Exam 1 Flashcards
Hyperplasia
Making more cells, cells are dividing
General cells
Hypertrophy
Makes cells bigger.
This can be different for different cells depending on time (muscles)
Accresion
Accumulation of stuff between cells. (Matrix)
Maturation
Process of maturing/mature state
Rate of maturation is measured over time. Genetically programmed, naturally occurring
Development
Depends on growth, maturation, etc. Increases the capacity to perform (Not all tissues grow at same rate) Cognitive, social, emotional, motor. Changes that occur over time as the result of maturation
Time frame for embryo, fetus, and infancy
Week 2-8
Week 9- birth
Birth- 2 years (walking and talking)
Scammons curve
Not all tissues in the body grow at the same rate. Lymphoid tall curve. Brain and head reach plateau . General is S curve. Reproductive lower and gets high in puberty
1st week of birth
Oocyte cells enters Fallopian tube and fertilizes with sperm. This matures into a zygote. Creates 2,4,8 cell stages and then create a morula. And then ball hallows into blastocysts. Starts to attach itself to endometrium layer of uterus. Implantation
2nd week of birth
Periods of twos
2nd week: inner cell mass change into two layers of cells. The epiblast and the hypoblast. Then end up with two cavities. The bigger cavity is the yolk sac in contact with hypoblast cells. The other cavity is amniotic cavity in contact with epiblast cells. (This becomes dorsal region). Epiblast are bigger than hypoblast cells.
Teratogens
Anything that might cause maldevelopment.
Teratogen susceptibility
Week 1-2: not susceptible to teratogens.
Week 3-8: heart and CNS develop first. Teratogens cause major congenital anomoties. Starve blood supply to developing limbs.
week 12-38: functional defects & minor congenital anomoties.
Organs that are not developing are not susceptible. As organs become more developed less sensitive to teratogens
3rd week of birth (period of threes)
Gastrulation: 3 layers, ectoderm, mesoderm, endoderm. Susceptible to teratogens. Miss your period and mom knows she’s pregnant.
Develop notochord, primitive streak, neural tube.
Prenatal development
Conception to birth. CNS and heart start to develop. Major congenital anomoties.
Week 3 period of threes.
3 layer embryo. Gastrulation of endoderm, mesoderm, ectoderm. They give rise to everything in us. They form primitive streak, notochord, and neural tube.
Primitive streak
Create mesoblast cells. That create epiblast cells. Streak sends signals to cells. When mesoblast cells destroy hypoblast cells they turn into endoderm cells. And middle cells turn into mesoderm cells. And putter surface turn into ectoderm cells
Mesoblast cells turn into
Muscle, bone,
Endoderm cells develop into what
The linings of our guts
Primitive streak signals gastrulation
Layers of cells start to fold underneath and create three layers of cells. All create neural plate that will become CNS
Ectoderm forms?
Becomes epidermis, skin
Notochord stops at oropharyngeal membrane
Leaves area for cells to get signaled by heart signals.
Notochord signals neural tube to form
Neural tube forms from ectoderm. And folds into tube and eventually punches of from ectoderm and becomes separate. Neural crest is also formed that become spinal ganglia.
Neural tube closes at what age?
Starts 4th week and fully formed in 5th week. Opened on both sides still on 4th week. End of 4th week/ start of 5th week it closes.
Somites
Mesoderm cells on the side of the notochord that clump up and form Somites. Future vertebrae
4th week of birth
Neural tube is formed. Embryo is undergoing folding on the sides to create the gut. (Picture your two arms touching like giving someone a hug) outside layer is ectoderm cells and inside endoderm. When two sides meet they pinch off yolk sac that becomes midgut. Start forming major organs, but functioning does not start. NOTOCHORD IS STILL OPEN AT ENDS
CNS derives from why tissue
Ectoderm
Skeletal muscle comes from which tissue
Mesoderm
Growth
Change in size
Head to tail folding occurs when
4th week. Head and tail start to form. Neural tube is fused but not at the ends. More Somites are also added. Teratogens might effect fusing of notochord to close. (Spinal Bifida)
Week 5
Neural tube has fused close on both ends. Upper limb bud forms first and Lowe limb bud then forms.
