Reproduction and Growth : Human Reproduction Flashcards
1
Q
what is the male gamete in humans?
A
- sperm
2
Q
what adaptations do sperm have?
A
- tail-like flagellum which moves them through the water
3
Q
what is the female gamete in humans?
A
- egg cell
4
Q
what are egg cells?
A
- female gamete
- produced monthly in female humans from the ovaries
- women are born with all of their eggs
5
Q
what is sperm?
A
- the male gamete
- males start producing sperm in puberty and will always continue to do so
6
Q
what is external fertilisation?
A
- in fish, the females release their ova into the water and the sperm have to swim through the water to fertilise the ova
- this kind of fertilisation happens outside the body and is therefore called external fertilisation
7
Q
what is internal fertilisation?
A
- other male animals, including birds and mammals, ejaculate their sperm in a special fluid (semen) into the bodies of females during sexual intercourse
- internal fertilisation then takes place inside the female’s body
- fertilisation is much more likely
- once the sperm has reached the ovum, its nucleus must enter the ovum and fuse with the ovum nucleus
8
Q
how many chromosomes does a normal human body cell have?
A
- with the exception of gametes and red blood cells, a normal human body cell will have 46 chromosomes
- these consist of 23 pairs of homologous chromosomes (contain the same genes)
9
Q
explain why a normal human body cell has 46 chromosomes.
A
- the body cell contains a set of chromosomes (23) which originated from the organisms father (sperm cell), and a set of chromosomes (23) that originated from the mother (egg cell/ovum)
- the cell therefore has two sets of chromosomes (maternal and paternal) and is known as a diploid cell
10
Q
how many chromosomes do gametes have?
A
- in humans, sperm and ova each only have 23 chromosomes, half the genetic information required for a human: cells with half the genetic information are known as haploid cells
- when the haploid sperm and haploid egg fuse, we say that fertilisation has occurred to form a diploid cell
11
Q
what is fertilisation?
A
- the fusion of haploid male and female gametes, restoring the diploid number of chromosomes in the zygote
12
Q
what is the first cell that is formed at fertilisation?
A
- it is known as the zygote
- as each gamete has only half the normal number of chromosomes, the zygote formed by fertilisation will have the full number of chromosomes
13
Q
label the female human reproductive system.
A
one note page
14
Q
define ovary.
A
- where egg cells are formed by meiosis (in the follicle).
- produces the hormones oestrogen and progesterone
15
Q
define oviduct (fallopian tubes).
A
- egg cells travel down this to the uterus
- lined with cilia which move the cell
- site of fertilisation
16
Q
define uterus.
A
- a lining forms in the uterus, where the embryo will implant
- the foetus develops in the uterus, which has a thick muscular wall
- this contracts during labour
17
Q
define cervix.
A
- narrow opening to the uterus
- this dilates (widens) during labour, to allow the baby to be born
18
Q
define vagina.
A
- muscular tube which leads from the cervix to the outside of the woman’s body
- a man’s penis goes into the woman’s vagina during sexual intercourse and the baby passes through the vagina when it is born
19
Q
label the male reproductive system.
A
one note page
20
Q
define testes.
A
- where sperm cells are formed by meiosis
- produces the hormone testosterone
21
Q
define sperm duct.
A
- maturing sperm are transported along this tube
22
Q
define seminal vesicles and prostate gland.
A
- release liquids into the sperm duct, which mixes with the sperm cells to form semen. the liquid provides nutrients to the sperm.
23
Q
define penis.
A
- transports urine and semen out of the body. contains tissue which fills with blood to become erect ; this helps to pass the semen out of the body and into the female’s vagina during sexual intercourse.
24
Q
define urethra.
A
- tube inside the penis which can transport either urine or semen.
25
describe the sperm's journey.
- during sexual intercourse, sperm pass along the sperm duct and are mixed with a fluid from the seminal vesicles
- this mixture, called semen, is ejaculated into the vagina of the female out of the urethra. The sperm then begin to swim towards the oviducts.
- one ovum is released into an oviduct each month from an ovary
- if an ovum is present, then it may be fertilised by sperm introduced during intercourse
26
what does random fertilisation produce?
- genetic variation of offspring
- each male ejaculate will contain millions of sperm cells
- each of these sperm cells is genetically different due to the process that has created them
- each female egg cell will also be genetically different due to how it was created
- which sperm cell fertilises the eggs is random
- this 'randomness' causes variation in the genetics of the new offspring
27
what does the placenta do?
- secretes the hormone progesterone to ensure the uterus lining remains thick, and prevents the embryo from aborting
28
what is the amnion and what does it do?
- during pregnancy, a membrane called the amnion encloses the developing embryo
- the amnion secretes a fluid called amniotic fluid, which protects the developing embryo against jolts and bumps (mechanical jolts), drying out, and temperature fluctuations (due to waters high specific heat capacity)
29
what do we call the embryo when it looks human?
