Physiology and Health (Reproduction) Flashcards
(95 cards)
1
Q
Where are gametes produced from?
A
Germline cells
2
Q
What are the two types of gamete called?
A
Male gametes
Female gametes
3
Q
Where are sperm produced?
A
In the testes in the seminiferous tubules
4
Q
What produces the hormone testosterone?
A
The interstitial cells of the testes
5
Q
What do the prostate gland and the seminal vesicles do?
A
Secrete fluids that maintain the mobility and viability of the sperm.
6
Q
What do the ovaries contain?
A
Immature ova in various stages of development
7
Q
What is each ovum surrounded by?
A
A follicle that protects the developing ovum and secretes hormones .
8
Q
Where are mature ova released?
A
Into the oviduct where they may be fertilised by sperm to form a zygote.
9
Q
What do hormones do?
A
Control the onset of puberty, sperm production and the menstrual cycle
10
Q
What happens during puberty?
A
The hypothalamus secretes a releaser hormone that targets the pituitary gland, which is then stimulated to release Follicle Stimulating Hormone (FSH), Luteinising Hormone (LH) in women or Interstitial Cell Stimulating Hormone (ICSH) in men.
11
Q
What hormones control the onset of puberty?
A
Follicle Stimulating Hormone (FSH)
Luteinising Hormone (LH) (in females)
or Interstitial Cell Stimulating Hormone (ICSH) (in males)
12
Q
What hormone promotes sperm production in males?
A
Follicle Stimulating Hormone (FSH)
13
Q
What hormone stimulates testosterone production?
A
Interstitial Cell Stimulating Hormone (ICSH)
14
Q
What does testosterone stimulate?
A
Sperm production and activates the prostate gland and seminal vesicles.
15
Q
What effects do FSH and ICSH have on the pituitary gland?
A
They exert negative feedback control on the pituitary gland decreasing the level of testosterone produced by interstitial cells.
16
Q
Where are sperm produced within the testes?
A
Seminiferous tubes
17
Q
Why do seminal vesicles secrete a liquid?
A
They secrete a liquid rich in fructose which gives the sperm energy to swim. The liquid also contains compounds which cause contractions of the female reproductive tract to help sperm reach the oviduct faster.
18
Q
Why does the prostate gland secrete a liquid?
A
Secretes a lubricating liquid containing enzymes to keep the fluid at the correct viscosity to allow the sperm to swim.
19
Q
What do the secretions from the prostate and the seminal vesicles do?
A
Maintain the motility and viability of the sperm
20
Q
Describe the roles of FSH in the production of sperm.
A
Promotes sperm production i the seminiferous tubules of the testes
21
Q
Describe the roles of ICSH in the production of sperm.
A
Stimulates testosterone production which stimulates sperm production.
22
Q
Describe the two roles of testosterone in the production of sperm.
A
Stimulates sperm production and activates the prostate gland and seminal vesicles
23
Q
Describe the negative feedback control of testosterone.
A
FSH and ICSH exert negative feedback control on the pituitary gland decreasing the level of testosterone produced by the interstitial cells.
24
Q
What is the name of the gland which produces FSH and LH?
A
Pituitary gland
25
Describe two roles of FSH in the menstrual cycle.
In the follicular phase (1st half of cycle) FSH stimulates the development of a follicle and the production of oestrogen by the follicle.
26
What is meant by the term follicular phase?
First half of menstrual cycle
27
What is the endometrium?
Inner lining of the uterus
28
What does oestrogen stimulate in the menstrual cycle?
Oestrogen stimulates the proliferation of the endometrium preparing it for implantation and affects the consistency of cervical mucus making it more easily penetrated by sperm.
Peak levels of oestrogen stimulate a surge in the secretion of LH which triggers ovulation.
29
Describe the two roles of LH in control of the menstrual cycle?
Triggers ovulation and then stimulates the development of the corpus luteum from the follicle.
30
What is meant by the term luteal phase?
Second stage of the menstrual cycle in which a corpus luteum is present which secretes progesterone
31
Name the hormone which the corpus luteum secretes and describe its role.
Progesterone- promotes the vascularization of the endometrium finally preparing it for implantation of blastocyst if fertilisation occurs..
32
What is the name given to the ball of cells which implants in the endometrium?
Zygote blastocyst
33
Describe the follicular phase.
