Topic 9 Flashcards
which 2 muscles help control the temperature of the testes?
- The tunica dartos: a layer of smooth sub-cutaneous muscle, contraction of which thickens the scrotal wall and brings the testes closer to the body.
- The cremaster muscle: associated with the spermatic cords can raise or lower the testes.
where is sperm produced?
seminiferous tubules
seminiferous tubules converge to one side of the testes to form what?
rete testis
efferent ducts run form the rete testis to the?
Epididymis
Transportation of mature sperm during ejaculation is completed by which part?
Vas deferens
what are the areas involved in the transportation of sperm during ejaculation?
Scrotum within spermatic cord > through inguinal canal > pelvic cavity > ends in ampulla > joins seminal vesicle duct > forms ejaculatory duct > prostatic urethra
what is the role of the epididymus?
- Site of sperm storage and maturation
- Sperm is ejaculated from the epididymis and not directly from the testes.
what are the 3 internal glands of the male reproductive system?
- Seminal valves
- Prostate gland
- Bulbourethral glands
what is the role of seminal valves?
- Their ducts join the vas deferens.
- Secretes fluids and substances which constitute 60% of the semen.
- Sperm and the seminal fluid mix in the ejaculatory duct.
what is the role of the prostate gland?
The secretions contain milky fluid and enzymes that contribute to semen.
what is the role of the bulbourethral glands?
Secrete mucus (lubricant) during sexual excitement and ejaculation
what are the 3 parts of the penis?
- Root (attached)
- Free shaft or body
- Enlarged tip (glans penis)
what are the 3 erectile bodies?
- One corpus spongiosum
- a pair of corpora cavernosa
- Sexual excitation causes erectile bodies to engorge with blood allowing erection
what are the 3 divisions of the male urethra?
- prostatic urethra
- membranous urethra
- spongy (or penile) urethra
what are the 2 general functions of the female reproductive system?
- Production of gametes (ova, or eggs)
- Preparation for support of developing embryo during pregnancy
what are the 5 parts of the female reproductive system?
1 The paired ovaries 2 Paired uterine/fallopian tubes 3 Uterus 4 The vagina 5 The vulva
which 3 ligaments support the ovaries
- Broad ligament
- Suspensory ligament of the ovary
- Ovarian ligament
what are the 2 functions of the ovaries?
- Oogenesis, production of female gametes
- Secretion of the female sex hormones, oestrogen and progesterone.
what is the structure of the ovaries?
- Covered by a fibrous capsule
- Outer cortex houses developing gametes (the oocytes) within follicles
- Inner medulla is loose connective tissue with large vessels and nerves
function of fallopian tubes
- Transports the ovum to the uterus
structure of fallopian tubes
- Inner lining is covered with ciliated epithelium
- Beating cilia and muscular peristalsis propel egg to uterus
function of the uterus
- Site of development of the foetus
what are the 4 parts of the uterus
- The fundus: the dome-shaped portion above the uterine tubes
- The corpus: the main body of the uterus
- The isthmus: a region below the corpus where the uterus narrows
- The cervix: a narrow neck-like extension that protrudes into the vagina.
which structures support the uterus?
- Mesometrium
- Cardinal ligament
- Round ligament
what are the 3 layers of the uterus?
- Perimetrium
- Myometrium
- Endometrium
structure and function of the perimetrium
- outer serous membrane connective tissue
- sheath continuous with the ligaments that support the uterus.
structure and function of the myometrium
- middle muscle
- smooth muscle
- contracts during child birth
structure and function of the endometrium
- inner mucosal lining
- Place where the embryo implants
- Functional layer sheds during menstruation
- Basal layer does not shed
- Rich in blood vessels and secretory glands
what are the two layers of the endometrium?
- Stratum functionalis (functional layer)- Sheds if there is no implantation
- Stratum basalis (basal layer)- Does not shed
what are the 3 layers of the vagina?
- Adventitia
- Muscularis
- Mucosa
what are the 6 parts making up the external genitalia?
- Mons pubis
- Labia (lips) majora
- Labia minora
- Vestibule
- Clitoris
- Perineum
what is spermatogenesis?
The process by which mature spermatozoa (sperm) are produced in the testes
when does spermatogenesis begin?
How long does the process take?
- Begins at puberty
- the process takes about 60 to 70 days
what are the 3 stages of spermatogenesis?
- Formation of spermatocytes
- Meiosis
- Spermiogenesis
what type of cells have a haploid number i.e. one set of chromosomes?
what type of cell division do these cells undertake?
- Gametes (sperm and egg)
- Meiotic cell division produces haploid cells
what type of cells have a diploid number i.e. 2 sets of chromosomes?
what type of cell division maintains this number?
