49.1 nervous systems

Question 1

cnidarian nervous system

Answer 1

nerve net: interconnected nerve cells

-controls the contraction and expansion of the gastrovascular cavity

Question 2

nerves

Answer 2

bundles of axons of multiple nerve cells

-better than nerve nets for elaborate movements

Question 3

CNS

Answer 3

brain and spinal cord

Question 4

brain

Answer 4

integrative power

Question 5

spinal cord

Answer 5

conveys information to and from the brain for locomotion

-also makes reflexes

Question 6

reflex arcs

Answer 6

1) reflex initiated by tapping the quadriceps
2) sensors detect
3) sensory neurons convey information to spinal cord
4) in response to signals from the sensory neurons, the motor neurons send signals to the quadriceps and contract to jerk the leg
5) sensory neurons communicate with Interneurons
6) interneurons inhibit other motor neurons to prevent contraction of hamstring

Question 7

how the brain and spinal chord forms

Answer 7

• derived from the dorsal embryonic nerve chord
• the hollow cavity is transformed into the narrow CENTRAL CANAL of spinal cord and 4 VENTRICLES of the brain
• they are filled with cerebrospinal fluid (nutrients, hormones, waste transport and cushioning)
• brain and spinal cord have gray and white matter

Question 8

gray matter

Answer 8

neuron cell bodies, dendrites, and unmyelinated axons mostly

Question 9

white matter

Answer 9

bundled axons that have myelin sheaths

Question 10

white matter in the spinal cord

Answer 10

outside

-for communicating with PNS

Question 11

white matter in brain

Answer 11

inside

-for signaling between neurons of the brain in learning, emotions, sensory information, generating commands