2Psy Neuro Zelf 1.-3.

Nervous system

=responsible for reception & processing of sensory information

 ->from both external & internal environments

2 major divisions

1) CNS (Central nervous system)
 1. Brain (protected by skull), connected with:
 2. Spinal cord (protected by vertebral column)

 

2) PNS (Peripheral nervous system)

 =nerves/zenuwvezels (liggen buiten ZS)
 ->division CNS & PNS=arbitrary (work together & are connected to each other)
 ->sensoric/motoric

3 specific functions nervous system

1) Receiving sensory input (PNS)

 >sensory receptors in skin & other organs
 ->respond to external/internal stimuli by generating nerve signals (travel via PNS to CNS)

 

2) CNS: information processing & integration

 ~summing up input it receives from all over the body

 ->reviews info, stores it & creates appropriate motor responses
 

3) CNS: generates motor output

 ->nerve signals travel via PNS to muscles, glands, organs…

Sensorische /afferente vezels

1. Somatisch (signalen van huid, spieren, zintuigen)
 2. Visceraal (signalen van inwendige organen)

Motorische

/efferente vezels

1. Somatisch: vrijwillig
  ~signalen naar skeletspieren

 

 2. Autonoom: ongecontroleerd
  ~signalen nr smooth muscle, hartspier, klieren

   ->sympatisch (fight/flight)

   ->parasympatisch (rest/digest)

2 types of cells

1. Neurons

 ~communication within NS via nerve impulses

2. Neuroglia (glial cells)
 ~support & nourish neurons

 ->outnumber neurons by many!

Types of neuroglia

1) Microglia
2) Astrocytes
3) Schwann cells
4) Oligodendrocytes

Microglia

=phagocytic cells: help remove bacteria & debris (fagocyten, verwijderen pathogenen & afval)

Astrocytes

=provide metabolic & structural support directly to neurons

Tightly spiraled neuroglia that form myelin sheaths

1. Schwann cells (in PNS)
  ->gaps between myelin=nodes of Ranvier
  ->1 schwann cell myeliniseert 1 deel van xon

 2. Oligodendrocytes (in CNS)
  ->1 olig. myeliniseert 1 deel v/meerdere axonen

3 types of neurons

~classified according to function

1) Sensory neurons
2) Interneurons

3) Motor neurons

 ->neurons vary in appearance but all have cell body, dendrites & axon

Sensory neurons

~in PNS: takes signals from sensory receptors & transports them to CNS

->sensory receptors =special structures that detect changes in the environment

Interneuron

~in CNS: 1. Receive sensory input from sensory neurons (& other interneurons)

2. Sum up all information received
3. Communicate with motor neurons

Motor neurons

~take nerve impulses away from CNS to an effector

 ->effectors carry out responses to environmental changes (both external & internal)

Dendrites

=short extensions: receive signals from sensory receptors or other neurons

 ->incoming signals from dendrites can result in nerve signals (which are then conducted by an axon)

Axon

=part of neuron that conducts nerve impulses

 ->can be very long

 ->individual axons=nerve fibers (collectively they form a nerve)
 ->many axons are surrounded by myelin sheath

Carrying nerve signals

Sensory neurons

 ->very long axon carries nerve signals from dendrites (associated with a sensory receptor) to CNS
 ->this axon is interrupted by cell body

 

Inter- & motor neurons

 ->multiple dendrites take signals to cell body

 ->then axon conducts nerve signals away from soma

Myelin sheath

=membranes of schwann cells (PNS) or oligodendrocytes (CNS) that are wrapped around an axon many times
 ->long axons usually have myelin sheath (short axons don’t)

Functions of myelin sheaths

1. Nodes of Ranvier =gasps with no myelin sheath

2. Important role in speed of transmission (rate at which signals move through neuron)

3. Important role in nerve generation in PNS (zenuwen herstellen)
 ->if axon is severed: myelin sheath remains & serves as a passageway for new fiber growth (nieuwe vezels)

4. Aandoening multiple sclerose: afbraak myeline (te veel)

Colours of matter

Gray matter in CNS: gray because contains no myelinated axons
<->white matter (does have)

 

<->PNS: myelin gives nerve fibers white appearance + serves as excellent insulator