The nervous system Chapters 48 & 49

You must know The anatomy of a neuron The role of active transport in establishing the membrane potential of a neuron How long-distance and short-distance signaling is done in neurons The mechanisms of impulse transmission in a neuron The process that leads to the release of neurotransmitter and what happens in the synapse The brain serves as a master neurological center for processing information and directing responses Different regions of the brain have different functions Structures and associated functions for animal brains are products of evolution and increasing complexity follows evolutionary lines How the vertebrate brain integrates information, which leads to an appropriate response

I. Neuron structure A. Functional unit of the nervous system Draw with them, add Nodes of ranvier

Neuron vocab Sensory receptors – collect information

2. Sensory neurons – carry info from receptors to CNS 3 2. Sensory neurons – carry info from receptors to CNS 3. Interneurons – within CNS, connect sensory neurons to motor neurons 4. Motor neurons – carry info from CNS to effectors (muscles and glands) that respond

Nerve Impulses A. The steps

II. Nerve impulses 1. Resting potential Annotate with them

Depolarization & Action Potential a. Must surpass threshold b. All or none response to stimulus

Repolarization & Hyperpolarization - Refractory period

4. Return to resting potential B. Saltatory conduction – transmission of an impulse through myelination

Communication at the synapse

Neurotransmitters 1. Chemical messengers 2. Can be excitatory (cause depolarization of postsynaptic cell or inhibitory (cause hyperpolarization)

Signal Termination 1. Enzymes break neurotransmitter into pieces, causing it to fall away from the receptor (ex. Acetylcholinesterase for Ach) 2. Pieces are reabsorbed by the presynaptic cell, reassembled, and repackaged in vesicles

Ach and toxins Sarin nerve gas – inhibits acetylcholinesterase Botulism toxin – prevents release of Ach from presynaptic axon

Iv. Nervous system anatomy Central Nervous System (CNS) – brain and spinal cord 1. Cerebrospinal fluid (CSF) – circulates through central canal of spinal cord and ventricles of brain provide nutrients and take away waste and also cushion the brain

2. White and Gray matter a. Gray composed mostly of neuron cell bodies b. White composed mostly of myelinated axons c. Glia cells – support cells

Peripheral Nervous System (PNS) 1. Consists of spinal and cranial nerves 2. Motor/Somatic Nervous System carries signals to skeletal muscles 3. Autonomic Nervous System – carries signals to glands, smooth muscle, and cardiac muscle, further divided into Sympathetic and Parasympathetic divisions

Sympathetic = Snake a. Sympathetic division – “Fight or Flight” Response to unusual circumstances – increases activity “E” division – exercise, excitement, emergency, embarrassment Sympathetic = Snake

Parasympathetic = Panda Parasympathetic division – “Rest and digest” Conserves energy and handles the usual circumstances “D” division – digestion, defecation, diuresis Parasympathetic = Panda

V. The Brain Brainstem – medulla oblongata, pons, and midbrain 1. Controls homeostatic functions like breathing, swallowing, digestion, and connects brain to spinal cord

Cerebellum – coordination and balance,

Thalamus – transmits info to and from proper area of cerebrum Hypothalamus – regulates homeostasis – body temperature, hunger, thirst, circadian rhythms

Cerebrum – divided into two hemispheres, information processing and memory

1. Cerebral cortex – outer layer of cerebrum, controls voluntary movement and cognitive function

2. Corpus callosum – communication between hemispheres