Nervous System Part 1 Flashcards
What can all thoughts, actions and emotions be boiled down to?
All thoughts, actions and emotions can be boiled down to three primary functions - sensory input - integration - motor output
Briefly describe the process your nervous system goes through to detect a spider crawling on your knee
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
What are the two main structures of the nervous system?
The main two structures of the nervous system are the central nervous system and the peripheral nervous system
What does the central nervous system consist of?
The CNS consists of your brain and your spinal chord. This is your main control centre
What does your peripheral nervous system consist of?
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
What division of your nervous system picks up sensory stimuli?
The Sensory Division (afferent) picks up sensory stimuli
What division of your nervous system sends directions from your brain to your muscles and glands?
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
What division of your nervous system keeps your heart beating, your lungs breathing and your stomach churning?
The Autonomic Nervous System (Involuntary Nervous System) keeps your heart beating, your lungs breathing and your stomach churning
What division of your nervous system, when stimulated, motivates the body?
The ANS has the Sympathetic Division that motivates the body and gets it all fired up (AAARGH SPIDER)
What division of your nervous system relaxes the body?
The Parasympathetic Division relaxes the body (Wasn’t a white tail chillax would ya)
What is nervous tissue densely packed with?
Nervous tissue is densly packed with cells. While 20% of the nervous tissue is extra cellular tissue everything else is cells!
How does a neuron function?
Neurons respond to stimuli and transmit signals
What do glial cells primarily do?
Glial cells primarily protect neurons. Different glial cell types provide support, nutrition, insulation and help with signal transmission in the nervous system
What are the types of glial cells found in the CNS?
- Astrocytes: support, regulate ions
- Microglial Cells: Defend
- Ependymal Cells: Line Cavities
- Oligodendrocytes: wrap and insulate, form myelin sheath
What are the types of glial cells found in the PNS?
- Satellite Cells: surround neuron cell bodies
- Schwann Cells: insulate, help for myelin sheath
What do astrocytes do?
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
What do Microglial cells do?
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
What do Ependymal cells do?
Ependymal cells - line cavities in brain and spinal chord
-create, secrete and circulate cerebrospiral fluid that fills those cavities and cushions those organs
What do Oligodendrocytes do?
Oligodendrocytes
- Wrap around neurons
- produce an insulating barrier called the myelin sheath
What do satelite cells do?
Satelite cells are found in the PNS
- They do mainly what astrocytes do in CNS
- Surround and support neuron cell bodies
What do Schwann cells do?
Schwann cells are found in the PNS
- Similar to oligodendrocytes
- Wrap around axons
- Produce insulating barrier called the myelin sheath
What are three things all neurons have in common?
- Neurons are some of the longest lived cells in your body
- Neurons are irreplaceable. Most neurons are Amitotic so once they are given a role in the nervous system they lose their ability to divide
- 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
Describe the basic structure of a neuron
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
What is the most common form of neuron?
99% of neurons are multipolar neurons
- 3 or more processes sticking out from soma (cellbody)
- 1 axon & bunch of dendrites
Which neurons are rare and can be found in the retina of your eye?
Bipolar Neurons
- have 2 processes, an axon and one single dendrite extending from opposite sides of soma (cell body)
Which neurons are found in sensory receptors?
Unipolar Neurons
- Have just 1 process
What do Sensory Neurons do?
Sensory Neurons (afferent neurons) transmit impulses from sensory receptors towards the CNS. They are found in skin or internal organs and most are unipolar
What do motor neurons do?
Motor Neurons (efferent neurons)
- Impulses move from the CNS to rest of the body (to muscles and glands)
- Mostly Multipolar
What do Interneurons do?
Interneurons (association neurons) live in the CNS
- Transmit impulses between sensory and motor neurons
- most abundant of bodies neurons
- Mostly multipolar
Describe how your neurons tell your body to react to an outside stimuli such as a spider crawling on your knee
- Those 8 tiny legs activate your
- Unipolar sensory neurons in skin on knee
- Impulse travels up an axon wrapped in schwann cells and into your
- 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
- 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
