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47 Cards in this Set
- Front
- Back
- 3rd side (hint)
When does preimplantation occur?
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Preimplantation = "fertilization"
The 1st week |
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What is a zygote?
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Zygote:
The union of "egg"+ "sperm" |
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When does the Embryonic Period occur?
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Embryonic Period:
2nd -8th week |
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When does the Fetal Period occur?
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Fetal Period:
third to ninth month * after the first trimester |
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The first trimester is composed of which two periods?
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First Trimester:
(1) Preimplantation (2) Embryonic period |
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How many chromosomes does the egg and sperm each have?
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Egg/Sperm:
haploid number = 23 chromosomes hap ="single" |
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How many chromosomes does the zygote have?
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Zygote:
diploid number = 46 di = "double" |
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Somatic Cells
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Somatic Cells:
all other cells other that have 46 chromosomes NOT egg and sperm |
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Gametes
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Gametes:
egg and sperm |
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Why must gametes only contain the haploid number of 23 chromosomes?
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IF the egg and sperm contained 46 chromosomes each the zygote would have 92 chromosomes!!!
a LOT of genetic problems can occur just having 1 extra chromosome |
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Meiosis
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Meiosis:
(1) The process by which chromosomes are separated during the formation of SEX CELLS (2) their number reduced from 46 - the haploid number (23) |
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What is the purpose of Meiosis
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PURPOSE of Meiosis:
The recombination (mixing) of chromosomes for (1) SEXUAL REPRODUCTION (2) GENETIC DIVERSITY |
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Meiosis undergoes how many cell divisions? How many daughter cells are produced?
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Meiosis:
(1) has 2 cell divisions (2) produces 4 daughter cells (each w/haploid (23) chromosomes) |
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Mitosis undergoes how many cell divisions? How many daughter cells are produced?
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Mitosis:
(1) has 1 cell division (2) produces 2 daughter cells (each with diploid (46) chromosomes |
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What is the purpose of Mitosis?
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Purpose of Mitosis:
(1) Cellular Reproduction (2) For normal growth and repair (3) want new cells--all the same |
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Where does fertilization occur?
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Fertilization occurs:
When in the fallopian tube |
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How does the Blastocyst form?
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Blastocyst Formation:
(1) AFTER fertilization (2) when the zygote undergoes MITOSIS and divides (3) contains 46 chromosomes |
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What is the zygote?
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Zygote:
(1) it's essentually an egg (ovum) (2) sperm come in--the it's destroyed |
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Where does implantation occur and when?
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Implantation occurs:
(1) in the ENDOMETRIUM-- (2) when the blastocyst travels to the uterus (3) 6th day |
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What attaches the blastocyst to the endometrium and develops into the placenta?
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Trophoblast Layer (outer)
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What develops into the embryo?
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Embryoblast Layer (inner layer)
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What occurs during the 2nd week of prenatal development as the result of continued cell divisions?
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Bilaminar Embryonic Disk Formation
After Embryoblast separates from Trophoblast layer ***Embryoblast flattens into an EMBRYONIC DISK (red section) made of 2 layers (1) Epiblast Layer "TOP"( facing the amniotic cavity) (2) Hypoblast layer "UNDER" (facing the yolk sac) |
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Embryogenesis
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Embryogenesis:
arrangement of blastomeres into three primary germ layers in the embryoblast |
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What are the (2) layers that make up the Bilaminar Embryonic Disk?
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Embryonic Disk (red section-middle)
(1) Epiblast layer (facing the amniotic cavity) (2) Hypoblast layer (facing the yolk sac) |
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Identify the epiblast and hypoblast layers. What does layers do they turn into?
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Epiblast (blue)
(1) ectoderm (2) mesoderm (3) neuroectoderm Hypoblast (yellow) (1) endoderm |
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What occurs during Trilaminar Disk Formation and when?
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Trilaminar Disk Formation: 2nd week of prenatal dev,
The cells from the epiblast layer migrate along the primitive streak and SEPARATE the epiblast layer (ectoderm) from hypoblast layer (endoderm) |
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What is the origin of the mesoderm?
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Mesoderm forms:
From the migrating EPIBLAST cells ***makes the embryonic disk TRILAMINAR |
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What is the Primitive Streak and what is it's significance?
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Primitive Streak:
thickened cell layer that forms along the midline of the epiblast SIGNIFICANCE: makes embryo BILATERALLY SYMMETRICAL (1) defines left/ right (2) dorsal / ventral sides (3 defines cephalic end / caudal end |
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What is mesenchyme?
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Mesenchyme:
are the migratory cells that locate in the middle b/w the epiblast and hypoblast layers that turns into EMBRYONIC CONNECTIVE TISSUE |
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What does mesenchyme produce?
