Ch. 29: Development and Inheritence Flashcards
Both the …. from parents (heredity) and … in the uterus (environment) play important roles in determining the … of a developing embryo and fetus and the …. of a healthy child.
Genetic material
Normal development
Homeostasis
Subsequent Birth
What are the steps from fertilization to birth? (8)
What is capacitation?
a 10 h process
-the change sperm undergo in the female reproductive tract that enables them to penetrate and fertilize an egg.
Only capacitated sperm are capable of …
Responding to chemical factors produced by the surrounding cells of the ovulated oocyte
Compare the structures and molecules of the 3 stages of sperm
Epididymal: plasma membrane contains complement of surface molecules (proteins and carbs)
Ejaculated: surface molecules become coated with seminal plasma proteins that mask the portions of the membrane molecules
Capacitated: when sperm are exposed to the female tract envrionment, these seminal plasma coating with some of surface molecules are removed, which exposes portions of molecules that can bind to zona pellicula of oocyte
What sperm receptor binds to the sperm head and what are the effects?
ZP3 glycoprotein
It triggers acrosomal reaction ->lead to enzyme release
What happens when sperm enters a secondary oocyte?
Oocyte completes meiosis
What forms the fertilized ovum?
Male pronucleus and female pronucleus fuse
Fusion of sperm cell with plasma membrane of 2nd oocyte results in what?
Syngamy, a process that blocks polyspermy – fertilization by more than one sperm
In a fast block to polyspermy the oocyte cell membrane…
depolarizes so another sperm cannot fuse
How many sperm are allowed to penetrate the oocyte in blocks to polyspermy?
only 1 sperm
What are the 2 mechanisms that ensure monospermy
Fast block to polyspermy: electrical barrier, preventing fusion of sperm and egg
*On contact of 1st sperm, Na diffuses into the oocyte from extracellular space
* Membrane depolarization prevents additional sperm from fusing with the oocyte membrane
Slow block to polyspermy: mechanical block to polyspermy, i.e. the fertilization membrane hardens and is impervious to further sperm.
*On sperm entry, Ca released by oocyte endoplasmic reticulum as part of preparation for cell division
* Cortical reaction: granules in plasma membrane rupture contents into extracellular space
* These zonal inhibiting proteins (ZIPs) destroy sperm receptors
Sperm already bound to receptors are forced to detach
What are the 3 characteristics of the IVF procedure regarding sperm swimming to the egg
- In the IVF procedure, sperm and eggs “interact” in a dish leading to insemination.
- They literally swim up to the egg and burrow toward the nucleus.
- The first one to get there wins, and all others are blocked out.
What are male fertilits issues in IVF procedure? What other procedure might they choose?
Male fertility issue: Sometimes sperm cannot latch onto and penetrate the egg.
They may choose to have Intra(within)-Cytoplasmic Sperm Injection (ICSI)
What are the 6 basic steps in IVF?
Ovary stimulation
Egg retrieval
Sperm retrieval-wash sperm
Fertilization
Embryo transfer
Progesterone
What is IVF and why is it done?
- IVF is a treatment for infertility or genetic problems. During IVF , mature eggs are collected (retrieved) from ovaries and fertilized by sperm in a lab. Then the fertilized egg (embryo) or eggs (embryos) are transferred to a uterus
- Sometimes, IVF is offered as a primary treatment for infertility in women over age 40. IVF can also be done for certain health conditions
What are 4 main health conditions that cause people to get IVF?
-
Fallopian tube damage or blockage:
This problem makes it difficult for an egg to be fertilized or for an embryo to travel to the uterus.
Ovulation disorders:
If ovulation is infrequent or absent, fewer eggs are available for fertilization which reduces the chances of pregnancy.
Endometriosis:
It occurs when the uterine tissue implants and grows outside of the uterus – often affecting the function of the ovaries, uterus and fallopian tubes.
Uterine Fibroids:
Fibroids are benign tumours in the wall of the uterus and are common in women in their 30s and 40s. These can interfere with implantation of the fertilized egg.
What is a stem cell and what does it have the ability to do?
A stem cell is a cell that is unspecialized (nonspecific in its functions) and has the ability to divide for indefinite periods and give rise to specialized (functionally specific) cells.
What are the 5 principle types of stem cells and what are each of them based on?
They are based on their ability to differentiate
1. Totipotent
2. Pluripotent
3. Multipotent
4. Oligopotent
5. Unipotent
What are totipotent stem cells? What are some examples?
Ccells that have the potential to form all of the nearly 220 different types of cells found in the human body.
Examples: a zygote (fertilized ovum) and cells (blastomeres) produced from the first several divisions of a zygote (blastocyst).
