Nervous System

Squid vs. Human

Nervous System of a Squid The squid has the most complicated brain of all the invertebrates. Has 300,000,000 neurons. Squid and Octopi have "good" memories and can also learn. The eyes are similar to mammals They have a cornea, lens, iris and retina. It can also focus and form images. It is different because instead of changing the shape of the lens it actually moves the lens closer and further away from the retina. The squid has NO blind spot because the optic nerve leaves from the outside of the eyeball.

Anatomy of a squid

Neurons Nerve cells Made up of a cell body and branches Axon – carries messages away from the cell body Dendrites - receive messages

Types of neurons Sensory neuron - receive information and send impulses to the spinal cord and brain Interneuron – go between sensory and motor neurons Motor neurons – go from the brain and spinal cord to the muscles

How do impulses move Synapse –a small space that impulses jump across. Neurotransmitters – chemicals released by the ends of the axons

Central Nervous System Brain and Spinal Cord (CNS) Brain is broken up into sections Cerebrum – senses, memory, voluntary muscle control Cerebellum – coordination, balance and muscle tone Brainstem – involuntary muscle movement, heartbeat, breathing, etc.

Corpus Callosum connects right to left sides of the brain Cerebrum Cerebellum Are you left brained or right brained?

Peripheral Nervous System Nerves that extend from the spinal cord Somatic – controls your muscles Autonomic – controls heart beat, digestion and gland functions

Reflexes Involuntary and automatic response to stimuli Reflex Arc – messages are sent from sensory neurons to spinal cord back to motor neurons Brain movie

Senses Light – receptors are eyes Taste – receptors are taste bud on tongue Pressure – receptors are in the skin Temperature – receptors are in the skin Pain – receptors are in the skin Vibrations – receptors are ears Scent – receptors are olfactory cells in the nose

Eyes

Ear

Taste buds