Human Reproduction Flashcards
How are gametes produced ?
When cells divide by meiosis
Where is sperm produced ?
Testes
Where are eggs produced ?
Ovaries
What produces cells that are NOT genetically identical?
Meiosis
What is the tail on a sperm cell called ?
Flagellum
What is external fertilisation?
Fertilisation that occurs outside the body
What is internal fertilisation?
Fertilisation that occurs inside the body
• this fertilisation is more likely
What happens when the sperm reaches the ovum ?
Its nucleus must enter the ovum and fuse with the ovums nucleus
How many chromosomes does each human gamete have ?
Half the normal number
• 23
What is fertilisation ?
Fertilisation is the fusion of haploid male and female gametes, restoring diploid number of chromosomes in the zygote
How many chromosome does the zygote (adult cell) have ?
46
Describe human fertilisation
- during sexual intercourse, sperm passes along the sperm duct and is mixed with a fluid. This mixture is called semen
- it is ejaculated into the vagina of the female out of the urethra m. The sperm then begins to swim towards the oviducts
- fertilisation occurs between the ovum and the sperm as there nucleus fuse
- the zygote travels down the oviduct. During this time the zygotes forms into an embryo
- it implants into the lining of the uterus wall
What hormone does the placenta secrete and what does it do ?
Progesterone which prevents the embryo from aborting
When do we call the embryo a foetus ?
When it looks human
What is the membrane called that encloses the developing embryo ?
Amnion
What does the amnion secrete and what does it do ?
Amniotic fluid and it protects the developing embryo from bumps and jolts
What does the placenta do
- anchors the embryo
- allows the embryo to obtain glucose and oxygen
- gets rid of waste products such as carbon dioxide
How is the placenta attached to the embryo ?
By the umbilical cord
How do the materials move between the maternal and the fetal blood ?
Diffusion
Why do the blood supplies not mix ?
The pressure would be too great for the baby
How is the placenta adapted for efficient exchange of substances ?
- it has lots of capillaries
- short distance for diffusion
- large surface area
- lots of villi
- high concentration gradient between the mother and the fetus
What is a period ?
The losing of the lining of the uterus from the woman’s body
What is a follicle ?
A fluid filled sack that contains an egg 🍳
What is ovulation ?
When are follicle moves towards the edge of the ovary and releases the egg
What does oestrogen bring about ?
The repairing and thickening of the uterus lining
What happens to the follicle after it releases an egg ?
It forms a structure in the ovary called a corpus luteum.
Does a corpus luteum do ?
It makes a hormone called progesterone
What does progesterone do ?
Maintains the uterus lining
What takes over the corpus luteum later on in the pregnancy and secretes progesterone ?
The placenta
What is puberty ?
The time that secondary sexual characteristics occur
What controls the development of secondary sexual characteristics ?
Hormones
What is the male hormone involved in the development of secondary sexual characteristics ?
Testosterone
What is the female hormone involved in the development of secondary sexual characteristics ?
Oestrogen
Secondary sexual characteristics in boys
- Voice breaks
- sperm production begins
- shoulders broaden
- body and pubic hair develops
- genitalia growth
- possible mood swings and acne
Secondary sexual characteristics in girls
- voice deepens
- menstrual cycle begins
- pelvis broadens in preparation for pregnancy
- body and pubic hair develop
- that deposit on breasts, hips and thighs
- possible mood swings and acne
