Vertebrates 13 - Nervous system

Question 1

Divisions of the PNS

Answer 1

Afferent, Efferent: Somatic, Autonomic: Sympathetic and parasympathetic

Question 2

Efferent; Afferent; Somatic

Answer 2

Away from brain; toward the brain; skeletal muscles

Question 3

Sympathetic and parasympathetic

Answer 3

They are antagonists and oppose each other

Question 4

Glial cells

Answer 4

Outnumber neurons, small. Support, development (form first and help neurons grow), function (some conduction, myelination)

Question 5

Glial cell types

Answer 5

Oligodendrocytes and astrocytes (CNS), Schwann cells (PNS). Schwann and oligoden. are pretty similar and mke myelin. Astrocytes affect signaling b/w neurons and release growth factors

Question 6

Neuron groups

Answer 6

Sensory, motor, interneurons.

Question 7

Characteristics of neurons

Answer 7

Post-mitotic, membrane proteins respond to voltage (excitable). Pass signals at synapses (chem or elec). Intricate connection patterns.

Question 8

General neuron structure

Answer 8

Dendrites: all around cell body, short, input; Soma: cell metabolism; Axon hillock: where axon leaves cell body, action potential begins here; Axon: myelinated and non, signal travel, usually only one. Synaptic terminals/boutons: end of axon, signal passed on; synapse: where two neurons communicate

Question 9

Amphioxus (cephalochordata) nervous system

Answer 9

Hollow dorsal nerve cord, no distinct brian, only 20000 neurons. Neuromuscular junction unique: muscles send projections to nerve cord (backwards!). No myelin. Simple photo-, chemo- and mechanoreceptors. Scattered.

Question 10

Lampreys nervous system

Answer 10

Simple brain. Diffuse autonomic nervous system (ex. heart rate control, but no distinct nerves). No myelin. Elec and chem synapses. Smallest brain/body mass ratio.

Question 11

Sharks nervous system

Answer 11

Brain/body mass ratio > bony fish, reptiles, amphibians. Autonomic NS more distinct. Myelin. Separate taste and smell receptors

Question 12

Bony fish nervous system

Answer 12

Diverse brains, lateral line, Mauthner nerve cells (for escape - called C-start). Cerebrum mostly for smell

Question 13

Amphibian NS

Answer 13

NS similar to fish. Cerebrum not well developed, mostly for smell. Similar nerves modified for limbs. Cerebellum less complex than fishes because it is coordinating in 2 planes.

Question 14

Reptile NS

Answer 14

Small brain/body ratio, but more developed cerebrum because it coordinates more there. thalamus important to relay info.

Question 15

Birds NS

Answer 15

Brain/body ratio high. Cerebrum enlarged. Decreased sensory nerves (touch, smell - not as needed, sight more important). Cerebellum large and highly folded (more coordination

Question 16

Primates NS

Answer 16

Brain/body ratio highest. Larger area in frontal and occipital lobes. High speed conduction (myelin)

Question 17

Blue Whale NS

Answer 17

Largest brain (9-10kg), cerebrum highly folded, inferior colliculi enlarged (better sound sense)

Question 18

Folding in brains

Answer 18

Creates more surface area, more rooms for layers. (wouldn’t fit it some animals’ heads!)

Question 19

Brain/body mass ratio

Answer 19

Log/log graph, above line is high, below is low. Generally the larger the smarter. Humans, chimps, crows, porpoise are smart, lampreys, eels are dumb

Question 20

Determining brain/body mass ratio in extinct species

Answer 20

Measure the size of the brain case. Troodon (velociraptor) considered smart, sauropods dumb.

Question 21

Conundrums of brain/body mass ratio

Answer 21

Stingrays and dogfish have high ratio, but don’t seem to be intelligent. Smaller cerebrum and larger medulla or cerebellum responsible for this.

Question 22

Size of parts of the brain

Answer 22

Fish have smaller cerebrum and larger cerebellum; humans have much larger cerebrum/cerebellum ration