From Nerves to Nervous Systems

Question 1

What are the functions of the nervous system?

Answer 1

1. maintain homeostatic control-body temp ph
2. process integration-require kidney and respiratory system to maintain ph equilibrium
3. receive and transduce environmental stimuli-change from one energy form to another-ex light energy coming into eye is transducer
4. process info various ways
5. Control motor response

Question 2

What is the nervous system?

Answer 2

excitable nerve groups providing an interface between sensory and motor responses

Question 3

What three parts is the Sensory-Motor Circuit made up of?

Answer 3

1. neuron receptor-neuron or epithelial receptor aka secondary receptor
2. motor neuron
3. effector cell

Question 4

What does the neuron receptor do?

Answer 4

primary receptor. report filter and send info to the nervous system

Question 5

What does the motor neuron do in the Sensory-Motor Circuit do?

Answer 5

Takes the information from the receptor and sends it to another point in the body aka effector cell

Question 6

What is the effector cell in the Sensory-Motor Circuit?

Answer 6

Muscle or gland

Question 7

Interneurons

Answer 7

In the circuit between the receptor and motor neuron. Allows for complex integration and interpretation.

Question 8

Divergence

Answer 8

A single nerve has many coaxons that branch off to different nerve tracks with each a different function,
Example: when you touch a hot stove you pull your hand away, yell, scream, jump, etc

Question 9

Convergence

Answer 9

Many different neurons directed to a single neuron. Amplify Signal. Pick up the signals and lead to a unified single response. ex the signal neuron will require a threshold to make an action potential-skin little stimuli to make integrative response

Question 10

Feedback Loops

Answer 10

Neurons begin the process and sustain it over time and example is autonomic processes digestion.

Question 11

Are the nervous system necessary to support highly integrated and coordinated life?

Answer 11

No.

Question 12

What are independent effector cells?

Answer 12

A single cell that contains all three components of the sensory-motor circuit. Does not require a sensory or neural innervation to function.

Question 13

Advantages of the independent effector cell?

Answer 13

Responses are immediate. No cellular organization. Effectors are specific they have one job and do it really well.

Question 14

Disadvantages of the independent effector cell?

Answer 14

Only have one simple, stereotyped responses to specific kinds of stimuli. No plasticity.

Question 15

Three Examples of independent effector cells?

Answer 15

1. Complex movement patterns of ciliates: Paramecium- control speed and direction hyperpolarized membrane-poke at posterior end K channels open cilia beat faster more frequently
   depolarized membrane-poke at anterior end ca channels open back away stimulus
2. Poriferians- porocytes-allow water to come through-respond to changes in environment
3. Cniderian cnidocytes-stingy cells when stimulus brushes up against them release harpoon and take prey only work once work independent of animal

Question 16

How do radiates show an evolution of true effector/motor nervous systems?

Answer 16

First group to evolve sensory/motor units.

Radial symmetry gives no option for a CNS. Developed sophisticated nerve nets.

Question 17

What are nerve nets and what do nerve nets do?

Answer 17

Diffused interneuron net between the sensory and motor neurons.

Motor Reflex responses: Like the ones seen in humans cannot control bypass the higher neural centers of control. Stimulus + response

Question 18

Two types of semi independent nerve nets?

Answer 18

1. Fast specific Nerve Net: Bipolar Neurons. Have a preferred direction of transmission. High rates of speed 1-2m/s. Contain some ganglionic masses-pulse makers regions-pulse of bell.
2. Slow Diffuse Nerve Net: Multipolar Nuerons. Slower. Regulates the slow local movements of tentacles and mouth and slow contractions that pass away from stimulation net.

Question 19

What evolutionary changes occurred in bilateral animals?

Answer 19

1. reduction in reflex motor units-fewer reflexes allows for higher control centers to take control
2. Cephalization-concentration of sensory organs in the cephalic region
3. Centralization of nervous control- give control to the neuronal clusters-fast and can implement effector control
4. Neuronal Aggregation-large clusters of nerves with specialized functions
   ganglia-neuronal cluster outside CNS
   nuclei-neuronal clusters inside CNS
5. Fusion/reduction of nerve cords-spinal cords

Question 20

Primitive forms of flatworms and nervous development?

Answer 20

Exhibit a Radiate like arrangement of nerve nets, however, they have 5 pairs of nerve cords that aggregate together. Also start to see the aggregation of neuronal tissue up toward cephalic region.

