Notes 20

Question 1

The human brain contains about how many neurons?

Answer 1

The human brain contains about 100 billion neurons,
organized into circuits more complex than the most
powerful supercomputers (from our text). Better estimate (Associate Professor Suzanna Herculano-
Houzel) 86 billion neurons and just as many non neuronal cells such as glial cells (and by the way, we use our entire brain).

Question 2

What recent advances in brain imaging involves expressing combinations of coloured proteins in brain cells?

Answer 2

The brainbow technique.May allow researchers
to develop detailed maps of information transfer between brain regions.

Question 3

By the time of the Cambrian explosion more than 500
million years ago, specialized systems of neurons had
appeared that enable animals to do what?

Answer 3

sense their environment and respond rapidly.

Question 4

T or F: The simplest animals with nervous systems, cnidarians,have neurons arranged in nerve nets.

Answer 4

true

Question 5

What is a nerve net?

Answer 5

A nerve net is a series of interconnected nerve cells

Question 6

T or F: More complex animals have nerves nets.

Answer 6

False. More complex animals have nerves

Question 7

What are nerves?

Answer 7

Nerves are bundles that consist of axons of multiple nerve cells. Sea stars have a nerve net in each arm that is connected by radial nerves to a central nerve ring.

Question 8

T or F: Bilaterally symmetrical animals exhibit cephalization, the clustering of sensory organs at the front end of the body.

Answer 8

True. Relatively simple cephalized animals, such as flatworms, have a central nervous system (CNS).

Question 9

What does the CNS consist of?

Answer 9

The CNS consists of a brain and longitudinal nerve cords

Question 10

What does the PNS consist of?

Answer 10

The peripheral nervous system (PNS) consists of
neurons carrying information in and out of the CNS.

Question 11

Annelids and arthropods have segmentally arranged
clusters of neurons called what?

Answer 11

Ganglia

Question 12

Nervous system organization usually correlates with
what?

Answer 12

Lifestyle. Sessile molluscs (for example, clams and chitons) have simple systems, whereas more complex molluscs (for example, octopuses and squids) have more sophisticated systems.

Question 13

What is the nervous system of chiton made of?

Answer 13

Anterior nerve ring, longitudinal nerve cords, and ganglia.

Question 14

What is the nervous system of squid composed of?

Answer 14

a brain and ganglia

Question 15

In vertebrates what are the CNS and PNS composed of?

Answer 15

The CNS is composed of the brain and spinal
cord. The PNS is composed of nerves and ganglia.

Question 16

What is the nervous system of a salamander composed of?

Answer 16

A brain, spinal cord (dorsal nerve cord), and sensory ganglia.

Question 17

What are the functions of glia cells?

Answer 17

Glia cells, or glia have numerous functions to nourish,
support, and regulate neurons. Embryonic radial glia form tracks along which newly formed neurons migrate.

Question 18

What are the astrocytes?

Answer 18

Astrocytes induce cells lining capillaries in the CNS to form tight junctions, resulting in a blood-brain barrier and restricting entry of most substances into the brain.

Question 19

What are the major types of glia in adult nervous systems?

Answer 19

Ependymal cells, astrocytes, oligodendrocytes, microglia, and Schwann cells.

Question 20

Radial glial cells and astrocytes can both act as what?

Answer 20

Stem cells

Question 21

Researchers are trying to find a way to use neural stem
cells to replace what?

Answer 21

brain tissue that has ceased to function normally.

Question 22

The CNS develops from what?

Answer 22

The hollow nerve cord.

Question 23

The cavity of the nerve cord gives rise to the narrow
___ ___ of the spinal cord and the ____ of the brain.

Answer 23

The cavity of the nerve cord gives rise to the narrow
central canal of the spinal cord and the ventricles of the brain.

Question 24

What does cerebrospinal fluid?

Answer 24

The canal and ventricles fill with cerebrospinal fluid
filtered from blood and functions to:
– to cushion brain and spinal cord
– to provide nutrients and remove wastes

Question 25

What do the brain and spinal cord contain?

Answer 25

-Gray matter, which consists of neuron cell bodies,
dendrites, and unmyelinated axons
– White matter, which consists of bundles of myelinated axons

Question 26

What is a reflex?

Answer 26

A reflex is the body’s automatic response to a stimulus. The spinal cord conveys information to and from the brain and generate basic patterns of locomotion. The spinal cord also produces reflexes independently of
the brain. For example, a doctor uses a mallet to trigger a knee-jerk reflex

Question 27

What does the PNS do?

Answer 27

The PNS transmits information to and from the CNS and regulates movement and internal environment. In the PNS, afferent neurons transmit information to the
CNS, and efferent neurons transmit information away from the CNS

Question 28

What are the 2 efferent components of the PNS?

Answer 28

The motor system carries signals to skeletal muscles and is voluntary. The autonomic nervous system regulates smooth and cardiac muscles and is generally involuntary.

Question 29

The autonomic nervous system has sympathetic and
parasympathetic divisions. What do they do?

Answer 29

The sympathetic division regulates arousal and energy
generation (“fight-or-flight” response) from the brain. The parasympathetic division has antagonistic effects on target organs and promotes calming and a return to “rest and digest” functions from the spinal cord.