Week 1 Flashcards
Body Wall
portion of the body that forms the external body surface and encloses the body cavity
Body wall layer organization
skin, muscle, connective tissue, thoracic (pleural/pericardial) cavity and abdominopelvic cavity (peritoneal cavity), limbs are extensions of the body wall
Body wall organization (cont.)
Skin (epidermis/dermis), Superficial fascia (Camper’s fascia, Scarpa’s fascia), Skeletal Muscle, Bones, Tendons, and Deep fascia (envelops bones and muscles), Celomic lining (parietal pleura/parietal peritoneum)
Body wall Muscles
Rectus+ external/internal/transversus (all concentric)
Abdomen- Rectus abdominus, Exernal abdominal oblique, internal abdominal oblique, transversus abdominis, transversalis fascia, parietal peritoneum
Thorax- external intercostal, internal, and transversus (which includes innermost intercostal)
Muscles involved in breathing
Inspiration: Pectoralis, Serratus Anterior, External intercostal, Diaphragm
Expiration: Internal Intercostal, addominals
Other abdominal muscles
Aponeuroses- where the 3 concentric layers of muscle terminate
Linea alba- where the aponeuroses fibers terminate
Rectus sheath (which are layers of aponeuroses) - encloses the rectus abdominis muscle
TBS
the wall of the abdomen and thorax is organized like a stack of similarly structured circles because each segment is derived from a single somite
Sites of Ectopic Pregnancy
Normal- upper posterior uterine wall
Ectopic sites- tubal (most common), abdominal (mesentary of the intestines), ovarian, cervical
Ex. blastocystwould escape to addominoplevic cavity, always terminate pregnancy because death due to hemorrhage is very likely
Week 2- Implantation
inner cell mass sinks into upper posterior uterine wall, extraembroynic membrane formation- amnion, chorinon, yolk sac
Extraembroynic membrane (origin and fate)
Chorion- derives from trophoblast(synctio and cytotrophoblast) and mesoderm, makes chorionic villi
Amnion- continuous with the epiblast/ectoderm
Yolk Sac- continuous with hypoblast/endoderm
Both amnion and yolk sac come from inner cell mass
How do the layers of the chorion relate to the structure of the placenta
All three layers of the chorion invade the endometrium as villi
The synctiotrophoblast is in direct contact with maternal blood, the extraembryonic mesoderm forms connective tissue core of the villi and the cytotrophoblast eventually disappears
Primordia (origin and general fate)
Primitive knot and primitive streak
Neural tube and neural crest
Cardiogenic plate
Notochord
Paraxial Columns
Intermediate column
Lateral plate
Surface ectoderm
Mesenchyme
embryonic ectoderm thickening; Intraembryonic mesoderm, notochord
notochord induces ectoderm to form plate; nervous system
mesoderm in front of the oral membrane from primitive streak; heart
Primitive knot; nucleus pulposis; induces neurulation
Intraembryonic mesoderm; segmental somites, bone, muscle and dermis
UG system
pleura, peritoneum, connective tissue of organs and body well (intraembryoic coelom)
Primitive streak
Describe how tri-laminar gastrula folds in 4th week
Gastrula folds into cylinder, forms vertebral body plan. Folds at two sites of the amnion
Describe how the endoderm is shaped into the gut tube during folding of the embryonic disc
Endoderm forms epithelial gut and airway lining, and intraembryonic mesoderm remain the same place, intraembryonic coelom (from lateral plate mesoderm) increases in size and compresses the mesodermal lining of the coelom
Lateral plate mesoderm
Somatopleure- surface ectoderm and mesoderm from lateral plate, body wall (bone, partietal pleura and peritoneum, muscle, skin)
Splanchnopleure- endoderm and mesoderm from lateral plate, gut wall (epithelium), visceral peritoneum and pleura
Mesentary- two sheets of visceral peritoneum that suspends the gut tube from the body wall and provides a rout for vessels and nerves to supply the GI organs
Dizygotic vs Monozygotic
Dizygotic- two zygotes= 2 chorions= 2 placentas= 2 amnions
Monozygotic- Inner cell mass division (totipotent) with 2 amnions but 1 of everything else
Spinal Nerves
Spinal nerves, innervate body wall, deep and cutaneous, contain both afferent and efferent
Cell bodies
Spinal- in DRG and ventral horn
Cranial- in brain
Autonomic- lateral horn
Neurulation
Neural plate folds into neural tube (all cell bodies in the CNS) and the neural crest pinches off (all ganglia outside of the spinal cord)
Neural tube defects: Rachischisis, menigocele, myelomenigocele, spina bifida occulta
Lumbar Tap
Epidural block
Needle placed in subarachnoid space below L1 to anesthetize cauda equina roots bathed in cerebrospinal fluid
Needle placed below S1 where subarachnoid space ends and superificial to dura mater, sacral spinal nerves are anesthetized
3 parts of somites
Sclerotome- vertebrae and parts of ribs
Myotome- striated musculature of the neck, trunk and extremities
Dermatome- subcutaneous tissue and skin
Epimere/Hypomere
Epimere- dorsal, innervated by dorsal ramus of spinal nerve; form the extensors and rotators
Hypomere- ventral, innervated by ventral ramus; form the body wall and limb muscles
Vertebral formation
- Sclerotome tissue surrounds neural tube and notochord by folding.
- Caudal and cranial segments of sclerotome separate
- Intersegmentation occurs as spinal nerve innervates the myotome.
- Muscles now are connected to 2 adjacent vertebra facilitating movement
Gastrulation
Primitive Streak, Knot
Intraembryonic mesoderm- 4 columns
Connecting Stalk, Oral and Cloacal membranes
Cardiogenic plate- mesoderm
When does patterning occur
Weeks 4-8
Primary Patterning- establishing the body axes
Secondary- Establishing regional or organ specific axes
Anterior-posterior axis in the embryo
Hox-B expression determining veretebral type
Dorsal-ventral axis in the CNS
Shh is secreted from notochord. Dorsal diffusion induces development of dorsal neural tube; Ventral neural tube forms motor neurons, dorsal neural tube forms sensory ganglia. Lateral diffusion affects adjacent somites. Ventral/medial somite becomes sclerotome, dorsal/lateral somite becomes dermomyotome
Anterior-posterior axis in developing limbs
Shh is secreted from zone of polarizing activity, located in proximal-posterior part of limb bud. Greatest amount of Shh on posterior side
Diseases
HOXD13
Sonic Hedgehog
Patched (receptor/repressor)
GLI3(transcription factor)
Synpolydactyly- polyalanine stretch of amino terminal region, causes the distal metacarpal bones to take on a more proximal phenotype
holoprosencephaly, abnormal septation of cerebral hemisphere
Basal cell nevus syndrome, calcifcation of cerebral hemisphere, predisposition to basal cell carcinoma
cephalopolysyndactyly or polydactyly
Features of placenta- endometrium lining
Connecting stalk- connection between embryo and placenta; shifts during gastrulation
Smooth chorion- covers the amnion
Villous Chorion- anchoring villi (connect placenta to decidua basalis)/free villi
Cytotrophoblastic shell- interface of villous chorion and decidua basalis
