Finals Prep- Notes Flashcards
Primitive Streak
Midline thickening beginning at one end of the pellucida. Begins at the rear of the embryo. Caused by cells of the area pellucida migrating and converging on a midline. Extends about 3/4 of the way up the area pellucida, but never all the way. The rate of the cells leaving the primitive streak becomes greater than those forming causing the streak to recede in anterior to posterior direction.
In birds, it doesn’t completely recede, some remains and forms the tail.
Primitive knot
Slightly rounded enlargement at cranial end of the primitive streak.
Primitive Groove
Depression in the primitive streak and knot. Cells “dive” through. First cells form the endoderm, joining the hypoblast. Mesoderm is the second. The ones that do not drop through forms the ectoderm.
Immigration
Type of cell movement that causes the primitive streak/groove/knot and the following germ layers.
Organogenesis
As soon as germ layers form, organs immediately begin to form, even if gastrulation isn’t 100% complete.
Neural Plate
Ectodermal
a cell mass falls out of the ectoderm and moves into the interior of the embryo, above the mesodermal layer. Folds into a cylinder
Neural tube
Cylindrical neural plate. Nervous system beginning. Ectoderm seals the gap.
Neurulation
Process of closing the neural plate into the neural tube
Notochord
Mesodermal. Forms in the center of three mesodermal masses.
Will be completely eliminated by the end of development. Early sensory rod for the fetus, but is gradually replaced by bone.
Mesodermal segments
Two remaining mesodermal derivatives. On either side of the notochord.
In humans, they are called “somites”
Break into three populations of cells (each segment):
- Dermatome, migrates and layers under epidermis to form dermis
- Sclerotome: Forms the skeleton
- Myotome: Muscle (all three types: cardiac, skeletal, and smooth).
Cerebral Hemispheres
Telencephalon. Ectoderm
Consists of both white and grey matter. White is core, surrounded by grey. Most sophisticated functions come from the grey matter. Grey matter is often called the “cerebral cortex”.
Cerebellum
Ectodermal
Sits inferior and posterior to the brain. Balances and regulates skeletal muscle movement.
Diencephalon
Ectodermal
Consists of:
- Epithalamus: cerebrospinal fluid produced here.
- Thalamus: the largest portion of diencephalon. It’s the relay center that addresses each impulse and sensory input. Sorting center.
- Hypothalamus: Major hormone producer, human emotions, massively important to diencephalon.
- Penal Gland: less than 1% of the human brain, hormone production (melatonin).
- Pituitary: “Master gland”.
Olfactory Lobes
Ectoderm
Sense of smell, directly under the frontal part of the hemisphere
Optic Vesicles
Ectoderm
Eyes
PNS
Ectoderm
Peripheral Nervous System:
The nerves that enter and exit the brain and spinal cord. 12 pairs of cranial nerves and 31 pairs of spinal nerves.
Lens
Ectodermal
Focusing crystal in eyes
Cornea
Ectodermal
Right in front, the tissue the covers the eyes. Involved in focusing.
Organs that develop from Mesoderm
Dermis, muscle, skeleton, blood vessels, ureters (drain urine from kidneys to bladder), bladder, urethra, gonads.
All blood vessel components are mesodermal derivatives:
- Arteries
- Arterials
- Capillaries
- Venules
- Veins
Endodermal Derivatives
GI Tract (mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus)
Pancreas, gallbladder, liver, kidneys, ducts that drain liver, gallbladder, and pancreas, eustachian tubes, thyroid, parathyproid, thymus
Liver
Makes bile (digestive fluid but not a digestive enzyme)
Ducts drain the bile from liver and into the right and left hepatic ducts (endodermal organs)
Continuously drips bile
Bile Ducts
Common hepatic duct
Cystic Duct: drains the gallbladder, connects to the hepatic duct.
Common Bile Duct: passes under the duodenum and emerges on the other side.
Gallbladder
Bile made from liver is stored in gallbladder
Pancreas
Most digestive enzymes produced.
Ducts that exit the pancreas: Pancreatic Duct of Wirsung. In 20% of people, there’s another duct. Common bile duct unites with pancreatic duct and connects to duodenum (forms the Hepatopancreatic Duct).
Sphincter of Oddi
Mesodermal
Most of the time, the sphincter is closed. Only open for about 1 hour every 24.
Prospective potency
All possible fates of the cell. Highest early in gastrulation, narrows to the prospective significance
Prospective significance
Actual fate of the cell.
Neural Tube dilates into pouches
Forms various portions of the brain. “Three Brain Vesicle Stage”
Prosencephalon
First of the three brain vesicle stage. Most cranial dilation is the forebrain.
Mesencephalon
Middle of the three brain stage. Midbrain.
Rhombencephalon
Last of the three brain vesicles. Hindbrain.
