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What were the divisions of the nervous system?• Central Nervous System
a. Brain and Spinal Cord
b. Interprets all information from sensory nerves and sends responses to the motor nerves.
• Peripheral Nervous System
a. Sensory nerves – 5 senses, picks up stimuli and sends to CNS.
b. Motor nerves – voluntary or involuntary, carries out response sent by CNS.
The Brain• Consists of mainly interneurons• Five main structures:
1. Cerebrum – largest section, intelligence, learning and judgment. All voluntary activities.
2. Cerebellum – coordination of voluntary movements.
3. Brain Stem – controls vital functions for life
4. Thalamus – Relay station for incoming sensory info.
5. Hypothalamus – Controls hunger, thirst, fatigue, body temperature.
Cerebrum• Two hemispheres
connected by the corpus callosum
• Four Lobes:• Frontal – movement,
problem solving, rational, personality
• Parietal – sensations and perceptions
• Occipital – vision• Temporal – hearing,
language, memory
Brain StemThree sections:1. Midbrain 2. Pons 3. Medulla
Oblongata –regulates heart rate, blood pressure, respiration, coughing, sneezing, vomiting, swallowing
Spinal Cord• Thick rope of interneurons • Main communication line to brain• 31 pairs of spinal nerves• Herniated disc – swelling of
intervertebral discs, pinches spinal nerves
Paralysis is when movement in lost. Depends on where the cord/nerve is injured.
Rapid, automatic responses to specific stimuli.
Their purpose is to preserve homeostasis.
Only a few neurons are needed.
Why do doctor’s test reflexes?
What is the advantage of having reflexes?
Reflexes
The Senses• Part of the PNS – sensory division• Five types of sensory receptors:
1. Pain receptor
2. Thermoreceptor
3. Mechanoreceptor
4. Chemoreceptor
5. Photoreceptor• 5 organs for sensory perceptions
Where in the body are these receptors located and what type of stimulus do they respond to?
The SkinThe Skin1. Touch and
Pressure (mechanoreceptors)
- Light and strong receptors
2. Temperature (thermoreceptors) - Warm and cold free nerve endings
3. Pain Receptors
(nociceptors) - Respond to all types of stimuli
The Eye• Rods and cones are the
photoreceptor cells• Located in the retina • Rods – peripheral and low
light vision• Cones – color vision and
greatest acuity• Optic nerve sends signals
to brain; no photoreceptors
Where are all the parts of the eye? Their functions?
The Ear• Mechanoreceptors are ciliated
cells• Function: hearing and balance• Hearing comes from cochlea
- vibrations in air are conducted to the: tympanum to ossicles to
cochlea to auditory nerve to brain
• Balance come from semi-circular canals
- bending or rotating of head moves fluid in canals
Eustachian tube – equalizes pressure, connects with throat
SmellingSmelling• Chemoreceptors – stimulated by chemicals• Olfactory cells – sensory cells for smell• Low threshold (only a few molecules needed to detect)• Watery mucus lines cells to act as solvent.• Olfactory bulb sends impulses to olfactory cortex region of brain.
• Anosmia – loss of sense of smell• Helps with taste perception.
Taste• Chemoreceptors – picks up chemical
stimuli• Molecules must be dissolved in a solvent
to activate receptors.• Saliva is the solvent! • Taste receptors are called “gustatory
cells”• Gustatory cells found in taste buds all
over tongue/mouth• So, a single taste bud has many gustatory cells.
• 5 main tastes: salty, sweet, sour, bitter, umami