UNIT 10 - REPRODUCTIVE SYSTEM I & II Flashcards
Male reproductive system function
To produce, transfer, and introduce sperm into female reproductive tract where fertilization occurs
Testes
Two oval shaped structures located in scrotum outside body cavity and produces testosterone and sperm
Spermatogenesis
Process by which sperm cell production occurs (65-75 days) and 300 million cells produced daily
Ideal environment for sperm
Lower temperature needed for survival
Male reproductive ducts (4)
- Epididymis
- Vas Deferens
- Ejaculatory duct
- Urethra
Epididymis
Comma shaped organs located posteriorly to testes and site of sperm maturation (gains mobility); sperm stored here for 4 weeks
Vas Deferen
Transports sperm to the ejaculatory duct; can also store sperm
Ejaculatory duct:
Short duct where contents from vas deferens and seminal vesicles merge, and the semen is ejected into urethra
Urethra
Large duct that passes through prostate gland and carries semen out of the penis consisting of 3 regions; also carries urine
3 regions of the urethra:
- Prostatic
- Intermediate (membranous)
- Spongy
Male reproductive accessory organs/gland function
Secretes liquid portion of semen
Male reproductive accessory organs/glands (3)
- Seminal vesicles
- Prostate gland
- Bulbourethral (Cowper’s gland)
Seminal vesicles
Glands located under the bladder and secretes alkaline, viscous fluid that provide about 60% of the total volume of semen and is needed to neutralize acidic female environment (high in fructose = supplies atp for sperm); provide necessary components of semen
Prostate gland
Size of a chestnut and produces a milky acidic substance that contains citric acid (for ATP), enzymes, and prostaglandins that help sperm mobility and viability and makes up 25% of total volume of semen; support sperm function
Bulbourethral (Cowper’s) gland
Located inferior to the prostate and secretes an alkaline mucous (precum) for lubrication/to create a more favourable environment for sperm and makes up 15% of total volume of semen; ideal environment for sperm
Female reproductive system function
To develop ova (eggs), prepare for fertilization, and to carry the fertilized egg through the development stages (egg –> zygote –> fetus)
Ovaries
Small oval shaped glands located on either sides of uterus responsible for the production of ova (eggs) and the production of estrogen and progesterone
Female reproductive ducts (3)
- Fallopian (uterine) tubes
- Uterus
- Vagina
Fallopian tubes
Pair of tubes that are the site of fertilization and the transport of ovum (eggs)/zygote from ovaries to the uterus (occurs approximately once a month)
Ectopic pregnancy
Condition when a fertilised egg implants itself outside the womb on fallopian tubes (non-viable)
Uterus
Site of menstruation and fetal development (implantation occurs here) and consists of 3 layers
Cervix
Lower uterine opening to the vagina
3 uterine layers
- Perimetrium
- Myometrium
- Endometrium
Perimetrium
Outermost serous layer part of visceral peritoneum
Myometrium
Middle layer of smooth muscle
Endometrium
Innermost layer of mucosal lining of the uterine cavity
Stratum functionalis
Thick superficial layer that is shed off during menstruation and grows new during each cycle
Stratum basalis
Layer that never goes away
Vagina
Responsible for copulation, birth canal and menstrual flow. It also produces organic acids to maintain acid environment to decrease microbial growth
Female reproductive glands (2)
- Bartholin’s glands
- Skene’s glands
Bartholin’s glands
Located on either side of vaginal orifice and produces mucous secretion for lubrication
Skene’s glands
Located on either side of urethral orifice and produce mucous secretion for lubrication
Clitoris
Erectile tissue responsible for female sexual orgasm
LH (Luteinizing hormone)
Stimulates leydig cells to secrete testosterone
FSH (Follicle stimulating hormone)
Indirectly stimulates spermatogenesis by ensuring that levels of testosterone stay high around spermatogenic cells
Inhibin
Inhibits the synthesis and release of FSH and LH
Mechanism and anatomical pathway of sperm release (4)
- Sperm is produced from spermatogenic cells
- As cells become sperm, they move towards lumen of seminiferous tubule
- By the time they are sperm, they travel to the epididymus
- Sperm propelled from epididymus along vas deferens to ampulla where sperm is stored for several months
Scrotum
Bag of skin that supports and protects the testes outside the body
Penis
Primary sex organ that introduce sperm when erect into female genital tract via sympathetic reflex
Parasympathetic vs sympathetic process:
- Erection: Parasympathetic process due to relaxation and increased blood flow
- Ejaculation: Sympathetic process associated with fight or flight due to preparation to body of intense physical activity and active process of muscle contraction
Ovarian cycle
Preparation of endocrine tissues and release of eggs from ovary ~ 28 days
Ovarian cycle characteristics (4)
- Each ovary has 200,000 primary follicles
- Each month 1 egg matures and is released
- Cycle is about 28 days
- Regulated by the hypothalamus (GnRH), anterior pituitary (FSH, LH), and ovaries (estrogen, progesterone)
Menstrual (uterine) cycle
Preparation and maintenance of uterine lining ~~ 28 days
If fertilization does not occur..
