Neurons & Neurotransmitters

Question 1

BRAIN quiz

1. how many lbs?
2. how many neurons?
3. synaptic connections avg neuron makes w others
4. percent of body’s oxygen & glucose used by brain?
   5.

Answer 1

1. 3 lbs
2. 86 billion
3. 1000 – ranges up to 200,000 in Purkinje cells
4. 20%

Question 2

level of organization of nervous system

Answer 2

• cell: individual neurons
• tissues: nerves, ganglia
• organ: brain, spinal cord
• system: nervous system

Question 3

overview

basic neuron structure

Answer 3

• cell body: cell’s life support center
• dendrites: recieve messages from other cells
• axon: passes messages away from cell body to other neurons, muscles, or glands
• neural impulse: electrical signal traveling down axon
• myelin sheath: covers axon of some neurons & helps speed neural impulses
• terminal branches of axons: form junctions with other cells

Question 4

soma

Answer 4

cell body of neuron; contains nucleus

Question 5

dendrite

Answer 5

branched, treelike extensions attached to soma of neuron; recieves info from neurotransmitters released from terminal button of other neurons

Question 6

axon

Answer 6

extension of neuron, ending in branching terminal fibers, through which messages are sent to other neurons, muscles, or glands

Question 7

terminal button

Answer 7

bud at end of branch of an axon; form synapses with other neurons; sends info to those neurons via neurotransmitters

Question 8

neurotransmitter

Answer 8

chemical released by terminal button; has excitatory or inhibitory effect on other neurons

Question 9

myelin sheath

+ research study

Answer 9

• layer of fatty cells segmentally encasing fibers of many neurons
• composed of glial cells, the support cells of the CNS
• enables vastly greater transmission speed of neural impulses because neural signal jumps from one node of Ranvier (naked portion of axon) to the next
• decreases amt of energy needed for neural conduction
• insulate neurons, preventing messages from spreading b/w adjacent neurons

AMA pediatrics study suggests (after controlling for age, gender, income), 3-5 year old children with higher use of screen based media:
- had lower measures of structural integrity and myelination
- scored lower on cognitive tests

Question 10

communication within a neuron: electrical transmission

2 electrical potentials: resting potential

Answer 10

• resting membrane potenrial (-70mV): occurs

Question 11

2 electrical potentials: action potential