1. Pituitary gland releases FSH
2. FSH stimulates follicle development and maturation and production of oestrogen
3. Oestrogen stimulates proliferation of the endometrium and production of LH
4. This surge in LH causes ovulation
5. Ova moves along the oviduct and fertilisation takes place if sperm are present.
34
Describe the luteal phase
1. LH stimulates follicle to form corpus luteum
2. Corpus luteum secretes progesterone
3. Progesterone promotes further development of the endometrium and inhibits pituitary gland
4. FSH and LH levels drop
5. Lack of LH causes the corpus luteum to break down
6. Progesterone levels decrease
7. By day 28 in the cycle progesterone is so low the endometrium cannot be maintained and menstruation begins.
35
What can we say about the fertility of males?
They are continuously fertile because of constant levels of pituitary hormones
36
What can we say about the fertility of females?
Cyclical- usually restricted to 1-2 days following ovulation
37
When are females most likely to conceive?
In a fertile period (approx. 6 days around the time of ovulation)
38
How can the time of ovulation be estimated?
By the number of days after menstruation, a slight rise in body temperature on the day of ovulation and the thinning of cervical mucus.
39
What causes female infertility?
Failing to ovulate
40
What drugs can female infertility be treated with and what can these drugs lead to?
Drugs that mimic FSH and LH or drugs that prevent the negative feedback of oestrogen on FSH secretion.
Can cause super ovulation that can result in multiple births or be used to collect ova for IVF programmes.
41
What can be done if a male is infertile?
Artificial insemination - collecting several samples of semen over a period of time, used if the male has a low sperm count.
Sperm donor if male is sterile
42
What happened in IVF programmes?
When ova are surgically removed from the ovaries after stimulation by hormones. Ova are then mixed with sperm in a culture dish outside the females body. The fertilised eggs are incubated until they have formed at least 8 cells and then are transferred to the uterus for implantation.
43
What is ICSI?
Can be used during IVF if mature sperm are defective or very low in number. The head of the sperm is drawn into a needle and injected directly into the egg to achieve fertilisation.
44
What is PGS?
Preimplantation Genetic Screening- used to check embryos for single gene disorders and chromosomal abnormalities (non specific)
45
What is PGD?
Preimplantation genetic diagnosis- used to check for known chromosomal or gene defects (specific)
46
What are the arguments for PGS and PGD?
1. Offers reassurance to couples who are at a high risk of having a child with a genetic disease , some of which would remain childless without PGS and PGD
2. Reduced frequency of genetic disorders/diseases is of great benefit to society.
47
What are the arguments against PGS and PGD?
1. Some people claim it is morally wrong to interfere with contraception.
2. Some argue these procedures are the start of eugenics selective breeding in humans and lead to 'designer babies '
48
What are the two methods of contraception?
Physical Barriers
| Chemical
49
What are some of the physical contraceptive barriers and what do they do?
Use a device to physically block the ability of sperm to reach the ova
Includes ; condom, diaphragm, cervical cap, IUD and sterilisation
Also avoiding fertile periods
50
What are some of the chemical contraceptive barriers and what do they do?
Based on combinations of synthetic hormones that mimic negative feedback which prevents the release of FSH / LH
Some prevent implantation (morning after pills)
Some cause cervical mucus to thicken (progesterone only pill)
51
What does antenatal screening do?
Identifies the risk of a disorder so that further tests and a prenatal diagnosis can be offered.
52
What are some of the antenatal screening methods?
Ultrasound imaging
Biochemical tests
Diagnostic testing
Rhesus antibody testing
53
At what stage in the pregnancy is the dating ultrasound scan performed?
8-14 weeks
54
What two pieces of information can be obtained from an ultrasound scan?
Stage of pregnancy
| Due date
55
During an ultrasound what other type of test is performed?
A biochemical test
56
At what stage of the pregnancy is the anomaly ultrasound scan performed and why is it performed?
18-20 weeks and performed to check for the presence of physical abnormalities, e.g a cleft lip
57
What are biochemical tests used to detect?
The normal physiological changes of pregnancy. Blood pressure and type and general health checks (routine blood and urine tests) are performed regularly throughout pregnancy.
Key markers, e.g. HCG (human chorionic gonadotropin)
AFP (Alpha fetal protein)
58
Why is it important that biochemical tests are carried out at specific times throughout the pregnancy?
HCG levels will decrease with time in a normal pregnancy but remain high in a Down's syndrome baby
59
What is meant by the term 'false positive result'?
Where someone is told their child has Down's syndrome when it does not.
60
What is meant by the term 'false negative result'?