If fertilization does not occur, progesterone levels fall and the thickened lining of the uterus that was prepared to support a potential pregnancy during menstrual cycle will shed causing bleeding (25-65mL of blood, tissue fluid, mucous and epithelial cells)
Menstrual cycle process (3)
- Days 1-5 (menstrual phase): Uterus sheds all except of the deepest part of the endometrium
- Days 6-14 (proliferative phase): Endometrium rebuilds itself
- Days 15-28 (secretory phase): Endometrium prepares for implantation of the embryo
Days 1-5 (Menstrual phase) (2)
- GnRH stimulates release of FSH and LH
- FSH stimulate follicle growth and maturation and follicles release estrogen
Days 6-14 (proliferative phase) (2)
- Rising estrogen levels inhibits FSH allowing one dominant follicle to enlarge
- Secreted estrogen thickens the endometrium
Pre-ovulatory phase (2)
- High estrogen has a positive feedback effect on the pituitary
- LH surge triggers rupture of the mature follicle and ovulation
Days 15-28 (secretory phase) post ovulation (2)
- LH stimulates the corpus luteum which secretes estrogen and more progesterone
- Progesterone and estrogen cause the endometrium to develop glands
End of cycle (3)
- Corpus luteum’s progesterone and estrogen inhibit LH production
- Decreased LH cause corpus luteum atrophy leading to fall in progesterone and estrogen
- Without these hormones, the endometrium cannot be maintained leading to menstruation
Pregnancy test
Measures the hCG (human chorionic gonadotropin; hormone produced by cells that form placenta) levels in urine or blood from day 8 post fertilization
Corpus luteum
Maintained by hCG and produced by the developing placenta and secretes estrogen and progesterone to maintain endometrium
Fertilization
Union of the nuclei of sperm and egg that occurs in outer third of fallopian tubes within 12-24 hours of ovulation to form a zygote
Fertilization statistics (4)
- 300 million sperm ejaculated
- 2 million reach cervix
- 2000 sperm reach ovum
- Head of only 1 sperm enters ovum
Zygote
A fertilized egg (fusion of sperm and egg)
Morula
Solid ball of cells after zygote undergoes multiple rounds of cell division
Blastocyst
Further cell division and differentiation of morula that attach to endometrium after 6-8 days of post fertilization
Trophoblast
Outer layer of cells in blastocyst responsible for initiating attachment of embryo to the lining of the uterus (endometrium)
Embryonic germ layers (3):
- Ectoderm
- Mesoderm
- Endoderm
Ectoderm
Skin and CNS/PNS
Mesoderm
Muscle bone, connective tissue, skeleton, heart, BV, kidneys
Endoderm
Epithelium of GIT, gallbladder, trachea and lungs
Extra-embryonic membranes (4)
- Chorion
- Amnion
- Yolk sac
- Allantois
Chorion
Outermost membrane that develops from trophoblast and becomes part of the placenta to absorb nutrients from endometrium
Amnion
Produces insulating fluid (fluid for embryo) and responsible for temperature maintenance and shock absorber
Yolk sac
Has little importance in humans (nutrient source for birds) but becomes part of umbilical cord later on
Allantois
Develops into stalk of embryo and responsible for role in formation of blood cells and umbilical blood vessels and becomes part of umbilical cord later on
Placenta
Temporary disc shaped organ that develops in the uterus during pregnancy from embryonic chorion and maternal endometrium that is well developed by 4 months and replaces corpus luteum; also produces estrogen and progesterone
Placenta functions (2)
- Nutrients exchange from mother to fetus, and waste exchange from fetus to mother
- Endocrine secretions of hCG, estrogen and progesterone
