Vertebrates 13 - Nervous system Flashcards Preview

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1

Divisions of the PNS

Afferent, Efferent: Somatic, Autonomic: Sympathetic and parasympathetic

2

Efferent; Afferent; Somatic

Away from brain; toward the brain; skeletal muscles

3

Sympathetic and parasympathetic

They are antagonists and oppose each other

4

Glial cells

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

5

Glial cell types

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

6

Neuron groups

Sensory, motor, interneurons.

7

Characteristics of neurons

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

8

General neuron structure

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

9

Amphioxus (cephalochordata) nervous system

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.

10

Lampreys nervous system

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.

11

Sharks nervous system

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

12

Bony fish nervous system

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

13

Amphibian NS

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.

14

Reptile NS

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

15

Birds NS

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

16

Primates NS

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

17

Blue Whale NS

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

18

Folding in brains

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

19

Brain/body mass ratio

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

20

Determining brain/body mass ratio in extinct species

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

21

Conundrums of brain/body mass ratio

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

22

Size of parts of the brain

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