Question 21

Moderately advanced forms of flatworms and nervous development?

Answer 21

More clusters of nerve found in commissures (link left and right side nerve cords) or nerve ladders

Question 22

Advanced forms of flatworms and nervous development?

Answer 22

2 pair of Nerve cords. Brain or endow-is not essential for normal daily function. Can remove the brain as it is not required for actions such as swallow food, phototaxic movement, and locomotion. Flatworms can be trained.

Question 23

What is the nervous development of mollusks?

Answer 23

Highly cephalized (most cephalized of invertebrates with exception of bivalves) with ganglia fused into a few large central masses. More highly developed nerve cords 2 pairs.

Question 24

What is the circumesophageal ganglia and what is it found in?

Answer 24

Large mass neuronal tissue that encircles the esophagus. Found in the mollusks. It is the brain of the mollusks.

Question 25

What are the two pairs of nerve cords in mollusks called and what do they do?

Answer 25

1. Ventral Pedal Nerve Cord: Innervates the foot. | 2. Visceral Nerve cord: Innervate the internal organs and modify/interpret signals coming into the visceral mass.

Question 26

How are cephalopod circumesophageal ganglia unique from the other mollusks circumesophageal ganglia?

Answer 26

They are the octopus etc...It contains the entire central nervous system. Most advanced. Evolutionary dead end cannot become more highly cephalized.

Question 27

What is the nervous development in the Annelids?

Answer 27

Bilobate brains: two halves and pair of nerve cords and contain a single ganglionic swelling of each nerve cord per body segment. Ganglionic Swellings: A swelling is present in each segment and controls the function in each segment. The function is decentralized. Each segment takes care of itself. Giant neurons: withdrawal response

Question 28

What is the nervous development in Arthropods?

Answer 28

Refines the basic annelid plan to the highest level of integration seen in the Protosome line.

Question 29

What type of diet do arthropods have?

Answer 29

Low Sodium diet. Insects highly specialized feeders feed typically on plant sap which is low in sodium. Perineurium-thin layer of impermeable layers around neurons to sequester all the sodium they collect here so their neurons function.

Question 30

What are the three distinct brain regions of the arthropod and what is its function?

Answer 30

1. Protocerebrum - integrates all visual sensory that comes from the compound eyes 2. Deutocerebrum- receives and processes all sensory information from the antenna 3. Tritocerebrum- receives and processes all the sensory info from the minor antenna and the mouth

Question 31

What are the segmental ganglia in arthropods?

Answer 31

Arthropods advanced the nervous plan seen in the annelids and the rest of the sensory information is received and processed throughout the body. The segmental ganglia have clusters of neurons that do a specific variety of jobs called central pattern generators.

Question 32

What do arthropod central pattern generators do?

Answer 32

Group of neurons organized in nerve cord ganglia that produce a complex series of neural activity patterns responsible for specific motor actions. Example: the legs and flying with insects like wont stop flying till legs hit ground. Also open up spiracles for more Co2 oxygen. a bursting neuron in metathoracic ganglia acts as pacemaker

Question 33

How is the nervous system of vertebrates different form invertebrates?

Answer 33

1. Highly centralized 2. CNS is in bony chambers for protection 3. Large number of neurons

Question 34

What three regions are vertebrate brains divided into and what is the function of each?

Answer 34

1. Rhombencephalon-hindbrain largest region contains autonomic functions. Pons medulla-where the spinal cord comes into brain stem and expands cerebellum-proprioreception-pressure, angular momentum, stress, deformation joint/muscles ex learn how to walk 2. Mesencephalon-midbrain most primative fish/amphibians-most complex behavior Submammalian- processing and some relay Human- relay station little processing 3. Prosencephalon-forebrain 2 parts 1. diencephalon-thalamus hypothalamus posterior pituitary send to cerebrum for processing and signals to right motor response 2. telecephalon-varied bc of evolution. in fish and amphibians least developed and it causes smell. In reptiles and birds it has no obvious purpose. And in mammals lobes greatly developed it is our area of greatest dominance and processing sensory and motor function measure intelligence.

Question 35

How to measure Intelligence?

Answer 35

1. Brain Size-no 2. Cephalic Index- weight of brain over weight of body-no 3. Cephalic Volume-number of neurons-no 4. Cortical Surface area- folded area-no 5. Cortical volume ratio- thickness- yes!