The Nervous System, Part 1: Crash Course Anatomy & Physiology #8

Today Hank kicks off our look around MISSION CONTROL: the nervous system.

Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App!

Chapters:
Introduction: Hank's Morning Routine 00:00
Nervous System Functions: Sensory Input, Integration, and Motor Output 1:17
Organization of Central and Peripheral Nervous Systems 2:16
Neurons & Glial Cells 3:42
Central Nervous System Glial Cells: Astrocytes, Microglial, Ependymal, and Oligodendrocytes 4:17
Peripheral Nervous System Glial Cells: Satellite and Schwann 4:56
Cool Neuron Facts! 5:15
Neuron Structure 6:20
Classifying Neuron Structures: Multipolar, Bipolar, and Unipolar 7:00
Classifying Neuron Functionality: Sensory (Afferent), Motor (Efferent), Interneurons (Association) 7:47
Review 9:42
Credits 10:14

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[mobius]

10% of views: people studying the field
10% of views: curious people
80% of views: students the day before an exam

[davidlah]

Three principle functions:
- SENSORY INPUT (nervous system senses the spider on your leg)
- INTEGRATION (your nervous system processes the input, and decides what should be done about it)
- MOTOR INPUT (your hand shakes off the spider, it's a response that occurs when your nervous system activates certain parts of your body)

NERVOUS SYSTEM DIVISION
--- CENTRAL nervous system - CNS
- brain
- spine cord

--- PERIPHERAL nervous system - PNS
- around your body
- SENSORY DIVISION (afferent) - picks up a sensory stimuli
- MOTOR DIVISION (efferent) - sends directions from your brain to muscles and glands
- SOMATIC nervous system - voluntary (skeletal movement)
- AUTONOMIC nervous system - involuntary (heart, stomach, lungs)
- SYMPATHETIC - sends the body into action
- PARASYMPATHETIC - relaxes the body

- Neurons (small part of your nervous tissue)

- Glial cells (50% of mass of your brain)
- provide support, nutrition, insulation, and help with signal transmission in the nervous system
- GLIAL CELL TYPES
- CNS
- ASTROCYSTES - support, regulate ions, exchange materials between neurons and capillary
- MICROGLIAL CELLS - defense against invading microorganisms
- EPENDYMAL CELLS - create, secrete and circulate cerebrospinal fluid
- OLIGODENDROCYTES - wrap and insulate, form myelin sheath
- PNS
- SATELLITE CELLS - surround neuron cell bodies
- SCHWANN CELLS - insulate, help form myelin sheath

1. Neurons are some of the longest-lived cells in your body.
2. Neurons are irreplaceable. Most are AMITOCIT - when they get assigned a role, they can't divide anymore.
3. Neurons have huge appetites. They need a lot of oxygen and glucose. About 25% of daily calories are consumed by your brain

NEURON STRUCTURE:
- Soma - cell body
- Dendrites- listeners
- Axons- talkers

NEURON TYPES:
MULTIPOLAR neurons
- three or more processes
- one axon, bunch of dendrites
BIPOLAR neurons
- one axon, one dendrite (found in special places - retina of your eye)
UNIPOLAR neurons
- have only one process (found in your sensory receptors)

NEURON FUNCTIONS:
SENSORY neurons - afferent neurons
-> transmit inpulses from sensory receptors toward the CNS
-> mostly unipolar
MOTOR neurons - efferent neurons
-> impulse moves from the CNS to the rest of the body
-> mostly multipolar
INTERNEURONS - association neurons
-> impulse moves between sensory and motor neurons
-> mostly multipolar

[jakub]

Who is system and why is he so nervous?

[ButterflyScarlet]

Hank: Imagine a spider walking on your knee
Me: I would really rather not

[aliyah]

I literally understand more  about this topic in these 10 minutes than I did in my 2 hour lecture

[tarenpineset]

I swear it's like you guys have telepathic powers that awaken whenever a biology student is in distress.

[regarozeve]

my 6 yr old loves u, and says she likes learning from u because "u sound like a funny guy who knows a lot of things" 😂

[brianlu]

You need to sell plushies of the cells

[jireh]

i watched the whole thing then i realized i wasn’t paying attention the whole time 🤦‍♀️
i need to rewatch it

[JD-rqur]

So basically all of the cells in our nervous system are adorable.

[SGFrida]

I'm glad I'm not the only one who draws cells with smiley faces.

I love you Crash Course

[AdamFelibrico]

I recently got a job at a hospital as an intraoperative neurodiagnostic technician and I'm here refreshing my knowledge of Anatomy. I watched this series when I was deployed and finally got the chance to use it in the real world. Thank you, Crash Course.

[danieldavila]

I love his english pronunciation, I'm practiciong english while I develop my english skills.
I'm from Venezuela and I send Greetings for everyone.

[IloveSPIDERZ]

Anybody else watching this the day before getting tested on it? lol

[XyZGamesAgar]

omg those cells are so cute

you need to sell them as plushies

im dying omg

[jenrobinson]

Just to let you know, I'm watching this nervous system series to brush up on my basics as I'm writing a lit review for publication about chemotherapy-induced peripheral neuropathy XD Just wanted to let you know while these videos are awesome for those in AP bio/high school/college, us professionals also very very much appreciate the fun animation and clear-cut explanations as a way to brush up on our basics before having to talk in depth about glial cells and astrocytes and such. Thank you, Hank and team!

[GreenDog]

Why do I go to school for 7 hours a day when I can watch these

[malingkas]

I find more joy and actual learning from this 10 min video, rather than my 2 hour 45 min lecture my prof gives. Thank you Crash Course.

[stacystanton]

Afferent = arriving. Efferent = exiting. You're welcome :-)

[Flush.]

Motor Output: The response that occurs when your Nervous System activates certain parts of your body.
Key:
(MC)”word”: if its behind the word then it means it branches from it
“word”(MC):means is it’s the nervous system or (NS) that it may have branches.

Central Nervous System(CNS):
Brain and spinal cord.
Main control center.
Peripheral Nervous System(PNS):
All the nerves that branch off from the brain and spine that allow your CNS to communicate with the rest of your body.
Works in both directions (PNS)
Sensory Division(SD):
Picks up sensory stimuli.
Motor Division(MD):
Sends directions from your Brain to Muscles and Glands.
(MD)Sematic Nervous System(SNS): voluntary
rules skeletal muscle movement.
(MD)Autonomic Nervous System(ANS): involuntary
keeps your heart beating.
(ANS)Sympathetic Nervous System:
Mobilizes the body into action
(ANS)parasympathetic:
Relaxes the body


Astrocytes (Nervous System):
Exchanges materials between neurons and capillaries.
Microglial Cells(MC):
Immune defense against invading microorganisms.
(MC)Satellite Cells:
Surround and support Neuron cell bodies.
(MC)Schwan Cells:
Produce an insulating barrier called by Myelin Sheath.


Crazy facts about neurons:
1.They are the longest-lived cells in the human body.
2.They are irreplaceable.
3.They have huge appetites


HERE ARE SOME NOTES IF YOU NEED THEM THE KEY MAY HELP YOU