Transcript Male Reproductive System - Websupport1

Anatomy & Physiology
SIXTH EDITION
Lecture 28, The Reproductive
System
Lecturer: Dr. Barjis
Room: P313
Phone: (718) 260-5285
E-Mail: [email protected]
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
Learning Objectives
• Specify the components of the reproductive
system, and summarize their functions
• Describe the components of the male and female
reproductive systems
• Outline the processes of meiosis and
gametogenesis in both sexes
• Explain the roles played by the male reproductive
tract and accessory glands in the functional
maturation, nourishment, storage, and transport
of spermatozoa
Learning Objectives
• Summarize the anatomical, physiological, and
hormonal aspects of the male and female
reproductive cycles
• Discuss the physiology of sexual intercourse
Reproductive System
• The only system not essential for life, but ensures continued
human existence
• Functions of Reproductive system include:
• Production of gametes
• Storage gametes
• Nourishment gametes
• Transport gametes
• In female additional functions such as provide nutrient
and support to the developing embryo, fetus and infant
• Fertilization
• Fusion of male and female gametes to form a zygote
Reproductive system includes:
• Organs of reproductive system include:
• 1) Gonads (testes, ovaries) – produce sperm/egg
• Testes produce gametes (spermatozoa/ sperm) 1.5 billion each
day and secrete sex hormones (testosterone)
• Ovaries release one immature gamete (oocyte) per month
• 2) Ducts – a passageway that opens to the exterior and
transport gamete
• Sperm is mixed with secretion of accessory glands along ducts
and converted to semen
• Oocyte travels along uterine tube to uterus
• 3) Accessory glands and organs – these organs secrete
fluid e.g. seminal vesicle secrete seminal fluid
• 4) External genitalia
Male Reproductive System: Sperm Passageway
1. Spermatozoa is produced in testes in the
seminiferous tubules
•
Seminiferous tubules are tightly coiled tubes
found in lobules of testes
2. From seminiferous tubules sperms are passed to
afferent ductules
3. Afferent ductules pass the sperm to rete stestes
4. From rete testes spearm leave the testes by
efferent tuctules
5. Efferent tuctules deliver the sperm to the
epididymis
The Structure of the Testes
Male Reproductive System: Sperm Passageway
6. Epididymis pass the sperms to the duct deference
7. From ductus deferens, sperms are passed to the ejaculatory
duct
8. Ejaculatory duct is connected to the urethra
Accessory organs of male reproductive system
1. Seminal vesicles
2. Prostate gland
3. Bulbourethral glands
4. Scrotal sac encloses testes
5. Penis
The Male Reproductive System
Sperm production: Spermatogenesis
• Sperm production takes place in seminiferous
tubules
• Seminiferous tubules contain sustencular cells
and stem cells called spermatogonia
• Stem cells involved in spermatogenesis
• Sustencular cells sustain and promote
development of sperm
• Interstitial cells between seminiferous tubules
secrete sex hormones (testosterone)
Sperm production: Spermatogenesis
• Spermatogenesis involves three processes
• 1) Mitosis
• In this process spermatocytes are produced
from spermatogonium
• 2) Meiosis
• In this process spermatocytes go through
meiosis I and meiosis II and produce 4
spermatids
• 3) Spermiogenesis
• In this process spermatids differentiate into
spermatozoa
Sperm production: Spermatogenesis
Figure 28.7
Sperm production: Spermatogenesis
Sperm production: Spermatogenesis
Sperm production: Spermatogenesis
Sperm production: Spermatogenesis
Sperm production: Spermatogenesis
The testes
• Descent of the testes
• Movement of testes through inguinal
canal into scrotum
• Occurs during fetal development
• Testes anatomy
• Tunica albuginea surrounds testis
• Septa extend from tunica albuginea
and divides testes into lobules
• Within each lobule tightly coiled
tubes called seminiferous are located
• Sperm production occurs in
seminiferous tubules
The Descent of the Testes
Anatomy of spermatozoon
• Each spermatozoon is divided into 3 part:
• 1) Head that contains:
• Nucleus and densely packed chromosomes
• 2) Middle piece that contains
• Mitochondria that produce the ATP needed
to move the tail
• 3) Tail
• The only cell with flagellum in the human
body
• It enables the spermatozoa to swim
Spermiogenesis and Spermatozoon Structure
Male reproductive tract: Epididymus
• Epididymus is elongated tubule with head, body and tail regions
• Functions of epididymus are to:
• 1) Monitor and adjust fluid in seminiferous tubules
• 2) Store and protect spermatozoa
• 3) act as a recycling center for damaged spermatozoa
• 4) Facilitates functional maturation of spermatozoa
• Although spermatozoa leaving the epididymis are mature, but they
remain immobile.
