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Medicine Year 1 Semester 1 > CB Quiz 3 > Flashcards

CB Quiz 3 Flashcards

1
Q

What is involved in the Pre-embryonic Period?

A
  1. Pre-embryonic Period (0-2 weeks):
    A. Cleavage, Blastocyst Formation
    B. Implantation, Placentation
    C. Gastrulation (Bilaminar => Trilaminar
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2
Q

What is involved in Embryogenesis (Mainly)

A
  1. Embryogenesis (weeks 3-8 )
    A. Three germ layers give rise to specific tissues & organs
    B. Neural tube, Notocord, and Somites
    C. Body Folding
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3
Q

What is Teratology

A

Study of Embryological Origins

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4
Q

Teratogenesis

A

Causes of Birth Defects

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5
Q

What is the origin of germ cells before Spermatogenesis and Oogenesis?

A

• Germ Cells:
◦ In yolk sac at 3 weeks of Intrauterine (Within the Uterus) life
◦ Migrate to developing Gonads (Organ that produces gametes) or Genital Ridges by 5 weeks
‣ In Female: Oogonia
‣ In Male: Spermatogonia

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6
Q

Outline the steps of spermatogenesis

A

• Spermatogenesis: In Spermatazoon: Spermatogonia -> Mitosis -> Some mature into Primary Spermatocyte -> Meiosis I -> Secondary Spermatocyte -> Meiosis II -> Spermatids -> Mature into Spermatozoa

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7
Q

Outline the process of Oogenesis

A

• Oogenesis: In Ovum: Oogonia -> Mitosis -> Some mature into Primary Oocyte —> Meiosis 1 (Arrested in prophase for up to 40 years as Primordial Follicles —> Secondary Oocyte & Polar Body —> Meiosis II (Arrested in metaphase and only completes if the cell is fertilized) —> Ovum + 3 polar bodies

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8
Q

Where do sperm and Ova typically meet and fertilize

A

Ampulla

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9
Q

What is polyspermy and how is it prevented

A

Polyspermy is the fertilization of an egg by more than one sperm.
Depolarization of the Zona Pellucida prevents polyspermy

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10
Q

What are the processes of fertilization and Implantation

A

Fertilization and Implantation:
1. Mature Ova is shed and gathered into the Fallopian tube
2. Capacitation of sperm in uterine tube
A. Removal of Glycoproteins coat from acrosome
B. Sperm and Ova typically meet and fertilize at the Ampulla
3. Acrosome Reaction: Enzyme released which allow
A. Phase 1: Penetration of Corona Radiata
B. Phase 2: Penetration of Zona Pellucida
C. Phase 3: Fusion of the oocyte and sperm cell membranes
a. Zona Pellucida depolarizes and becomes impenetrable preventing polyspermy
b. Resumption of meiosis 2 for the oocyte resumes
D. Male & Female pronuclei Merge - Zygote
E. Division begins 24-36 hours after fertilization with resulting cells getting smaller as no net-growth takes places
F. Morula is formed 3-4 days and still enclosed by Zona Pellucida
G. Cavity is formed in the cell mass - Blastocoel
H. Blastocyst emerges from the Zona Pellucida and begins to adhere to uterine wall

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11
Q

Where do Blastocysts emerge from, what do they adhere to, and what are they composed of?

A

They emerge from the Zona Pellucida, adhere to the uterine wall and are composed of a Trophoblast and Embryoblast

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12
Q

What are the types of trophoblasts

A

Syncytiotrophoblast

Cytotrophoblast

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13
Q

Describe the 2 types of Trophoblasts briefly

No need for full details just basic function

A

◦ Trophoblast: Outer cell mass with two types of cells:
‣ Syncytiotrophoblast: Externally
• Very invasive
• Eats into uterine wall
• No distinct cell boundaries
• Can’t proliferate (rapid cell division)
‣ Cytotrophoblast: Internally
◦ Cells divide by mitosis and migrate into Synctiotrophoblast

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14
Q

What are the two types of Embryoblasts

A

Hypoblast

Epiblast

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15
Q

Describe the two types of Embryoblasts briefly

A

◦ Embryoblast: Inner cell mass with two types of cells:
‣ Hypoblast:
• Cells close to blastocyst activity
• Primitive Endoderm
• Migrate around Blastocoel Cavity and eventually line it
• Fluid filled cavity which shapes the Primitive Yolk Sac
‣ Epiblast:
• Primitive Endoderm
• Fluid filled cavity which shapes the amniotic space or cavity

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16
Q

What is the purpose of the Bilaminar Disc

A

◦ Bilaminar Disc forms the embryo

17
Q

Where does normal implantation take place?

