Human Reproductive System Flashcards
Structure of Penis
Spongy erectile tissue
Strcture & Function of Testes
- Made up of lobules with seminiferous tubules -> Produces sperms
- Produces testosterone
Pathway from testes to ejaculation
Testes -> Epididymis -> Vas Deferens -> Ejaculatory Duct & Seminal Vesicle -> Prostate & Cowpers Gland -> Uretha
Structure of epididymis
Highly coiled tubules
Sperms complete maturation and become motile
Function of Seminal Vesicle
- Fluids contains fructose -> provides energy to increase sperm mobile
- Alkaline fluid -> neutralises acidic vagina environment
Function of Prostate Gland
- Alkaline fluid -> neutralise acidity of female reproductive tract
- Enzymes -> increases sperm mobility
What happens during erection?
- During sexual arousal -> nerve impulses transmitted from brain to penis arterioles
- Arterioles dilate -> spongy erectile tissue filled with blood
- Swelling of penis squeezes off veins that drain blood -> erectile tissues become engorged with blood -> erection
Function of Ovaries
- Produces follicles
- Produces hormones oestrogen and progesterone
Structure & Functions of Oviducts
- Ciliated epithelial lining and feathry fimbriae -> draws in egg from ovary
- Fertilisation occurs here -> Cilia movement and contraction of muscles move fertilised egg to uterus
Structure & Function of Uterus
- Endometrium (Inner vascularised wall) -> Implantation of Embryo
- Myometrium (Outer contracting wall) -> push out foetus during labour
- Accomodates growth of baby
Function of Cervix
- Controls opening of the uterus
- Dilates during labour
Function of Vagina
Vagina
- Site of insertion of penis
- Birth canal
What are the concurrent cycles and phases of menstrual cycle
Ovarian Cycle -> Follicular Phase (Day 1-14) and Luteal Phase (Day 15-28)
Uterine Cycle -> Menstruation Flow Phase (Day 1-5), Proliferative Phase (Day 6-14) and Secretory Phase (Day 15-28)
Describe the Follicular Phase of the Ovarian Cycle (Day 1-14)
- Gonadotrophin Releasing Hormone (GnRH) released from hypothalamus
- Stimulates anterior pituitary gland to secrete small amounts of follicle-stimulating hormone (FSH) and lutenizing hormone (LH)
- FSH stimulates growth of primary follicles, one will become a Graafian follicle
- FSH and LH stimulate follicles to produce oestrogen -> low levels of oestrogen at first inhibit FSH and LH by negative feedback
- Accumulation and steep rise of oestrogen -> surge in FSH and LH through positive feedback -> Surge in LH -> Triggers ovulation on Day 14
Describe the Luteal Phase of the Ovarian Cycle (Day 14 - Day 28)
- LH stimulates cells of ruptured Graafian follicle to form corpus luteum
- Corpus luteum secretes progesterone and oestrogen -> both hormones together inhibit FSH and LH by negative feedback
- If no fertilisation -> constant low levels of LH cause corpus luteum to disintegrate -> progesterone and oestrogen levels fall
- New ovarian Cycle begins
Describe the menstrual flow phase of the uterine cycle (Day 1 - Day 5)
- Arteries in endometrium constrict due to fall in oestrogen and progesterone
- Endometrial tissues deprived of circulation -> begin to disintegrate
- Shedding of endometrial tissues along with blood
- New follicles begin to grow
Describe the proliferative phase of the uterine cycle (Day 5 - 14)
- Oestrogen secreted by follicles promotes repair of endometrium -> endometirum thickens and becomes vascularised
Describe the secretory phase of the uterine cycle (Day 14 - Day 28)
- Progesterone and oestrogen stimulate maintenance of endometrium -> prepares uterus for possible implantation of egg
- Corpus luteum breaks down -> oestrogen and progesterone levels fall -> endometrium breaks down
- Menstruation begins
What is the role of Gonadotrophin Releasing hormone (GnRH)?