What are pluripotent stem cells? What do they have the potential to from and what can’t they develop into? What are some examples?
- Tissue-specific stem cells, are cells of an embryo past five days of development and are derived from totipotent stem cells.
- They have the potential to form many (but not all) cells of the body. They cannot develop into extraembryonic structures such as the placenta, chorion, umbilical vesicle, and umbilical cord.
- Examples: primary germ layers (endoderm, mesoderm, and ectoderm) and cells derived from them which go on to form the various tissues and organs of the body.
What are multipotent stem cells? What are some examples?
Cells that can differentiate into a group of closely related cells.
Examples: mesenchymal cells that can form almost all types of connective tissue and hemopoietic cells that can develop into myeloid stem cells and lymphoid stem cells.
What are oligopotent stem cells? What are some examples?
- Stem cells that develop into only a few cell types.
- Examples: myeloid stem cells and lymphoid stem cells that differentiate into the different types of blood cells.
What are unipotent stem cells? What are some examples?
- Stem cells produce only one cell type.
- Examples epidermal stem cells, which develop into epidermal cells only, and spermatogonia, which develop into sperm only.
What is cell potency? What gives a cell greater potency?
Cell potency is a cell’s ability to differentiate into other cell types.
The more cell types a cell can differentiate into, the greater its potency.
What do adult stem cells include?
- Hematopoietic stem cells
- Mesenchymal stem cells
- Neural stem cells
- Epithelial stem cells
- Skin stem cells
Describe what hematopoietic stem cells give rise to
Gives rise to all of the types of blood
Describe what mesenchymal stem cells give rise to
Gives rise to osteocytes, chondrocytes, adipocytes, and other connective tissue
Describe what neural stem cells give rise to
Gives rise to neurons, astrocytes, and oligodendrocytes
Describe what epithelial stem cells give rise to
Gives rise to cells lining the digestive tract (absorptive cells, goblet cells, paneth cells, enteroendocrine cells)
Describe where skin stem cells occur in and give rise to
Occur in the basal layer of the epidermis and at the base of the hair follicles
Give rise to new epidermal layers of skin.
What additional stem cells are included in adult stem cells besides the main 5 and what do they give rise to?
Cord blood stem cells in the umbilical cord of a baby which give rise to platelets, red and white blood cells, and mesenchymal cells.
What is umbilical cord blood? Describe what types of blood cells it has and what is it used for
Technically, umbilical cord blood is
– White and red blood cells, platelets and plasma rich in blood forming stem cells
– Used much like bone marrow to regenerate a weakened or sick immune system
What are some diseases treated with cord blood? (4 categories)
-
Malignancies: leukemia, lymphoma
* Blood Disorders: Sickle cell anemia, Thalassemia Aplastic anemia, and Fanconi anemia
* Immunodeficiencies: Severe combined immunodeficiency syndrome (SCID)
* Future: Regenerative medicine
The oocyte is viable for ..hours
* Sperm is viable ..hours after ejaculation
12 - 24 h
24 to 48 h after ejaculation
For fertilization to occur, coitus (sex) must occur no more than …h before or … h after ovulation
48 hours before
24 hours after
Human reproduction is an inefficient process ~..% of conception do not …
a further ~…% die and abort after implantation
50%, implant, 30%
What are some commonly known birth defects? (5)
Congenital heart defects
Cleft Lip and Cleft Palate
Spina Bifida
Club Foot
Down Syndrome
What is congenital heart defect?
Congenital heart defects are problems with the structure of the heart and can change the way the heart pumps blood. They may make blood flow too slowly, go the wrong way, or block it completely
What is a cleft lip and cleft palate?
A cleft lip happens if the tissue that makes up the lip does not join completely before birth. This results in an opening/slit in the upper lip.
A cleft palate happens if the tissue that makes up the roof of the mouth does not join together completely during pregnancy.
What is spina bifida?
Describe the condition and cause
A condition that affects the spine and is usually apparent at birth
Happens along the spine if the neural tube does not close all the way. When the neural tube doesn’t close all the way, the backbone that protects the spinal cord doesn’t form and close as it should. This often results in damage to the spinal cord and nerves.
What is club foot?
Clubfoot is a deformity in which an infant’s foot is turned inward, often so severely that the bottom of the foot faces sideways or even upward.
What is down syndrome?
Decribe the condition, how chromsomes come into play
Down syndrome is a condition in which a person has an extra chromosome. Chromosomes are small “packages” of genes in the body. They determine how a baby’s body forms and functions as it grows during pregnancy and after birth.
Typically, a baby is born with 46 chromosomes. Babies with Down syndrome have an extra copy of one of these chromosomes, chromosome 21.
When is implantation completed by?