Umbilical cord
Formed by allantois and yolk sac and contains 1 vein that carries blood form placenta to fetus, and 2 arteries that carry blood from fetus to placenta
Zygote
Fertilized egg
Embryo
After fertilization to 8 weeks of development
Fetus
Week 9 to childbirth
Identical twins (monozygotic)
Occurs when one fertilized egg splits and develops into two babies with the exact same genetic information; shared placentas
Fraternal twins (dizygotic)
Occurs when two eggs are fertilized by two sperm and produce two genetically unique children; separate placentas
Estrogen (pregnancy)
Stimulates uterine contraction
Progesterone (pregnancy)
Inhibits uterine contraction
Estrogen (labour)
Promotes contraction at the start of labour since their levels rise more rapidly than progesterone
Progesterone (labour)
Levels fall dramatically before labour
Oxytocin (labour)
Forceful uterine contractions regulated by positive feedback
Estrogen (lactation)
Early breast development
Progesterone (lactation)
Development of glandular tissue
Oxytocin (lactation)
Milk ejection reflex regulated by positive feedback
Prolactin
Milk production that can be inhibited by estrogen and progesterone
3 stages of labour:
- Dilation
- Expulsion
- Placental
Dilation
Cervix relaxes causing it to dilate and thin out
Expulsion
Uterine contractions increase in strength and infant is delivered
Placental
Placenta is expelled
Umbilical vein
Fetal blood vessel carrying oxygenated blood from placenta to developing fetus
Ductus venosus
Fetal blood vessel shunting oxygenated blood from umbilical vein directly into inferior vena cava
Foramen ovale
Small opening between the atria of fetal heart that allow blood to bypass lungs facilitating redirection of oxygenated blood from right atrium to left atrium (closes after birth)
Ductus arteriosus
Connects pulmonary trunk to aorta
Umbilical artery
Fetal blood vessel carrying deoxygenated blood from the fetus back to the placenta
Inefficiency of fetal circulation cause
Caused by the mixing of oxygenated blood from the ductus venosus with deoxygenated blood in fetal inferior vena cava but the fetus is still able to get adequate amount of oxygen because fetal hemoglobin binds with oxygen more efficiently than adult hemoglobin
When does fetal circulation process end
Right after delivery of baby, the structures that bypassed the lungs fill with connective tissue or close off
Fetal circulation transformation (5)
- Umbilical veins –> ligamentum teres
- Ductus venosus –> ligamentum venosum
- Foramen ovale –> fossa ovalis (depression in the wall between atria)
- Ductus arteriosus –> ligamentum arteriosum
- Umbilical arteries –> medial umbilical ligaments
Neonatal blood cells
Higher RBC count (less than 1% still nucleated), higher Hb concentration, higher WBC count
Site of fetal erythropoeisis (4)
- Liver, spleen, bone marrow and lymph nodes
- After birth
- RBC are produced entirely by red bone marrow
- Number of blood cells decrease to adult level
Pulmonary surfactant
Complex substance containing lipids and proteins that decrease surface tension
Phospholipoprotein
Component of pulmonary surfactant produced by fetal lung from week 26-28 that plays a crucial role in reducing surface tension within alveoli of lungs preventing tendency to collapse during exhalation
Respiratory distress syndrome
Caused by surfactant deficiency in premature babies
Fetal lungs (3)
- Filled with fluid prior to delivery
- During labour, fetal thoracic cavity is compressed and expels about 33% of fluid
- Initial breath of fetus push rest of fluid into cardiovascular and lymphatic system
