Human Nervous System

Nervous System


3 Main Parts of the Nervous System

  1. Brain
  2. Spinal Cord
  3. Nerves - Sensory and Motor Nerves

The Neurone

Neuronal Function


The Central Nervous System


The Hypothalamus


The Peripheral Nervous System


The Autonomic Nervous System

ORGAN ACTION OF SYMPATHETIC NERVES ACTION OF PARASYMPATHETIC NERVES
Heart Strengthens and speeds up heartbeat Weakens and slows heartbeat
Arteries Constricts arteries and raises blood pressure Dilates arteries and lowers blood pressure
Digestive Tract Slows peristalsis and decreases activity Speeds up peristalsis and increase activity
Urinary Bladder Relaxes bladder Constricts bladder
Bronchi Muscles Dilates passages, makes for easier breathing Constricts passages
Iris Muscles Dilates pupil Constricts pupil
Hair Muscles Causes erection of hair Causes hair to lie flat
Sweat Glands Increases secretion Decreases secretion

A Reflex Arc

Nervous System Example



Senses

SENSE SENSE ORGANS STIMULUS
Touch, pressure, heat, cold, pain Skin, joints, internal organs Internal or external force or temperature
Smell Nose Airborne chemicals
Taste Taste buds on tongue Ingested chemicals
Sight Eyes Light
Hearing Ears Sound


The Eye

The Path of Light through the Eye

Cornea
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Aqueous Humour
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Pupil
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Lens
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Vitreous Humour
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Retina


Functions of the Parts of the Eye


Light-Sensitive Sense Receptors - Rods and Cones


Vision

Did You Know That...?

The Ear

Path of Sound through the Ear

Pinna (OUTER EAR)
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Auditory Canal (OUTER EAR)
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Eardrum (OUTER EAR)
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3 Earbones or Ossicles (MIDDLE EAR)
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Oval Window (MIDDLE EAR)
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Cochlea (INNER EAR)

Functions of the Parts of the Ear

OUTER EAR

MIDDLE EAR

INNER EAR


Pitch and Amplitude of Sound


Other Features of the Ear