Nervous System

Functions of the nervous system

Receives, processes and responds to sensory input

Structure of a neuron

Has branched dendrites to receive signals and axon terminals that send signals

Neuroglial cells: CNS

1. Astrocytes: anchors neurons to capillaries, controls brains chemical environment

2. Microglia: monitors neuron health, disposes of debris

3. Ependymal cells: circulates CSF

4. Oligodendrocytes: makes myelin sheath

Neuroglial Cells: PNS

1. Schwann cells: forms myelin sheath

2. Satellite cells: protects and cushions

Nodes of Ranvier

Gaps in myelin sheath that carry info in and out of the CNS

Neurotransmitter

Released into the synaptic cleft and binds to neurons to transmit signals

Motor neurons

Carries impulses out of the CNS to glands or muscles

Sensory neurons

Carried impulses from extremities to brain and spinal cord

Interneuorns

Transmits impulses from one part of the brain or spinal cord to another

Reflex arc

1. Sensory receptor: reacts to stimuli

2. Sensory neuron: Carrie message to integration center

3. Integration center processes and directs motor output

4. Motor neuron carries message to effector

5. Effector organ: the muscle or gland carrying out the reaction

4 main parts of the brain

1. cerebral hemispheres: cortex: interprets sensory input controls muscles, emotions Basal nuclei: muscles

2. Diencephalon: thalamus: cerebral cortex relays impulses hypothalamus: temperature, thirst, limbic system: memory

3. Brain stem: midbrain: visual and auditory, medulla oblongata: merges into spinal cord, pons: breath

4. Cerebellum: sight and movement

Gray matter

Mostly cell bodies,

White matter

Transmits signals between brain regions and parts of the body, myelinated fiber tracts

Meninges

Dura matter, folds inward , outermost layer of protection to nervous system

CSF

Formed by choroid plexus protects the pain and spinal cord

CSF circulation

1. Through ventricles

2. Into subarachnoid space

3. Through central canal of the spinal cord

Sympathetic nervous system

Prepares bodily response during threatening situations “fight or flight”

Parasympathetic nervous system

Division of autonomic nervous system “ rest and digest” homeostasis

1. Olfactory

Sensory, smell

2.Optic

Sensory, sight

3.Oculomotor

Motor, movement of eye

4.Trochlear

Motor, movement of eye

5.Trigeminal

Mixed, mouth movement

6.Anducens

Motor, movement of eye

7.Facial

Mixed, movement of face

8.Vestibulochlear

Sensory, hearing

9.Glossopharyngeal

Mixed, taste, swallowing

10.Vagus

Mixed, speaking

11.Accessory

Mixed, speech, swallowing

12.Hypoglossal

Motor, movement of head and shoulders