Nervous Systems

Nervous Tissue Found in All Animals Allows simple reactions to environment

3 Steps Sensory input Integration Motor output

Example

More realistic example

A Reflex Bypasses the brain Shortest circuit

CNS vs. PNS Brain and spinal cord Interneurons Central Nervous System Peripheral Nervous System Brain and spinal cord Interneurons Interpretation and organization Nerves out to the body Sensory and motor neurons

Sensory Division Way more than 5 senses! E.g. gravity, proprioreceptors, itch, pain, balance, magnetic (weak in humans) etc.

Motor Division Convey signals to muscles or glands

Somatic v. Autonomic Voluntary movement of skeletal muscle Sub-conscious control of smooth muscle and glands

Cephalization – Concentration of neural tissue in the head

Brain About 100 billion interneurons Incredibly, incredibly complex and very poorly understood (rapidly understanding more!) We use all of the brain (10% is a myth) 2% of body weight, uses 20% of oxygen Humans have the largest brains relative to body size and the largest cerebral cortexes

Brain Presentations – For Tomorrow As a group research one of the following brain structures. Create a basic presentation, focusing on: In what organisms is this structure found (when did it evolve)? What are the major functions of this structure? Any major differences in this structure between humans and other animals? Any interesting or surprising facts about this structure

Brain Parts (Cerebrum/ Cerebral Cortex) -Frontal lobe -Occipital lobe -Parietal lobe -Temporal lobe (Limbic System) -Amygdala -Thalamus -Hippocampus -Cerebellum -Brain Stem