By the 14th day after ovulation
Blastocyst attaches to what and what is the result?
blastocyst attaches to the endometrium oriented in a way where the developing inner cell mass is directed toward the endometrium
what is the activity of embryology from day 6-9
Blastocyst
Implantation
Trophoblast Development
Formation of Amniotic Cavity
Trophoblast develops how many distinct layers? Describe these layers’ role
Develops 2 distinct layers
1.Syncytiotrophoblast: secretes enzymes [digest endometrial cells]
2.Cytotrophoblast: defines the original shape of the embryo
What does the trophoblast secrete?
Trophoblast secretes human chorionic gonadotropin (hCG) helps the corpus luteum maintain the uterine lining
What are the 3 blood supplies for the fetus?
Describe where it carries blood to and what does the blood contain
Umbilical arteries
* Carry blood from the developing fetus to the placenta
* Blood is deoxygenated and full of waste products
Chorionic villi
* Provide surface area for exchange of gases, nutrients, and wastes between fetal and maternal bloodstreams
Umbilical vein
* Carries blood from the placenta to the fetus
* Blood contains nutrients and oxygen
What process begins around the third week of embryo formation? Why is this early development needed?
Angiogenesis, the formation of blood vessels, begins in the extraembryonic mesoblast in the umbilical vesicle, connecting stalk, and chorion.
This early development is necessary because there is insufficient yolk in the umbilical vesicle and ovum to provide adequate nutrition for the rapidly developing embryo.
What is the 3 functions of the placenta?
- The placenta is an organ that develops in the uterus during pregnancy.
- This structure provides oxygen and nutrients to a growing baby.
- It also removes waste products from the baby’s blood.
- It takes over the job of hormone secretion (hCG, estrogen, progesterone, as the corpus luteum in the ovary gradually atrophies (deteriorate)
Actual connection between the placenta and embryo, and later the fetus, is through the ..
umbilical cord
What is placenta previa? What can placenta previa lead to and why is it dangerous? What is the most important symptoms and preferred delivery method?
The entire placenta or part of it may become implanted in the inferior portion of the uterus, near or covering the internal os of the cervix.
* May lead to spontaneous abortion
* Dangerous to the fetus becaue it may cause premature birth and intrauterine hypoxia due to maternal bleeding
* The most important symptom is sudden, painless, bright-red vaginal bleeding in the 3rd trimester.
* Cesarean section is the preferred method of delivery in placenta previa.
What are teratogens?
Substances that cause defects or abnormalities in fetal development
What are some drugs and environmental pollutants that are factors of teratogens? What are some maternal diseases?
Drugs: alcohol, birth control pills, caffeine, heroin
Environmental pollutants: lead, mercury
Maternal diseases: AIDS, Chicken pox, chlamydia, genital herpes, mumps
Describe condition, and consequences both appearance and physiologcal
What is fetal alcohol syndrome?
An unborn child exposed to alcohol
* Neurological consequences: attention deficits, language difficulties, learning disabilities
* Appearances: microcephaly, small eyelid opening, short upturned nose, thin upper lip
What happens to cells due to presence of alcohol in fetus’s bloodstream?
The presence of alcohol in the fetus’s bloodstream triggers widespread cell death in the fetal brain.
What are some strains on the maternal systems during pregnancy?
Physiological and physically
- Mother has to absorb enough oxygen, nutrients, and vitamins for herself and the fetus
- Weight gain of (25-35 lb)
- Changes balance because the additional weight is not evenly distributed
- Requires more energy to maintain balance
- Increasing size of the uterus and fetus pushes maternal abdominal organs out of normal position
What are some physiological changes in pregnancy? (4)
- Maternal respiratory rate and tidal volume increase
- Maternal requirements for nutrients increase by up to 30% above normal
- Mammary glands are fully developed by the end of the 6th month
- Since volume of urine produces increases and weight of uterus presses on urinary bladder, there is frequent urination
What is premature labor?
- Occurs when true labor begins before normal fetal development is completed
- Survival changes are directly related to body weight at birth
1. <400g(14oz) will not survive since respiratory, cardiovascular, urinary systems are unable to support life
2. <600g(22.1oz) not likely to survive
What is premature delivery?
- Birth at 28-36 weeks (birth weight over 1kg or 2.2lb)
- With care, newborn has a good change of surviving and developing normally
Labor is divided into how many stages?
- Dilation stage
- Expulsion stage
- Placental stage
What occurs during the dilation stage?
Mention how long stage lasts
- When the cervix starts to soften and to open, fetus shifts toward cervical canal, moved by gravity and uterine contractions (having one’s water break)
- First stage is complete when the cervix has opened to around 10 centimetres.
- Lasts 8 or more hours
What occurs during the expulsion stage?
