What does a Nervous System do for you?•Detect (sense) changes in the environment (light, sound, smell, taste, touch, heat)

•Detect (sense) changes in the internal environment (blood pressure, blood chemistry, temperature, etc.)

•Integrate and evaluate sensory information

•Plan, problem-solve, predict

•Store and retrieve information (memory)

•Control contractions of skeletal muscles (movements / behavior)

•Control internal glands, muscles (heart rate, hormone secretions, metabolism)

The Nervous System OrganizationCentral Nervous System

- completely surrounded by bone

- suspended in cerebrospinal fluid

- covered by meninges

- protected by “blood-brain barrier”

Peripheral Nervous System

- nerves leaving and entering the CNS

- motor nerves = control muscles and glands

- sensory nerves = transmit information to the CNS from sensory receptors.

- emerge from cranial and spinal nerves

How the Peripheral and Central Nervous Systems Interact

Cells of The Nervous System

Neurons- Detect physical and chemical changes in their environment

-Transmit electric impulses (action potentials) from one end to the other (one cell may be more than 3 feet long)

- Communicates with other neurons, muscles and glands using chemicals called neurotransmitters.

Neuroglia (supporting cells)- Provide physical support to neurons

- Provide electrical insulation to neurons

- May be involved in processes such as memory.

Two neurons releasing neurotransmitters that act on a third neuron. The first two neurons could be in the Central Nervous System, and the third might be a motor neuron leading out to a muscle or gland.

Motor neurons have their cell bodies in the spinal cord, but their axons extend outward into the body to stimulate muscles or glands.

Spinal cord smear

Dendrites

Microglia

Terminal of a motor neuron axon - where the neuron stimulatesthe muscle cell to contract.

Musclecell

Axonterminus

Axon

Neuromuscular junction(motor end plate)

Pyramidal cells (neurons) of the cerebral cortex

Action potentials are tiny electric impulses produced by neurons.They are used for transmitting information away from the cell body and toward the axon terminals. When they reach the axon terminals, the action potentials cause the release of neurotransmitter from the terminals.

When a neuron is stimulated, not every stimulus will cause an action potential. The stimulus must be sufficient to cause the neuronto reach threshold. Only then will an action potential be produced.

Cells of the

Central Nervous

System

Microglia - immune-like cells

Oligodendrocyteproduce myelin sheath

Astrocyte - blood brain barrier

Ependymal cells - line ventricles and help produce cerebrospinal fluid

A Single Action Potential

ATP PADP

P

The Na/K ATPase pumps set up the necessary conditions across the membrane of a neuron so that the neuron will be capable of producing an action potential.

A. High Na outside (3 ions pumped out)

B. High K inside (2 ions pumped in)

C. Produces a transmembrane potential (-70 mV)

The Ventricles of the Brain Are Shown in Dark Blue

LateralVentricle

FourthVentricle

ThirdVentricle

Transverse Section Showing Lateral Ventricles

Gyrus (ridge)

Sulcus (groove)

Central Sulcus

FrontallobeLateral sulcus

Temporallobe

Parietallobe

Occipitallobe

cerebellum

cerebrum

cerebellumPons

Medulla oblongata

Central Sulcus

Lateral FissureTransverseFissure

Gyrus(ridge)

Sulcus(groove)

Temporal Lobe

Frontal LobeParietal Lobe

Occipital Lobe

Pre-Central GyrusPost-Central Gyrus

Basal Nuclei are Found Deep Below the Cerebrum

Limbic System - amygdala - hippocampus - cingulate gyrus - hypothalamus

Corpus CallosumThalamus

Hypothalamus

Midbrain

Pituitary

Pons

Medulla oblongata

Olfactorybulb

Opticnerve

pons

cerebellum Medullaoblongata

Inferior View of Brain and Cranial Nerves

Nervous System showing spinal nerves emerging from the spinal cord

Small segment of spinal cordShowing two pair of spinal nerves

Location of spinal cord inside canal of vertebra

Gray matter

White matter

Dorsal root

Dorsal root ganglionVentral root

Spinal nerve

dorsal root

Dorsal root ganglion

sensory

motor

Sensory neuroncell body

Motor neuroncell body

Organization of the Spinal Cord

Ventralroot

Simple Knee Jerk Reflex Coordinated by the Spinal Cord

Sensory neuron

Quadriceps muscleMotor neuron

Dorsal root ganglionDorsal root

Ventral root

Withdrawal Reflex

interneuron