A

Anterior/posterior uterine wall

18
Q

What is an Ectopic implantation

A

Implantation in an abnormal positions

19
Q

What happens when implantation occurs

A

• If implantation occurs:
◦ Developing placenta produces Human Chorionic Gonadotrophn (HCG) which makes Corpus Luteum persist
◦ Corpus Luteum continues to produce Progesterone
◦ Progesterone sustains endometrial lining

20
Q

Explain the process of Gastrulation

A

Gastrulation: (Begins Day 15):
• Bilaminar Disc Formation including the Epiblast & Hypoblast
• Primitive Streak, Groove, and Node develop in Epiblast
◦ Indicates the main line/body axis
◦ Node is at Cranial or Cephalad end
• Epiblast migrate to streak and Invaginate
◦ Some completely displace Hypoblast - Embryonic Endoderm
◦ Some lie between Epiblast and Endoderm - Embryonic Mesoderm
◦ Cells remaining in Epiblast - Embryonic Ectoderm

21
Q

What is the Trilaminar Disc composed of and briefly state their primitive role

A

• Trilaminar Disc:
◦ Ectoderm: All epidermis and the nervous system
◦ Mesoderm: Bone, muscle, connective tissue, dermis
◦ Endoderm: Inner lining of the gastrointestinal & respiratory tracts
‣ The Ectoderm and Endoderm are only continuous at the Oropharyngeal (mouth and pharynx) and Cloacal (anal) areas

22
Q

What is the notochord and what is it’s significance

A

• Notochord:
◦ Distinguishing characteristic of vertebrates
‣ Lies underneath neural tube
‣ Becomes cartilaginous

23
Q

Define the Notochordal process

A

◦ Notochordal Process:
‣ Develops in primitive node
‣ Hollow and grows cranially (towards skull)

24
Q

Explain the overall significance of the Notochord including its formation

A

• No need for so much detail just describe the process

Notochord:
◦ Distinguishing characteristic of vertebrates
‣ Lies underneath neural tube
‣ Becomes cartilaginous
◦ Notochordal Process:
‣ Develops in primitive node
‣ Hollow and grows cranially (towards skull)
◦ Notochordal Plate: Notochordal Process then fuses with Endoderm, to form solid Notochordal plate
◦ Notochord: Notochordal Plate detaches from endoderm to form a solid rod called the Notochord

25
Q

Define Caudal

A

Tail or posterior part of body

26
Q

Explain the process of formation of the Neural tube

A

No need for so much detail, just be able to describe process
Neural Tube: (Begins day 17/18)
• Ectoderm overlying the notochord will thicken to form the Neural Plate
◦ It then begins to fold, forming neural tube
• Closure begins in the middle of the Dorsum of the embryo and then extends cranially and Caudally (tail or posterior part of body) until “Zipped up”
◦ The Zipping process begins at about day 22
• Tube closes completely at the cranial end a few days later and caudal end a few days after that
• Neurulation is then complete with the CNS being a closed tube
◦ Narrow Caudal End = Spinal Chord
◦ Broader Region at head region = Brain

27
Q

What is the cranium

A

Skull

28
Q

What are the different classifications within the mesoderm with a brief description of the Lateral Plate components

A

Mesoderm:
• Paraxial Mesoderm: Somitomeres & Somites
• Intermediate Mesoderm: Urogenital
• Lateral Plate:
◦ Somatic Mesoderm: Attached to Ectoderm and helps form body wall (Parietal). Bones, dermis, muscles, and connective tissue
◦ Splanchnic Mesoderm: Attached to Endoderm (Visceral). Gut Epithelium, Bladder, Urethra, and Lungs

29
Q

Discuss the Paraxial Mesoderm including

A

Segmentation and Somites:
• Paraxial mesoderm organizes into segments Craniocaudally (from head to tail) called Somitomeres & Somites
• Somitomeres first appear in the Cephalad Region and are associated with neuromeres
• Somites appear Craniocaudally

30
Q

Briefly describe the formation of vertebrae through induction

A

Induction:
• Neural Tube and Notochord Induce formation of vertebrae
◦ Neural tube & Sclerotome - Vertebral arch
◦ Notochord & Sclerotome - Vertebral body
◦ Notochord forms Nucleus Pulposus

31
Q

Spina Bifidia

A

Neural Tube Defects

32
Q

Describe the different ways the body of an embryo fold

A

Body Folding:
• Longitudinal Folding (Craniocaudal)
◦ Endoderm also layer becomes incorporated into the body of the embryo
◦ Connection with yolk sac narrows - Vitelline Duct
• Transverse Folding: Surface Ectoderm and Amniotic Cavity fold around laterally
• Development or incorporation of embryonic body cavity (Coelum)

33
Q

What is an aneurysm?

A

Weakness in the arterial wall causing a bulge. There are often no symptoms. A ruptured aneurysm can be fatal.

Another variation is a false lumen that could redirect the blood

Medicine Year 1 Semester 1 (23 decks)

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