Mention how long the stage lasts
- The period of time from when the cervix is fully dilated to when the baby is born.
- Lasts less than 2 hours
What occurs during the placental stage?
- Begins after your baby is born and finishes when the placenta and membranes have been delivered.
- Uterine contractions continue
- Size of uterus gradually decreases
- Continued contractions compress uterine blood vessels to restrict blood loss
Menopause is a normal, natural event, defined as the..
Final menstrual period (FMP), confirmed after 1 year of no menstrual bleeding
What is the difference between menopause, perimenopause, and premenopause?
- Menopause: average age is 51, 12 consecutive months with no menstruation
- Perimenopause: commonly occurs in the 40s, may experience irregular periods, weight gain, mood swings and more
- Premenopause: no noticeable changes, but hormones start to shift
What are some hormonal fluctuations during menopause?
- Decrease in circulating estrogens
- Decrease in ratio of estrogen to androgen
- Decrease in sex hormone-binding globulin secretion
- No significant change in testosterone levels
What are some results of ovarian dysfunction? Describe the process
- Degeneration of granulosa and thica cells
- Failure to react to endogenous gonadotrophine
- Decreased levels of estrogen
- Increased levels of FSH and LH
Describe the milk production by the end of the 6th month of pregnancy and a few days into nursing
- By the end of 6th month of pregnancy, mammary glands are fully developed and secreting colostrum
- Colostrum is the first form of breastmilk and contains antibodies to help fight infection until the newborn’s immune system develops
- A few days into nursing, mamary glands produce breast milk which is mucher higher in fat content than colostrum, also contains antibodies and lysozome (antibiotic enzyme)
What is milk ejection reflex (milk let-down reflex)? Describe the 5 steps
1.Stimulation of tactile receptors (by infant suckling)
2.Neural impulse transmission (to the spinal cord and brain)
3.Oxytocin secretion
-By secretory neurons in the paraventricular nucleus of the maternal hypothalamus
4.Oxytocin release
-By the posterior lobe of the pituitary gland
-Oxytocin is distributed throughout the body by the bloodstream
5.Milk ejected
- Oxytocin causes contraction of myoepithelial cells in the walls of the lactiferous ducts and sinuses
What are the 3 steps in gene expression?
Genetic information is stored in sequence of base pairs.
Genetic information is expressed using sequence of triplet codons in mRNA as intermediate.
Effect of gene on phenotype is mediated via specific sequence of amino acids (aa) in polypeptide gene product.
What are the 3 types of diseases?
Genetically determined
Environmentally determined
Genetics and environment determined
Up to ..% of pediatric in-patients have genetic abnormality
* about ..% of spontaneous abortuses have chromosomal aberration
* only mutations that are not lethal are..
20%
50%
Reservoir of genetic diseases
What X chromosomes are affected for the following: Alzheimer’s, Down syndrome, Sickle cell anemia, Duchenne’s and Alzheimer’s, Margan’s syndrome
Alzheimer’s: Chromsome 14
Down syndrome: Chromosome 21
Sickle cell anemia: Chromosome 11
Duchenne’s and Alzheimer’s: Chromosome 19
Margan’s syndrome: Chromosome 15
What predictive testing?
Tells a person if she/he carries a mutation that will cause, or put her/him at a higher risk for disease later in life
What is newborn screening?
Detects common disorders in newborns, where immediate treatment can prevent dangerous symptoms
What is carrier testing?
Tells a person whether or not s/he carries a mutation that could be passed on to his offspring. One can be a carrier, but not be at risk for a disease (as in recessive genes)
What are the 4 types of genetic testing and what they analyze?
- Analysis of whole chromosomes – for large changes; extra chromosome, very large deletions or insertions
- Analysis of sequence – for small changes; mutations in the sequence, small deletions or insertions
- Analysis of protein shape – for any change that may affect the folding of the protein
- Analysis of protein function – if the functional protein is supposed to make something, then some tests can detect the presence or absence of the product
What does amniocentesis do?
Describe it and when it is done
samples amniotic fluid to examine a baby’s chromosomes, can be invasive procedure (15-22 weeks)
Sloughed-off fetal cells within the fluid
can be sampled for…
* Up to .. abnormalities can be identified
chromosome defects
350
What is umbilical cord blood sampling?
Takes fetal blood directly from the umbilical cord and is a quick check. Doctors use it to check for disorders in the fetus. Usually done if other tests are inconclusive
What is chorionic villi sampling? What are some limitations
Mention the timing of when the procedure is done
A prenatal test that involves taking a sample of tissue from the placenta to test for chromosomal abnormalities and certain other genetic problems. (10-13 weeks)
* Is an invasive procedure, can be risk for miscarriage
