Bio 215 Unit 4 - Neurons, glial cells, and divisions of nervous system

Neurons

cells that send and receive signals

Glial cells

cells that support and protract neurons

Dendrites

receive signals from other neurons

Cell body 

for cell maintenance 

Axon

sends outgoing signals to other neurons

Synaptic knobs

part of cell delivering message (neurotransmitters) to other cells

In peripheral nervous system (PNS) - Schwann cells 

• each cell forms a single myelin sheath which axons in PNS to increase speed of electrical impulses 

In central nervous system (CNS)- Ependymal cells

• line the cavities inside the brain and spinal cord much like an epithelium

• they have cilia which beat back and forth to circulate the cerebrospinal fluid (CSF) within these cavities

In central nervous system (CNS)- Astrocytes

• surround blood vessels of the brain to maintain blood-brain barrier

• Astro- star, cytes- cell = star cell

In central nervous system (CNS)- Oligodendrocytes 

• form multiple myelin sheaths axons in CNS

In central nervous system (CNS)- Microglia

immune cells

Divisions of the nervous system

1. Central nervous system (CNS)

2. Peripheral nervous system (PNS)

Central nervous system (CNS)

• brain and spinal cord

• receives sensory information from Peripheral nervous system (PNS) , analyzes sensory information, sends motor commands to PNS

Peripheral nervous system (PNS)

• nerves going to and from CNS (central nervous system)

Sensory neurons

• bring info to the CNS (central nervous system)

Special sensory

• highly localized senses coming from a single discrete organ (smell, vision, hearing)

General sensory 

all other senses (pain, pressure, touch) from body wall and limbs or internal organs 

Motor neurons

• carry motor commands from central nervous system (CNS) to effector organs

Somatomotor

• control skeletal muscle (body walls and limbs)

Visceromotor (Autonomic nervous system)

• control glands smooth muscle and cardiac muscle 

Sympathetic division

“fight or flight” activities

Parasympathetic division

“rest and digest” activities