Chapter 29 By: Allan Chong

Central Nervous System(CNS)

Includes the brain and spinal cord evolved from dorsal cord. A dorsal nerve cord is one of the defining features of chordate embryos. Meninges are membranes that enclose the brain and spinal cord. Cerebrospinal fluid surrounds the brain and spinal cord; fills ventricles. Blood brain barrier prevents unwanted substances from entering cerebrospinal fluid

Peripheral Nervous System(PNS)

Nerves that carry signals between the central nervous system and the rest of the body. All nerves outside the brain or spinal cord. Each nerve has outer layer of connective tissue surrounding bundles of axons.

Somatic Nervous System

Controls skeletal muscles; relays sensory signals about movements and external conditions

Autonomic Nervous System

Relays signals to and from internal organs and glands. Parasympathetic neurons: encourage digestion and other “housekeeping” tasks. Sympathetic neurons: activated during stress and danger

Sensory Neurons

Become activated when receptor endings detect a specific stimulus


Both receives signals and sends signals to other neurons

Motor Neuron

Controls muscles or glands

Neuromuscular Junction

Synapse between a neuron and a muscle. Steps include: Action potentials travel along the neuron’s axon to the axon terminals. Then arrival of the action potential at an axon terminal triggers the release of neurotransmitters into the synaptic cleft. Motor neurons release the neurotransmitter acetylcholine (ACh). ACh binds to receptors on skeletal muscles, allowing Na+ to pass into these cells. Subsequent action potentials stimulate muscle contraction


Binds to receptors on skeletal muscles, allowing Na+ to pass into these cells.

Norepinephrine and epinephrine

Stress response or excitement


Region where axon terminals transmit neurotransmitters to another cell. Action potentials cannot pass directly from a neuron to another cell. Signaling molecules (neurotransmitters) relay signals between a neuron and another cell

White and Grey Matter

White matter is myelinated axons. Tracts are bundle of axons in the central nervous system. Gray matter is axon terminals, cell bodies, dendrites, and neuroglial cells

Cerebral Cortx

Cerebral cortex is the outer gray matter layer of the cerebrum. Responsible for most complex behavior. Making reasoned choices, concentrating on tasks, planning for the future, behaving appropriately in social situations are functions of the cortex. Primary motor for cortex is to control voluntary movement

Lobes of the Brain

Limbic System

Limbic system is a group of structures deep in the brain that function in expression of emotion. Hippocampus is the brain region essential to formation of declarative memories

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