Nervous System

Question 1

nervous system cells + parts

Answer 1

NEURONS – three (and a half) parts (:) dendrite, cell body, axon, axon terminals

Question 2

gap is called…

Answer 2

synapse

Question 3

What “closes” the gap?

Answer 3

neurotransmitters

Question 4

resting potential

Answer 4

Sodium-potassium pumps in neuron membranes use ATP (Na+/K+ ATPase) to actively pump sodium OUT and potassium IN
Potassium leak channels allow some potassium to flow out of the cell, BUT…
Resting potential is at -70 mV (millivolts)

Question 5

depolarize definition

Answer 5

make less negitive

Question 6

action potential

Answer 6

NOTE: Membrane has potassium leak channels, Na+/K+ ATPase, and sodium and potassium voltage-gated channels.
(1) Chemical signals depolarize the dendrites, changing values from -70 mV to -50 mV.
(2) -50 mV is the threshold potential for the sodium voltage-gated channels. So they open!
(3) Sodium ions rush in, further depolarizing to +35 mV.
(4) Sodium voltage-gated channels close and potassium voltage-gated channels open.
(5) Potassium ions rush out, repolarizing to -90 mV.
(6) Potassium voltage-gated channels close.
(7) Resting potential (-70 mV) is restored.
This is a CHAIN REACTION traveling down the neuron. The closing of sodium voltage-gated channels prevent the reaction from going backward.

Question 7

What makes action potential more efficient?

Answer 7

MYELIN SHEATH: helps to speed up movement of action potentials along the axon; made of Schwann cells; gaps in between Schwann cells are called the nodes of Ranvier.
**The action potential JUMPS from node to node (SALTATORY CONDUCTION) = efficient. **

Question 8

How to increase intensity of signals?

Answer 8

Fire action potentials faster or slower!

Question 9

Action Potentials: Crossing the Gap (THE LEAP OF FAITH!!!!!!)

Answer 9

When action potentials reach the synapse, they cause release of vesicles, which have neurotransmitters in them.

Question 10

TWO types of neurotransmitters

Answer 10

excitatory: cause action potential to continue by causing + ions to enter next neuron
inhibitory: cause - ions to enter next neuron, preventing action potential

Question 11

What’s that actual gap?

Answer 11

synaptic cleft

Question 12

cnidaria nervous system

Answer 12

simple collections of nerves

Question 13

annelids & mollusks nervous system

Answer 13

clusters of neurons called ganglia (sometimes form primitive brain)

Question 14

arthropods nervous system

Answer 14

ganglia + sensory organs

Question 15

vertebrates nervous system (two parts)

Answer 15

central (CNS) and peripheral (PNS) nervous systems

Question 16

three types of neurons

Answer 16

sensory (afferent) – info to CNS
interneurons – connect sensory & motor
motor (efferent) – info away from CNS

Question 17

CNS

Answer 17

brain: made of interneurons
– cerebrum: largest, voluntary movement, conciousness, memory, speech
– cerebellum: balance & coordination
– brainstem: involuntary functions (specific part known as medulla oblongata)
– hypothalamus: homeostasis, emotion
spinal cord: made of all three neurons, simple reflexes
– glial cells: provide support for neurons

Question 18

PNS

Answer 18

sensory: info from senses to CNS
motor: CNS to organs & muscles

Question 19

motor nervous system (part of PNS)

Answer 19

somatic: voluntary movement, skeletal muscles, always excites using acetylcholine (neurotransmitter)
autonomic: involuntary movement, tissues other than skeletal muscles, can excite or inhibit

Question 20

autonomic nervous system (part of motor –> part of PNS)

Answer 20

sympathetic: prepares for emergency situations (fight or flight!!!!!), stimulates release of epinephrine and norepinephrine into bloodstream (reinforcing effects)
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parasympathetic: rest & digest, also uses acetylcholine

Question 21

eyes (structure)

Answer 21

from outside to inside: cornea –> pupil (size controlled by iris) –> lens –> retina
Rods & cones in retina sense differences in light, firing action potentials to optic nerve to the occipital lobe of brain.

Question 22

ears (and balance!!)

Answer 22

eardrum (tympanic membrane) –> auditory ossicles (ear bones) –> cochlea
Cochlea hairs change vibrations to action potentials. This is sent to the auditory nerve to the brain.
Three semicircular canals detect the position of the head, sending action potentials when position (balance) changes.

Question 23

taste & smell

Answer 23

taste: taste bud chemoreceptors create action potentials; sent through facial and glossopharyngeal nerves
smell: Molecules pass along olfactory epithelium, dissolve in its mucus, bind to receptors, activate action potentials

Question 24

somatic senses

Answer 24

basically feelings of touch felt in skin, muscles, tendons, joints