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