Chapter 30- Nervous system

Question 1

Nervous system

Answer 1

Communication lines that can detect, process, and call for responses to internal and external stimuli. Uses chemical and electrical signals. Similar to endocrine system only loads faster.

Question 2

Neurons

Answer 2

Make up the communication lines of the nervous system. 3 kinds: sensory, interneurons, and motor.

Question 3

Neuroglia

Answer 3

Collection of diverse cells that support the neurons, both structurally and metabolically.

Question 4

Sensory neurons

Answer 4

Detects stimuli and signals other cells in response.

Question 5

Interneurons

Answer 5

Integrate signals from sensory neurons and signals motor neurons.

Question 6

Motor neurons

Answer 6

Receives signals from interneurons and activate effectors such as muscles and glands in order to respond to the signals.

Question 7

Simplest nervous system?

Answer 7

A nerve net, which a mesh of neurons that detect stimuli and control contractile cells. Found in radial animals, such as jellyfish, hydras, and cnidarians.

Question 8

Bilateral nervous system

Answer 8

Most common system, with paired organs and organs along an axis of symmetry. Animals are often cephalized, with ganglia or a brain in the head end.

Question 9

Cephalization

Answer 9

The concentration of neurons and sensory organs at the body’s anterior end. (Head)

Question 10

Nerves

Answer 10

Long cordlike communication lines found in bilateral cephalized nervous system

Question 11

Ganglion (plural ganglia)

Answer 11

Cluster of nerve cell bodies that act as a local information processing center.

Question 12

Simplest bilateral cephalized nervous system

Answer 12

Found in planarians and related flatworms. Has 2 nerve cords through the length of body and interconnects with branching nerves. Connects to pairs of ganglia in the head.

Question 13

Nervous system of annelids and arthropods

Answer 13

Have a simple brain with paired ganglia. Ganglia also found in each body segment for muscle control. Has either 1 or 2 ventral nerve cords (runs along stomach/lower surface).

Question 14

Nervous system of chordates

Answer 14

One dorsal nerve cord (runs along back). Anterior region of cord connects to complex brain in vertebrates.

Question 15

Two divisions of nervous system

Answer 15

Central nerd system (brain and spinal cord) and peripheral nervous system (all the other junk/spinal and cranial nerves)

Question 16

Divisions of peripheral nerd system

Answer 16

Autonomic nerds (Carry signals to and from smooth muscle, cardiac muscle, and glands) and somatic nerds (Carry signals to and from skeletal muscle, tendons, and skin)

Question 17

Division of autonomic nerves

Answer 17

Sympathetic division and parasympathetic division

Question 18

Axon

Answer 18

Long extensions of nerves, made of sensory or motor neurons, or both. Myelinated axons covered in fatty sheaths made of Schwann cells.

Question 19

Dendrites

Answer 19

Short branching extensions of neuron that receive signals and bring them to the cell. Sensory neurons only have one. Motor neurons and interneurons have many. No sheath or covering.

Question 20

Axons

Answer 20

Ridiculously long extensions of neuron that bring signals away from cell. Most neurons only have one, and some are surrounded by fat which helps information flow faster.

Question 21

Resting membrane potential

Answer 21

When a neuron is not being stimulated, it keeps a small electric gradient throughout the membrane, making the cytoplasm slightly more negative than outside the cell. In most neurons, about -70 millivolts.

Question 22

Action potential

Answer 22

Abrupt reversal in voltage difference across plasma membrane. Signal starts in trigger zone and travels all the way to output zone. Only found in neurons, muscle cells, and other excitable cells.

Question 23

Threshold level

Answer 23

Voltage difference where all Na channels in trigger zone open and start an action potential

Question 24

3 steps of cell to cell communication

Answer 24

Signal reception, signal transduction, and cellular response.

Question 25

Chemical synapse

Answer 25

Region where signals from one neuron’s axon is received and transduced by another cell.

Question 26

Neurotransmitters

Answer 26

Type of signaling molecule that relay messages between presynaptic and postsynaptic cells.