4.1 - Sexual Reproduction in Humans Flashcards
Define acrosome
An organelle in the tip of a sperm containing hydrolase enzymes which digest the zona pellucida of a secondary oocyte.
What is the amniotic fluid?
The liquid surrounding the embryo in the amniotic sac that protects the foetus and acts as a shock absorber.
What is the blastocyst?
A ball of cells that arises from the repeated mitotic divisions (cleavage) of a zygote
Explain what the cervix is
A neck of tissue that connects the uterus and the vagina and protects the fetus
What is the chorionic villi?
Finger-like projections that arise from part of the placenta known as the chorion and provide a large surface area for the exchange of products between maternal and fetal blood
What is the corona radiata?
An outer layer of follicular cells that protect the secondary oocyte in the oviduct
Define what the corpus luteum is
A mass of cells that forms from the Graafian follicle after ovulation. It serves as a temporary endocrine structure during pregnancy, secreting progesterone.
What are the cortical granules?
secretory organelles found in oocytes that, upon entry of a sperm, fuse with the plasma membrane and harden the zona pellucida to prevent polyspermy.
Explain what the endometrium is
The inner lining of the uterus, which, during the menstrual cycle, thickens in preparation for embryo implantation
What is the epididimis?
A coiled tube in the male reproductive system that links a testicle to a vas deferens and stores sperm prior to ejaculation
Define the female reproductive system
An organ system that includes the ovaries, oviducts, uterus, endometrium, cervix and vagina
What is fertilisation?
The fusion of the nuclei of a male and female gamete to form a zygote
What is the Follicle-stimulating hormone (FSH)?
A hormone secreted by the anterior pituitary gland that binds to follicle cells, stimulating them to mature and secrete oestrogen
What is gametogenesis?
A sequence of nuclear and cellular divisions that result in the production of gametes
Define the germinal epithelium
A surface layer of cells surrounding the ovaries in females and testicles in males that is involved in gametogenesis
What is the Graafian follicle?
A mature fluid-filled follicle in the ovary within which an egg cell develops
Explain what the Human Choronic Gonadotropin (HCG) hormone is?
A hormone secreted by the developing embryo that maintains the corpus luteum during early pregnancy
Define implantation
The early stage of pregnancy in which the blastocyst adheres and sinks into the endometrium
What are intervillous spaces?
Spaces between the chorionic villi that contain maternal blood
What are leydig cells?
Cells located adjacent to the seminiferous tubules in the testes that secrete testosterone. Also known as interstitial cells of Leydig.
Define the Luteinising Hormone (LH)
A hormone secreted by the anterior pituitary gland that initiates ovulation and stimulates the development of the Graafian follicle into a corpus luteum
Explain what the male reproductive system is
An organ system in males which includes the scrotum, testes, epididymis, vas deferens, seminal vesicles and prostate gland
What is the menstrual cycle?
The monthly cycle in women that involves the development of the endometrium, ovulation and the shedding of the endometrium
What is oestrogen?
A female sex hormone secreted by the mature follicle that inhibits the production of FSH and causes a surge in LH production. During pregnancy, it stimulates uterine growth and the development of the mammary glands
What is oogenisis?
Gametogenisis in females that takes place in the ovaries and results in the production of secondary oocytes
What is oogonia?
Immature female reproductive cells that have formed from primordial germ cells and mature to give primary oocytes
What are the oviducts?
The tubes that transport egg cells from the ovaries to the uterus. They are the site of fertilisation and are commonly known as Fallopian tubes
What is ovulation?
The release of an ovum from a mature ovarian follicle into the oviduct
Define what the ovum is
The female haploid gamete produced by gametogenisis
What is oxytocin?
A hormone secreted by the posterior pituitary gland that triggers the contraction of the uterus wall. It is controlled by a positive feedback mechanism
Define what the penis is
The male sex organ that penetrates the vagina and releases sperm
What is the placenta?
A temporary organ attached to the lining of the uterus during pregnancy. It has a variety of roles including the exchange of gases and nutrients, serving as a barrier between fetal and maternal blood and hormonal control
Explain what a polar body is
A haploid cell produced during meiosis in females that does not have the ability to be fertilised
What is the primary follicle?
An immature ovarian follicle surrounded by two layers of follicular cells
Explain what the primary oocyte is
A diploid oocyte that has undergone growth but has not completed its first meiotic division
What is a primary spermatocyte?
A diploid spermatocyte that has undergone growth but has not completed its first meiotic division
What is progesterone?
A female sex hormone secreted by the corpus luteum that causes the development of the endometrium and inhibits the production of FSH and LH. During pregnancy, it suppresses contractions of the uterine wall
What is prolactin?
A hormone secreted by the anterior pituitary gland that stimulates lactation during and after birth
Explain what the prostate gland is
A gland found between the bladder and the penis that secretes an alkaline fluid to neutralise vaginal acidity
Define what the scrotum is
A pouch of skin that holds and maintains an optimum temperature for the testes
What is the secondary follicle?
A larger follicle that has developed from a primary follicle
Explain what the secondary oocytes are
Haploid cells that have completed meiosis I
What are secondary spermatocytes?
Haploid cells that have completed meiosis I and give rise to spermatids
What are seminal vesicles?
A pair of glands in the male reproductive system that secrete a protein and fructose-rich to nourish sperm
Define what sertoli cells are
Cells located within the seminiferous tubules in the testes that provide nourishment and protection to cells produced during spermatogenisis
Define what sexual intercourse is
The entry of the male reproductive organ and the deposition of sperm into the female reproductive tract
What is a spermatid?
A haploid cell that results from the completion of the second meiotic division in spermatogenesis
What is spermatogenesis?
Gametogenesis in males that takes place in the seminiferous tubules and results in the production of spermatocytes
What are spermatogonia?
Immature male reproductive cells that have formed from primordial germ cells and mature to give primary spermatocytes
What are spermatozoa?
The male haploid gamete produced by spermatogenesis
Define what testes are
A pair of organs in the male reproductive system that produce sperm and testosterone
Explain what an umbilical artery is
A paired artery that carries deoxygenated blood from the fetus to the placenta
What is an umbilical vein?
A vein that takes oxygenated blood from the placenta to the fetus
What is the urethra?
A tube responsible for the transfer of urine during urination (in both males and females) and semen during ejaculation (in males)
Define what the uterus is
The organ in the female reproductive system in which the embryo develops
What is the vagina?
The canal that extends from the cervix to the outside of the body. During sexual intercourse, it stimulates the penis to ejaculate.
What is the vas deferens?
A tube in the male reproductive system that transfers sperm from the epididymis during ejaculation
What is the zona pellucida?
A glycoprotein layer surrounding the plasma membrane of a secondary oocyte that provides protection and prevents polyspermy
What is a zygote?
A diploid cell formed by the fusion of a haploid oocyte and spermatozoa during fertilisation
