Chapter 29 - Human Development and Aging Flashcards
1
Q
The study of prenatal development
A
Embryology
2
Q
Examines changes in form and function from fertilized egg through old age
A
Developmental biology
3
Q
3 primary germ layers of an embryo
A
ectoderm, mesoderm, endoderm
4
Q
an individual becomes an embryo when it is _ days old
A
16
5
Q
events leading up to the stage of an embryo
A
embryogenesis
6
Q
what stage is the first 16 days after fertilization
A
pre-embryonic stage
7
Q
fertilized egg at 16 days old
A
embryo
8
Q
the egg must be fertilized within _ - _ _ of ovulation, if it is to survive
A
12-24 hours
9
Q
how long after the sperm reaches the uterine tube does it take to fertilize the egg
A
10 hours
10
Q
where do the sperm generally meet the egg during ovulation
A
distal uterine tube
11
Q
How long are sperm viable for after ejaculation
A
6 days
12
Q
when sperm encounters an egg, it undergoes what
A
acrosomal reaction
13
Q
exocytosis of the acrosome, releasing enzymes needed to penetrate the egg
A
acrosomal reaction
14
Q
what two things do sperm need to clear out of the way for the one sperm to penetrate the egg
A
granulosa cells and zona pellucida
15
Q
what are the two acrosomal enzymes
A
hyaluronidase and acrosin
16
Q
this digests hyaluronic acid that binds granulosa cells together
A
hyaluronidase
17
Q
a protease similar to trypsin
A
acrosin
18
Q
combines the haploid set of sperm chromosomes with the haploid set of egg chromosomes producing a diploid set
*must know for test
A
fertilization
19
Q
fertilization by two or more sperm which would produce a doomed fertilized egg
A
polyspermy
20
Q
two mechanisms to prevent polyspermy
A
fast block and slow block
21
Q
binding of sperm to the egg opens na+ channels in egg membrane
A
fast block
22
Q
involves secretory vesicles, cortical granules, just below membrane
stimulates cortical reaction, in which cortical granules release secretion beneath zona pellucida
sperm penetration releases an inflow of ca+
A
slow block
23
Q
two eggs ovulated and both are fertilized by separate sperm forming two zygotes
implant separately in uterine wall and each have own placenta
no more genetically similar than any other siblings
2/3 of twins
A
dizygotic twins
24
Q
one egg is fertilized but embryoblast later divides into 2
genetically identical
A
monozygotic twins
25
this begins meiosis II before ovulation but completes it only if fertilized
secondary oocyte
26
sperm and egg swell and become _______
pronuclei
27
what is a fertilized egg called
zygote
28
pregnancy is divided into 3 month intervals called...
trimester
29
during this trimester conceptus is most vulnerable to stress, drugs and nutritional deficiencies
first trimester
30
during this trimester organs complete most of their development
fetus looks human
second trimester
31
during this trimester, fetus grows rapidly and organs achieve enough cellular differentiation to support life
third trimester
32
the first 16 days of development culminating in the existence of an embryo
pre embryonic stage
33
the 3 major processes of the pre embryonic stage
cleavage, implantation, embryogenesis
34
mitotic divisions that occur in first 3 days while conceptus migrates down uterine tube
cleavage
35
what's it called when the zygote splits in to two daughter cells
blastomeres
36
how long does it take for conceptus to arrive in uterus
72 hours after ovulation
37
a solid ball of 16 cells - resembles mulberry
occurs during cleavage process of pre embryonic stage
morula stage
38
how long does the morula lie free in the uterine cavity
4-5 days
39
when the zona pellucida disintegrates and releases conceptus - it's called...