When someone is told their child does not have Down's syndrome but they do.
61
What is a karyotype?
A visual display of someone's chromosome complement.
62
When is an amniocentesis performed?
14-16 weeks
63
Describe the amniocentesis procedure.
1. Needle inserted into amniotic sac
2. Fluid removed
3. Liquid centrifuged
4. Fetal cells cultured then tested
64
When is an CVS performed?
8-10 weeks
65
What can an amniocentesis and CVS be used to detect?
```
A range of genetic disorders including;
Down's syndrome
Edwards syndrome
Turners syndrome
Kleinfelters syndrome
```
66
What are the advantages and the disadvantages of an amniocentesis?
Advantage- it is an accurate test for disorders
Disadvantage- takes longer than CVS to obtain results
Have to wait longer in the pregnancy
Risk of a miscarriage
67
What are the advantages and disadvantages of Chorionic Villus Sampling?
Advantages- can test sooner than an amniocentesis
Results are given faster
Disadvantages- higher risk of miscarriage
Potential to harm the baby's fingers or toes
68
What does rhesus positive blood mean?
RhD positive - the antigen is present
69
What does rhesus negative blood mean?
RhD negative - the antigen is not present
70
What is meant by the term 'sensitising event'?
When the material blood comes into contact with the fetus
71
How can a Rh+ mother being pregnant with a Rh+ fetus cause problems for subsequent pregnancies?
1. A Rh+ father and Rh- mother have a baby
2. During pregnancy or at birth some Rh+ blood cells cross into the mothers blood
3. After the baby is born the mothers immune system starts to produce anti-rhesus antibodies
4. The mother becomes pregnant with a Rh+ baby
5. Some anti-rhesus antibodies cross the placenta causing the baby's blood to clot ( haemolytic disease)
72
What is haemolytic disease and how can it be prevented?
Some anti-rhesus antibodies cross the placenta causing the baby's blood to clot, which is known as haemolytic disease.
Can be prevented by ensuring
73
What is postnatal screening?
Diagnostic testing used to detect metabolic disorders after the baby is born.
74
Give an example of a metabolic disorder.
Phenylketonuria (PKU)
75
What effect does PKU have on the body?
The body can't produce phenylalanine and if undetected soon after the baby's birth, the baby's mental development is affected.
76
How can PKU be managed?
Individuals can be placed on a restricted diet.
77
What is autosomal inheritance?
Genes carried by normal cells
78
What does recessive mean?
A gene whose effect doesn't show if there is a dominant allele too. A recessive characteristic only shows if there are two recessive genes, traditionally represented by small letters.
79
What does dominant mean?
A gene whose affect always shows (normally represented by capital letters)
80
What is an example of autosomal recessive inheritance?
Cystic fibrosis
81
What can be said about cystic fibrosis?
All sufferers of the trait are homozygous recessive
| Non sufferers are homozygous dominant or heterozygous
82
What does homozygous mean?
Both genes for a particular characteristic are the same
83
What does heterozygous mean?
The two alleles are different, one dominant, one recessive
84
What can be said about autosomal dominant inheritance?
It appears in every generation
85
Give an example of autosomal dominant inheritance.
Huntington's chorea
86
What is incomplete dominance?
Where the recessive gene still has an effect and there is an intermediate phenotype
87
Give an example of autosomal incomplete dominance.
Sickle cell anaemia
88
What can be said about sickle cell anemia?
A heterozygous person will have a milder form of the condition.
89
Give an example of a sex linked recessive trait?
Haemophilia
90
What can be said about sex linked genetic problems?
They are slightly different because only the X chromosomes carry an effective gene.
91
How many X chromosomes do females have?
Two
92
How many X chromosomes do males have?
One X and a much shorter Y chromosome which has fewer genes.
93
What can be said about sex linked conditions in terms of chromosomes?
If one female X chromosomes has a recessive gene it is likely that the other X chromosomes will have a dominant gene to prevent the recessive condition having an effect, but if a male has a recessive gene on their only X chromosome there is no allele on the shorter Y chromosome and so the condition will show in their phenotype.
Males receive s Y chromosome from dad and an X from mum, so as any recessive genes are on the X chromosome sons will always inherit the sex linked condition from their mother .
94
What is a carrier in terms of sex linked recessive traits?
A female who is normal for a given characteristic yet is heterozygous.
95
What happens if a normal male and normal but carrier female have a number of children?
They might expect half their daughters to be normal and half to be carriers and half their sons to be normal and half to be affected.