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Mesenchyme Produces:
some cells make ***MESODERM MAKES TISSUE FORMING CELLS- (1) fibroblasts (2) chondroblasts (3) osteoblasts |
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Discuss the early formation of the "central nervous system" and when does it occur?
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CNS Formation: Spinal cord, brain
WHEN: (later part 3rd wk) (1) some cells differentiate from the ectoderm (NEUROECTODERM) (2) and localize at the NEURAL PLATE (3) Plate thickens-forms NEURAL GROOVE (4) Groove deepens-form NEURAL FOLDS (5) Folds form NEURAL TUBE (aka Spinal Cord) |
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What are the "neural crest cells" produced by
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Neural Crest Cell:
PRODUCED BY: Neural Ectoderm They migrate from crests of NEURAL FOLDS and disperse within Mesenchyme |
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How are "neural crest cells", related to the development of structures in the head and neck region?
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Neural Crest cells- FACE & NECK
(aka "4th embryonic layer") INVOLVED IN FORMATION OF: (1) Nervous System (2) Connective Tissue (3) certain DENTAL TISSUES**** |
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What are "somites"
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SOMITES:
the 38 PAIRED BLOCKS of mesoderm that form on each side of the dev. midline of CNS in embryonic disk |
DEHA Ch 3 p 35
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How are "somites" related to the development of structures in embryo?
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SOMITES:
Give rise to - (1) Axial skeleton (Skull, spine, pelvis) (2) muscles (3) dermis of skin |
DEHA Ch 3 p 35
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What happens during the fourth week of prenatal development?
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4th week of Prenatal dev.
EMBRYONIC FOLDING |
DEHA Ch 3 p 35
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What is Embryonic Folding?
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Embryonic Folding: (occurs 4th week)
(1) Trilaminar Disk forms into EMBRYO, (2) estab the human axis (3) placement of tissues in their proper positions |
DEHA Ch 3 p 35
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What is the location of the three germ layers during Embryonic Folding?
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Germ layers (Embryonic Folding)
LOCATION (1) Ectoderm = outside/top (BLUE) - Brain (2) Mesoderm = middle (PINK) - Heart (3) Endoderm = inside/bottom (YELLOW) - Gut |
DEHA Ch 3 p 35-36
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Where does Ectoderm originate from and what does it produce?
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Origin ECTODERM: Epiblast layer
FORMS (think "outer") (1) Connective Tissue ***SKIN = EPIdermis (epi= outer) ***MOUTH = muscosa (2) Nervous system (3) eyes, ears, nose (4) Neural Crest cells (5) cutaneous glands |
DEHA Ch 3, p.33 (Table 3.4)
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Where does Mesoderm originate from and what does it produce?
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Origin MESODERM: (Migrating Epiblast layer)
FORMS (think "Middle") (1) Connective Tissue ***SKIN = Dermis ***MOUTH = SUBmucosa (2) Muscle (Ex: Cardiac Muscle-Heart) (3) Bone (4) blood cells (5) Reproductive/Excretory organs |
DEHA Ch 3, p.33 (Table 3.4)
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Where does Endoderm originatefrom and what does it produce?
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Origin ENDODERM: Hypoblast layer
FORMS (Think "inner") (1) LININGS (Resp. and Digestive sys) (2) Liver and Pancreatic cells |
DEHA Ch 3, p.33 (Table 3.4)
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Describe the oral complications associated with ectodermal dysplasia.
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Ectodermal Dysplasia
the ABNORMAL dev. of 1 or more ECTODERMAL STRUCTURES (1) teeth (2) skin (3) hair (4) nails (5) eyes (6) facial structures (7) glands Ex: Anodontia (missing teeth) |
DEHA Ch 3, p.35
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What are the landmarks of the embryo present during the fourth week?
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4th week Landmarks:
(1) Developing HEART (2) Develoing BRAIN (3) Developing DIGESTIVE SYSTEM |
DEHA Ch 3, p.36
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Describe the development of the Digestive Tract and when does it occur?
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Digestive Tract Dev. (begins 4th week)
From ENDODERMAL Tube (1) Foregut = ant. PHARYNX (2) Midgut & Hindgut = post. PHARYNX |
DEHA Ch 3 p.36
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Define the fetal period of prenatal development and what important milestone occurs?
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FETAL PERIOD (9th week-birth)
it is the period of MATURATION of the existing structures as the embryo enlarges and becomes a FETUS. MILESTONE: 4th month (1) Fetal Heart beat & mvmt felt |
DEHA Ch 3 p.36
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Teratogenesis
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Teratogenesis
the production of congenital malformations in the dev. EMBRYO |
CH 3 Powerpoint
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Teratogens
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Teratogens
Environmental agents that can cause congenital malformations in the dev. embryo Ex: Rubella virus, Thalidomide, Tetracycline |
Ch 3 Powerpoint
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