*know for test
blastocyst
40
a hollow sphere
*know for test
blastocyst
41
outer layer of squamous cells
destined to form placenta and nourish the embryo
trophoblast
42
what is the embryoblast and what does it become
*know for test
the inner cell mass of a blastocyst
it becomes the embryo
43
*know migration of conceptus photo for test
slide 29-16
44
during implantation ______ attaches to uterine wall 6 days after ovulation
usually on the fundus or posterior wall of uterus
blastocyst
45
the process of attachment of blastocyst to uterine wall
implantation
46
trophoblasts on attachment side separate into ___ layers
2
47
what are the layers of the trophoblast called once it separates
and where are they located
superficial layer - in contact with endometrium
deep layer - close to embryoblast
48
What hormone does trophoblast secrete
human chorionic gonadotropin (HCG)
49
trophoblast develops into membrane called....
chorion
50
HCG stimulates corpus luteum and it secretes (2) hormones
estrogen and progesterone
51
arrangement of blastomeres into 3 primary germ layers in embryoblast
embryogenesis
52
what are the names of the 3 primary germ layers of an embryoblast
ectoderm, mesoderm, endoderm
53
multiplying epiblast cells migrate medially into primitive groove
gastrulation
54
gastrulation replaces the original hypoblast with layer called
endoderm
55
migrating epiblast cells form a 3rd layer btwn first two. this layer is called...
mesoderm
56
the remaining epiblast layer is called...
ectoderm
57
this is a more loosely organized tissue which differentiates into a loose fetal connective tissue, called mesenchyme
the mesoderm
58
this gives rise to muscle, bone, and blood
mesoderm
59
what is complete once the 3 primary germ layers are formed
embryogenesis
60
once embryogenesis is complete, an individual is considered a....
embryo
61
this begins when all 3 primary germ layers are present (usually day 16)
embryonic stage
62
this is the embryo's primary source of nutrition. after the first 2 weeks are complete, it forms over the next 6 weeks
the placenta
63
germ layers differentiate into organs and organ systems
organogenesis
64
organs are present at how many weeks
at 8 weeks when the embryo becomes a fetus
65
formation of organs from primary germ layers:
what derivatives from the ectoderm
epidermis, nervous system, lens and cornea, internal ear
66
formation of organs from primary germ layers:
derivatives of mesoderm
skeleton, muscle, cartilage, blood, lymphoid tissue, gonads and ducts, kidneys and ureters
67
formation of organs from primary germ layers:
derivatives of endoderm
gut and respirator epithelium and glands, bladder and urethra
68
what are the accessory organs that develop with embryo
placenta, umbilical cord and 4 embryonic membranes
69
what are the 4 embryonic membranes
amnion, yolk sac, allantois, and chorion
70
the transparent sac that develops from epiblast
amnion
71
arises from hypoblast cells opposite amnion
yolk sac
72
begins as an outpocketing of yolk sac
forms foundation for umbilical cord
becomes part of urinary bladder
allantois
73
outermost membrane enclosing all the rest of membranes and embryo
chorion
74
the shaggy outgrowths of the chorion. are around the entire surface
chorionic villi
75
know photo on 29-30
76
during gestation, the conceptus is nourished in 3 different ways. what are the 3 ways
uterine milk, trophoblastic nutrition, placental nutrition
77
this is the glycogen rich secretion of the uterine tubes and endometrial glands
uterine milk
78
conceptus consumes decidual cells of endometrium
trophoblastic nutrition
79
as conceptus burrows into endometrium, ___________ digests these cells and supplies nutrients to embryoblast
syncytiotrophoblast
80
from the corpus luteum, this stimulates decidual cells to proliferate
progesterone
81
nutrients diffuse from mother's blood through placenta into fetal blood
placental nutrition
82
disc shaped organ attached to uterine wall; attached by way of umbilical cord to fetus
placenta
83
period beginning week 9
placental phase
84
by the end of week 8 - what is the embryo like
1. all organ systems are present
2. considered a fetus
3. bones have begun to calcify
4. heart has been beating since week 4, now circulates blood
5. head is nearly half of total body length
6. skeletal muscles have spontaneous contractions
85
what is the baby called from week 9 - birth
fetus
86
6-8 hour period immediately following birth when neonate must adapt to life outside mother
transitional period
87
the first 6 weeks of life
neonatal period
88
