7 - Sexual Reproduction in Humans (C2) Flashcards
Doesn't include spermatogenesis and oogenesis (53 cards)
What does the seminal vesicle do in the male reproductive system?
During ejaculation it adds alkaline mucus, containing fructose and amino acids, to nourish the sperm
What does the vas deferens do in the male reproductive system?
Transports sperm to the urethra via a peristaltic wave during ejaculation
What does the prostate gland do?
- Produces a zinc containing alkaline secretion which neutralises any urine left in the urethra and acidic vaginal secretions
- Aids in sperm mobility
What does the urethra do in the male reproductive system?
Transfers urine and semen out of the penis
What does the epididymis do in the male reproductive system?
It’s where sperm are collected and mature
What does the seminiferous tubule do in the male reproductive system?
It’s the site of sperm production
What does the testicle do in the male reproductive system?
Produces male gametes (spermatozoa)
What is the scrotum and what is its function?
- It’s an external sac that holds the testes outside of the body
- This provides an optimum temperature for sperm production of 35 degrees
What is the penis and what is its function?
- An organ containing blood filled erectile tissue
- Passes semen into the vagina
What is the ovary and what is its function?
- Female sex organ (gonad)
- Starts gamete production and releases secondary oocytes
- Secretes oestrogen and progesterone
What is the role of the uterus wall?
- Retains the foetus
- Contracts during birth (controlled by oxytocin - positive feedback)
What is the cervix and what does it do?
- A muscular ring at the neck of the uterus
- Closes the entrance to the uterus
- Dilates during birth from resting diameter of 2mm
What is the function of the fallopian tube/oviduct?
- Ciliated epidermis wafts the oocyte/embryo to the uterus
- Site of fertilisation
What is the endometrium and what does it do?
- Mucus rich membrane
- Rich in blood capillaries
- Shed monthly
- Provides nutrients to implanted embryos
What is the vagina?
- Muscular tube
- Site of sperm deposition
What are the 5 major roles of the placenta?
- Production of oestrogen and progesterone
- Exchange of O2/CO2, nutrients/waste
- Barrier to high blood pressure, blood borne pathogens and toxins in maternal blood
- Allows maternal antibodies to protect the foetus
- Prevents antibodies attacking the foetus
What are problems the placenta can cause?
- The immune system may attack the placenta or foetus due to Rhesus incompatibility
- Small viruses or toxins are transferred across the placenta e.g. rubella, alcohol
What is the function of leydig cells?
Secrete testosterone
What is the amnion?
Fluid filled sac which eventually surrounds and protects the embryo from mechanical damage
What does amniotic fluid contain?
- Foetal skin cells
- Can be sampled to check for chromosome abnormalities
What is the acrosome reaction?
- Triggered when sperm bind to a protein
- Acrosome membranes rupture and hydrolytic enzymes are released
- Acrosin enzyme digests the zona pellucida
What happens as the sperm enters the egg?
- Proteins in sperms cell membrane bind to the oocyte membrane and they fuse
- Sperm nucleus enters
- Entry of the head of the sperm causes the egg to complete meiosis and the 2 haploid nuclei fuse to form a zygote
What is the cortical reaction?
- Calcium ions enter the egg and vesicles of cortical granules move to and fuse with the oocyte membrane
- Zona pellucida lifts and hardens, forming a fertilisation membrane
- Binding proteins change shape
How is polyspermy prevented?
Membrane polarity changes, due to cortical reaction