Fetal period
Keep developing organs and start getting these organs to function. Get baby to the size where it can survive a harsh environment, Gravity.
Heart starts beating at which week?
Week 3.
Cerebral cortex
Conscious, memory, little voice your hear inside your head, decision making.Thin layer of cells
2 major cells in CNS
Neurons-transmit dance of electrical signals between synapses (developed between inner and outer layer of neural tube.
Glial cells-nonneuronal cells, make synaptic contact with neurons.
Neuron
Has all components of a cell in cell body, dendrites (meant to receive info), has axon( flow of info), atonal terminals. Sodium channels between junction of cell body and axon that allow signal to pass through.
Myelin
Speeds up communication of action potential. Signal can jump from node to nose and speed up signal even further.
Inside of neural tube will have what?
Cerebral fluid, no neurons yet. Cells literally move with actin and myosin I between the layers of the neural tube and develop into neurons.
6 parts of brain
- Spinal cord
2 medulla 3. Pons 4. Midbrain (brainstem) - Diencephalon
- Cerebral hemisphere
What are the 7 phases of brain development?
- Cell division and specification in germinal matrix
- Cell migration along glial fibers
- Cell differentiation
- Cell axon formation
- Myelination
- Dendritic maturation
- Cell death/dissolution (apoptosis)
When do you neurons start developing in cerebral cortex?
Week 8-20 cells start dividing to create neurons in ventricular zone. Not even making neurons in cerebral cortex until week 8. No pain, consciousness before that. More primary areas start dividing first.
When do glial cells develop?
After week 8-30. Neurons need to develop first EXCEPT radial glial cells. Neurons climb up radial glial like ropes. Neurons born around ventricle climb away towards pial surface so they get to the right places. Neurons create layers of themselves.
Neurons that are born first are found where?
Neurons born first are found in the deepest layers. lazy first ones jump of radial glial in deeper layers
Inside-out rule: (migration)
Deepest layers neurons arrive first later neurons know whether they belong in layer 6 or if they need to go up to layer 5. (Cells that are born earlier, end up in the deepest layers, cells divided later end up in more superficial layers)
Neuron migration
Preplate neurons do not give rise to neurons but release a reelin. That come in from the sides.
Reelin
Acts as a guidance molecule for where glial cells should align so that when neurons climb glial cells they go to correct area. They are the reason for glial cells being lined straight up. No reelin, glial cells don’t align properly and cortical plate won’t develop correctly
Cortisol plate stage
Where cells developed different layers
Progenitor cells
Progenitor cells once they create daughter cells pulls itself up glial cells using anaerobic metabolism (uses its own motor)
When neuron gets to correct area on corticol plate what happens?
The neuron starts to change size and shape (differentiation)
Philopedia
The little feet of a axon growth cone. They contain actin and myosin and move the growth come towards molecules with energy or away from certain molecules. They do this with their chemosensors. Axon growth come is growing by adding more to the top of cone, getting longer (had lot of mitochondria)
Laminin
Axons are attracted to this, axons grow wherever laminin is
Ephrin
Chemorepellant, where ephrin is axons will not grow there even if laminin is there.
Semaphorin-1
Cehmorepellant the guides sensory axons in limb buds to find chemoattractive cells that guide them to CNS. without both the axons would search randomly for CNS. This gives them more of a direct path to CNS
Netrin
When fibroblast cells secrete netrin there is axon growth towards cells. Without netrin axon growth does not appear towards fibroblast cells. Chemoattractive
Myelin functions
Acts as electrical insulator, speeds up conduction velocity, helps support health of neurons. Myelin develops first in peripheral, spinal cord, then brain. Some parts of brain to myelinated till 20s
Schwann cells
Cells that wrap around axon. They myelinate peripheral nerves. Larger neurons tend to get myelinated while smaller neurons do not. Different cells in CNS myelinate those neurons. Neurons born earlier are matured earlier
Dendrites
Outgrowths from cell body that are made for receiving information
When do you start seeing different layers of neurons/differentiation
Week 16. Neurons that are older start to differentiate first. Motor functioning starts first because neurons in deeper layers are dedicated to these functions. Just because you can start seeing layers does not mean anything is connected yet
Brain at 16 weeks, 24 weeks, 32 weeks, 38 weeks
- Small cerebellum, smooth, no hills or valleys, no blood supply. Cells are not done dividing.