what is considered a premature baby
infants born weighing less than 5.5lbs
89
infants born before 7 months suffer from (4)
infant respiratory distress syndrome (IRDS)
thermoregulatory
digestive issues
immature liver
90
what causes infant respiratory distress syndrome
insufficient surfactant which causes alveolar collapse with exhalation
91
what digestive issues does a premature baby have
small stomach volume, undeveloped sucking and swallowing reflexes
92
what liver problems do premature babies have
failure to synthesize adequate proteins which results in edema, and clotting deficiency
jaundice
93
abnormal structures or positions of organs at birth resulting from defect in prenatal development
birth defect or congenital anomalies
94
what is the study of birth defects
teratology
95
1. these are agents that cause anatomical deformities in the fetus
2. they fall into 3 categories - what are the 3 classes
1. teratogens
| 2. drugs and other chemicals, infectious diseases, radiation such as xrays
96
what is the drug that caused birth defects; was taken by mothers for morning sickness or insomnia
thalidomide
97
what causes more birth defects than any other drug
alcohol
98
this is characterized by small head, stunted growth, nervousness, poor attention span, cardiac and central nervous system defects
cause by alcohol
fetal alcohol syndrome
99
this contributes to fetal and infant mortality, ectopic pregnancy, cleft palate and cardiac anomalies
cigarette smoking
100
what kinds of microorganisms can cross placenta and cause serious anomalies, stillbirth, neonatal death
viral infections and bacterial infections
101
1. these appear to account for one third of all birth defects
2. there are two types - what are they
1. genetic anomalies
| 2. mutations and mutagens
102
changes in dna structure
mutations
103
environmental agents cause mutation
mutagens
104
failure of homologous chromosomes to separate in meiosis; can cause genetic disorder
nondisjunction
105
the presence of an extra chromosome or lack of one
aneuploidy
106
lack of a chromosome leaves one without a match
monosomy
107
the extra chromosome produces a triple set
trisomy
108
examination of cells in amniotic fluid
amniocentesis
109
biopsy of cells from chorion
chorionic villi sampling
110
egg receiving two X chromosomes fertilized by X carrying sperm
-infertile female with mild intellectual impairment
triplo-X syndrome (XXX)
111
egg receiving two X chromosomes fertilized by Y carrying sperm
-sterile males with average intelligence (undeveloped testes)
klinefelter syndrome (XXY)
112
egg contains no X chromosome but is fertilized by X carrying sperm
- 97% die before birth
- webbed necks, widely space nipples, sterile, short stature, sexual characteristics fail to develop at puberty
turner syndrome (XO)
113
what 3 autosomal trisomies are survivable
involve chromosomes 13, 18, 21
114
trisomy -13
patau syndrome
nearly all die before birth
infants born are severely deformed and less than 5% survive first year
115
trisomy-18
edward syndrome
nearly all die before birth
infants born are severely deformed, and less than 5% survive 1 year
116
trisomy - 21
down syndrome - most survivable trisomy
short stature, relatively flat face with flat nasal bridge, low set ears, epicanthal folds at medial corners of eye, stubby fingers
1 in 700-800 live births in US
chance of down syndrome is 1 in 3000 in woman under 30; 1 in 365 in woman over 35; 1 in 9 in woman by 48
117
all changes occurring in body with passage of time: growth, development, and degenerative changes occur later in life
aging
118
degeneration occurs in organ systems after age of peak functional efficiency
senescence
119
what is intrinsic aging of skin
photoaging - degeneration in proportion to UV exposure: skin spots, skin cancer, wrinkling
120
senescence of the skeletal system
osteopenia - loss of bone mass
osteoporosis - loss is severe enough to affect person's physical activity and health
121
senescence of joint diseases
osteoarthritis - common cause of physical disability
synovial fluid less abundant and articular cartilage thinner or absent producing friction that causes pain
122
senescence of muscular system
muscular atrophy - causes replacement of muscle with fat
123
senescence of the nervous system
involves cerebral and neuronal atrophy
nervous system reaches peak at 30 years
plaques of fibrillar proteins appear: Alzheimer disease - most common nervous disability of old age
124
senescence of the endocrine system
degenerates less than any other system