• Spermatozoa will become functionally mature when:
• 1) mixed with secretions of the seminal vesicles,(become mobile
• 2) exposed to conditions in the female reproductive tract(become
capable of fertilization)
The Epididymus
Ductus deferens AKA vas deferens
• Begins at epididymus
• Passes through inguinal canal
• Enlarges to form ampulla
• Peristaltic contractions propel spermatozoa and fluid along
the duct
• Functions of Duct Deferens:
• Transport spermatozoa,
• Store spermatozoa (for several months)
• The junction of the ampulla with the duct of the seminal
vesicle marks the start of the ejaculatory duct
• Ejaculatory duct is a short passageway that penetrates
the muscular wall of the prostate gland and empties into
the urethra
Urethra
• This passageway is used by both urinary and
reproductive systems
• This passageway begins at the urinary bladder
and ends at the tip of the penis
• Urethra divides into three regions
• Prostatic
• Membranous
• Penile
Accessory glands
• Important glands include the seminal vesicles, the prostate
gland, and the bulbourethral glands
• Seminal vesicles
• Contributes about 60% of the total volume of semen
• Secretions of seminal vesicle contain fructose,
prostaglandins, fibrinogen
• Fructose is metabolized by spermatozoa and used as a source of
energy
• Prostaglandins stimulates smooth muscle contractions along the
reproductive tracts (e.g. vagina), thus it helps spermatozoa to
move
• Fibrinogen forms a temporary clot within the vagina to prevent
damage to the spermatozoa by the acidic environment of vagina.
•
Spermatozoa become mobile after mixing with seminal vesicles
secretion
Accessory glands
• Prostate gland
• Secretes an alkaline prostatic fluid that
accounts for about 20-30 % of semen volume
• Contains seminalplasmin (an antibiotic that
prevents urinary tract infection)
• The alkaline secretion helps to neutralizes acid
along the urethra and in the vagina
• Bulbourethral glands
• Secrete alkaline mucus with lubricating
properties
The Ductus Deferens and Accessory Glands
Contents of Semen
• Typical ejaculate = 2-5 ml fluid that contain:
• 1) Contains between 20 – 100 million spermatozoa per
ml
• 2) Seminal Fluid about 60%
• 3) Prostatic Fluid about 20-30 %
• 4) Enzymes such as:
• Protease – helps dissolve mucous secretion in the vagina
• Seminalplasmin – antibiotic enzyme that kills bacteria
• Enzymes that convert fibrinogen to fibrin that will clot the
semen
• Fibrinolysis – liquefies the clotted semen after the virginal
environment is neutralized
External genitalia
• Male external genitalia consist of the scrotum and
the penis
• Skin overlying penis resembles scrotum
• Penis
• Contains three masses of erectile tissue
• 2 corpora cavernosa beneath fascia
• 1 corpus spongiosum surrounding urethra
• Dilation of erectile tissue produces erection
The Penis
Hormones of male and female reproductive
system
• At puberty Hypothalamus produces GnRH (Gonadotropin releasing
hormone)
• GnRH stimulates production of FHS and LH by the pituitary gland
• FSH (Follicle stimulating hormone)
• In male FSH targets sustentacular cells of testes and stimulates
spermatogenesis (production of sperm)
• In female FSH stimulates development of follicle (egg)
• Developing follicle produces estrogen
• LH (leutinizing hormone)
• In male LH causes secretion of testosterone and other androgens by
the interstitial cells
• In female LH stimulates secretion of progesterone by corpus luteum
• In female LH surge leads to ovulation
Hormones of male and female reproductive
system
• Testosterone
• 1) stimulating spermatogenesis
• 2) affect sexual drive(libido)
• 3) stimulate metabolism
• 4) stimulate the male secondary sexual characteristics
• 5) maintaining accessory glands and organs of male reproductive
tract
• Progesterone
• Stimulate endometrial growth and secretion
• Estrogen
• 1) stimulating bone and muscle growth
• 2) stimulate female secondary sexual characteristics
• 3) initiating the repair and growth of the endometrium
Hormonal Feedback and the Regulation of the
Male Reproductive Function
The Hormonal Regulation of Ovarian Activity
The Reproductive System of the Female
Principle organs of the female reproductive
system
• Ovaries
• Uterine tubes
• Uterus
• Vagina
The Female Reproductive System
The ovaries
• Held in position by ovarian and suspensory
