How We Grow & Change
Neural Development What makes up nerves? Neurons! (single cells) Interesting Facts About Neurons: Average brain has approx 100 billion neurons and we only use 10% (10 billion neurons)! Neurons can fire around 100 times per second! Neural messages can travel approx. 120m/sec in myelinated neurons and 10m/sec in unmyelinated neurons (glial cells)
Neural Communication How does a neuron work? Dendrites (latin tree) Function: receives chemical messages (neurotransmitter) from other neurons Soma (body) Largest part of the neuron Filled with fluid (cytoplasm) Contains a nucleus like other cells Functions: 1) cellular maintenance and 2) allows Na+ and K+ to pass in and out of the cell in response to chemical messages (neurotransmitter)
Neural Communication How does a neuron work? Axon Function: sends electrical impulse (action potential) to the end of the neuron in response to amount of Na+ inside cell Covered in a fatty substance (myelin sheath) Functions: 1) insulates and 2) increases speed of electrical impulse Terminal Button Contains sacks/containers called vesicles Function: sends chemical messages (neurotransmitter) to the next neuron.
dendrite Neuron at it s resting potential nothing happening soma synapse axon terminal button
Pencil is being pushed rather strongly into the arm.
Receptor neuron responds by releasing neurotransmitter into the synapse.
Receptor neuron responds by releasing neurotransmitter into the synapse.
Neurotransmitter binds to the sensory neuron.
Na++ channels open up allowing Na++ inside the sensory neuron. Notice the change in internal voltage.
More neurotransmitter is released by the sending neuron, more Na++ channels open, more Na++ goes inside. Notice the voltage has hit the threshold!
When the internal voltage reaches the threshold, ALL of the Na++ channels open up (Action Potential) causing Na++ to rush inside the neuron. Notice the voltage.
As the Na++ and the internal charge reaches the neuron terminal, neurotransmitter is released into the next synapse, chemically transmitting the message to the next neuron.
As the Na++ and the internal charge reaches the neuron terminal, neurotransmitter is released into the next synapse, chemically transmitting the message to the next neuron.
Now the recovery stage begins. Na++ channels close and K+ channels open up, allowing K+ to passively, but quickly exit the neuron. Notice the change in internal voltage.
Notice that as the K+ rapidly leaves the neuron, the internal voltage drops below the resting potential. The neuron hyperpolarizes.
At this point, the Na/K pumps actively pump out the Na++ and actively pump back in the K+ in order to restore the neuron to it s resting potential. The neuron may also attempt to re- uptake some of the used neurotransmitter.
Neuron is now back to it s resting potential, ready to respond.
Central Nervous System (CNS) (Brain & Spinal Cord) Brain Brain stem (hindbrain) 1 st to develop in utero Brain stem -> Cerebrum -> Cerebral Cortex Convoluted for more surface area in a small space 2 hemispheres Connected by the Corpus Callosum ( super-highway ) Lateralization = hemispheric Specialization Left - Speech, language writing and math Right - Non-verbal cues, spatial tasks, emotions & pattern recog.
Central Nervous System (CNS) (Brain & Spinal Cord) Brain Lobes Occipital lobe vision Parietal Lobe proprioception & somatosensory Frontal Lobe movement control & higher mental functions Pre-frontal lobe inhibits inappropriate behavior Brocas Area (left frontal) speech & writing mechanics Temporal Lobe auditory / hearing Wernickes Area (left temporal) speech & reading comprehension
Motor Development Built-in i reactions to stimuli Govern newborn s movements Genetically carried survival mechanisms Allow interaction with environment Provides opportunity to learn Some disappear (e.g.: grasping), some last throughout life (e.g.: coughing)
Motor Development Sucking reflex Rooting reflex Automatic sucking object placed in newborn s mouth SURVIVAL REFLEXES Reaction when infant s cheek is stroked or side of mouth touched Moro reflex Startle tl response in reaction to sudden, intense noise or movement Grasping reflex PRIMITIVE REFLEXES Occurs when something touches infant s palms; infant response is to grasp tightly
Motor Development Milestones in Gross Motor Development Fig. 5.3
Motor Development Involves more finely tuned movements, such as finger dexterity Infancy: Reaching and grasping Size and shape of object matters Ulnar Grasp by 6 mos Pincher Grasp by 9-12mos Experience affects perceptions and vision
Motor Development Childhood Improved walking, running, jumping, climbing, learn organized sports skills Positive i and negative sport outcomes Movement smoother with age
Motor Development Guidelines for Parents and Coaches of Children in Sports The Dos The Don ts make sports fun Yell or scream at child mistakes are okay Continue condemning Allow questions, Point out errors in front show calm manner of others Respect child s Expect instant learning participation Expect child to be pro Be positive role model Make fun of child Be supportive Compare child to other Make sports all work
Motor Development Involves more finely tuned movements, such as finger dexterity Early Childhood: Pick up small objects Some difficulty building towers Age 5: hand, arm, fingers move togetherth Middle Childhood Writing and drawing skills emerge, improve Steadier at age 7; more precise movements By 10-12, 12, can do quality crafts, master difficult piece on musical instrument