only reproductive, growth and thyroid hormones show major declines
type II diabetes more common
125
senescence of vison and hearing
vision: cataracts; loss of flexibility of lenses; glaucoma; night vision impaired
hearing: tympanic membrane and ossicle joints stiffen; death of vestibular neurons results in dizziness;
taste and smell are blunted as receptors decline
126
loss of flexibility of lenses in eye
presbyopia
127
senescence of the circulatory system
anemia - results from poor nutrition, lack of exercise, diseases, low level of intrinsic factor needed for vitamin B12 absorption and low levels of erythropoietin
coronary atherosclerosis - leads to degeneration of myocardium
varicose veins - due to weaker valves
128
senescence of immune system
lymphatic tissue and red bone marrow decline with age
lymphocytes fail to mature
both types of immune response are less efficient - less protection from cancer and infectious disease
129
senescence of the respiratory system
declining pulmonary ventilation
elderly less able to clear lungs of irritants, pathogens
- pneumonia
- respiratory infections
chronic obstructive pulmonary diseases (copd):
-emphysema and chronic bronchitis
130
senescence of urinary system
renal atrophy: 20-40% smaller by age 90 vs 30
fluid balance
voiding and bladder control
130
senescence of urinary system
renal atrophy: 20-40% smaller by age 90 vs 30
-loss of nephrons; filtration rate decreases
fluid balance
- dehydration common
- less responsive to antidiuretics, sense of thirst reduced
voiding and bladder control
-80% men over 80 have benign prostatic hyperplasia
131
senescence of digestive system
reduced saliva makes teeth more prone to cavities and makes swallowing difficult.
gastric mucus atrophies and secretes less acid and intrinsic factor***
intestinal motility decreased due to weaker muscle tone, less fiber, water and exercise
constipation
reduced food intake due to loss of appetite increases malnutrition
**know for exam
132
senescence of male reproductive system
gradual decline in testosterone secretion, sperm count and libido
fertile in old age
impotence may occur due to atherosclerosis, hypertension, medication or psychological reasons
133
senescence of female reproductive system
abrupt changes due to menopause
elevated risk of osteoporosis and atherosclerosis
vaginal dryness, genital atrophy and reduced libido
134
best ways to slow senescence
good nutrition and exercise
135
resistance exercise reduces ____ ____
bone fractures
136
decline in mitotic potential with age
- telomeres
- organ functions depends on cell renewal keeping pace with cell death, but human cells only divide a limited number of times
replicative senescence
137
ends of the chromosomes that diminish with each division
telomeres
138
what plays role in senescence
extrinsic (environmental) factors - progressively damage cells over lifetime
heredity
intrinsic process governed by inevitable or even programmed changes in cell function
139
genetic disorder showing accelerated aging
progeria
140
- dna suffers thousands of damaging events per day
- most damages are repaired, some persist and accumulate as cells age, especially in nondividing cells
- cumulative damage impairs function
DNA damage theory
141
- autoimmune diseases become more common with old age
- altered macromolecules may be recognized as foreign
- may stimulate lymphocytes to mount an immune response against bodys own tissues
autoimmune theory
142
is there a definable instant of biological death
no
- some organs function for an hour after heart stops
- brain death is lack of cerebral activity, reflexes, heartbeat and respiration for 30 min-24 hrs
143
What is letter A
Cleavage
144
what is letter B
zygote
145
What is letter C
Second polar body
146
what is letter D
morula
147
what is letter E
Blastocyst
148
what is letter F
implanted blastocyst
149
what is letter G
blastomeres
150
what is H
egg
151
what is I
sperm
152
what is J
zona pellucida
153
what is K
fertilization
154
what is L
first polar body
155
what is M
ovary
156
what is N
Maturing follicle
157
what is O
corpus luteum
158
What is P
ovulation
159
What day of implantation is this
6-7 days
160
what day of implantation is this
day 8
161
what germ layer is A
ectoderm
162
what germ layer is B
mesoderm
163
what germ layer is C
endoderm
164
What is letter A
chorionic villlus
165
what is letter B
placenta
166
what is letter C
yolk sac
167
what is letter D
umbilical cord
168
what is letter E
amniotic fluid
169
what is letter F
amnion
170
what is letter G
chorion
171
what is letter H
lumen of uterus
