Nervous system is also build by tissues, nervous tissue differs in other tissue for it has no epithelium, connective tissue and muscle tissue. Nervous system has two types:
1. Neuroglia- specialized cells allowing nervous tissue o perform its function
CNS
- astrocytes- metabolic and support
- microglia- remove debris
- ependymal- covering and lining cavities
- oligodendrocytes- lipid insulation, production of myelin
- Schwann cells- produce myelin
- Satellite cells- support
2.Neurons-excitable cells that carries electrical charges
- control functions
- dendrites- receive information from the environment
- axon- generates and send information into other cells
polarized cells- resting cells ( more negative inside the cell)
depolarized cells-more positive than resting
hyperpolarized-more negative than when its at rest
refractory period-time when cells can't accept stimulus
Impulse Conduction
~the speed is defined by the presence of myelin sheath and diameter of the axon.
Chemical Synapse
~nerve impulse imformation flow using nuerotransmitters.
spinal cord- is located in the hollow tube running inside the vertebral column from the foramen magnun to the 2nd lumbar.
meninges- protective membranes that surround the brain and spinal cord
- cover the sensitive structure of the brain and spinal cord.
Divided into 3 layers:
1. dura mater: outermost layer of thick fibrous tissue
2.arachnoid mater- contains CSF, middle layer, composed of collagen and elastic fiber
3.pia mater: innermost layer, contains vessel
spaces between the layer of meninges:
1.epidural space-space between dura and vertebral, filled with fat and blood vessel
2.subdural space-between dura and arachnoid mater, filled with tiny bit of fluid
3.subarachnoid space-between arachnoid mater and pia mater, filled witg CSF
reflexes- simplest form of motor output
3 types:
1.withdrawal
2.vestibular
3.startle
