic cavity and is composed of two parts: the upper portion, the body and a lower part called the cervix
  • The bulgind prominence of the uterus is called the fundus
  • The uterine wall consists of three layers: perimetrium (covers the wall of the uterus), myometrium, and endometrium (the inner most layer)
54
Q

What are uterine fibroids?

A
  • Most common disorder of the uterus & are enlarged masses of smooth muscle in the myometrium
  • Some women do not have any symptoms
  • Enlarged mass compresses the uterine lining which results in ischemia, inflammation and infrequent and severe menstruations
  • Women most commonly choose to have a hysterectomy (removal of uterus), because of constant menstruation which is a manifestation of these tumors
55
Q

Outline pelvin inflammatory disease (PID)

A
  • Caused by bacterial infection of the pelvic organs, including the ovaries, uterine and uterus tubes
  • Bacterial infections of vagina or uterus may spread through the pelvis
  • Chlamydia and gonorrhea are most common causes of PID
  • Pelvic pain and vaginal discharge are early symptoms of PID
  • Antibiotics as an early treatment can stop the spread of PID but lack of treatment can be life threatening
  • PID also can lead to infertility
56
Q

Describe the location and structure of the vagina

A
  • Tube that extends from the uterus to the outside of the body
  • Female organ of copulations and allows menstrual flow and childbirth
  • Vaginal wall consists of and outer muscular layer and an inner mucous membrane
  • Muscular layer consists of smooth muscle that allows the vagina to increase in size during sexual intercourse and during child birth
  • Mucous membrane consists of moist stratified squamous epithelium that forms the protective surface layer
  • Hymen is a thin mucous membrane which covers the vaginal opening
57
Q

What do the external female genitalia (the vulva) consist of?

A
  • Consist of:
    • Vestibule
    • Labia minora
    • Labia majora
    • Clitoris
    • Mons pubis
58
Q

Describe the mammary glands

A
  • Organs responsible for milk production and are located within the breast
  • In both males and females the external breast has a nipple and a surrounding area called the areola
  • Each adult female mammary gland consists of divisions or lobes
    • Each lobe has a lactiferous duct which enlarges to form a lactiferous sinus which accumulates milk
59
Q

Outline breast cancer, what the risk factors are and how it is detected

A
  • Breast cancer is often fatal
  • Risk factos include: late monopause, obesity, family history of breast cancer, radiation of the chest, genetic factors and hormone replacement therapy
  • Use of mammography can detect breast cancer early
60
Q

What is oogenesis?

A
  • Oogenesis refers to the production of secondary oocyte within the ovaries
61
Q

What do oocytes develop from and when do they begin developing?

A
  • Ovaries contain millions of oogenia from which oocytes develop by the fourth month of prenatal life
  • At the time of birth oogonia what re still present have begun meiosis which stops at prophase I - at this stage the cell is known as the primary oocyte
  • Granulosa cells surround the primary oocyte and the structure is known as the primordial follicle
62
Q

Describe what happends with regards oogenesis during puberty

A
  1. The secretion of FSH stimulates the development of primordial follicle (primary oocyte surrounded by granulosa cells) which is converted into a primary follicle when the oocyte enlarges
  2. The zone pellucida consists of several layers of granulosa cells that surround the primary oocyte
  3. Some primary follicles develop and become secondary follicles which enlarge and become graafian (mature) follicles - usually only 1 graaffian follicle is ovulated
  4. Remaining follicles that do not reach advanced stages of development are degenerated
  5. Just before ovulation the primary oocyte in the graafian follicle completes the first meiotic division to produce a secondary oocyte and a polar body
    1. Division is unequal and most of the cytoplasm goes to secondary oocyte & polar body receive little cytoplasm
  6. Release of secondary oocyte via expansion and rupture of graafian follicle is known as ovulation
63
Q

What happends during ovulation?

A
  • The secondary oocyte has begun the secondary meiotic division which stops at metaphse II
    • If sperm cells do not penetrate the secondary oocyte it degerates and does not complete a second division
  • Fertilisation (spermatozoa penetrates secondary oocyte) triggers the secondary oocyte to proceed with the second meiotic division
  • Once spermatozoe penetrated secondary oocyte the second meiotic division is completed and the fertilised oocyte is called the zygote
    • Upon completion of the second meiotic division a second polar body is formed
64
Q

What is meant by the term “ectopic pregnancy”

A
  • Term used to describe the implantation of a secondary oocyte anywhere other than the uterine cavity
  • Implantation in the uterine tube is most common site of ectopic pregnancy
    • Implantation in this site can be fatal to the fetus and can cause the uterine tubes to rupture
  • Chance of hemorrhage makes ectopic pregnancy dangerous to mother
65
Q

What does the term menstrual cycle refer to?

