Nervous System

Chapters 10 and 11

Learning obejectives

• Major divisions• Cell types• Characterize neurons by their action• Resting to Action Potential• Gray v white matter• Parts of the brain and spinal cord• Cranial and spinal nerves

Major divisions of nervous system

• Central Nervous System (CNS)– Brain– Spinal Cord

• Peripheral Nervous System (PNS)– Cranial nerves– Spinal nerves

Functions of the Nervous System

Types of cells found in Nervous System

• Neuron: sends and receives electrical signals

• Neuroglia: provides support, protection, nourishment for the neurons

Parts of the neuron

1.Dendrites2.Cell body

(Soma)3.Axon–Can have myelin

sheath

• Axon terminals–Contains

neurotransmitters

Three main types of neurons

A.Sensory (Afferent) neurons– To CNS

B.Interneurons–Within CNS

C.Motor (Efferent) neurons– From CNS

Three phases of signal transmission

1.Resting Potential

2.Depolarization

3.Repolarization

Resting potential• Neuron at rest• Intracellular charge is

negative• Potassium (K+) is found on the

inside of the cell• Sodium (Na+) is found on the

outside• Maintained by Na+/K+ pump

Depolarization

• Neuron has been stimulated• Sodium (Na+) “rushes” into the neuron• Inside cell goes from negative to

positive• Send signal (electrical)

Repolarization

• Getting neuron “relaxed” – back to normal

• Three steps:1. Stop sodium coming in2. Allow potassium to leak out3. Na+/K+ pump

Neurons communicating

Electrical chemical electrical

Tracking the flow of information

1.Impulse (electrical signal) to axon terminal

2.Neurotransmitter released from terminal

3.Binds to receptors on next neuron

4.Stimulates next neuron to depolarize and send impulse

Synapse terms• Neurotransmitter released

from the presynaptic membrane (axon)

• Neurotransmitter travels across the synaptic cleft

• Neurotransmitter binds to the receptors on the postsynaptic membrane (dendrite)

• THINK: What if the dendrites don’t have receptors for that neurotransmitter?

Any questions?

GROUP ACTIVITY

Main parts of the brain1. Cerebrum2. Diencephalon

a. Thalamusb. Hypothalamus

3. Brain Stema. Midbrainb. Ponsc. Medulla

Oblongata

4. Cerebellum

CerebrumLobes:• Frontal

– “voluntary motor”

• Parietal– “general sense”

• Temporal – “hear, smell”

• Occipital– “vision”

Basal Ganglia• “Regulate body

movement”

Diencephalon

• Thalamus–“Relay station”

• Hypothalamus–“Maintain

homeostasis”

Brain stem

• Midbrain• Pons• Medulla Oblongata–“Vital center”

Cerebellum

• “Little brain”• “Coordination &

prediction”–Notice:• Folia• Arbor vitae

Other special parts of the brain

• Limbic system–“emotion and behavior”

• Reticular formation–“sleep-wake”–“filter the noise”

• Basal ganglia–Parkinson’s disease

Meninges of the cns• Protection!

–3 layers!1. Pia mater2. Arachnoid mater3. Dura mater

–2 important spaces• Epidural space

(outside dura)• Subarachnoid

space–CSF

Spinal cord

• Spinal cavity• Connected to the

brain– Extends from foramen

magnum to L1

• Decussation• 3 Main functions of

spinal cord– Sensory pathway– Motor pathway– Reflexes

Spinal nerves

• Spinal nerves: 31 pairs– 8 cervical– 12 thoracic– 5 lumbar– 5 sacral– 1 coccygeal

• Plexus– Cervical plexus

• Dermatome – Skin

Cranial Nerves• CN I

– Olfactory Smell

• CN II– Optic Vision

• CN V– Trigeminal Sensory face

• CN VII– Facial Motor face

• CN VIII– Vestibulocochlear

Hearing and balance

• CN X– Vagus Major

parasympathetic nerve

Spinal reflexes

Effectors

• What Motor Neurons communicate with

1. Muscles (skeletal, smooth, cardiac)

2. Glands

Group activity