- Secreted by hypothalamus
- Stimulates secretion of FSH and LH from anterior pituitary gland
What is the role of Follicle-stimulating hormone (FSH)
- Secreted by anterior pituitary gland
- Stimulates development of follicles
- Stimulates secretion of oestrogen from developing follicles
What is the role of Lutenising Hormone (LH)?
- Secreted by anterior pituitary gland
- Triggers Ovulation
- Causes formation of Corpus Luteum
- Stimulates secretion of oestrogen from developing follicles
What is the role of oestrogen?
- Secreted by developing primary follicles and corpus luteum
- Promotes growth and repair of uterine lining , allowing it to be thick and spongy with blood vessels
- With progesterone, inhibits FSH production -> prevents ripening and growth of additional follicles
What is the role of Progesterone?
- Secreted by corpus luteum
- Maintains thick uterine lining and well vascularised -> for implementation of embryo
- Inhibits production of FSH and LH
What is the structure of the sperm?
- Head, middle piece and tail
- Head -> dense nucleus, haploid chromosomes
- Tip of head -> Acrosome, huge lysosome with hydrolytic enzymes to breakdown zona pelludica
- Middle piece -> mitchondria generates energy for sperm to swim
What is the structure of the egg?
- Contains haploid chromosomes
- Outer membrane -> zona pelludica (glycoprotein jelly coat)
- Inner membrane -> corona radiata (follicle cells)
Outline the process of Fertilisation
- Sperm cells deposited in vagina
- Swim from vagina -> cervix -> uterus -> oviduct (Aided by muscular contraction of uterus and oviduct)
- Moves through follicle cells of corona radiata -> reaches zona pelludica
- Contact with zona pelludica releases hydrolytic enzymes from acrosome -> breaks down zona pellucida
- Sperm enters nucleus
- Fuses with haploid egg gamete to form zygote
- Egg releases substances to alter zona pelludica -> impenetratable to other sperms
Outline the implantation of zygote in uterus
- Zygote formed moves towards uterus -> movement of cilia lining oviduct and contraction of oviduct muscles
- Divides repeatedly by mitosis to form blastocyst (ball of cells)
- Blastocyst undergoes implantation -> embeds in endometrium
Outline the development of placenta of the foetus
- Villi containing blood capillaries of embryo grow from outer blastocyst epithelium
- Release hydrolyctic enzymes which break down endometrium capillaries -> maternal blood fills space
- Forms placenta containing capillaries surrounded by maternal blood spaces
- Maternal blood seperated from foetal capillaries by thin tissue layer -> allows for diffusion of substances
What are the functions of the placenta?
- Seperate foetal blood system from mothers blood system
- Allow exchange of substances between mother and foetus
- Produces Hormones progesterone and oestrogen
Why must foetal blood and mothers blood be seperated
- Blood pressure of mother much higher -> can kill foetus
- Blood group of mother could be different -> mothers antibodies cause agglutination of foetus blood cells
What substances does the placenta transport?
- Diffusion of oxygen and nutrients from mother to foetus
- Removal of metabolic waste products from foetus blood to mothers blood
- Diffusion of antibodies from mothers blood to foetus blood -> confer foetus with immunity
Why does the placenta produce progesterone and oestrogen?
- Progesterone and oestrogen -> Prevents ovulation and menstruation AND maintains vascularised uterine lining
Reproduction by mitosis
Asexual
- By Mitosis
- Genetically identical offspring
- Allows for well adapted organisms to produce similarly well adapted offspring -> maintains survivability
Reproduction by gametes
- Union/Fusing of two haploid gametes -> form a single diploid zygote
- Offspring have genetic variation -> some have better survivability
What does the placenta foetal capillaries consist of?
- Two umblical arteries and one umblical vein circulates blood from placenta to foetus
- Umblical arteries -> transports deoxygenated blood and metabolic waste products from foetus to placenta
- Umblical vein -> transports oxygenated blood and nutrients from placenta to foetus