- Blood supply stars to increase
- Folding start to occur, volume increases
- Looks like adult brain but smaller
When do dendrites start forming?
Explosion of dendrites at 32 weeks.
First major motor event is when?
3 months
When do neurons start connecting?
32 weeks and on
Synaptogenesis begins when?
8 months and continues after birth. Connection of neurons is not complete before birth.
Apoptosis
Programmed cell death. Kill neurons that are weak, not used
Each muscle fiber can have how many axons?
Only one axon, but may have multiple junctions on one axon
If a limb is cut off do those motor neurons not develop since limb is gone or do they die off?
All motor neurons are there but they die off because they are not being used. Only motor neurons that are used are there. If two limbs twice as many motor neurons will appear and less will die off since more are being used. Mammals develop more motor neurons than needed and some always die off because not all are used
How do growth factor and depolarization effect survival rate?
Growth factor increase survival rate when neurons are on laminin. And depolarization increases all neurons survival rate because they are being used.
Majority of the brain grows/weight gain when?
Birth-2 years
Velocity curve of growth
First 1-2 years growth is fast than growth rate slows down and stays somewhat constant in childhood years. Accelerates again during puberty and then growth rate slows back down.
Peak height velocity
Age of peak height velocity, fastest growth rate you will experience during puberty. Happens to everyone at different ages depending on genetics. But female will go into puberty 2 years earlier than boys
What causes boys to grow more than girls?
Not because peak height velocity and in puberty for same amount of time. Boys spend 2 more years in childhood growing usually occurs in legs and torso.
Sitting height/total height ratio over lifespan
Torso and head length take a greater proportion in first couple of years. Then legs start to grow faster and that proportion shrinks (legs grow faster than trunk) girls head and trunk are little longer than boys
Bicristal breadth (hips)
Same width for girls and boys at adult hood. Women pass men for a while then the same again
Biacromial width
Boys tend to be significantly wider than women in adulthood. Girls are not having a growth spurt in their shoulders.***
Growth rates in childhood
Are slow and steady. No random changes in growth rates occur. Percentile stays pretty constant
What age is the best time to check a child’s percentile of height?
Middle of childhood because there are no random growth spurts. Constant growth rate for all kids
R and r^2
R- correlation between two variables
R^2- percent of variability in y that is accounted by x. How well you can predict y from your x value.
Autocorrelations
Plot of r values. higher r values indicate better correlations so good indicator at predicting future
Osteoblast cells
Bone forming cells, secrete osteoid matrix that becomes bone. When these cells get stuck in matrix they differentiate into osteocytes.
Osteocytes
Originate from osteoblasts cells that get stuck in osteoid matrix. They are responsible for bone maintenance and calcium homeostasis. Also have mechanoreceptors that help bone adapt to forces/pressures
Osteoclast cells
Break down bone to release calcium for other functions in the body
Compact bone is made up of?
Concentric rings
What is the outside layer of spongy bone?
Osteoblast cells
Spongy bone is important for?
Reabsorption of calcium, does not help with support against forces
Chondrocytes
Cartilage cells
Major Steps of Bone formation
- Tissue compacts to form cartilage which turn into Chondrocytes
- Chondrocytes hypertrophy and cell death creates cavity in bone
- Blood vessels enter cavity and bring osteoclasts and osteoblasts
- Cartilage turns into growth plates and same process happens in epiphysis.
Metaphysis
Developing long bone, mechanism for bone getting longer (between epiphysis and diaphysis)
How do Chondrocytes turn into bone?
Chondrocytes encounter blood vessel that carry osteoblasts and osteoclasts they then calcify into bone at growth plates. When Chondrocytes in growth plate are gone, long bone is done growing.
When does the growth plate disappear?
When growth rate factor slows down, Chondrocytes stop dividing and osteoblasts convert those cells into bone.
Where does resorption occur to make bones longer?
Breaks down bone from Metaphysis and building bone inside of epiphysis inward and up. Narrows down Metaphysis and creates longer diaphysis.
When does ossification start?
Begins in week during embryo and whole skull ossifies in one week. (Major ossification changes)