ligaments
• Blood vessels enter at ovarian hilus
• Tunica albuginea covers ovary
The Ovaries and Their Relationships to the
Uterine Tube and Uterus
Oogenesis
• Oogenesis is the process
of ovum production
• It occurs monthly in
ovarian follicles
• Part of ovarian cycle
• Follicular phase
(preovulatory)
• Luteal phase
(postovulatory)
The ovarian cycle
• Steps in the ovarian cycle
• 1) Formation of primary, secondary, and
tertiary follicles
• 2) Ovulation
• 3) Formation and degeneration of the corpus
luteum
• Corpus luteum begins to degenerate roughly
12 days after ovulation if fertilization does
not occur
• 4) Degradation of the corpus luteum
The Ovarian Cycle
The Ovarian Cycle
The Uterine tubes
• Uterine tubes (Fallopian tubes or oviducts) is divided into:
• 1) Infundibulum
• End of infundibulum closest to the ovary has
numerous fingerlike projections called fimbriae
• 2) Ampulla
• The middle portion
• 3) Isthmus
• A short segment connected to the uterine wall
• Each uterine tube opens directly into uterine cavity
• Fertilization occurs in uterine tube
• 12-24 hours after ovulation
The Uterine Tubes
The uterus
• The uterus is a muscular organ
• Its functions are:
• 1) Mechanical protection
• 2) Nutritional support
• 3) Waste removal for the developing embryo and fetus
• Major anatomical landmarks of uterus
• Body
• Isthmus
• Cervix
• Cervical os (internal orifice)
• Uterine cavity
• Cervical canal
• Internal os (internal orifice)
The Uterine Wall
• Uterine wall consists
of 3 layer:
• Myometrium –
outer muscular
layer
• Endometrium – a
thin, inner,
glandular mucosa
• Perimetrium – an
incomplete serosa
continuous with
the peritoneum
Uterine cycle
• Repeating series of changes in the endometrium
• Uterine cycle continues from menarche (the first
minstruation) to menopause (the last
minstruation)
• Uterine cycle is divided into 3 phases:
• 1) Menses
• Degeneration of the endometrium
• Menstruation
• 2) Proliferative phase
• Restoration of the endometrium
• 3) Secretory phase
• Endometrial glands enlarge and accelerate their rates of
secretion
The Uterine Cycle
The vagina
• Vagina is an elastic, muscular tube
• Major functions of vagina are:
• 1) Passageway for elimination of menstrual
fluids
• 2) Receives the penis during sexual intercourse
• Also hold spermatozoa prior to their
passageway into the uterus
• 3) Forms the inferior portion of the birth canal
External genitalia
• Vulva
• Vestibule
• Labia minora
• Labia majora
• Paraurethral glands
• Clitoris
• Lesser and greater vestibular glands
The Female External Genitalia
Hormones of the female reproductive cycle
• Control the reproductive cycle
• Coordinate the ovarian and uterine cycles
The Hormonal Regulation of the Female
Reproductive Cycle
The Hormonal Regulation of the Female
Reproductive Cycle
Animation: Regulation of the Female Reproductive Cycle (see tutorial)
The Physiology of Sexual Intercourse:
Male sexual function
• Arousal
• Leads to erection of the penis
• Parasympathetic outflow over the pelvic
nerves
• Emission and ejaculation
• Occur under sympathetic stimulation
• Results in semen being pushed toward external
urethral opening
• Detumescence
• Subsidence of erection
• Mediated by the sympathetic nervous system
Female sexual function
• Stages are comparable to those of male sexual
function
• Arousal causes clitoral erection
• Vaginal surfaces are moistened
• Parasympathetic stimulation causes engorgement
of blood vessels in the nipples
Aging and the Reproductive System
Menopause
• The time that ovulation and menstruation cease
• Typically around age 45-55
• Accompanied by a decline in circulating estrogen
and progesterone
• Rise in GnRH, FSH, LH
Male climacteric
• Levels of circulating testosterone begin to decline
• FSH and LH levels rise
• Gradual reduction in sexual activity
You should now be familiar with:
• The components of the reproductive system, and
their functions
• The components of the male and female
reproductive systems
• The processes of meiosis and gametogenesis in
both sexes
You should now be familiar with:
• The roles played by the male reproductive tract
and accessory glands in the functional
maturation, nourishment, storage, and transport
of spermatozoa
• The anatomical, physiological, and hormonal
aspects of the male and female reproductive
cycles
• The physiology of sexual intercourse