Bio 30 UNIT A - Chapter 13 - Neurons

neurons

special cells that conduct electrochemical implulses over long distances

glial cells

* glial comes from ‘glue’
* they support neurons
* helps neurons close without letting them touch

where are glial cells important?

they support neurons and help neurons close without letting them touch

examples of glial cells

* astrocytes: clean up brain debris and transports nutrients
* Schawann cell: form the myelin

cell body / soma of a neuron (4)

* contains special cytoplasm called neuroplasm
* shape/location of cell body varies based on type of neuron
* contains nucleus
* widest part of the neuron

dendrites (3)

* short extensions from the cell body which contain receptors for neurotransmitters (no bumps)
* they pick up electrical impulses and direct them down the neuron
* diff patterns based on the location and what they recieve

axon

* extension in neuroplasm from the cell body (long up to 1m in length, and skinny)
* carries impulses picked up in dendrites to another neuron or effector
* axons can branch out and make new connections
* can be covered w/ schwann cells (myelin sheath)

schwann cells

* protects axon
* sends messages fast

axon terminals / synaptic terminals (3)

* bumps at the end of axon
* contain little sacs called synaptic vesicles
* little sacs ^ that look like cookies, they contain neurotranmitter that will activate their neighbouring dendrite

myelin sheath (5)

* increases speed which neural implulse can travel
* made up of schwann cells, a type of glial cell
* contains fatty protiens (looks white)
* wraps around axons like a cinnamon bun and provides axon w/ nutriens and protects it
* outlayer called neurilemma

what are myelin sheath made up of?

schwann cells, a type of glial cell

neurilemma

* outlayer of myelin sheath that contains nucleus
* partially regenerates damaged neurons

what neurons don’t have schwann cells?

* any ‘grey’ matter
* any neurons to do with thinking

node of Ranvier (4)

* space between schwann cells where the axon is unprotected (the gaps)
* impulses jump from one node to another
* the more myelin a neuron has, the faster an impulse can travel
* saltatory conduction (cos sodium is involved)

saltatory conduction (node of ranvier) (2)

* impulse jumps form one node to another
* more myelin a neuron has, the faster an impulse can travel

white matter

nerves throughout the body/brain that DO contain myelin

grey matter

* the part of the brain responsible for mental function
* this part does NOT contain myelin and cannot be fixed when destroyed

motor neurons (5)

* implulse travels from the **c**entral **n**ervous **s**ystem towards the effectors (body)
* cell body is located **opposite** of axon terminatls
* dendrites located @ the bottom of the cell body
* long axon
* covered in myelin cells = white matter

interneurons (6)

* impulses carried in the CNS
* interprets sensory information and sends out motor information
* cell body located at the top of the axon terminals
* dendrites are attached to the CB
* short axon
* no myelin = grey matter

sensory neurons

* impulses travel to the CNS
* relays info from environment to CNS for processing
* cell body is attached on axons
* dendrites in the skin
* dendrites have modified sensory receptors on their ends to receive external stimuli
* long axon
* covered in myelin = white matter

if a substance looks white then: (myelin sheath)

it contains fatty proteins

what can partially regenerate damaged neurons?

neurilemma