NERVOUS SYSTEM :>

Nervous system is divided into two parts CNS (brain and spinal cord) and PNS (nerve outside the cns) . The peripheral nervous system is further divided in two w/c depends on its function. The Somatic which focuses on skeletal muscle while autonomic in cardiac and smooth muscle and glands. Autonomic nervous system is divided into parasympathetic system which is responsible for nesting and digesting while sympathetic system is responsible for the flight or fight.

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

PNS

• 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

Action potential

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