Nervous System Part 1

Question 1

What can all thoughts, actions and emotions be boiled down to?

Answer 1

All thoughts, actions and emotions can be boiled down to three primary functions - sensory input - integration - motor output

Question 2

Briefly describe the process your nervous system goes through to detect a spider crawling on your knee

Answer 2

Sensory detectors on the skin detect 8 little legs - This is the sensory input

From there your nervous system processes that input and decides what should be done about it - This is called integration, deciding whether to be zen about it or run around screaming

Your hands lashing out to remove the spider is the motor input - The response that occurs when your nervous system activates certain parts of your body

Question 3

What are the two main structures of the nervous system?

Answer 3

The main two structures of the nervous system are the central nervous system and the peripheral nervous system

Question 4

What does the central nervous system consist of?

Answer 4

The CNS consists of your brain and your spinal chord. This is your main control centre

Question 5

What does your peripheral nervous system consist of?

Answer 5

The PNS consists of all the nerves that branch out from the brain and spinal chord. This allows the CNS to communicate to with the rest of the body. Since its job is communication PNS is set up to work in both directions

Question 6

What division of your nervous system picks up sensory stimuli?

Answer 6

The Sensory Division (afferent) picks up sensory stimuli

Question 7

What division of your nervous system sends directions from your brain to your muscles and glands?

Answer 7

The Motor Division (efferent) sends directions from your brain to your muscles and glands.

The motor division also includes the Somatic Nervous System (voluntary nervous system) that controls your skeletal muscle movement

Question 8

What division of your nervous system keeps your heart beating, your lungs breathing and your stomach churning?

Answer 8

The Autonomic Nervous System (Involuntary Nervous System) keeps your heart beating, your lungs breathing and your stomach churning

Question 9

What division of your nervous system, when stimulated, motivates the body?

Answer 9

The ANS has the Sympathetic Division that motivates the body and gets it all fired up (AAARGH SPIDER)

Question 10

What division of your nervous system relaxes the body?

Answer 10

The Parasympathetic Division relaxes the body (Wasn’t a white tail chillax would ya)

Question 11

What is nervous tissue densely packed with?

Answer 11

Nervous tissue is densly packed with cells. While 20% of the nervous tissue is extra cellular tissue everything else is cells!

Question 12

How does a neuron function?

Answer 12

Neurons respond to stimuli and transmit signals

Question 13

What do glial cells primarily do?

Answer 13

Glial cells primarily protect neurons. Different glial cell types provide support, nutrition, insulation and help with signal transmission in the nervous system

Question 14

What are the types of glial cells found in the CNS?

Answer 14

• Astrocytes: support, regulate ions
• Microglial Cells: Defend
• Ependymal Cells: Line Cavities
• Oligodendrocytes: wrap and insulate, form myelin sheath

Question 15

What are the types of glial cells found in the PNS?

Answer 15

• Satellite Cells: surround neuron cell bodies
• Schwann Cells: insulate, help for myelin sheath

Question 16

How much of the brain do glial cells make up?

Answer 16

Glial cells make up about 1/2 the mass of our brain and outnumber neurons about 10 to 1

Question 17

What do astrocytes do?

Answer 17

Astrocytes are found in the CNS. They are the most abundant and versitile glial cell. They exchange materials between neurons and capillaries and they anchor neurons to their blood supply

Question 18

What do Microglial cells do?

Answer 18

Microglial cells are protective and are found in CNS. They are smaller and thorny looking. They act as a main source of immune defense against invading micro organisms in brain and spinal chord

Question 19

What do Ependymal cells do?

Answer 19

Ependymal cells - line cavities in brain and spinal chord

-create, secrete and circulate cerebrospiral fluid that fills those cavities and cushions those organs

Question 20

What do Oligodendrocytes do?

Answer 20

Oligodendrocytes

• Wrap around neurons
• produce an insulating barrier called the myelin sheath

Question 21

What do satelite cells do?

Answer 21

Satelite cells are found in the PNS

• They do mainly what astrocytes do in CNS
• Surround and support neuron cell bodies

Question 22

What do Schwann cells do?

Answer 22

Schwann cells are found in the PNS

• Similar to oligodendrocytes
• Wrap around axons
• Produce insulating barrier called the myelin sheath

Question 23

How do neurons vary in size?

Answer 23

Neurons vary in sizes and shapes from tiny ones in your brain to ones that run the entire length of your leg

Question 24

What are three things all neurons have in common?

Answer 24

1. Neurons are some of the longest lived cells in your body
2. Neurons are irreplaceable. Most neurons are Amitotic so once they are given a role in the nervous system they lose their ability to divide
3. Neurons have huge appetites. They have high metabolic state and need a high intake of glucose and oxygen. About 25% of the calories that you consume every day are consumed by your brains activity

Question 25

Describe the basic structure of a neuron

Answer 25

Neurons share the same basic structure - Soma (cell body): Neurons life support. Has cell goodies like nucleus, DNA, mitochondria, ribosome and cytoplasm - Dendrites: Bushy, branch like things protruding from cell body. They're the listeners, pick up messages from other cells and convey that info to the cell body - Axon: The talker. Can be super short or run a full metre such as from your spine to your ankle. There are a few different axon layouts but in most abundant away from the cell body to other cells

Question 26

What is one way we can tell nerve cells apart?

Answer 26

Nerve cells aren't all identical, differences in structure can be used to differentiate them. Ie how many processes extend out from the cell body. (Process being a projecting part of an organic structure)

Question 27

What is the most common form of neuron?

Answer 27

99% of neurons are multipolar neurons - 3 or more processes sticking out from soma (cellbody) - 1 axon & bunch of dendrites

Question 28

Which neurons are rare and can be found in the retina of your eye?

Answer 28

Bipolar Neurons - have 2 processes, an axon and one single dendrite extending from opposite sides of soma (cell body)

Question 29

Which neurons are found in sensory receptors?

Answer 29

Unipolar Neurons - Have just 1 process

Question 30

How can you clasify neurons in terms of their functions?

Answer 30

You can clasify neurons by which way an impulse travels through a neuron in relation to the brain and spine

Question 31

What do Sensory Neurons do?

Answer 31

Sensory Neurons (afferent neurons) transmit impulses from sensory receptors towards the CNS. They are found in skin or internal organs and most are unipolar

Question 32

What do motor neurons do?

Answer 32

Motor Neurons (efferent neurons) - Impulses move from the CNS to rest of the body (to muscles and glands) - Mostly Multipolar

Question 33

What do Interneurons do?

Answer 33

Interneurons (association neurons) live in the CNS - Transmit impulses between sensory and motor neurons - most abundant of bodies neurons - Mostly multipolar

Question 34

Describe how your neurons tell your body to react to an outside stimuli such as a spider crawling on your knee

Answer 34

1. Those 8 tiny legs activate your 2. Unipolar sensory neurons in skin on knee 3. Impulse travels up an axon wrapped in schwann cells and into your 4. Spinal chord where it gets passed on to several multipolar interneurons. Some of those interneurons may send a signal straight down a set of multipolar neurons to your quads triggering you to kick your leg out before you even know whats going on 5. Other interneurons pass the signal on to neurons that carry it up your spinal chord and in to your brain. Thats where your body first recognises the stimuli as a spider. The connections between neurons interpret and split the signal so you can either scream and swing your arms around or calmly and with dignity remove the spider from your person