- as the embryo develops, it becomes more and more complex
- when it looks human, we call it a foetus
30
what happens to the foetus at the end of nine months development?
- there isn't any room left for the foetus to grow and it sends a hormonal 'signal' to the mother to initiate birth - this is called 'going into labour'
- once the foetus is born, we refer to it as a baby
31
what develops from the embryo?
- a placenta, connected by an umbilical chord
- the placenta anchors the embryo in the uterus
32
what does the placenta allow?
- nutrients (i.e glucose, amino acids and salts) and oxygen to move from the mother to the embryo
- metabolic wates - carbon dioxide and urea - to move from the embryo to the mother
33
how do the materials pass through the placenta?
- by diffusion
34
there is no physical connection between the circulatory systems of the embryo and the mother, so their blood doesn't mix. why is this the case?
- the mothers blood is much higher pressure than the fetal blood
- the mother's blood has white blood cells and other chemicals that would see the fetal as foreign, and attack it!
35
what controls the changes which happen to both boys and girls which lead to sexual maturity?
- hormones
- time when they happen = puberty
36
what is the main hormone involved in puberty in males?
- testosterone
37
what is the main hormone involved in puberty in females ?
- oestrogen
38
what do testosterone and oestrogen cause?
- the development of secondary sexual characteristics
39
what are secondary sexual characteristics in boys?
- voice breaks
- sperm production begins
- shoulders broaden
- facial, armpit, body and pubic hair growth
- greater muscle development
- growth and development of genitalia
- possible mood swings and acne
40
what are secondary sexual characteristics in girls?
- voice deepens, but doesn't break
- menstrual cycle begins
- pelvis broadens in preparation for pregnancy and labour
- armpit and pubic hair growth
- muscle development and fat deposits on breasts, hips and thighs
- growth and development of genitalia
- possible mood swings and acne
41
what does the menstrual cycle begin with?
the breakdown and loss of the uterine lining
42
describe the menstrual cycle.
- at the same time as the breakdown and loss of the uterine lining, the pituitary gland has begun to produce increasing amounts of the hormone FSH.
- This tells the ovary to form a mature egg cell - a follicle develops with the maturing egg inside it. The follicle produces the hormone oestrogen.
- The lining of the uterus has been repaired after menstruation and has thickened – this repair and thickening of the uterus lining has been brought about by the hormone oestrogen.
- As oestrogen levels rise, the stop FSH production and trigger LH production in the pituitary
gland. LH stimulates ovulation - the release of the mature egg from the ovary.
- After the egg has been released, it travels down the oviduct (Fallopian tube) to the uterus. It is in the oviduct that fertilisation may happen, if sexual intercourse has taken place. What is left of the follicle in the ovary now forms a structure in the ovary called the corpus luteum. The corpus luteum makes another hormone called progesterone. Later on in
pregnancy, the placenta secretes progesterone, taking over the role of the corpus luteum.
43
what is the first sign which tells a woman she is pregnant?
- when her monthly periods stop
44
what are days 1-5 of the menstrual cycle?
- uterine lining breaks down, menstruation occurs
45
what are days 6-10 of the menstrual cycle?
- uterine lining thickens again
46
what are days 11-18 of the menstrual cycle?
- ovulation occurs- usually on day 14
47
what are days 19-28 of the menstrual cycle?
- uterine lining continues to thicken
48
what is the function of the menstrual cycle?
- to control the development of the lining of the uterus, so that if the ovum is fertilised, the lining will be thick and ready to receive the fertilised egg
- if the egg isn't fertilised, the lining of the uterus is lost from the woman's body as the flow of menstrual blood called a period
49
which four hormones control the timings of the events in the menstrual cycle?
- FSH
- oestrogen
- LH
- progesterone
50
name the gland the hormone 'FSH' is secreted from, the target organ/tissue and the effect of it.
- pituitary gland
- follicle in ovary
- follicle develops and ovum matures (not released yet)
- maturing follicle releases oestrogen
51
name the gland the hormone 'oestrogen' is secreted from, the target organ/tissue and the effect of it.
- ovary (follicle in the ovary)
- pituitary gland
- inhibits FSH production (stops another ovum being matured
- stimulates LH production
- thickens uterus lining
52
name the gland the hormone 'LH' is secreted from, the target organ/tissue and the effect of it.
- pituitary gland
- follicle in ovary
- ovulation - the follicle on ovary releases mature ovum into fallopian tubes
- remnant of follicle (on ovary) becomes corpus luteum
53
name the gland the hormone 'progesterone' is secreted from, the target organ/tissue and the effect of it.
- ovary (corpus luteum)
- pituitary gland
- FSH and LH inhibited (stops further ovum being matured and released)
- thickness of uterine lining maintained