- Zygote and all body cells (somatic cells) other than the gametes
- Mitotic cell division maintains diploid number
what are spermatogonia?
- undifferentiated male germ cell.
- Divide by mitosis to produce spermatogonia and primary spermatocytes
- diploid
what happens to primary spermatocytes after 1st meiotic division?
- produce two secondary spermatocytes
- These are haploid (possess only 23 chromosomes)
what happens to the secondary spermatocyte?
- Undergoes meiosis II to become two spermatids (n)
what is the end result of spermatogenesis of one spermatogonium?
- A total of four spermatids (n) from one spermatogonium (2n)
what happens during the third stage of spermatogenesis?
-Spermatids (n) differentiate into sperm (n).
what are the 3 parts of a sperm?
Head:
- contain nucleus with chromatid (genetic material)
- Acrosome with enzymes for penetrating egg
Midpiece:
- mitochondria spiralled around the core of the tail
Tail:
- is an elaborate flagellum (allows sperm to swim)
where do sperm leave the testes?
- efferent ductules
- only once they have left the testes can they swim
how long does it take sperm to mature on the epididymis?
20 days
which 2 hormones control spermatogenesis?
- FSH (Follicle Stimulating Hormone) from anterior pituitary gland
- Testosterone (primary male hormone, produced by testes)
what is oogenesis?
- The process by which mature ova (plural; singular- ovum) are formed in the ovary, particularly within the follicles.
when does oogenesis start?
- foetal period
what are Oogonia?
- Stem cells that undergo repeated mitotic division to create primary oocytes
what is an oocyte?
- immature egg/ovum
- Oocytes are in their early stage of meiosis I at the time of birth
- called primary oocyte (2n) - development arrested
- No more oocytes (immature egg) made after about 7th month
what happens to the primary oocyte after puberty?
- FSH rescues a small number of growing follicles each month
- meiosis I in primary oocytes (2n) is completed.
what is the result of meiosis I in primary oocytes?
- first polar body (n) and secondary oocyte (n)
what happens to the secondary oocyte?
- arrested in meiosis II
- released during Ovulation
when does meiosis II occur in secondary oocyte and wha is the result?
- Meiosis II not completed unless sperm penetrates its plasma membrane (fertilisation)
- Of the four daughter cells, only one becomes ovum (n), the other three becomes polar bodies.
what happens during the follicular stage of the ovarian cycle?
- Oocyte develops within a follicle
- Stimulated by Follicle stimulating hormone (FSH)
- Oestrogen is produced by the ovarian follicles
what is the zona pellucida?
Oocyte develops a protective (glycoprotein coat) eggshell
what is the corona radiata?
the surrounding coat of granulosa cells
what is a graafian follicle?
A fully mature, ready to ovulate follicle
what occurs during the ovulation phase?
- The secondary oocyte (egg) is released from follicle, ovarian wall ruptures
- still surrounded by zona pellucida and corona radiata
- picked up by fimbria of fallopian tube
- Signal for ovulation is LH (Luteinizing hormone) surge
what happens during the luteal phase?
- Corpus luteum develops from exploded follicle
- Produces progesterone and oestrogen (Progesterone stimulates uterus to be ready for baby)
- If no pregnancy, corpus luteum degenerates
what is embryology?
The branch of biology that is concerned with the study of embryos and their development.
what is capacitation?
changes to the sperm that allow it to fertilise the secondary oocyte which involves:
- enhanced motility and vigorous tail beating
- sperm membranes become fragile in order to release acrosomal enzymes.
how long is the secondary oocyte viable for after release from ovary?
12-24 hours
what is polyspermy?
depolarisation/ changes that occur on the surface of the fertilised ovum to prevent other sperm from binding and entering
what are the events leading to fertilization? (5)
- Sperm binds to receptors on zona pellucida
- Acrosomal reaction – enzymes digest a slit
- Sperm passes through zona and binds to sperm-binding receptors
- Fusion of a single sperm’s plasma membrane with oocyte’s plasma membrane
- Cortical reaction: sperm receptors are destroyed in zona so no more sperm can enter. Sperm nucleus is engulfed by egg’s cytoplasm
what happens to sperm after penetration?
- Sperm sheds its tail.
- Its nucleus increases in size and develops into the male pronucleus and seeks the nucleus of the oocyte.
what happens to the secondary oocyte after sperm penetration?
- Secondary Oocyte completes meiosis II
- The ovum (mature egg) and the 2nd polar body are formed.
- Ovum nucleus swells and becomes the female pronucleus.
what happens once male and female pronucleus have formed?