A
  • refers to cyclic changes that occur in non-pregnant, sexually mature females
  • typically 28 days long and is a period of mild hemorrhage during which the uterine epithlium is sloughed and expelled
66
Q

What does the term menstruation refer to?

A
  • Menstruation is the term which refers to the discharge of blood and element of the uterine mucous membrane
67
Q

Describe the different phases of menstruation

A
  • The first day of menses (menstrual flow) is day 1 of the menstrual cycle which is characterised by menstrual bleeding that lasts 4-5 days
  • Timing of ovulation varies but it generally occurs on day 14 of the 28 day cycle
  • The time between ending of menses and ovulation is called the folliculart phase (or the proliferative phase) during which both ovarian follicles and the uterine mucosa develop
  • Time between ovulation on day 14 and the next menses is around 14 days which is referred to as the secretory phase (or luteal phase)
68
Q

What does the ovarian cycle refer to?

A
  • Refers to a sequence of events that occur in the ovaries during the menstrual cycle
  • Hormones secreted by the hypothalamus and anterior pituitary regulate these events
69
Q

Described what happens in the ovarian cycle between day 1-7 of the menstrual cycle

A
  • GnRH stimulates the anterior pituitary to secrete FSH which is release from the anterior pituitary and is responsible for initiating the development of primary follicles
  • FSH also stimulates granulosa cells to convert androgens to estrogen
  • Both estrogen and GnRH stimulate the anterior pituitary to secrete LH
  • Gradual increase in estrogen levels in late follicular phase has postivie feedback effect on LH anf FSH secretion causing an increase in level of both of these in the blood
70
Q

What is the increase in blood levels of LH and FSH called during ovulation?

A
  • Called the LH surge and FSH surge
71
Q

What are the roles of LH and FSH in ovulation?

A
  • LH surge stimulates ovulation and conversion of the ovulated follicle to become the corpus luteum
    • Primary oocyte completes its firts meiotic division before or during ovulation which is caused by the LH surge
  • FSH makes the follicle more sensitive to LH
72
Q

What effect does ovulation have on the production of estrogen and progesterone?

A
  • The production of estrogen by the follicle deceases shortly after ovulation and the production of progesterone increases as the granulosa cells are converted to the corpus luteum cells.
    • corpus luteum develops and secretes progesterone and estrogen
73
Q

What is the effect of the increased levels of progesterone during ovulation?

A
  • Increased levels of progesterone and estrogen have a negative feedback effect on GnRH release from the hypothalamus, which causes a reduction in the secretion of LH and FSH from the anterior pituitary
  • Decrease in levels of FSH and LH also causes the levels of estrogen and progesterone to decline.
  • The decrease in estrogen and progesterone secretion from the ovaries towards the end of the leuteal phase causes uterine lining to degenerate and menses to occur.
74
Q

What happens in the ovarian cycle if fertilisation of the secondary oocyte does occur?

A
  • The devloping embryoic mass begins to secrete human chorionic gonadotropin (HCG) which prevents the corpus luteum from degenerating
    • Consequently levels of estrogen and progesterone do not increase and menses does not occur
    • HCG is not produced if fertilisation does not occur
75
Q

Describe the uterine cycle

A
  • Uterine cycle refers to changes that occur in the endometrium of the uterus during the menstrual cycle
  • After menses, the endometrium of the uterus begins to proliferate which is initiated by estrogen
  • Estrogen causes the uterine tissue to become more sensitive to progesterone
  • After ovulation progesterone cuases hypertrophy of the endometrium and myometrium
  • If pregnancy doesn’t occur by day 24/25 of the menstrual cycle progesterone and estrogen levels decline as the corpus luteum degenerates
76
Q

What is endometriosis and what does it effect?

A
  • Endometriosis is a condition which reduced fertility in which the endometrial tissue is found in abnormal locations
  • Generally a result of some endometrial cells passing from the uterus into the pelvic cavity which then invade the peritoneum of the pelvic cavity
  • Periodic inflammation results in areas where the endometrial cells are, also occurs because the endometrium is very sensitive to estrogen and progesterone
  • Chronic abdominal pain is a result
77
Q

How can fertility in females be deliberately suppressed?

A
  • Oral contraceptives contain high levels of estrogen and progesterone which has a negative feedback effect on the anterior pituitary which prevents the release of LH and FSH that stimulates ovulation