Nervous System Organization

Question 1

what is the big picture of the nervous system?

Answer 1

enable organisms to sense and react to the environment.

• has been evolving for billions of years
• increase survival and reproduction in changing environments

Question 2

cnidarians

Answer 2

• simplest animals with NS
• nerve net: interconnected neurons for movement
• NO CENTRAL CONTROL ORGAN

Question 3

echinoderms

Answer 3

• nerve ring: central control structure

- signal radial nerve (signals muscles)

Question 4

bilateria

Answer 4

• lots of variation
• Platyhelminthes (Planarians)
• anterior end; eyespots for detecting light and brain
• ladder-type NS; 2 longitudinal nerve cords and transverse nerves (“rungs”)

Annelids and Arthopods

• more complex brain
• ganglia: segmentally arranged clusters of neurons

Question 5

vertebrates (NS)

Answer 5

CNS- brain and spinal cord

PNS - nerves and ganglia

Question 6

chiton

Answer 6

slowing moving -> simple

Question 7

squid

Answer 7

fast moving -> complex

Question 8

what is special about chiton and squid?

Answer 8

they are both molluscs, but they live different lifestyles

Question 9

neuron

Answer 9

basic functional unity of NS

-conduct electrical signals, integrate info

Question 10

neuron anatomy

Answer 10

• cell body: contains organells and nucleus

- dendrites (=”trees”); cytoplasmic extension from cell body - usually many and short, receive info

Question 11

axons

Answer 11

• also cytoplasmic extensions from cell body - but usually one and long
• send info
• axon hillock: base of axon - where signals are generated
• synaptic terminals: end of axon - often branched

Question 12

glia

Answer 12

• non-neuron cells of the NS

- MANY functions; neuron support, protections, maintenance, embryonic NS development

Question 13

myelin sheath

Answer 13

bundles of insulation around axons - faster signaling

• in CNS: produced by oligodendrocytes
• in PNS: produced by Schwann Cells

Question 14

radial glia

Answer 14

form tracks in developing embryos; help newly formed neurons migrate from neural tube

Question 15

CNS

Answer 15

• contains interneurons -responsible for integration and process of info
• gray matter - mostly neuron cell bodies
• white matter - mostly bundled axons

Question 16

brain

Answer 16

• ventricles with cerebrospinal fluid
• white matter (axons) inside
• gray matter (cell bodies) outside

Question 17

spinal cord

Answer 17

• within spine

- links brain and rest of NS

Question 18

spinal cord structure

Answer 18

• small central canal with cerebrospinal fluid
• gray matter surround canal - inside
• white matter surrounds gray - outside

Question 19

spinal cord functions

Answer 19

• transmit impulses to/from brain
• reflex actions: rapid, involuntary response to stimulus
• ex: knee-jerk reflex; quad stretched unexpectedly -> helps you stay upright

Question 20

PNS

Answer 20

• all remaining nervous tissue not part of CNS
• transmit info to/from CNS
• includes nerves: axons of many neurons held together with connective tissue`

Question 21

what do sensory receptors do?

Answer 21

they detect stimuli

Question 22

afferent neurons

Answer 22

send info from sensory receptor -> CNS

Question 23

what are the two types of senses

Answer 23

visceral and somatic

Question 24

visceral

Answer 24

not aware of - BP, thyroid hormone levels

Question 25

somatic

Answer 25

are aware of - vision

Question 26

efferent neurons

Answer 26

CNS -> effectors: no receptors

Question 27

what are the two target systems of efferent neurons?

Answer 27

motor system and autonomic nervous system

Question 28

motor system

Answer 28

- efferent neurons -> skeletal muscle - voluntary and reflexes - no receptors

Question 29

autonomic nervous system

Answer 29

- efferent neurons -> glands, heart, smooth muscle | - what CNS controls that we are not aware of

Question 30

what are the three divisions of the autonomic nervous system

Answer 30

- enteric: controls digestive tract, pancreas, gall bladder - parasympathetic: "rest and digest" - sympathetic: "fight or flight"

Question 31

what are the three broad regions/categories of the vertebrate brain

Answer 31

forebrain, midbrain, and hindbrain

Question 32

forebrain

Answer 32

sensory input, learning, complex processing

Question 33

midbrain

Answer 33

coordinates routing on sensory input

Question 34

hindbrain

Answer 34

involuntary activities

Question 35

cerebrum

Answer 35

- derived from forebrain - most prominent part of brain - voluntary movement - learning, emotion, memory, perception

Question 36

divisions of the cerebrum

Answer 36

- right/left hemisphere - left/right reversed perception/control - corpus callosum: thick band of axons, connects 2 halves

Question 37

cerebellum

Answer 37

- from hindbrain | - movement. balance, motor skills/coordination

Question 38

diencephalon

Answer 38

- from forebrain - thalamus: routes sensory info to correct part of cerebrum - hypothalamus: regulates HS

Question 39

brainstem

Answer 39

- basic life functions - respiration, heartbreat, BP | - 3 components: midbrain, pons, and medulla oblangata

Question 40

pons

Answer 40

from hindbrain; respiratory and sleep centers

Question 41

medulla oblongata

Answer 41

from hindbrain; continuous with spinal cord