L10 - Organisation of Nervous System Flashcards
General organisation of NS:
NS is split to CNS and PNS.
CNS is brain and spinal cord where brain can have parasympathetic and sympathetic neurons.
PNS is split to autonomic and somatic. Autonomic is involuntary actions and somatic is voluntary actions. Somatic is split into motor and sensory.
Autonomic is split into parasympathetic and sympathetic. Both work against each other. Sympathetic increase heart rate using adrenaline. Dilate muscles in eye.
Parasympathetic decrease heart rate and constrict muscles in eye when bright light.
CNS and PNS neurons:
If neuron entirely in brain and/or spinal cord then CNS neuron.
If neuron has any part outside brain and SC then PNS neuron.
Grey and White matter:
In brain:
In spinal cord:
In brain: Grey matter (cell bodies) on outside and white matter (axon tracts-lipid of myelin) on inside.
In spine:
Grey matter on inside and white matter on outside.
Anatomical compartments of brain:
Forebrain:
Has cerebrum which has lots of cell body. Includes cortex.
Midbrain:
Reflexes in eye which can see movement.
Hindbrain:
- Pons (bridge for brain and SC)
- Cerebellum (motor control and movement, has many neurons, small part of brain)
- Medulla (cardiovascular and respiratory centre)
Planes:
Coronal
Sagittal (parasagittal)
Horizontal
Dorsal up ventral down usually. Anterior right and Posterior left.
Spinal Cord:
31 nerves: 8 cervical 12 thoraic 5 lumbar 5 sacral 1 coccygeal
Each neuron leaves through corresponding intervertebral foramen.
Spinal cord not as long and ends at vertebral level but vertebral column bigger so nerves travel down forming cauda equina.
Neurons in spinal cord:
Dorsal spinal cord: Sensory neurons found there.
Ventral spinal cord: Motor neurons found there.
Spinal cord is segmented and nerves leave as rootlets.
Towards top of SC, nerves are more spread out as they leave through intervertebral foramen. Towards cauda equina, nerves are closer together.
Sulci, Gyri and Fissures:
Brain has cerebrum and outer layer is cerebral cortex. This has ridges (gyri) and grooves (sulci) which are deeper than ridges. Deeper grooves are fissures. Increases SA for more neural info stored.
Functions of lobes:
A certain function can be more associated to one lobe but no function is only for one lobe. 4 different lobes can carry out same function.
Lobes: Frontal lobe Parietal lobe Occipital lobe Temporal lobe
Spinal cord and Brain:
They are hollow as filled with CSF.
Ventricular system:
Lateral ventricle where CSF made. 3rd Ventricle connected to lateral ventricle. 4th ventricle is connected to central canal. This ventricle has holes allowing CSF to pass into arachnoid space.
Lateral ventricle provides CSF to large parts of brain and this is found in subarachnoid space.
CSF made and function:
Hydrocephalus:
Made:
Vertricles contain CSF and is made by choroid plexus (specialised ependymal cells).
Function:
Buoyancy
Protection
Remove waste products.
Hydrocephalus:
CSF is usually reabsorbed back into venous bloodstream. If not, the ventricles expand. Cortex expand. Skull plates move apart and head grows.
Meningeal layers of CNS:
- pia mater (innermost layer) - fine, delicate
- arachnoid mater (middle layer) - web-like, silky
- dura mater (outer layer) - tough, handy
CSF is found between 1. and 2. which is known as subarachnoid space.
Pia Mater:
Protects CNS
Allows entry of blood vessels in CNS.
Impermeable layer to CSF.
Outer layer of brain and spinal cord are lined with astrocytes which is above pia mater (flat layer of cells).
Arachnoid Mater:
Protects CNS
Web-like/silky
Upper limit of subarachnoid space.
Closely associated with dura mater.
