Lecture 1- Why have a nervous system?

Question 1

What is Aridopsis thaliana and what is its significance?

Answer 1

• very distant relative of humans
• 27 000 genes but no nervous system
• demonstrates that nervous system is not essential for life
• the first organism to have its entire genome sequenced

Question 2

Where is the first primitive nervous system found?

Answer 2

• corynactis californica, simple sessile invertebrate
• very little organ/tissue specialization
• a “nervous system” comprising a network of nerve cells

Question 3

What is the distinguishing feature of nerve cells?

Answer 3

• excitable cells, relay information between cells

- cells communicate with each other

Question 4

What are the functions of a nervous system?

Answer 4

• homeostatic regulation (nervous system has a big role in that)
• control movement (-huge proportion of the human nervous system is dedicated to movement control, controlling the biochemical machine )
• reveal the universe= make us think, conscious, we don’t know of any other thing capable of producing consciousness other than brain

Question 5

What are the basis for the thought that heart is the center of thinking for Early Egyptians?

Answer 5

-early Egyptians= observed that everything that the world depended on the flow of fluids (Nile) and the heart has lot of connections of fluids= the center

Question 6

Who was the first to say the brain was a center of thought?

Answer 6

• Hippocrates

- 460 BC

Question 7

What are the reasons for the idea that heart is the center of thinking not the brain?

Answer 7

• brain just sits there whereas the heart moves
• simple animals move and react when they don’t have a brain (Aristotle’s argument, he was cardiocentric and his thinking influenced the coming generations)
• warmth (=life) emanates from the body’s core (the heart)
• all the ancient civilizations thought the heart to be the centre of conscious being

-the observation that more sophisticated animals have bigger brains was explained by saying that they needed more cooling as they have more blood= more heat (brain= coolant)

Question 8

What did Galen do?

Answer 8

• admired Hippocrates and accepted brain as the seat of intellect but he observed that the brain has fluid filled chambers right in the middle= that’s and thus said it works on fluids and flows as well, the classical explanation of bodily humours
• Galen observed the bodies of injured gladiators and unlike the Greeks the Romans were able to investigate corpses
• Galen didn’t like the idea that how big brain is determines intelligence=as donkeys have a big brain and not clever!
• in the Renaissance the importance of detailed observation and questioning of doctrine was reinstated but the mechanistic explanation of humours remained

Question 9

What are the two main divisions of the nervous system?

Answer 9

• CNS= brain and spinal cord (central because it is encased in bony structures)
• PNS= cranial nerves and spinal nerves (peripheral because it connects the central and the muscles etc.)

Question 10

What systems does the CNS convey information too?

Answer 10

-sends information to motor components that are divided into visceral motor system and somatic motor system

Question 11

What does visceral motor system convey information to and what is does it consist of?

Answer 11

• consists of: parasympathetic, sympathetic and enteric divisions
• the autonomic ganglia and nerves send info to:
• Effectors: smooth muscles, cardiac muscles and glands

Question 12

What does somatic motor system convey information to and what is does it consist of?

Answer 12

• consist of motor nerves that send info to:

- effectors: Skeletal (striated) muscles

Question 13

How does the CNS obtain information about the internal and external environment?

Answer 13

• internal and external environment conditions are detected by sensory components, first by sensory receptors (at surface of the body and within) and then info passed onto sensory ganglia and nerves that send it to the CNS
• CNS then analyses and integrates the information

Question 14

What is the role of the CNS?

Answer 14

-analysis and integration of sensory and motor information

Question 15

What was Descartes’ view of the brain?

Answer 15

• fluid and pumped and sends fluid around the brain and out of the brain and taht is how it works the muscles
• how is it that process produces a concious being, he said= humans have a mechanical communicates with the spiritual= pineal gladn (because there is only one and directly above the ventricles with the fluid)

Question 16

What did Paul Broca do?

Answer 16

-Paul Broca= brain is not a holistoc thing, it has modules, different bits that do different things

• figured it out from a case of a patient who was quadriplegic and had damaged bit of a brain= couldn’t speak
• only make one sound= Tan
• he could understand speech but couldn’t produce it
• broca collected about 11 of these cases and on the basis of that decided that bit of teh brain produces speech

Question 17

How can we observe the brain today?

Answer 17

• MRI- harmless, radio waves
• CT scan (X-Ray)
• fMRI -follows oxygen levels in the brain to determine which areas are active,subtle changes in blood flow= to determine how active which regions of the brain are
• we can find out which bits do what but we still do not know how!

Question 18

What do we have to understand to understand how an organ works?

Answer 18

• how the individual components and cells work

- neurons are vastly varied

Question 19

How do neurons communicate?

Answer 19

-nervous system receives processes and outputs information in the form of electrical signals that travel along the processes of neurons (axons and dendrites)

Question 20

Are nervous systems of different organisms similar?

Answer 20

• small scale reveals most similarity
• neurons operate in the same way in all animals
• the mechanisms of excitability, information, transmission, transfer and integration are essentially identical

Question 21

What determines the complexity of an organism?

Answer 21

-not how many genes but how complex the brain is

Question 22

What are the roles of most of the genes in the body?

Answer 22

• house-keeping genes
• only a small number of cells determines the phenotype of a cell
• there are more cellular phenotypes in the nervous system than there are in any other organ or organ system

Question 23

What about consciousness?

Answer 23

• don’t know how it arises
• brain creates the image of the universe for us, without it only the universe as it exists= just energy and matter distributed spatially in space= but we see something else because the brain produces that image