the brain and spinal cord / cns

unit 2 elem physio

central nervous system

brain and spinal cord

peripheral nervous system

afferent and efferent divisions

afferent divisions

carry information into CNS

somatic

carries sensory info from skin and skeletal muscles

viscerla

carries sensory info from smooth muscle, glands, and organs

efferent divisions

carry info out of CNS

somatic nervous system

motor neurons that supply skeletal muscles

autonomic nervous system

motor neurons that innervate smooth muscle, cardiac muscle, glands

• sympathetic and parasympathetic

enteric nervous system

nerve network of digestive tract

neuron classes

afferent, efferent, interneurons

interneurons

responsible for integrating afferent info and formulating efferent response

glial cells

don’t initiate or conduct nerve impulses

• physically, metabolically, and functionally support neurons

astrocytes

1. physically support neurons in proper spatial relationships

2. serve as scaffold during fetal brain development

3. induce formation of blood brain barrier

4. help transfer nutrients to neurons

5. form neural scar tissue

6. take up and degrade released neurotransmitters

7. take up excess K+ to help maintain proper brain ECF ion concentration and normal neural excitability

8. enhance synapse formation and strengthen synaptic transmission via chemical signaling with neurons

9. communicate by chemical means with neurons and among themselves

oligodendrocytes

form myelin sheaths in CNS

microglia

1. play a role in defense of brain as phagocytic scavengers

2. release nerve growth factor

ependymal cells

1. line internal cavities of brain and spinal cord

2. contribute to formation of cerebrospinal fluid

3. serve as natural stem cells with potential to form new neurons and glial cells

dura mater

tough outer coat

arachnoid mater

blood vessels

subarachnoid space

filled with CSFp

pia mater

on brain surface

blood brain barrier

limits access of blood-borne materials into brain tissue

cerebrospinal fluid

cushioning fluid that surrounds CNS