Five Brain vesicle stage
Forebrain splits into two:
- Telencephalon: cerebral hemispheres
- Diencephalon
Midbrain does not subdivide:
- First inch of the brainstem is the mesencephalon
- Larger the telencephalon gets, the less important the midbrain becomes.
- Reflexive part of the brain.
Hindbrain subdivides into two:
- Metencephalon: region below mesencephalon, cerebellum and pons.
- Cerebellum pinches off from the brain stem and forms a bud behind the brain stem.
- Myelencephalon: lowest part of the brain. Medulla oblongata: autonomic nervous system.
Foramen Magnum
hole through which the spinal cord exits.
Heart atria
Collecting blood
Ventricles
Pump blood. Both ventricles contract at exact same time.
Right sends blood to the lungs to get oxygen. Left pushes blood through the body.
Pulmonary Trunk
Right ventricle connection. Transports blood to lungs, splits into two to go to both lungs.
Gathers oxygen and turns through four pulmonary veins to the left atrium.
Aorta
Connected to left ventricle. Pumps blood throughout the body. Cells extract oxygen and deposit CO2. Blood carries CO2 back to the right atrium.
Venae Cavae
Superior Vena Cava:
-Empties blood from the body into the right atrium. Drains head and neck blood back to the heart.
Inferior Vena Cavae
-Empties into the right atrium. Draining from below the heart (rest of the body).
Coronary Sinus
Drains the heart’s right atrium.
Fetal heart
Cannot operate like an adult heart because lungs are collapsed.
Umbilical arteries
Two of them
Fetal blood vessels that pass through the umbilical cord. Several branches off branches off branches from the aorta.
Transports waste blood to the placenta, picks up oxygen, minerals, etc. from the placenta and deposits wastes.
Becomes umbilical ligaments immediately after birth. Vasoconstrict immediately when the fetus begins to breathe.
Umbilical Vein
One
Returns the blood back to the fetus. Empties into the inferior vena cava, which transports the blood to the right atrium. The good blood is mixed with used blood.
Lymphatic vessel
One
In umbilical cord. Returns leaked plasma back to the circulatory system. The plasma would build up and otherwise destroy the environment.
Ductus Venorus
Detours the blood around the fetal liver and back to the inferior vena cava and into the right atrium.
Foramen Ovale
Defect in the wall of the heart that allows 1/3 of the blood into the left atrium from the right atrium.
Ductus Arterious
Fetal structure that connects the pulmonary trunk to the aorta, allowing the other 2/3 to go back to the left part of the body.
Weight gain during pregnancy
8 lbs for the baby. 2 lbs for placenta 2.5 lbs for amniotic fluid 3 lbs of uterine weight 3 lbs of breast milk at term 3.5 lbs of blood volume 3.5 lbs of normal water retention.
Total: about 25 lbs of normal weight gain.
9-12 Weeks
First day of 9th week begins the fetal period.
Head is large compared to body, head growth slows from this point on. CR length (crown-rump length) is mostly head.
Face is broad, eyes are wide and abnormally separated. Ears are way low on the head (by the throat). Eyes are closed because they are fused shut.
Limbs short. Bones have JUST started to grow. Genitals ambiguous.
12 weeks, sex can be determined, but not by ultrasound.
13-16 Weeks
Fetus is still smaller than a pack of cigarettes. Limbs grow dramatically. Eyes point forward, distance between eyes decrease. Face starts looking more normal. Ears move towards their normal position.
17-20 Weeks
Quickings (first detection of fetal movement).
Can estimate delivery time based on quickening.
20 weeks can determine sex via ultrasound.
Vernix Cuseosa/Vernix: white goo that covers fetus.
Lanugo: downy hair that covers fetus that anchors vernix.
Dramatic reproductive tract development in both sexes: Uterus begins to form, testicles begin to head to scrotum.
21-25 Weeks
Surfactant produced.
Around 24 weeks, baby might be able to survive on its own without ventilator. Will have life-long problems if born at this stage.
26-29 Weeks
capable of living outside uterus if born. 90% chance of survival. Eyes are open. Fingernails and toenails developed.
29 is a landmark age.
30-34 Weeks
AT LEAST 32 weeks if going to have a premature delivery. No complications and no life long issues.
35-38 Weeks
Finishing period prior to birth. Plump fetus. Approaching birth weight.
CR length of 360mm
Testes are in scrotum in a male at this time.
39-40 Weeks
Birth
Post Maturity Syndrome
Birth is delayed. Skin becomes parched, babies continue to gain weight. Skin gets raw and red.
Baby must be delivered via c-section when they get to a week to ten days past their due date.
Labor may be induced or C-section.
Surfactant
Substance produced for the lungs. Reduces surface tension so the lungs don’t collapse after the first breath.
