Nervous System III
Nervous systems (Fig. 44.1)
- Nerve nets
o No CSN, just reflex arcs
- Nerous systems with ganglia
o Ganglia are collections of neurons, very primive “brain”
- Ours
o Well developed brain to control rest of system
Brains
- Three basic divisions, can see developmentally and anatomically (Fig. 44.2)
o Hindbrain
§ Medulla oblongata, pons, cerebellum
· Basic functions
o Homeostasis and coordination of body movements
o Midbrain
§ Processing sensory info and sending it on to
o Forebrain
§ Higher functions
· Thought
· Planning
· Emotion
§ Cerebrum
· Folded to fit into skull
Nerves
- Collections on axons extending are “nerves”
o Crainial – directly connected to brain
o Spinal – connected to spine
Meninges (Fig. 44.7)
- Layers of epithelium that cover CNS
o Dura mater
o Arachnoid mater
o Pia mater
PNS
- voluntary (somatic nervous system)
o nerves go directly from PNS to spine or brain
- involuntary or( autonomic) (regulates internal things like heartbeat, pupils)
o ganglia between CNS and rest of PNS
o divided into sympathetic and parasympathetic
§ work in opposition to each other
§ sympathetic is “fight or flight”
· 44.8 shows responses
§ parasympathetic has opposite responses