- The DNA replicates within the male and female pronuclei
- The pronuclei approach one another
- A spindle develops between them
- Their membranes rupture and their chromosomes are released
- When the two haploid pronuclei fuse, they form a diploid segmentation nucleus
what is a zygote?
a diploid fertilised cell consisting of a segmentation nucleus, cytoplasm and surrounded by a membrane.
what are the 4 stages of embryology?
- Mitotic cell division
- Formation of the Morula
- Formation of Blastocyst
- Implantation
what happens during mitotic cell division?
- Increase in the number of cells
- no increase in size of developing organism
- 1st cleavage begins 24 hours after fertilisation and takes about 6 hours
- The resulting cells are called blastomeres
- These divide to produce four cells, then eight and so on.
what is the morula?
A solid mass of 16 or more cells/blastomeres about the same size as the original zygote
what is a blastocyst?
- A hollow ball of hundreds of cells consisting of:
- An outer covering of cells called the trophectoderm
- An inner cell mass (20 to 30 cells)
- A fluid filled cavity called the blastocyst cavity/ blastocoel
what becomes of the trophectoderm of the blasocyst?
- will become a part of the chorion (one of the extraembryonic membranes)
what becomes of the inner cell mass of the blastocyst?
- One part later becomes the embryonic disc, which forms the embryo proper.
- Other part will become three of the four extraembryonic membranes (amnion, yolk sac and allantois)
what happens when the blastocyst attaches to the endometrium?
• Cells of the trophectoderm secrete enzymes that digest and liquefy the endometrial cells > allows the blastocyst to penetrate the endometrium
• The blastocyst attaches firmly to the endometrium
- Endometrial glands enlarge
- Endometrium becomes more vascular
The inner cell mass of the blastocyst differentiates into 3 primary germ layers, what are they?
- Upper Ectoderm
- Middle Mesoderm
- Lower Endoderm
The ectoderm develops into what?
the skin and nervous system
The mesoderm forms what?
the peritoneum, muscle, bone and other connective tissues
The endoderm becomes what?
the epithelial lining of the digestive tract, respiratory tract and other organs
what is the placenta?
A highly vascular organ that develops in the uterine wall through which exchange of materials occurs between the foetal and maternal circulations
what are the 4 functions of the placenta?
- Respiratory
- Excretory
- Nutritive
- Endocrine
how is the placenta formed?
- Trophoblast from embryo becomes Chorionic villi > Foetal part of placenta
- Endometrial tissue becomes Decidua basalis > Maternal portion of placenta
- Placenta attached to the umbilicus (navel) of the foetus by the umbilical cord
where do exchanges through placenta occur?
All exchanges occur through capillary walls & chorion.
what separates the blood of mother and child ?
Chorionic lining
what does the umbilical cord contain?
• Umbilical cord carries two umbilical arteries and one umbilical vein
what are the two branches of the umbilical vein?
- one joins hepatic portal vein, goes to liver
- other is the ductus venosus - it bypasses the liver
- Carries fully oxygenated blood
describe the ductus venosus
- Carries most of the blood from umbilical vein, bypassing the liver
- Drains into the inferior vena cava
- Blood is highly oxygenated
what is the foramen ovale?
- Opening between right & left atria in the interatrial septum
- Allows 1/3 of blood in right atrium to pass directly into left atrium
- Is covered by a flap of tissue that acts like a one-way door
describe the ductus arteriosus
- Small vessel connecting pulmonary trunk with aorta
- Allows blood leaving the right ventricle to bypass the lungs and go more directly into the aorta and the systemic circulation
- Carries over 90% of blood leaving the right ventricle
after birth the umbilical arteries become what?
Medial umbilical ligaments
after birth the umbilical vein become what?
Ligamentum teres (Round ligament of the liver; attaches the umbilicus to the liver)
after birth the Ductus venosus become what?
Ligamentum venosum (A fibrous cord in the liver.)
after birth the Foramen ovale become what?
Fossa ovalis (A depression in the interatrial septum.)
after birth the Ductus arteriosus become what?
Ligamentum arteriosum
what happens to the foramen ovale after birth?
- Closes at birth because when the lungs are inflated
- increased pressure in L. atrium causes closure
- Physiological closure only; anatomical closure takes from three months to one year
failure of foramen ovale to close is called?
Interatrial Septal Defect - effects about 10% of adults
changes in ductus arteriosus after birth?
- When there is a change from high O2 to low O2 levels after cord clamping
- Constriction and fusion of the vessel walls occurs and there is formation of the ligament in 3 to 5 weeks
- Failure to close - Patent Ductus Arteriosus
